[Extracted from the American Journal of tlie Medical Sciences for July, 1870.] 
ON THE 
INFLUENCE OF SECTION 
OF THE 
CERVICAL PNEUMOGASTRICS 
UPON THE 
ACTION OF EMETICS AND CATHARTICS. 
By HOBATIO Q, WOOD, M.D., Jr., 
PROFESSOR OP UNIVERSITY OP PENNSYLVANIA. 
Last summer, whilst making-thi? myeetigations upon theveratrum alka- 
loids, which were reported in the January number of this Journal, I had 
occasion to kill animals with veratria, after division of the pneumogastrics 
in the neck, and was surprised to find that neither vomiting nor purging 
were induced. At first the simple explanation of idiosyncrasies suggested 
itself, but when several experiments coincided, it was obvious that indivi- 
dual peculiarities could not account for habitual results—that there must be 
some connection between the pneumogastric nerves and gastro-intestinal 
secretion; especially was this the case when the use of veratroidia was fol- 
lowed by similar absence of symptoms. 
The experiments performed last summer were too few in number to lead 
to any conclusion whatever, but acted simply as an incentive to the present 
research, which was undertaken the more freely as tending to throw light 
upon the causes which, in various diseases, prevent purgatives from acting 
except in an increased dose. 
The first question that arose in my mind in entering upon this investi- 
gation was as to the anatomical relations of the pneumogastrics and the 
intestines. 
A prolonged search through English and French anatomical works re- 
sulted only in the confirmation of my previous idea, that the pneumogas- 
tric nerves do not descend in the abdomen below the upper end of the duo- 
denum. 
Finally, however, my attention was directed to a beautifully illustrated 
prize essay published in the Zeitschrift fur Wissenschaftliche Zoologie, Band X., by Dr. J. Rollnaan. In this the author claims to have demon- 
strated that, whilst the anterior or left pneuraogastric is distributed in the 
abdomen to the stomach and liver only, the posterior or right nerve, giv- 
ing off but few filaments to the former viscus, passes to the liver, the 
spleen, the kidneys, supra-renal capsules, and the whole of the small intes- 
tines. 
There consequently seemed ground for believing that such anatomical 
relation exists between the par vagura and the intestinal canal as might 
account for a connection of function between them. In order to dis- 
cover the opinions of other observers as to the effect of section of the pneu- 
raogastrics upon secretion in the stomach and bowels, a search through 
all accessible French, English, and German authorities was instituted. 
I believe it is now generally admitted that division of these nerves in the 
neck arrests secretion in the stomach, but I have not found more than two 
allusions to a similar influence upon intestinal secretion, one in a paper 
by Sir Benjamin Brodie, and the other in Dr. Reid’s essays. These will 
be considered hereafter. As to the immediate cause of arrest of secretion 
in the stomach, there appears to be great diversity of opinion. This will 
also be commented on subsequently. 
The series of experiments which will be first detailed was instituted to 
determine how far section of the par vagura interferes with vomiting. The 
latest published experiments bearing upon this point, as well as the fullest 
that I have met with, are those contained in the elaborate work of M. 
Schiflf on digestion. 
One set of his experiments would seem to prove that under certain cir- 
cumstances vomiting can occur after the pneumogastrics have been cut in 
the neck. In these experiments, after such division of the nerves, M. 
Schiff introduced a stomach tube through an artificial opening into the 
cervical oesophagus, and passed it into the stomach. He then pushed 
through this tube, by means of a flexible piston, semi-solid food, of such a 
character as to be easily recognized. Out of 12 dogs subjected to this 
procedure, I, after prolonged efforts, threw up a portion of the matters 
injected into the stomach. 
M. Schiff does not appear to have tried whether, after section of the 
cervical pneumogastrics, it were possible to produce emesis by the action 
of ordinary emetics. He states, however, that when the nerves are cut 
below the diaphragm, tartar emetic causes efforts at vomiting as quickly as 
in healthy dogs, but that these efforts are rarely successful, or, if they be 
so, it is only after they have been very frequently repeated and long con- 
tinued. His explanation of this is, that the division of the nerves prevents 
the co-ordination of the dilating fibres of the cardia and the associated 
actions of vomiting. The cardiac sphincter occasionally relaxes, but it does 
so, apparently, spontaneously, and without relation to the contractions of 
the stomach. So that if the opening of the cardiac orifice occurs at the 
same time as the expulsive efforts it is simply by chance. Successful 
vomiting is, therefore, dependent upon the fortuitous consentaneousness 
of complicated acts—which can happen but rarely. The function of the 3 
par vagum in this regard, then, according to this authority, is simply to 
harmonize the numerous acts necessary to successful vomiting. 
Expt. I.—Youngish mongrel hound. One hour after section of the pneu- 
mogastrics in the neck, the dog being strongly under the influence of sulphate 
of viridia, gr. of the sulphate of veratria was given internally. Dog died in 
30 minutes without vomiting or purging. 
First Series of Experiments. 
Expt. 2. A good-sized Scotch terrier. One hour after section of the 
pneumogastrics in the neck, I gave hypodermically about jth grain of sulphate 
of veratria. Thirty minutes afterwards I administered | grain in similar man- 
ner. The animal died one hour and twenty-five minutes afterwards without 
being purged or having made any efforts at vomiting. 
Expt. 3.—1 cut the pneumogastrics in the neck of a stout poodle dog. and 
some time after administered hypodermically one half of a grain of sulphate of 
veratria. Animal died in fifteen minutes without any vomiting or purging. 
Expt. 4.—1 cut the pneumogastrics in the neck of a small Scotch terrier, and 
a few minutes afterwards gave hypodermically one-half of a grain of sulphate 
of veratroidia. Thirty minutes after this there had been no vomiting or purg- 
ing. I gave 5 grain additional after twenty minutes. No efforts at vomiting; 
no purging. Injected another quarter of a grain. Dog died about two hours 
after this without having purged or made any elfort at vomiting. 
I have used tartar emetic once, after section of the cervical pneumogas- 
trics, without causing vomiting, but I do not attach any value to this ex- 
periment,1 as I have failed to cause vomiting in the only two animals with 
uninjured nerves to which I have given it. The experiments differ some- 
what in their results from what is generally stated as to the action of anti- 
monials, and I therefore insert them. They are, of course, too few to lead 
to any positive conclusion. 
Expt. s.—Full-grown English rabbit. Cut pneumogastrics 12.40 P.M. Gave 
lg grain tartar emetic in solution in both thighs—grains in all. 5.30 P. M. 
No vomiting or purging; no other symptoms except those of general prostra- 
tion. Gave gr. ij elaterium in alcohol hypodermically. 6. P. M, Rabbit dying 
in a convulsion ; for five minutes previously has had convulsive movements. In 
five minutes afterwards the animal was dead. No vomiting or purging. 
Expt. 6.-—Full-grown English rabbit suffering from injury to throat; has not 
eaten anything for two days, but running about pretty lively. Gave gr. ijss of 
tartar emetic at 4P. M. hypodermically. 6 P.M. No vomiting or purging; 
rabbit weak. Gave gr. jss additional. Animal died between this and half past 
seven without vomiting or purging. 
Expt. 7.—Nov. 9. Large female cat. 10 A. M. Injected into cellular tissue 
of thigh gr. j antiraonii et potassae tartras, dissolved in fgj of water. No ap- 
parent symptoms were induced up to 5 P.M., except unusual quietness. Cat 
not under observation after 5, until 9 o’clock, when she was found in the agonies 
of death. There had been apparently some slight purging, but no signs of 
vomiting could be discovered. 
Besides the already detailed experiments, ten others will be subsequently 
related, having a direct bearing upon this point. In eight of these, lethal 
doses of veratria failed to provoke vomiting after section of the nerves ; in 
the other two, arsenic wras used with similar results. These experiments, 
1 This experiment is further vitiated by having been made with a rabbit, which 
vomits with great difficulty, if at ail. M. Bernard says, I believe, not at all. 4 
therefore, in every way confirm those of the first series. With the latter 
they are to my mind sufficient to prove that emetics will not act after 
division of the cervical pneumogastrics. In my experience arsenic has 
never failed to cause violent emesis when introduced into the circulation 
of an uninjured animal, and all authorities agree as to the constancy of its 
purging and vomiting, without regard to the method of its administration. 
As to veratria, it also always, in uninjured animals, produces violent, dis- 
tressing, repeated vomiting; doing so in small doses even with more cer- 
tainty, if possible, than arsenic. 
That the non-occurrence of emesis is caused by the arrest of gastric secre- 
tion is, I think, demonstrated by the absence of watery fluid in the stomach 
on post-mortem examination, and by the absence during life of any attempts 
at vomiting, such as Prof. Schiff has shown to occur in animals with similar 
lesions, when food is injected in some quantity into the stomach. 
It will be observed that nearly all the experiments which have been de- 
tailed to demonstrate the failure of emetics to act after section of the cer- 
vical par vagum, have direct bearing upon the question of the action of 
purgatives, since the most powerful emetics are at the same time purga- 
tive. In order to determine positively the relation between the nerves and 
purgation, the following experiments were instituted : 
Second Series of Experiments. 
Expt. B.—l cut the pneumogastrics of a large sized English rabbit at 4.30. 
Gave gtt. jof croton oil in emulsion in thigh. 4.45. Eabbit lively. 5.30. Rab- 
bit quiet; moaning in breathing; no purging ; passed some dry feces. Gave 
gr. ijss of gamboge dissolved in alcohol, injected in four or five different places 
in cellular tissue. 6.20 P. M. No purging or vomiting. Injected gr. ij resinse 
podophylli dissolved in fgss alcohol into peritoneal cavity. 7 P. M. Yery weak, 
breathing quietly, not moving at all when touched. 7.30. Lying on side; 
breathing quietly, seemingly more conscious than at 7 o’clock; no purging; 
passed urine. 8. Tries occasionally to get on side but cannot. 9. Rabbit 
seems a little livelier. 10.45 P. M. Dying; only breathing three or four times a 
minute. Neither purging nor vomiting has occurred. 
Remarks.—Not much importance can be attached to this experiment, 
as it is uncertain whether the same drugs would have purged the animal 
had the nerves been entire. 
Expt. 9.—12.45. I cut pneumogastrics of a full-grown cat. Injected into 
peritoneal cavity gr. ijss podophyllin in alcoholic solution ; into cellular tissue 
gr. j gamboge. 2.40 P. M. No purging. Injected into peritoneal cavity fgij 
extr. sennte fluid. 4 P.M. No purging. 6.10. Cat still alive, able to mew 
faintly; no purging or vomiting. 9P. M. Still alive ; no purging. Died during 
night without purging. 
Remarks.—This experiment is open to the same objections as the pre- 
ceding. I find podophyllin a somewhat uncertain purgative in cats. 
Expt. 10.—3 P.M. Out pneumogastrics of a dog and injected gr. iij podophyllin 
in fgflss alcohol into peritoneal cavity; also gr. j gamboge dissolved in alcohol. 
4 P.M. No purging, dog quiet. 6.10. Alive, heart acting pretty regularly 
though feebly; no purging or vomiting. BP. M. Dog just dead. No purging 
or vomiting. 5 
Remarks.—lt may be very well objected to this experiment that the 
dog did not live long enough for the medicine to act. I thought, how- 
ever, on the whole, best tb detail it. It certainly does not weaken the proof. 
Expt. 11.—Nov. 14. Gave gtt. ij 01. tiglii to a moderate sized cat at 2 P.M. 
by mouth. 4 P.M. Cat has been vomiting pretty freely. 6 P.M. No purg- 
ing. Nov. 15. Has been some purging during night, apparently two passages, 
one partially formed, and one not so—perhaps all one passage. Cat seems all 
right. 
Expt. 12.—Nov. 10, 10J A. M. I gave to a large female cat gtt. ij of 01. 
tiglii by the mouth. 12 noon. No effect yet visible. 1.30 P.M; Oat has been 
purging several times; very weak; trembling all over and perfectly quiet in 
corner; apparently suffering. 2.30. No purging since. 4 P.M. Has been free 
from purgation since; cat mews livelier. Nov. 11. There has been more purg- 
ing in the night, but cat seems quite lively. Nov. 12, A. M. Gave cat 
gtt. ij 01. tiglii by the mouth. 12 noon. No vomiting. Cut pneumogastrics. 
1.30. No purging; cat seems strong, but quiet. Nov. 13. Has been no purg- 
ing. 12 A. M. Gave hypodermically gr. ss of veratrice sulph.; cat previously 
was weak but pretty lively. IA. M. Cat dead; do not know exactly how long 
after injection ; had urinated freely; no purging. 
Expt. 13.—Nov. 14. Gave between gtt. vi and x 01. tiglii by the mouth to a 
large cat at 101 A. M. 12 noon. Has been profuse vomiting but no purging. 
2j P.M. Has been more vomiting, but no purging. 6 P.M. No purging, but 
very profuse vomiting. Nov. 15. Cat seems recovered. Gave 10£ A. M. 
castor oil, of which she probably got about half. Cat vomited directly ; no 
effect on bowel. Nov. 16, 10 A. M. Gave same cat a bolus containing gr. x 
extr. jalapse. IP.M. No vomiting or purging. 4£ P. M. No purging. No 
purging during night. 
Remarks.—l think the excessive vomiting will account for the croton 
oil not purging in this case. It was constant, immediate, very much more 
prolonged—more violent, with more effusion of liquid than in either of the 
other instances. It was probably dependent upon the very large dose. 
Expt. 14.—Nov. 13. Gave to a male and female cat each five drops of 01. 
tiglii by mouth, at 9.30 A. M. 11.30. Both cats have vomited freely; tom cat 
purged once. Attempting to cut pneumogastrics on latter, he died from effects 
of ether. 12 A.M. Cut the pneumogastrics of female cat successfully. 1.30 
P.M. No purging. 4 P.M. No purging; cat seems very weak. 9 P.M. Cat 
still alive; no purging. Nov. 14. Cat died some time during night without 
purging. There had been urination. 
Expt. 15.—Nov. 19. Kitten apparently about three months old, gave, 10.30 
A. M., fgss liq. potassce arsenitis, hypodermically. 2 P. M. Has been freely purg- 
ing and vomiting. 2.45 P. M. Cut the pneumogastrics, and injected into cellular 
tissue liq. potass, arsenitis. 3P. M. Kitten seems suffering a good deal; 
very uneasy and restless. 3.10. Kitten very weak. 3.15 P.M. Kitten dead, 
without vomiting or purging. 
Expt. 16.—Nov. 19, 3.5. Cut pneuraogastrics of a large cat, and injected 
into cellular tissue liq. potassce arsenitis. 3.15. No symptoms. Injected 
additional into abdominal cavity. 3.30. No especial symptoms; cat quite 
lively ;no vomiting or purging. 4P. M. Injected gr. j acid, arsenics, in water 
into peritoneal cavity. SP. M. Cat dead. No purging or vomiting. 
Expt. 17.—Nov. 16. Gave a small spaniel by the mouth a bolus containing 
extr. jalapce gr. x, 01. tiglii gtt. jat 2 F. M. Fog vomited the bolus twice in 
twenty minutes; each time it was given to him again; in about ten minutes 
more he vomited again, but this time no bolus could be found in the matters 
rejected. Nov. 17. Has been pretty freely purged during the night. 6 
Expt. 18.—Nov. 17. Gave a moderate size cur a bolus containing extr. 
jalap, gr. x, 01. tiglii gtt. iss at 10 A. M. 11. No effects manifested. 12 noon. 
Has been free purgation'; dog vomited directly after exhibition of dose, but did 
not throw up bolus. At 3.30 gave same dog another similar bolus. 4P. M. 
Dog has not vomited since last dose. 4.30 P.M. Have just cut the pneumo- 
gastrics ; dog came up from ether with great difficulty, but at 5 was able to 
walk. Nov. 18. Dog had no passage since operation. Nov. 19, 2.30 P. M. 
Injected by means of hypodermic syringe If fluidrachms of liq. pofassss arsenitis 
into cellular tissue. 3.10. The doghashad a firm passage since 10 o’clock; it possi- 
bly had been in the rectum ever since the nerves were cut; possibly was the re- 
sult of secretion in the large intestines ; no symptoms save general uneasiness. 
Gave in similar manner fgijss additional. 4.15. No marked change in symp- 
toms. 4.30. Gave gr. iss acid, arsenics., injected into cellular tissue dissolved 
in water. 5 P. M. Dog still alive; no purging or vomiting. 9 P.M. Dog 
still alive ; no purging. Nov. 18. Dog died during night without purging or 
vomiting. 
Expt. 19.—Nov. 21. I gave by mouth to a large female cat a bolus contain- 
ing 15 grains of calomel, at 4 P. M. Nov. 24. Cat has been purged, and 
vomited freely during the night. 10 A. M. Gave a bolus containing 15 grains 
of calomel. 2P. M. Gave a bolus containing 10 grains of extract of jalap, and 
one and a half drops of croton oil. 3P. M. Out the pneumogastric nerves just 
one hour after last dose, five hours after the calomel. Neither bolus was 
vomited. Nov. 23. There has been no purging during the night, but appa- 
rently urination. 2.45 P. M. Injected by means of Wood’s syringe gr. ijss of 
arsenious acid into cavity of the peritoneum. 3.20 P. M. Cat in pretty much 
the same condition as before the injection. 4.40. Cat still alive; no purging 
or vomiting. It being about two hours since injection of arsenious acid, time 
sufficient to purge if it had the power, and wanting the carcass for dissection, 
I cut the carotids. 
Expt. 20.—Nov. 25, 4P. M. Gave 10 grains of calomel to a large male cat. 
Nov. 26. Has been purged pretty freely during the night. 9.30 A.M. Gave 15 
grains of calomel. 12 P. M. The cat has vomited a small portion of the mer- 
curial. Gave a bolus containing 2 grains of podophyllin, 1 drop of croton oil, 
and 10 grains of extract of jalap. 2.30 P. M. The cat has been purged very 
freely since last dose, once or twice. Cut the pneumogastrics. 6P. M. Cat 
pretty lively; no purging or vomiting. 9 A.M. Still alive; no vomiting or 
purging. Nov. 26, 9A. M. Oat died during the night without purging or 
vomiting. 
Autopsy.—Small bowels strongly contracted, not much larger than a large 
goose-quill; almost semitranslucent; waxy; almost as white as white wax; 
bloodless, with a small amount of very thick mucus in their interior; mucous 
membrane very pale and white, with here and there reddish flecks. 
Expt. 21.—Dec. 10, 4P. M. I gave 10 grains of calomel to a kitten appa- 
rently six months old. 4|- P. M. Vomiting. SP. M. Seems better. Dec. 11. 
Vomited and purged freely once or more during the night. 10 A. M. Gave gr. 
xof calomel. 3.15 P. M. Has been purged once since last visit. Gave gtt. j 
01. tiglii in a bolus. 3.30 P. M. Cut the pneumogastrics. 4P. M. Cat seems 
pretty lively; no vomiting or purging. 6P. M. About same ; no vomiting or 
purging. 10 P. M. Still alive ; no vomiting or purging. Dec. 11. Cat died 
some time during the night without any vomiting or purging. 
Expt. 22.—Dec. 13. I gave 10 grains of calomel at 4A.M. to a tortoise- 
shell kitten apparently six months old, perhaps older. Dec. 14. Kitten was 
purged very freely during the night. 10 A. M. Gave 10 grains of calomel in 
addition. 2.30 P. M. Kitten was purged since morning. Gave two pills con- 
taining each one drop of croton oil and two grains of rhubarb. Cat fought 
against taking them violently, chewed them up in her mouth, spit them out. 
AVe replaced the fragments several times, and she certainly swallowed equiva- 
lent to one pill. 2.45 P. M. Cut her pneumogastrics in the middle cervical 
region. 3.30. Cat seems pretty lively, walking about, fighting heroically upon attempting to seize her. 4.30. There has been no purging or vomiting since 
pnenmogastrics were cut. Cat is weak, very quiet, when it walks staggering. 
Injected into the cellular tissue of the back a solution of arsenious acid sup- 
posed to contain one-sixth of a grain, may have contained more, certainly not 
less. 5. Seems about the same, still able to walk, although staggering and 
uneasy. There is no apparent disturbance of the respiratory function. 5.30. 
Cat able to walk ; lies still most of the time ; no vomiting or purging. 6. 
Seems better. 6.30. Attempted to inject grain of arsenious acid into cellular 
tissue of back ; cat flew into a violent passion thereat, bit, scratched, and be- 
haved otherwise unseemly, so I was glad to let her go, with not more than a 
third the dose. 6.35. Cat running round the room wildly and stiffly, with head 
down ; limbs and neck stiff; no vacillation in her gait; seems as it were con- 
vulsed. 6.45. Cat still in “ tantrums.” 6.55. Oat collapsed, nearly motionless; 
dying. Eespiration for fifteen minutes has been markedly that of section of the 
pneumogastrics. No purging or vomiting. 
Autopsy some time after death.—Stomach containing a quantity of thick, 
somewhat gelatinous, semitransparent, mucoid fluid. Small intestine con- 
tracted ; nearly bloodless ; empty ; mucous membrane very pale. 
Expt. 23.—Dec. 13. Gave 10 grains of calomel by the mouth at 4P.M. to 
a black kitten, stout, vigorous, apparently nine months old. Dec. 14. Was 
purged freely during the night. 10 A.M. Gave an additional 10 grains. 2.40 
P. M. Has been purging since morning. Gave a pill containing one drop of 
croton oil and two grains of rhubarb; swallowed without much difficulty. 3 
P. M. Cut pneumogastrics. 3.30. Oat seems pretty well and strong, simply 
showing general signs of section of the par vagum. 4.30. Seems very lively ; 
the marked evidences of respiratory disturbance have passed off. No vomiting 
or purging as yet since section of the nerves. Dec. 14, 10 A. M. Seems very 
bright, running about as if nothing was the matter. During the night she has 
passed water freely, and I found a few shreds of fecal mucoid matter, not half 
a teaspoonful, at her tail, which is covered with the remains of previous purging. 
This probably was from the wet, moistening the dirty, matted mass. Gave 
hypodermically gr. ss acidum arseniosum. 10.33 A. M. Oat seems sick, but 
running about and drinking. Gave gr. of the arsenic additional. 2.30 P. M. 
Cat about the same, seems hardly so ill as at 11 A. M.; no vomiting or purg- 
ing. Gave gr. | acidum arseniosum hypodermically. 3 P.M. Not much change. 
3 25. No vomiting or purging ; cat very quiet. Gave gr. |of arsenious acid 
hypodermically. 3.35. Cat dead, without vomiting or purging. 
Autopsy five minutes after death.—Stomach empty; much of its mucous 
membrane swollen, and intensely dark red. Small intestine. Peristaltic action 
evident upon opening abdomen ; excited very readily by pricking the gut; in- 
testine empty ; mucous membrane mostly pale, a little reddish in spots ; every- 
where very dry. 
Expt. 24.—Dec. 15, 3.30 P. M. Gave to a stout cat a bolus containing one 
drop of croton oil, and directly after cut the pneumogastrics. 4.30. No purg- 
ing ; cat pretty well. Dec. 16. Has been no purging during the night ; cat in 
good state, 2.30. Injected by means of Wood’s syringe into cellular tissue, in 
four or five different places, 2 grains of arsenious acid diffused in water. 3.30. 
No new symptoms developed, save cat seems very quiet and weak. Injected 
2 grains additional of the acid. 4P. M. Cat very weak and sick, making some 
motions as though she would vomit, but really no vomiting or purging. 5 P.M. 
No change ;no vomiting or purging. 9P. M. Cat still alive ; no vomiting or 
purging. Dec. 17. Gat died some time during the night. After 9 she had a 
single firm passage ; this had apparently been formed, and then flattened by 
being laid on. 
Autopsy.—Stomach containing considerable liquid; its mucous membrane 
excessively red and congested. Small intestine, containing in places some thick 
mucus, in others dry and empty; its mucous membrane in places somewhat 
reddened, in others normal. 
Expt. 25.—Dec. 16, 3.10 P. M. Gave to a kitten apparently six months old, 
a bolus containing 10 grains of calomel, and ten minutes after cut the pneumo- 8 
gastrics. 3.30. Disturbance of respiration excessive, almost convulsive. In- 
jected into cellular tissue gr. j arsenious acid in water. 3.45. Put 3 grains of 
arsenious acid on the cat’s tongue, and washed it down with 8 grains of gam- 
boge imperfectly suspended in an ounce of water; probably half of this was spilled. 
5 P. M. Cat apparently much better, symptoms of disturbed respiration have 
subsided; no vomiting or purging. 9 P. M. Cat dead. No vomiting or 
purging. 
Autopsy.—Stomach containing a considerable amount of watery fluid. Small 
intestines, in many places dryish, in others containing some thick mucus. 
The experiments just detailed, taken in conjunction with those of the 
first series, seem sufficient to prove that purgation is impossible after divi- 
sion of the cervical pneuraogastrics. As previously stated, the first two 
experiments of the series do not carry much weight, but experiments 10 
and 12 are very conclusive. In 12, a cat, after free purgation has been 
produced by two drops of croton oil, the nerves being intact, receives again 
the same dose and in the same manner; two hours and a half are then 
allowed for absorption, and the nerves are divided ; twenty-four hours 
afterwards, the medicines not having produced any effect, the animal is 
killed with veratria, dying without the stomach and bowels being excited 
to action. In experiment 13, two hours after the exhibition of a large 
dose of croton oil, when purgation had commenced in another animal to 
wdiom the same dose had been given at the same time, the nerves w7ere cut, 
and the animal died without purging. Experiments 15 and 16 were made 
with arsenic, which, according to all observers, vomits and purges always 
when given in lethal doses, without reference to its mode of exhibition. 
In experiment 15 a non-fatal dose of the poison had previously freely 
purged the animal. Experiment II was merely tentative,, and proved that 
croton oil and jalap act as purgatives to the dog. Experiment 18 is a 
very decisive one. A dog receives a bolus of croton oil and extract of 
jalap, and five and a half hours afterwards, this having freely operated, 
receives a second similar one. An hour after this the nerves are divided, 
and nearly two days aftenvards the animal is slowly poisoned by arsenic, 
and yet is not purged or vomited. Experiment 19 is apparently an experi- 
mentum cruets. A cat, previously purged with fifteen grains of calomel, 
receives the same dose, and four hours after this ten grains of extract of 
jalap and a drop of croton oil. An hour after this the nerves are divided. 
Purgation is not induced, although the animal the next day is killed by 
two and a half grains of arsenious acid. Experiment 20 is very similar to 
this, except that the second mercurial was aided by ten grains of the jalap 
extract, a drop of croton oil, and two grains of podophyllin, and purgation 
allowed to commence before division of the nerves, ceasing immediately upon 
this. No arsenic was used. At the autopsy the small bowels were found 
contracted, with simply a slight amount of mucus in their interior. Experi- 
ment 21 is similar, except that the mercurial was aided by croton oil alone. 
Experiment 22 differs chiefly in the use of about a third of a grain of ar- 
seniate of potash. In experiment 23 the results were not quite so positive, 9 
although I believe there was no purging during the night, and it is certain 
that there was none when the animal was killed the next day with arsenic. 
In experiment 24 croton oil was alone used at the time the nerves were 
divided, but the animal died of arsenical poisoning nearly thirty-six hours 
after this without purging. In experiment 25 calomel, gamboge, and ar- 
senious acid failed to induce purgation after division of the cervical pneu- 
mogastrics, the kitten living some six hours after the exhibition of the 
mercurial. 
The results of these experiments were pretty plainly shadowed forth, 
although not definitively proven, by the late Sir Benjamin Brodie, in a 
paper published in the Philosophical Transactions, 1814, p. 102. His 
experiments were only four in number, and were all made with arsenious 
acid. 
In the first, ten grains of the acid were inserted into the thigh of a dog 
after section of the pneuraogastrics in the neck, the animal dying in three 
hours and a half. The stomach and mucous membranes on post-mortem 
examination were found to contain no mucus or watery secretions—only 
food and feces. The mucous membrane of the stomach and intestines was 
found inflamed. The second experiment was in all respects similar to the 
first, except that the dog lived nine hours. In the third experiment two 
ounces of a saturated solution of the white oxide of arsenic were given by 
the stomach, after section of the pneumogastrics, the dog dying three 
hours afterwards. The stomach and intestines are said to have been 
slightly inflamed, but to have contained no mucus or watery fluid. Sir 
Benjamin Brodie, in the fourth instance, divided the nerves just above the 
cardiac orifice of the stomach, and consequently below the origin of the 
pulmonary and cardiac branches. After the operation the respiration was 
perfectly normal. The dog was now inoculated in the thigh with arseni- 
ous acid. He died in a few hours with the ordinary symptoms of arsenic 
poisoning, except vomiting or purging. No watery or mucous fluid was 
found in the stomach or small intestine. A small quantity of mucus in 
the colon. 
There are two sides to every question, and so far, in this study, we have 
seen but the one; there is, however, another. 
Dr. John Eeid, in his investigation of the pneumogastrics, repeated the 
experiments of Brodie, with, as he believed, opposite results. 
His manner of experimentation seems to me to be somewhat faulty, 
although he claims that it is the only true method. He took two dogs in 
each experiment, one with the vagi entire, the other with them cut, killed 
them with arsenic, and then examined the intestines to see whether there was 
any difference in the amount of fluid contained, and on finding equal quanti- 
ties, reasoned that there had been no arrest of secretion produced by the 
cutting of the nerves. Now, it is evident that if the uninjured dog had been 
purging freely, and the other not, the intestines of the latter might con- 
tain more fluid than those of the former, although secretion had been far 
less active. Especially is a doubt thrown over this method of experimen- 10 
tation, when it is remembered, in addition to the above, that it is wholly 
uncertain how much mucus was in the bowel of the dog before the section 
of the nerves and the subsequent poisoning. The experiments were five in 
number, and in only one (Expt. 40, Essay on the Pneumogastric Nerves) 
is it noted that diarrhoea was present after division of the nerves. Even 
in this it is barely possible there was some misapprehension, as the nerves 
were not examined at the autopsy to prove that they were actually cut. 
Still, it is most probable that this experiment gave an opposite result to 
those already detailed in this paper. All my experiments coincided, until 
over twenty had been made, when one occurred in which there was free 
purgation, and another in which there was some slight muco-fecal dis- 
charges after division of the nerves. 
These experiments were as follows : 
Expt. 26.—Dec. 15, 10 A. M. I gave by the mouth to a very large and pow- 
erful mongrel pointer 20 grains of calomel. 3P. M. Has been vomiting and 
purging freely. Out the pneumogastrics in the middle cervical region. The 
usual symptoms developed themselves. SP. M. Has recovered pretty well 
from the operation ; no vomiting or purging since. Dec. 16. Dog quiet, al- 
though in pretty good condition. There has been no purging during the night. 
10 A. M. Gave two boluses, containing together ten grains of compound ex- 
tract of colocynth, two drops of croton oil, and five grains of extract of jalap. 
The dog swallowed them ; of course they did not go fully down into the sto- 
mach, but, as they were soft, I conceive they must have melted and gradually 
been absorbed in the oesophagus, or found their way into the stomach. 2.25 
P. M. There has been no purging or vomiting since 10 A. M. Have just given 
the dog 7 grains of arsenious acid, suspended and partially dissolved in about 
six drachms of water, injected into as many places in the cellular tissue of back 
and thighs. 3.30 P. M, Purged several times freely since 2.25 ; some very 
watery, some thick mucoid matter; some blood. I now gave 3 grains addi- 
tional of arsenious acid in the same way as before. 4.30 P. M. Dog has purged 
once or twice since. Gave a solution hypodermically which had contained 
over two grains of veratria; some of the alkaloid, however, had probably been 
decomposed by a fungus growing in it. 4.45. Dog has exhibited most of the 
usual symptoms of veratria poisoning; had a single, very small passage from 
his bowels ; profuse salivation ;no vomiting; now lying on side, unable to stand 
on his feet. Dec. 16. Dog has purged freely during the night; is now dead. 
Autopsy.—Stomach containing considerable fluid ; its mucous membrane 
normal. Small intestine ; its mucous membrane intensely congested ; often 
markedly injected ; the gut containing considerable fluid. Large intestine nor- 
mal, except that it contains considerable liquid feces. 
Third Series of Experiments. 
Expt. 27.—Dec. 15, 3P. M. Gave by the mouth to a not very large, but 
very powerful and vicious male cat, 10 grains of calomel, and fifteen minutes 
afterwards cut the pneumogastrics. SP. M. Cat seems in good condition; no 
purging or vomiting. Dec. 16. There has been some purging during the night, 
consisting of very thick, gelatinous mucus, with a faint fecal tinge. 3.45 P. M. 
Poured into the mouth 6 grains of arsenious acid in dry powder, nearly all of 
which was swallowed. I also gave a bolus containing 1 grain of podophyllin, 
5 grains compound extract of colocynth 2j grains extract of jalap, and 1 drop 
of croton oil. How much of this actually found its way into the stomach it is 
impossible to state. A quantity of thick saliva and mucus came from the 
mouth, much of it very deeply coloured by the extracts. SP. M. Oat seems 
lively ; no purging. Dec. 17, 10| A. M. Oat still alive, but weak ; there has 
not been any purging. Injected into cellular tissue a little over two drachms of 11 
Pointer's solution. P. M. In about the same condition as two hours ago ; 
no purging. 4P. M. Just alive. There has been some mucoid discharge from 
the anus, just enough to wet the surrounding parts. 
Autopsy.—Dec. 18. Stomach containing considerable watery fluid ; mu- 
cous membrane normal. Small intestine, containing in considerable quantity 
a thickish, yellowish, mucous liquid ; mucous membrane in places intensely 
injected and inflamed. 
Speaking of the different results obtained by himself and Sir Benjamin 
Brodie, Dr. Reid says : 
“ We cannot pretend to account for the discrepancy between the results ob- 
tained in the experiments detailed above and those related by Sir B. Brodie. It 
is possible, however, that Sir B. had not taken the precaution of securing a free 
ingress of air into the lungs in the three experiments in which the nerves were 
cut in the neck, for it is stated in the first experiment the breathing of the ani- 
mal was laboured and it died after three hours and a half. .... Whatever 
be the cause of this discrepancy, it is obvious that the negative evidence ob- 
tained by Sir B. Brodie cannot affect the value of the positive experiments we 
have detailed.” 
Probably no words have been more misused in physiological reasoning, 
or, indeed, in scientific reasoning generally, than negative and positive. 
Negative in one sense, the results of Sir Benjamin Brodie, are in fact, but 
in a higher and truer sense, they are positive, just as much positive as 
those obtained by Dr. Reid. If a poison be introduced into the system, 
possessing the power of invariably producing a fixed train of symptoms, 
and by any means such symptoms are prevented, the result is absolutely a 
positive one. Opposite results certainly were obtained by the different 
observers, but it is of no use to brand one as negative and pass it by. The 
true scientific sense will be awakened by such circumstances, not to ignore 
facts, but, if possible, to reconcile that which is apparently flatly contradic- 
tory. My experiments conclusively show that both observers were right, 
some of them agreeing with the one, some with the other. I think they 
are sufficient in number to prove absolutely that, after division of the 
cervical pneumogastrics, it is, in the majority of instances, impossible to 
purge, but in a few cases the normal action of the purgatives seems to 
be scarcely interfered with. The question is, Why is this? and the answer 
to this is evidently wrapped up in that of the question, How does the divi- 
sion of the nerves cause arrest of intestinal secretion ? 
It is, I believe, now generally conceded that section of the cervical par 
vagum arrests secretion in the stomach, and that, generally, the power of 
digestion is permanently destroyed. In certain instances, however, there 
is no such arrest of secretion in the stomach. This is precisely what I 
have found to be the case in the bowels, and it needs no elaborate argument 
to convince one that both depend upon a common cause, whatever that 
may be. 
What then is this cause? To my mind but three plausible explanations 
presented themselves : 12 
First. The par vagum is possibly the direct antagonist of the contracting 
vaso-motor nerve of the alimentary canal, or, in other words, it is the dilating 
vaso-motor nerve of Bernard. This being true, it is evident that the 
cause in question is contraction of the capillaries after the section of the 
pneumogastrics by the unresisted contracting vaso-motor nerve, so as to 
prevent secretion. 
Third. Accumulation of carbonic acid in the blood owing to the im- 
peded respiration. 
Second. Shock. 
The former of these supposed causes is the one which first presented 
itself to my mind as very probably correct. The experiment of Bernard 
in which he cut the pneumogastrics of a dog, after having established a gas- 
tric fistula, has apparently direct bearing upon this point, for he found 
that the mucous membrane of the stomach instantly became pale and co- 
lourless when the nerves were divided. 
The subject of the relation of the par vagum to digestion has attracted 
a great deal of attention, and in order to elucidate it, Magendie, Schultz, 
Bernard, Schiff, and others, have made numerous experiments. Several of 
these observers have many times cut the pneumogastric nerves just as they 
emerge into the abdomen from the diaphragm, and, therefore, after their 
cardiac and pulmonary branches have been given olf. The results obtained 
have been somewhat various, digestion sometimes continuing, sometimes 
ceasing ; the best observers, however, agreeing that secretion generally 
continues. The discovery of Brachet, that many branches of the pneumo- 
gastrics pass through the walls of the oesophagus and were consequently 
unharmed by the various experimenters, apparently accounted for this. Es- 
pecially did this seem plausible, when it was found that if the oesophagus 
with the contained nerves was divided gastric secretion ceased. The facts 
brought forward in this paper to show that there is an arrest of secretion 
in the intestine as well as stomach after cervical section of the pneumo- 
gastrics, seem in themselves, however, enough to invalidate the explana- 
tion of Brachet, for the small intra-oesophageal branches, which by in- 
creased activity were supposed to do the work of the whole nerve in the 
stomach, certainly do not reach the intestine. There is not wanting, how- 
ever, more positive experimental proof of the falsity of this theory. Prof. 
Schiff has shown (Legon sur la Physiologie de la Digestion, vol. ii.) that 
section of the oesophagus close to the cardia, the nerves being carefully 
dissected off and left uninjured, is in itself sufficient to cause the instant 
and permanent arrest of digestion ; and has also modified the experiment 
of Magendie, Bernard, etc., so as completely to meet the objections of 
Brachet, and at the same time avoid the disordering effects of section of 
the oesophagus. His operation consists in cutting down upon the cardia 
in the usual way, exposing and dividing the anterior and posterior branches 
of the pneumogastric, and then seizing the oesophagus between the finger 13 
and thumb as close to the diaphragm as possible, rotating it, and at the 
same time carefully dividing it down to the muscular coat, which is left 
intact. In this way the nerves are all divided, and at the same time the 
oesophagus left practically unhurt. Prof. Schilf has repeated this experi- 
ment a number of times, always with the one result. He has assured him- 
self, in the most positive manner, that there is no suspension whatever of 
digestion, even during the first twenty-four hours. Founding his opinion 
upon these experiments, he concludes that the arrest of secretion in the 
stomach is due simply to the disturbance of the circulation and respi- 
ration. At first this conclusion was not satisfactory to my mind, espe- 
cially as I was slow to conceive how such disturbances could modify the 
action of the glands of the bowels. In order to satisfy myself whether 
the par vagum was a vaso-motor nerve or not, the following direct expe- 
riments were instituted. As a local stagnation in the circulation from 
capillary contraction would of necessity modify the rapidity of absorption, 
the first experiment was directed to discover whether section of the par 
vagum has any influence upon intestinal absorption. 
Fourth Series of Experiments. 
Expt. 28.—Yery large powerful male cat, and much smaller female cat. 
Dec. 13, 11 A. M. Cut the pneumogastrics of the large cat. 2.54 P. M. 
Seems pretty well, but breathing noisily, and with slow, laboured effort. Without 
giving an anaesthetic I opened abdomen in linea alba, and, exposing small intes- 
tine, placed in it a pill containing | grain of strychnia. 2 minutes. No per- 
ceptible effect. 4 minutes. Oat apparently feeling the poison ; standing erect 
with some stiffness. 1 minutes. Just seized with violent tetanic convulsions, 
in which he died. 3.5 P. M. Put smaller cat under the influence of ether; 
opened abdomen in linea alba, and placed a pill, in all respects similar to last, 
in small intestine. 2 minutes. No effect visible. 4 minutes. Perhaps some 
stiffness. 6 minutes. Marked tetanic stiffness of all the muscles. 8 minutes. 
Stiffness persisting, with constant convulsive shudders. 10 minutes. Same 
condition. 12 minutes. Cat dead, without any wild convulsions. 
Bernards.—This experiment shows that it makes very little difference 
in the rate of intestinal absorption whether the pneumogastrics be entire 
or divided. The reason the injured animal died in the shorter period of 
time is probably not that absorption was more rapid, but that the breath- 
ing was already so much interfered with that death occurred from suffo- 
cation in the first convulsive paroxysm. The length of time from the 
administration of the poison to the appearance of the first symptom was as 
nearly identical as possible in the two cases. 
Expt. 29.—Dec. Ist, 4P. M. Cut pneumogastrics in the middle cervical 
region of a full-grown female cat. Exposed the small intestine ; inserted a 
suture through it, and at the spot injected two and a half fluidrachms of the 
linimentum cantharidis into the gut, which instantly became deep red. I now 
replaced the intestine, and sewed up the wound. SP. M. Cat still living. Dec. 
2d. Died some time during the night, without purging or vomiting. 
Autopsy.—The small bowel was remarkably red, especially near point of 
injection. The colour was darkish rather than bright, but still marked. On 
opening gut it was found to contain a considerable amount of thick whitish 14 
mucoid substance. On washing the raucous membrane it was found not so red 
as the outside of the bowel, often pale, grayish ashy. In no place was there 
any injection of the mucous membrane. 
Expt. 30.—A full-grown cat. Abdomen opened, suture inserted into the 
intestine, and of linimentum cantharidis U. S. P. injected. During the 
night the cat got out of the box in which she was placed, and in the morning 
was found dead with bowels protruding. Small intestine a very deep red, both 
externally and internally; the epithelium of the inside had the same grayish 
ashy appearance noted in previous experiments. Bowels more intensely red 
than in Experiment 29. 
Expt. 31.—Jan. 26. Under ether exposed and cut the pneumogastrics in 
the neck of an adult female cat. At 4P. M. opened the abdomen and injected 
into the small intestine about two fluidrachms of linimentum cantharidis, in 
which two Chilian peppers had been soaked. At another place two Chilian 
peppers were introduced into the small intestine through a slit, which was then 
sewed up, and the bowels were replaced. 6P. M. Cat seems pretty lively; 
no purging. Jan. 27. Died during the night. 
Autopsy.—Small bowels nowhere very intensely reddened; in some places 
injected, containing a considerable quantity of a semi-fluid mucoid substance 
smelling strongly of turpentine, which probably was largely the injected mate- 
rial. There was no injection of the mucous membrane at the position of the 
peppers, although considerable blood, which almost certainly had oozed into 
the bowel from the cut. 
Expt. 32.—Large female cat. Present Dr. McQuillen, Professor of Physi- 
ology, Philadelphia College of Dentistry, and Messrs. Dixon and Chaninel, 
office students. Etherized the animal and, after cutting the pneumogastrics in 
the neck, slit open the small bowel opposite to its attachment to the mesen- 
tery, and applied a galvanic current of moderate intensity to the distal ends of 
the severed nerves. The colour of the mucous membrane of intestine changed 
from a pale whitish hue to a very decided reddish tint. The current was inter- 
mitted, and a fresh portion of the bowel on being exposed was found of the ori- 
ginal pale colour. The current was then passed through the nerve again, and 
the mucous membrane again reddened. The current was again broken, a fresh 
portion of the bowel exposed, and again an increased redness followed a com- 
pletion of the current. After this, however, the bowel failed to change colour, 
upon electrical stimulation. Dr. McQuillen, after the experiment was over, 
stated that he was thoroughly satisfied as to the change of colour in the raucous 
membrane of the intestine following the earlier application of the galvanism. 
Expt. 33.—A large and old English rabbit. Under ether, cut down to the 
pneumogastrics and placed a string loosely around each, so that it could be 
drawn out of the wound at pleasure ; at the same time the trachea was exposed 
and a tube inserted therein, for purposes of artificial respiration if required. 
Operation complete at 3.30 P. M., and the ether withdrawn. 4P. M. The 
intestines were exposed by a median incision in the abdomen, through which 
the large bowel immediately protruded. It was laid open, the contained fecal 
matter removed, and the mucous membrane carefully washed with a soft sponge. 
After some minutes’ exposure, the mucous membrane was decidedly red. The 
pneumogastrics were now pulled out of the wound and cut. In less than half 
a minute the bowel had become very decidedly pale; the change was marked, 
and persisted for fifteen minutes, when the animal was given what was sup- 
posed to be woorara, which produced in a short time violent tetanoid convul- 
sions, and put an end to the experiment. No medical gentleman but myself 
was present. I asked my assistant—a very intelligent man—if there was any 
change in the bowel. He instantly replied, “Itis of very much lighter colour.” 
He knew nothing as to my expectations, whether there was to be any change, 
or, if so, of what nature. 
Expt. 34.—Attempted to etherize a large cat, but had great difficulty in 
accomplishing it, and remarked to my assistant that I had never seen a cat resist 15 
an anaesthetic so long. However, she finally became thoroughly anaesthetized, 
and I cut down on the left nerve. At this time it was discovered we had been 
using alcohol for ether, so that complete anaesthesia had been produced by 
vapour of cold alcohol. The abdomen was now opened. Peristaltic action 
was completely suspended in the bowels, reappearing, however, readily when 
the galvanic current was applied to them. When left to themselves they were 
always relaxed, perfectly passive. The small bowel was laid open, and the 
pneumogasti’ics cut. No change was perceptible in the colour of the mucous 
membrane on division of the nerves. The distal ends of the divided nerve 
were now galvanized, at first with a very weak, afterwards with a much stronger 
current. Respiration was very sensibly affected, but no change whatever was 
perceptible at any time in the colour of the mucous membrane of the bowels. 
Expt. 35.—Fu11-grown English rabbit. Under ether the pneumogastrics 
were exposed without cutting them. The abdomen was now opened and a por- 
tion of the small intestines drawn out. The animal was then allowed to lie for 
half an hour, the intestines being covered with a wet sponge, until the effects of 
the ether had passed off. The intestine was now laid open, and after four or 
five minutes a very mild induced current was passed through the uninjured 
pneumogastrics. At first no change; in two or three minutes darker points be- 
came apparent, and in five to ten minutes the whole intestine became markedly 
darker. After ten minutes the pneumogastrics were cut; the bowel, however, 
scarcely changed. My assistant said he could see no change whatever. I 
thought it became a shade lighter, but was not positive. Galvanizing of the 
distal ends of the cut nerves for some five minutes produced no change what- 
ever in the bowel. The proximal end of one nerve was also galvanized for a 
couple of minutes without effect. The currents used were very weak, but suffi- 
ciently powerful to influence respiration in a marked manner. No interference 
with the heart’s action was apparent. 
Expt. 36.—Fu11-grown English rabbit. Under ether cut down and exposed 
pneumogastrics in the neck without injuring them ; then opened the abdomen 
and dragged out the intestines. I now waited half an hour until the effects of 
the ether had thoroughly passed off, and then slit open the small intestine oppo- 
site its attachment to the mesentery. There was some bleeding, but it stopped 
on the application of a little cold water. Five minutes after this a tight ligature 
was placed around each pneumogastric. This apparently caused great pain, 
and the animal struggled violently. In two or three minutes the nerve was cut. 
Owing possibly to struggles the bowel reddened very decidedly after section of 
the nerve, and it continued so after the animal became quiet. Five minutes 
after this we galvanized the proximal ends of the nerves with a mild induced 
current. For some time no change was perceptible, but afterwards the bowel 
became somewhat lighter coloured, and persisted so until experiment closed. 
The peristaltic action of the bowels was apparently not affected by section of 
the nerves being about equally active after as before. There was apparently 
some increase in its activity upon galvanizing the nerve, but this seemed more 
of a coincidence than an effect. 
A careful study of these experiments will, I think, convince any one 
that there is no direct connection between the pneumogastric nerve and 
the abdominal circulation. Experiment 28 shows, as already stated, 
that intestinal absorption is not affected by division of the cervical par va- 
gum. The 29th demonstrates that important changes can be produced in 
the intestinal circulation by local influences after division of the nerves. In 
the 31st experiment the reddening was not so marked but still was quite 
apparent. Experiments 32, 33, 34, 35, and 36, taken together, I think 
prove that neither division of the nerve, nor galvanization of either of the 
cut ends, has any fixed effect upon the intestinal circulation. In some cases 16 
there was some effect, but results were so often wanting, and when obtained 
were so often contradictory, that I have no doubt the changes in the colour 
of the mucous membranes were always either mere coincidences or were 
brought about indirectly, by the transmission of currents to other nerves, 
as has been shown to occur (Bernard, Med. Times, 1865, vol. ii.), or by 
effects upon the respiratory function, or upon the heart, or perhaps by ex- 
posure of the intestine, or in some other way, not readily discoverable. 
Exactly how “ shock” could cause a loss of power in the intestinal 
glands I do not understand, but it has suggested itself as an efficient cause. 
In order to test it the following experiments were instituted. They are not 
numerous, nor are they very decisive, but I think are sufficient to show 
that the intestinal effects of the division of the nerves cannot be accounted 
for by “ shock” alone, although it very probably enters as one of the factors 
in the problem, and the sudden blanching of the mucous membrane of the 
stomach observed by Bernard was probably due to it. The experiments 
of Schiff upon division of the oesophagus corroborate the idea that 
“shock” has influence in the matter. As already stated, that observer 
found that cutting the oesophagus across low down was in itself sufficient 
to abolish gastric secretion. 
Fifth Series of Experiments. 
Expt. 37.—Etherized stout female cat, and by blows with the thick end of a 
heavy axe broke the thigh-bones of both hind legs completely, also the bones 
of the forelegs ; in the latter there was a good deal of crushing, and from one 
considerable hemorrhage. 3.20. Cat has recovered from the ether; seems in 
good condition; administered hypodermically about gr. ss veratriae sulphas 
dissolved in alcohol. 3.30. Making violent efforts at vomiting. 3.35. Vomit- 
ing violently. As the design of the experiment had been fully carried out, I 
now put an end to the animal’s sufferings by a blow on the head with the axe. 
Expt. 38.—March 1. At 3.50. P. M. tied the right carotid of a moderate 
sized cur. At 4 passed a ligature around the left carotid, without tying. 4.05. 
Dog has come out from under the ether to a considerable extent; tied the 
ligature tightly. 4.10. Dog sensible; perfectly quiet; immediately after the 
occlusion of the artery there was some stiffening of the muscles, and some appa- 
rently involuntary raising of the head; no convulsions. 4.12. Dog perfectly 
quiet; saliva dripping from mouth. Injected into cellular tissue of side about 
grain of commercial veratria in alcoholic solution. 4.20. Dog very restless, 
with a constant suppressed howl or moan. 4.30. Dog shows some indications 
of sick stomach. 4.35. Quiet. Repeated the dose. 4.40. Howling violently, 
and continued to do so for fifteen minutes. No vomiting, or purging, or con- 
vulsions. 5. Wild; biting; trying to get loose. Gave hypodermically, gr. £ 
commercial veratria. 5.15. Perfectly quiet; injected £ grain of the alkaloid. 
6.30. Quiet; considerable salivation : heart beats 75 per minute. Injected into 
peritoneal cavity gr. £of the veratria; immediately vomiting occurred without 
effort or straining a large quantity of partially digested food—a “ puddeny” 
mass. Injected into cellular tissue of thighs gr. £of the alkaloid. 5.40. Dog 
rigid all over ; body bent forward very much ; emprosthotonos ; limbs stiff. 
5.43. Dog relaxed; no convulsion ; making constant violent efforts at vomiting ; 
retching; straining; vomiting “dry;” no mucus or fluid rejected. 5.47. 
Retching still continues ; very violent; mostly without any results ; occasion- 
ally a little thick stuff rejected similar to that first thrown up. Heart beat 36. 
€.lO. Still alive, but no more; no vomiting or no convulsions since last entry; 17 
sometimes an apparent tendency to convulsions ; lie appears to be below the 
convulsion state ; at times apparently dead. 
Escpt. 39.—March 9. 2.30 P. M. Gave a large male cat a bolus containing 
arsenic 3 grs., compound extract of colocynth 7 grs., gamboge 2 and a half 
grains, croton oil one drop. 2.40. Administered ether, and 2.45 tied left caro- 
tid. 2.55. Put a ligature loosely around right carotid. 3.10. Cat pretty well 
recovered from effect of the anaesthetic ; tightened ligature ; respirations imme- 
diately became punting, exceedingly rapid, 150 per minute; expression of face 
wild, anxious ; a constant low, suppressed moaning; head constantly moving 
from side to side with a sort of slow, rolling vibration. 3.15. Untied the cat. 
He made no effort to walk, but laid on his side, with the same constant motion 
of his head. 3.20. Breathing much more natural, not strikingly abnormal; when 
approached, cat shows desire to fight by spitting and growling, but makes no 
effort to get away or actually fight. Smart whipping has no effect on him ; he 
will not attempt to rise or move forefeet save to alter their position slightly; 
when pushed forward with the foot he finally, however, rose and ran three or four 
steps and then fell, with limbs bent under him. There is some power in limbs, 
but great weakness as well as indisposition to move them. 3.35. Cat lying still, 
head erect; is roused with difficulty, but when finally pushed into getting up, 
can run quite well. 3.40. Cat pretty well, running about room some ; no 
vomiting or purging. 4.30. Cat seems pretty well, but quiet, liking to creep 
into corners and cower there ; has just vomited a considerable quantity of 
dark watery fluid, apparently discoloured by the compound extract of colo- 
cynth given some hours before. 5.30. No change; no more vomiting or purg- 
ing. March 10. Still alive, and in pretty good condition. I am uncertain 
whether there has or has not been any purging during the night; certainly, if 
so, not more than a single passage; I think none. 10 A.M. Eepeated the 
bolus. 12 M. Still alive ; no vomiting or purging. Died some time after 
last visit; there has been no purging or vomiting. 
Expt. 40.—March 9. 3.35. Administered to a young cat, apparently some 
nine months old, a bolus containg 3 grains of arsenic, 7 grains of compound ex- 
tract of colocynth, 2J grains of gamboge, and one drop of croton oil. 3.40. 
Tied the external jugulars ; produced no very marked symptoms. 3.50. Seems 
in good condition ; howling loudly, and trying to get away. 5.33. No change; 
no vomiting or purging; cat howling. 10. Still alive. March 10. Gat died 
during the night; there was evidently free purging. 
The question which next suggested itself for investigation was, Is the 
arrest of intestinal secretion after division of the pneumogastrics in the 
neck dependent upon disturbances in the respiratory function ? That it 
cannot be owing solely or chiefly to the lessening of the heart’s power, is 
evinced by the fact that purgation frequently does take place when by other 
means the heart’s action is lessened much more than it is by the operation 
alluded to. That the latter does profoundly interfere with the lung func- 
tions and that after it there is during life a gradual accumulation of car- 
bonic acid in the blood, admits of no dispute. Now, if it can be shown 
that such an accumulation is in itself sufficient to check secretion, a great 
advance will have been made towards the solution of the problem. The 
following experiments were therefore instituted. They are in two series. 
In the first, measures were adopted to more or less completely suspend the 
action of one lung, and then purgatives were administered. In the second, 
the action of the medicines upon animals exposed to an atmosphere loaded 
with carbonic acid gas was studied. It is evident that in the first set of 18 
cases “shock” entered as a possible factor, whilst in the latter it was 
altogether excluded. 
In exposing cats to the gas an apparatus was used which com- 
mended itself by its cheapness, portability, and efficiency. An ordinary 
candle-box, with a sliding lid, was knocked to pieces, and its joints made 
tight by nailing them very closely and forcibly, with a strip of flannel be- 
tween the boards. A pane of glass was set into the lid and a hole bored 
into the side of the box near the bottom. Into this a cork was placed which 
was fitted with a luted glass tube, such as the chemist frequently uses. 
Another hole was bored in the side near the top of the box at the oppo- 
site end to the first hole. A cork fitted this upper opening so that it 
could be opened or stopped at pleasure. The box was now connected by an 
India-rubber tube with a bottle or flask in which some carbonate of soda had 
been placed, and the apparatus only needed the addition of an acid to 
the latter to be in action. 
Expt. 41.—21 P. M. Pregnant cat. Made an incision on left side and 
forced a silver grooved director into and through right pleural cavity until it 
rested upon the vertebral column. Then inserted a tube in its place and pumped 
in air until cat was swollen like a drum. No bleeding of any moment. 3P. M. 
Gave hypodermically about 2 grains of arseniate of potash. 4P. M. No 
vomiting or purging; repeated operation ; gave gr. j additional. 4.15 P. M. 
Gave gr. j additional. 4.30 P. M. Gave 2 grains more of the arseniate. 5 P.M. 
Cat just purged once with some effort; very loose ; not very large discharge. 
6.15 P. M. Cat dead. 
Autopsy 15 minutes after death.—Cellular tissue almost everywhere infil- 
trated with air. Stomach filled with frothy liquid. Right lung not cut; con- 
gested ; in places very darkly and looking as though bruised ; heavier than the 
other lung and less crepitant; not collapsed. 
Sixth Series of Experiments. 
Expt. 42.—Feb. 4. 4.10. Made a free incision in a large male cat on the right 
side near the sternum down to the ribs, and cut obliquely through one of these, 
making an opening into pleural cavity sufficiently large to introduce the finger. 
4.15. Right lung pretty well collapsed, ascertained by introducing finger. 
Breathing laborious. Passed a cord very tightly around the chest in two 
places, so as to completely prevent thoracic breathing. 4.20. Oat well reco- 
vered from effects of the ether. Injected in four places into the cellular tissue 
two grains of arseniate of potash in half fluidounce of water, and half a grain 
into peritoneal cavity. 4.30. No change in condition of the animal. Breathing 
laboured, deep, abdominal. No vomiting or purging. 5. No change. Cat 
has been able to howl some. No purging or vomiting. Gave hypodermi- 
cally gr. £ of commercial sulphate of veratria in solution. 5.15. Cat appa- 
rently dying of suffocation. Cut the string binding the chest. 5.17 Revived, 
got up and walked some steps, tottering considerably in so doing. 5.25. 
Had a convulsion, leaping some six or eight inches backwards, three or four 
inches from the ground. 5.30. Gave hypodermically gr. | commercial sulphate 
of veratria in alcoholic solution. 5.35. Just dead. 
Autopsy immediate.—Heart still beating. Stomach filled with a little frothy 
liquid. Small intestines very dry, almost no mucus in them. Arteries and 
left ventricle full of black blood. 
Expt. 43.—Feb. 11. 3.40. Put a kitten apparently eight months old, under 
the influence of ether, and divided the cord between the third and fourth lumbar 
vertebrae. Collapse of respiration came on immediately; the heart kept beat- 19 
ing rapidly, but breathing ceased almost entirely, and the kitten was at one time 
apparently dead. Cold water was dashed against her face and she began to 
breathe again. 3.50. Kitten showing signs of consciousness ; paralysis perfect 
in posterior portion of her body. 4. Able to pull herself with her forefeet, 
going round and round and round, with her hinder end for a pivot. Admin- 
istered hypodermically one-sixth of a grain of commercial veratria. 4.10. Pull- 
ing herself forward; seems well and strong. Gave gr. as before. 4.20. No 
change ;no vomiting. 4.25. Saliva running freely from mouth and some gag- 
ging ; breathing excessively hurried, very shallow, thoracic. No vomiting. 
4.30. No decided change; mewing feebly; good deal of salivation. 4.35. 
Breathing as before, exceedingly rapid, irregular, shallow, 160 per minute. 
No change; no vomiting. I was now forced to leave the animal to my assistant, 
who informs me she was seized at 4.40 with violent convulsions, which recurred 
frequently until her death, which took place at 5.30. No vomiting or purging 
occurred. 
Expt. 44.—3.20. P. M. T made an oblique incision an inch long over the 
right lung near the sternum, cutting through the cartilages of two ribs, of an 
impure black and tan terrier. Immediately dyspnoea was very marked. There 
was considerable arterial hemorrhage, but not enough to seriously affect the 
animal. 3.25. By means of a Wood’s syringe threw into the peritoneal cavity 
one grain of arseniate of potash, dissolved in a fluidrachm of water, and 
directly after 3 grains in six different places, in the cellular tissue of thigh, 
flanks, sides, and back. 3.25. I bound a cord tightly around the chest so as to 
totally suspend thoracic breathing, Yery great distress and laboured respira- 
tion was the result. In about five minutes the symptoms of suffocation were so 
urgent that I thought I would have to take off the string, but they abated 
somewhat, and the string was not removed until just before death. The breath- 
ing was always exceedingly laboured and almost completely diaphragmatic. 
3.34. Administered two grains additional of the arseniate of potash, dissolved 
in water, injected into the cellular tissue in four different places. No vomiting 
or purging as yet. 4.10. No vomiting or purging as yet. Efforts at breathing 
very laboured. Dog evidently very ill. 4.30. No especial change in symptoms 
except dog apparently weaker. No vomiting or purging. 4.45. No vomiting 
or purging. Dog dying. 
Autopsy immediate.—4.46. Right lung thoroughly collapsed. Heart still 
beating feebly and irregularly; distinctly two auricular to one ventricular sys- 
tole. Left ventricle, aorta, and other arteries containing very dark blood. No 
bright aerated blood in the arteries. Intestines with the mucous membrane 
sometimes reddened ; containing considerable mucus, but not enough to drop 
from them when cut, except perhaps in one or two spots; in some places 
dryish. Peritoneum contains considerable fluid. 
Expt. 45.—Feb. 7. 4P. M, Etherized a large male cat and exposed the ribs 
freely on left side; then made a long transverse incision into the pleural cavity, 
cutting through two ribs. 4.10. Cat having well recovered from the ether, gave 
him hypodermically one-sixth of a grain of commercial veratria dissolved in 
alcohol. 4.18, Bound a cord tightly once around the chest so as partially to 
suspend thoracic breathing. 4.25. Quiet. No vomiting or convulsions. Breath- 
ing very laboured. 4.30. Gave one-sixth of a grain of commercial veratria 
hypodermically. 4.35. Cat has had a formed passage from bowels, and appears 
to be making efforts at vomiting. 4.37. Yomiting. 4.40. Vomiting again. 
In this vomiting there has been little or no discharge from the stomach. No 
forcible pouring out of greenish fluid, such as is seen ordinarily in veratria 
vomiting. 4.48. String removed. 4.50. One-sixth of a grain additional given 
and cat placed in the carbonic acid box and the gas allowed to flow in freely. 
5.20. No vomiting since being put in box. Still alive but unconscious. I now 
took him out and killed him with a blow on the head. 20 
Seventh Series of Experiments. 
Expt. 46.—Feb. 6. 8.15 P. M. Injected into the subcutaneous cellular tissue 
of a powerful male cat, one-half grain of commercial sulphate of veratria, dis- 
solved in alcohol. The cat was then put into the box. 3.18. Struggling and 
fighting. 3.20. Lying on side perfectly quiet, with deep laboured breathing, 
30 per minute. Taper goes out immediately when plunged in the box. 3.30. 
No change; no vomiting or purging, 3.35. Injected subcutaneously one-third 
of a grain of commercial sulphate of veratria. No vomiting or purging as 
yet. Salivation considerable but not nearly so profuse as generally under the 
influence of veratria. 3.40. Quiet; breathing deeply; somewhat rigid. Nothing 
at all like convulsions. 3.50. Oat died without vomiting or purging. Some- 
what rigid. Died in an atmosphere in which taper was instantly extinguished. 
Autopsy five minutes after death.—Stomach empty. Bowels containing a 
moderate amount of mucus. Peristaltic motion exceedingly active, more so 
than I remember ever to have seen it before ; constant and active without 
stimulus ; when intestine was cut across expelling the little contained mucus 
with violence through the cut. 
Expt. 47.—Feb. 5. 12.35. Injected into cellular tissue of a powerful female 
cat, a little more than the eighth of a grain of commercial sulphate of veratria, 
dissolved in alcohol. Put the beast immediately into the box. 12.30. Taper 
goes out immediately in box, but cat struggling yet. 12.45. Has been lying 
perfectly passive on side for some time ; breathing deep, laboured, 28 per 
minute; mouth open, tongue hanging out; pupils widely dilated; taper 
plunged in box instantly goes out. 12.50. No change. Salivation profuse, 
wetting every part of the box near the head ; no vomiting. 12.55. Breath rate 
26. No change ; cat perfectly motionless save breathing. 1.15. No new 
symptoms or change. Atmosphere of box all the time containing sufficient car- 
bonic acid to extinguish taper when brought into it. 1.20. No change.- 1.25. 
No vomiting or purging as yet. No new symptoms. 1.30. No change. 2. 
No change. No vomiting. Salivation excessively profuse. Taper goes out. 
Injected into cellular tissue one-sixth of a grain of commercial sulphate of 
veratria, in alcoholic solution.. 2.15. No change in cat or air of box. 2.50. 
Gave hypodermically one-sixth of a grain of commercial sulphate of veratria. 
3.10. Took the cat out of the box, where she had lain perfectly passive. 
3.15. Oat in convulsions, unable to stand, but lying on her side. 3.20. 
Almost constantly convulsive, or at least constantly and paroxysmally, kicking 
into air; occasionally some opisthotonos, still a good deal of salivation. 
Pupils still widely dilated. 4.00 Constant convulsive movements. Still con- 
siderable salivation. No vomiting or purging. Pupils widely dilated. 4.30. 
Knocked the cat in the head. 
Autopsy.—Stomach empty. Intestines empty. Arteries and left ventricle 
containing dark blood. 
Expt. 48.—Feb. 7. Injected into the cellular tissue of a powerful male cat, 
by means of a Wood’s syringe, | of a grain of commercial veratria dissolved 
in alcohol, and immediately placed animal in the carbonic acid box 5 minutes 
before 4 o’clock. 4.15. Restless ; paper burns feebly in the box. 4.20. Quiet; 
breathing labored. 4.25. Exceedingly restless, apparently in a convulsion. 
Carbonic acid gas now passing in more freely. 4.28. Quiet; breathing laborious, 
feeble; no vomiting, but a moderate amount of salivation. 4.30. Nearly dead; 
perfectly unconscious and relaxed. Dragged her head out of the box; mouth 
open, tongue hanging out, lips pale; pupils alternately dilating and expanding 
without any reference to the intensity of the light. 4.34. Revived, able to 
raise his head up, look about, and apparently make an attempt to bite ; suddenly 
seized with a violent vomiting fit. Returned him immediately to the box, and 
allowed carbonic acid gas to flow in freely. 4.40. Quiet; breathing laborious. 
4.45. lying on side, breathing slowly and laboriously, apparently perfectly un- 
conscious; tongue out: a moderate amount of salivation. No vomiting since 
return to box. 4.48. Dead, without vomiting since return. 21 
Autopsy, within five minutes after death.—Peristaltic movements of intes- 
tines exceedingly active; they being constantly vernacularly moving on exposure 
to the air, and a touch of the knife throwing them into all sorts of contortions 
and writhings. Intestines dry, containing no mucus. Stomach with a small 
amount of watery fluid. 
Expt. 49.—Feb. 5. 11.15. Gave hypodermically to a large female cat | of a 
grain of commercial veratria dissolved in alcohol, and put the animal immedi- 
ately in box. 11.20. Breathing exceedingly laboured, deep. 11.30. Struggling 
violently, it was impossible to say with certainty whether convulsively or vol- 
untarily; she kicked, doubled on herself, etc., violently in the narrow box. 
11.35. Some violent struggles. 11.45* Opened box; cat appeared very much 
under influence, but still kept her head up. 11.48. Box lid has been entirely off 
for five minutes, and cat shows evident signs of coming up from her semi- 
asphyxiated state; taper burns freely at bottom of box. Cat just seized with 
sudden violent vomiting of greenish mucus. 11.60. Vomiting again violently. 
Took the cat out of the box and undid the cords that bound feet together; cat 
was able to walk pretty well. 12.30. In last half hour has vomited freely 
several times. 1.10. Injected into cellular tissue 3 grains of arseniate of potash 
dissolved in water, and put cat back in the box. 2P. M. have been away; box 
wet all round head, cannot say certainly whether merely from saliva or from 
vomiting; has had a formed passage. 3. Convulsive seizures; has been quiet 
before, since 2 o’clock, in convulsions; muscles work disjointedly, often more 
twitchings than convulsions—often without movement of the limb. 3.10. Dead; 
no purging save a little fecal mucus, say a teaspoonful. 
Autopsy.—3.2o. Intestines deep red, containing a large quantity of mucus. 
Stomach full of frothy liquid. Heart not beating, not irritable to knife; left 
ventricle with dark blood, not absolutely black. Lungs pinkish, congested. 
Peristaltic motion of bowels marked 15 minutes after death, 10 after exposure 
to air; constant twitchings of muscles right behind thigh and leg, with occa- 
sionally jerking of the paw, continuing 25 minutes after death, 20 after opening 
thorax and abdomen. 
In series No. 6, there are five experiments. In the first of these a 
lethal dose of arsenic produced some slight purging, consisting of but a 
single loose passage. It is evident that this was not nearly so great as 
should normally be produced by the drug. There can be little doubt but that 
I failed in this case to open freely the pleural cavity. The air which was 
pumped into the animal located itself in the cellular tissue and not in the 
pleural cavity, and the autopsy showed that the lung did not collapse. 
There was, it is true, a good deal of embarrassment of the respiratory func- 
tion, just enough apparently to check, but not entirely to suspend the 
action of the intestinal glands. 
In Experiment 42, suffocation was certainly a very efficient agent in pro- 
ducing the death of the cat. The blood after death was everywhere 
highly carbonized. During life there was no purging or vomiting, although 
both veratria and arsenic were freely administered. Experiment 44 is 
very similar, and in every way confirmed the preceding. It differs only 
in the circumstance that arsenic only was used. 
Experiment 43 is chiefly interesting in confirming, as far as it goes, the 
others, and in showing that veratria may produce convulsions even when 
it is prevented from vomiting. The shock caused by a section of the 
cord manifestly, however, prevents much reliance being placed on the ex- 22 
periment as proving that an interference with respiration is an interference 
with intestinal secretion. 
In Experiment 45 an apparent contradictory result was obtained, yet the 
vomiting was by no means so severe as it normally is, after the use of such 
doses of veratria. There is no certain gauge in such experimentation as 
to how far the lung function is interfered with, and it seems to me that as 
there was an actual diminution of the gastric action of the poison, the 
results obtained really strengthen rather than weaken the testimony of 
the other experiments. The amount of respiratory disturbance was cer- 
tainly not so great as in some other cases, and the vomiting was entirely 
checked by a carbonic acid atmosphere. 
The experiments of series No. 7 are even more decisive and reliable 
in their testimony on the influence of an excess of carbonic acid in the blood 
upon gastro-intestinal secretion, since the equation is reduced to its simplest 
form. 
In Experiment 46, a cat, kept in an atmosphere loaded with carbonic 
acid gas, receives hypodermically nearly a grain of commercial veratria, 
and dies 35 minutes after receiving the first £ grain without vomiting, 
and on opening the stomach and bowels, they are found in about a normal 
condition. 
In Experiment 41, two doses of veratria, of grain each, are adminis- 
tered, and the cat is kept profoundly under the influence of the gas; no 
vomiting whatever occurs. Twenty minutes after the last dose and about 
two hours and a half after the first of a grain, the cat is taken out of 
the box, but never sufficiently recovers to be able to stand, or for her pupils 
to become natural. After severe convulsions she is killed, and the stomach 
and bowels are found empty. 
In Experiment 48, a cat, into whom £ of a grain of veratria has been 
injected, is kept in an atmosphere loaded with carbonic acid, and shows no 
signs of vomiting. He then is allowed to breathe fresh air, and as soon 
as he comes pretty well out from under the gas, vomits violently. On his 
being thrust back into the box, the vomiting ceases and does not recur. 
At the autopsy the stomach contains but a small amount of liquid. 
Experiment 49 is very similar to the last. So long as the animal is 
strongly under the influence of the gas the veratria fails to provoke secretion 
and vomiting, which, on the other hand, appear just so soon as the effects 
of the carbonic acid pass off. A lethal dose of arsenic failed to produce 
any purging, although at the autopsy a considerable amount of mucus 
was found in the intestine, showing that secretion had to a certain extent 
been excited. The explanation of this, I think, is to be found in the im- 
perfect narcosis produced. 
The experiment, although placed near the last in this series, was in 
reality the first made, and I had not learned the best way of managing the 
apparatus, and did not keep up the necessary steady flow of the gas. 23 
That the narcosis was not complete was shown by the pinkish colour of the 
lungs and the partially arterialized blood found after death in the left ven- 
tricle. 
The experiments of these series seem to me, when studied one with the 
other, to prove conclusively that an excess of carbonic acid in the blood is 
capable of lessening, and when carried beyond a certain point of altogether 
preventing, in most instances, emesis and purgation. In doing this, the 
poison does not merely arrest the muscular movement necessary to the 
performance of those acts, but actually arrests secretion. This is proven 
by the results of post-mortem examination, for if secretion continued and 
peristalsis was checked, there would be an accumulation of fluid in the 
stomach and bowels such as is said to be seen in certain cases of cholera. 
Moreover, I think the experiments already detailed afford proof that 
the peristaltic action, although in some cases apparently checked by the 
anaesthetic, is not necessarily so. To aid in elucidating this point the 
following experiments were instituted : 
Eighth Series of Experiments. 
Expt. 50.—Feb. 7, 3P. M. Placed in the box a large female cat, pregnant, 
and let carbonic acid flow in freely. Died in about twenty minutes. 
Autopsy within jive minutes after death.—Opened her abdomen first. Peristal- 
tic action of the bowels absolutely wanting ; bowels relaxed, perfectly motion- 
less. When pricked with a knife a local persistent contraction took place, forming 
a depressed constricted ring around the bowel. Pricking gave rise to no true 
peristaltic motion whatever. The constrictions spoken of sometimes lasted 
full two minutes, perhaps more. After between five and ten minutes’ exposure 
to the air, peristaltic action commenced to appear. The cat was then thrown 
out doors, where the temperature was probably about fifty. Fifteen minutes 
afterwards the peristaltic movement was exceedingly active, the bowels worm- 
ing and writhing spontaneously. 
Expt. 51.—Feb. 5. Without in any way injuring it, I placed a young cat, 
apparently about a year old, in the carbonic acid box. After it had lain there 
about half an hour perfectly unconscious, I threw into the box a very rapid 
stream of carbonic acid gas. Kitten died in about 20 minutes. 
Autopsy five to ten minutes after death.—Heart not beating but starting and 
beating a few strokes when vessels were cut across, and the blood choking it was 
allowed to escape. Blood everywhere very black. Peristaltic action of the 
intestines very evident, but rather sluggish. Some spontaneous movements on 
exposure to the air, and a certain, but rather slow and feeble response to prick- 
ing with the knife. 
The experiments which have bearing upon the question of the influence 
of carbonic acid gas upon the peristaltic action of the intestine are then 
Nos. 46, 48, 50, 51. In the first of these the cat had been for half an 
hour in an atmosphere so loaded with carbonic acid that a taper, when 
brought near the box, was extinguished before it entered it from above, 
and dying in such an atmosphere, was examined immediately. In 
spite, however, of the everywhere present black blood, the intestines 
exhibited the most active peristaltic motion I have ever witnessed, con- 
stantly and rapidly writhing and twisting over one another. In Experiment 24 
48 the exposure to the gas was not so prolonged, but it was, if possible, 
more intense, and the cat died, I believe, chiefly of suffocation, and here 
again peristaltic action was very active. On the other hand, in Experi- 
ments 50 and 51, the cats were undoubtedly killed solely by the gas, and in 
the former there was absolute abolition of the vermicular movements until 
after the exposure of the bowels to the air for fifteen minutes, and in the 
other the peristalsis was sluggish, although evident. 
Putting these results together, I do not see how any other conclusion 
can be arrived at than that already mentioned, namely, that lethal poison- 
ing with carbonic acid gas does not in all, or even the majority of cases, 
completely suspend intestinal movements. 
The whole of the experiments, therefore, prove that carbonic acid gas 
in excess in the blood has the power of arresting intestinal secretion. 
It seems well established by the facts and arguments previously adduced, 
that the failure of purgatives after cervical section of the par vagum, is 
not owing to any direct influence which the nerve exerts upon the intestine. 
That section of the nerve is followed by accumulation of carbonic acid in 
the blood is also well known. Taking these facts with the influence of the 
gas upon intestinal secretion just proven, it appears to be a logical infer- 
ence that the impossibility of vomiting or purging after division of the 
nerves, is due to the accumulation of carbonic acid in the blood. My ex- 
periments with the gas, however, showed that in order for it to produce 
absolute arrest of secretion it must be in sufficient quantity to manifest very 
plainly its presence by other than gasiro-intestinal symptoms, such as more 
or less complete unconsciousness. 
Now after division of the pneumogastrics in the neck, the gas does not 
accumulate, at least until near death, sufficiently to do this. It is there- 
fore evident that there must be some other cause or causes aiding it in 
controlling secretion. 
“ Shock” has already been shown to be a probable adjuvant, but is 
apparently not the only one. For its influence would scarcely endure, or, 
if it did, would diminish rather than increase, while the resistance to 
the action of eraeto-cathartics mostly steadily persists until death takes 
place, mayhap several days after division of the nerves. 
In those experiments in which the pleura was opened there was a similar 
arrest of secretion without profound carbonic acid narcosis. 
It therefore being probable that there is some cause for the symptoms 
besides those enumerated, the question naturally arises—ls there any lesion 
to be found which, existing in a marked degree both among the results of cer- 
vical section of the pneumogastrics, in collapse of the lung from wounds, 
and in profound carbonic acid narcosis, is capable of acting efficiently 
in restraining intestinal secretion ? Such lesion I conceive is the great 
interference with the circulation in the lungs, which occurs in each case, 
and, of course, backs the blood upon the right heart, then upon the portal 25 
circulation, and hence tends to prevent intestinal gland-action by producing 
a more or less complete local capillary stasis. This, then, I believe to ba 
a third agency in aiding the arrest of secretion in the bowels after division 
of the cervical pneumogastrics. That it is not the sole cause is evinced by 
the previously detailed experiments upon intestinal absorption, which prove 
conclusively that there is no absolute cessation of circulation in the intestines 
after the operation. 
In conclusion, the results of this protracted study of the subject may be 
summed up as follows : 
First. The division of the cervical pneumogastric does, in the majority 
of instances, but not always, absolutely arrest free gastro-intestinal secre- 
tion, emetics and cathartics being absolutely powerless to produce it. 
Second. That this arrest is not due to any direct influence which the 
nerve has upon the intestine or its circulation, but is owing to two or three 
causes: accumulation of carbonic acid in the blood, interference with the 
circulation of the lungs backing up the blood upon the portal circulation, 
and perhaps shock. 
These things being granted, the, opposite results obtained by Brodie and 
Reid are readily explainable. 
It is well known that in a small proportion of cases division of the 
nerves does not induce the changes in the lungs ordinarily so fatal. In 
such instances there is no great accumulation of carbonic acid in the 
blood, nor is there any backing up of the blood in the pulmonary artery, 
and consequently upon the right heart, and finally portal circulation. 
The secondary results of section of the par vagum—the actual causes of 
the arrest of gastro-intestinal secretion—are therefore wanting in these 
cases ; and I believe it to be in such that emetics and cathartics act freely 
after division of the nerves. The rarity of such cases is the reason why 
those experiments are proportionately so few, in which such drugs act in 
their ordinary manner after the operation.