[From The Johns Hopkins Hospital Bulletin, No. G, July, 1890.] 
REPORT OF DR. WELCH’S REMARKS AND EXHI- 
BITION OF SPECIMENS OF ANIMAL PARASITES 
AT THE MEETING OF THE JOHNS HOPKINS 
HOSPITAL MEDICAL SOCIETY, ON MARCH 17th, 
1890. 
Dr. William IT. Welch exhibited gross and microscopical specimens of 
entozon which he had found in domestic animals in Baltimore. These para- 
sites had been collected during the last two years as opportunity offered, no 
attempt having been made to have the collection complete. Dr. Welch said 
that the interest in animal parasites had been overshadowed of late years 
by the study of the pathogenic bacteria, but nevertheless the entozoa are 
of great interest and importance and deserve our careful attention. 
The following is a list of the parasites exhibited, all of which were found 
in Baltimore: 
1. From the Horse: 
Spiroptera Megastoma (or Filaria Megastoma). Stomachs were exhi- 
bited showing the honey-combed submucous tumors, with ulcerated 
mucosa, containing the large-mouthed maw-worms. This parasite 
is not very rare in the horses of this region, but in none of the cases 
in which it was found by Dr. Welch was there evidence that it had 
materially damaged the usefulness of the animal. 
Strongylus Armatus. Several specimens, gross and microscopical, of 
verminous aneurism of the anterior mesenteric artery were shown. 
The interesting histological changes caused by the presence of the 
palisade worms in the blood-vessels were explained and illustrated 
by microscopical sections. This parasite with the resulting aneu- 
risms is common in the horses of this region. In one instancy it 
had caused fatal colic. 
Gastrophilus Equi. A stomach, the mucous membrane of which near 
the cardia was completely covered with bots, was presented. 
2. From the Cow: 
Actinomyces Bovis. Although this is a vegetable parasite, the oppor- 
tunity was taken to show a number of specimens of actinomycotic 
tumors from the jaws and other parts of the cow. On account of 
the absence of any satisfactory laws regulating the inspection of 
meat in this State, the number of cattle affected with actinomyces 
brought to Baltimore and slaughtered here for the market is unusu- 
ally large and there is rarely any difficulty in procuring specimens 
of this disease. Attempts had been made to cultivate the organisms 
according to the directions given by Bostrom but without success. No instance in which the actinomyces had been found in human 
beings in Baltimore has been recorded. 
Cysticercus Taeniae Mediocanellatae-—found once in heart-muscle of cow. 
Strongylus Micrurus. A number of cases of verminous bronchitis and 
pneumonia in calves due to this parasite had been observed and 
microscopical sections of lungs so affected were shown. 
Filaria Labiato-papittosa (Alessandrini). This worm was found free on 
the peritoneal surface of a cow without causing any apparent injury. 
3. From the Sheep: 
Taenia Fxpansa—found in the small intestine. Common. 
Strongylus Contortus—found in large numbers in the stomach of several 
sheep which had died at Druid Hill Park without other apparent 
cause of death. 
4. From the Hog: 
Echinococcus. Echinococci were found in several hogs which had 
been born and reared in the neighborhood of Baltimore, but this 
parasite is not common in this region. Sections of liver were shown 
illustrating every stage of development of this bladder-worm from 
cysts smaller than a pea up to cysts as large as an orange. The 
taenia echinococcus produced by feeding the cystic worms to a dog 
was shown. 
Cyslicercus Cellulosae. The pork-measle had been found in only a few 
instances. 
Echinorhynchus Qigas. This worm is common in the swine of this 
region and appears to be common throughout the United States. 
The ulcerated and necrotic patches in the inner wall of the small 
intestine caused by the attachment of the thorn-headed worm, bear 
some resemblance to the necrotic foci resulting from hog cholera. In 
only one instance had the gut been actually perforated by this worm. 
Trico-cephalus Crenatus—very common in the coecum. 
Ascaris Suilla, believed by many to be identical with the ascaris 
lumbricoides, was not very often met with. In one case the small 
intestine for a distance of 40 cm. was found packed full of ascarides, 
. but there were no evidences of intestinal obstruction and it is 
questionable whether this accumulation of the worms, so as appar- 
ently to obstruct the gut, is not a post-mortem occurrence. 
Sclerostoma Pinguicola (Verrill), believed to be identical with Steph- 
anurus Dentatus (Diesing), although this identity is not absolutely 
certain. This interesting worm was found in the abdominal adipose 
tissue and in the liver. As the presence and mode of migration of 
this parasite in the liver of swine have not hitherto been described, 
Dr. Welch showed a number of specimens making these points clear. 
The sclerostoma pinguicola was found in the livers of eleven swine, 
and, while not very frequent, cannot be considered a rarity in this 
situation. It is found, often in large numbers, in the main trunk 
and branches of the portal vein, which then usually contain parietal 
or occluding thrombi in which the worms are imbedded. The real habitat of the worm is, however, the connective tissue around the 
portal vessels. In this tissue it burrows its way, producing inflam- 
matory masses of new connective tissue rich in leucocytes. On 
section of the liver, nodules and bands with sinuous cavities con- 
taining a brownish or reddish white purulent fluid are observed. 
Similar nodules are also visible projecting on the surface of the 
liver. In these sinuous cavities the parasite may be found, or it may 
be absent, having made its way to other parts. The worm finds its 
way into the portal vessels by ulceration from the peri-portal tissues 
through the walls of the vessels, and in several instances the worm 
could be demonstrated partly within and partly without the vein. 
Before actual penetration into the vein there occurs a bulging 
inward of the vessel wall on which forms a thrombus composed 
primarily of blood plates. One of the most interesting histological 
changes produced by the invasion of this parasite into the liver is 
an extensive new growth of the mucous glands in the walls of the 
bile ducts. This new growth occurs in the areas of newly formed 
connective tissue in the neighborhood of the parasites. Actual 
adenomatous formations of undoubted parasitic origin are produced 
in this way. The same alteration has been recently described and 
pictured by Schaper in connection with distomatosis of the liver 
(Deutsche Zeitschrift fur Thiermedecin, Bd. xvi, p. 1). On 
sections of the worms, as found in the liver, leucocytes with well- 
stained nuclei, resembling those in the fluid of the cavities contain- 
ing the worms, can be seen in the intestinal canal of the worm, but 
whether this can be interpreted as evidence that the pus cells pro- 
duced by the presence of the worm actually serve as its food is un- 
certain. Sometimes the lesions of the liver, which have been 
described, were extensive, the surface and interior of the organ 
presenting a large number of parasitic foci, and it would seem as if 
such an extent of the disease must be injurious, but no cases were 
observed in which the death of the animal could be attributed to 
the presence of the sclerostoma pinguicola. The identity of the 
parasite as found in the liver and as found in the well known foci 
in the abdominal fat tissue was demonstrated. Instances in which 
the main trunk of the portal vein as it enters the liver was com- 
pletely occluded by a thrombus containing the sclerostomata were 
exhibited. 
Strorujylus Paradoxus. This strongyle is extremely frequent in 
the bronchi of swine in this region. Its presence was found 
to be the direct cause of death in three pigs. In these cases 
the trachea and bronchi contained an almost incredible num- 
ber of strongyles, so that on sections of the lung, the medium- 
sized and small bronchi appeared filled with worms. The 
strongylus paradoxus is usually associated with some bron- 
chitis and often with broncho-pneumonia, but it may be pres- 
ent, even in large numbers, without either bronchitis or pneu- 
monia. In fact in one of the fatal cases mentioned in which the strongyles appeared to fill the medium-sized and small bronchi and 
were present in enormous numbers in the trachea and large bronchi 
there was no trace of pneumonia and scarcely any bronchitis. The 
animals suffered from extreme dyspnoea and the heart pulsated so 
violently as to be visible at a distance and to communicate its mo- 
tion to the entire thorax. At the autopsy the right ventricle was 
hypertrophied. The favorite habitat of the worms when present 
only in moderate number is in the bronchi in the posterior part of 
the caudal lobes, and sometimes their number is so small that con- 
siderable searching is required to detect them. There is usually a 
little muco-pus in the bronchi where the strongyles are lodged even 
when there is no general bronchitis. The adjacent lung parenchyma 
is often emphysematous or on the other hand it may be simply 
atelectatic or it may be the seat of a broncho-pneumonia. Frequently 
there is broncho-pneumonia of the ventral lobes when the worms 
are to be found only in the posterior parts of the caudal lobes. The 
broncho pneumonia associated with the strongylus paradoxus ap- 
pears as a brownish or grayish red consolidation in which the in- 
dividual lobules and lobulettes can be felt and seen as nodules. The 
affected part is not much swollen and there is generally no pleuritic 
exudation. On microscopical section the air cells contain leucocytes, 
epithelioid cells, sometimes fibrin and red blood-corpuscles and 
frequently ova of the strongyles. These ova are often partly or 
completely enclosed within giant cells. By a combination of Weigert’s 
fibrin stain and picrocarmine very beautiful pictures in which the 
ova are stained blue and the cells red and yellow with picrocar- 
mine can be obtained. A very instructive lesson in embryology is 
furnished by the ease with which all stages of development of the 
ova from the simple cell up to the developed embryo worm can be 
followed in these preparations. 
5. From the Dog: 
Taenia Oucumerina. This is by far the most common tapeworm of the 
dogs used for experiment in the laboratory, being found in 60 per 
cent, of these animals. 
Taenia Serrata. Specimens produced by feeding dogs the cysticerci 
pisiformes from the rabbit were shown. 
Taenia Echinococcus was found only in dogs artificially fed with the 
echinococcus from the hog. 
Eustrongylus Gigas. A specimen of this worm, 95 cm. long, was found 
free in the peritoneal cavity of a dog and was exhibited. It had 
been found three times in this situation in dogs used for experiment 
in the laboratory. 
Strongylus or Dochmius Trigonocephalies ( Uncinaria Trigonocephala) was 
found in the small intestine of 70 per cent, of the dogs used in 
the laboratory, a much larger proportion than has hitherto been 
observed. The head of the worm was often found imbedded in the 
mucous membrane and surrounded by a small extravasation of blood. Sometimes scanty, it was in many cases found in large numbers. 
Positive evidence that the parasite was the cause of anamiia in the 
animals could not be found. It was occasionally met with in the 
stomach as well as in the small intestine. 
Tricocephalus Depressiusculus appears to be a constant inhabitant of the 
dog’s coecum. 
Ascaris Marginata (doubtless a variety of Ascaris mystax) was found in 
only a few cases. It was found both in the stomach and small intestine. 
The filaria immitis was not met with in any of the dogs used in 
the pathological laboratory and is not common in this region. It, 
however, occurs here as it has been observed occasionally in the 
Biological Laboratory of the Johns Hopkins University. 
6. From the Rabbit: 
Ooccidium Oviforme was present in the liver of one-third of the rabbits 
used for experiment in the laboratory. Coccidia are also common in 
the intestines of rabbits. Attention was called to the existence of 
small, opaque, grayish-white patches, suggesting somewhat a super- 
ficial necrosis, on the surface of the mucous membrane of the small 
and the large intestine. These patches contain large numbers of 
coccidia, often enclosed in epithelial cells. 
Chjsticercus Piriformis is common in the peritoneal cavity. Specimens 
were shown illustrating the nodules and scars caused by the migra- 
tion of this parasite through the rabbit’s liver. 
From the rat and cat were shown respectively the cysticercus fasciolar is in 
the liver and the taenia crassicollis in the intestine. 
No instance of distoma in the animals examined was discovered and in 
general distomatosis of domestic animals appears to be rare in this region. 
Through the kindness of Prof. Brooks, Dr. Welch was in the possession of 
a number of living water snails, many of which were infested with cercaria 
and living specimens of these interesting forms in the life history of distoma 
were exhibited under the microscope. These snails were obtained in the 
neighborhood of Baltimore, so that opportunity for infection with disto- 
mata is present here. REPORT OF DR. WELCH’S REMARKS ON THE 
DIPLOCOCCUS PNEUMONIAE AT THE MEET- 
ING OF THE JOHNS HOPKINS HOSPITAL MED- 
ICAL SOCIETY, ON FEBRUARY 17th, IS DO. 
Dr. William H. Welch reported results of liis bacteriological examinations 
of cases of acute croupous pneumonia, and exhibited cultures and micro- 
scopical specimens of the micro-organisms found in these cases. In all of the 
cases examined, ten in number, the Diplococcus Pneumoniae was found and 
isolated in pure culture. This organism is probably constantly present in 
croupous pneumonia, and the evidence that it is the specific cause of this 
disease is very strong. In the cases examined by Dr. Welch, roll cultures 
or plate cultures were made from the affected parts of the lungs, from the 
spleen, from complicating lesions and frequently from the blood and other 
situations. Nutrient agar, glycerine agar and gelatine agar, according to 
Guarnieri’s formula, were the media usually employed for this purpose. 
The growth of the pneumo-coccus on the last named medium is particularly 
luxuriant. In addition mice and rabbits were inoculated with bits of hepa- 
tized lung, with the spleen, etc. In one instance the presence of the pneumo- 
coccus would have been overlooked in consequence of the prevalence of 
other organisms, if the precaution had not been taken to inoculate animals 
with the tissues. Dr. Welch expressed the opinion that the diplococcus 
pneumoniaj could not be said to be absent simply on the ground of negative 
results from cultures. This result must be controlled by the inoculation 
of susceptible animals. Moreover, even the failure to kill mice and rabbits 
by inoculation can not be considered conclusive evidence of the absence of 
the diplococcus pneumoniae, for this organism may be present in the human 
body in cases of croupous pneumonia in a form incapable of killing rabbits 
or even mice. 
One of the most interesting and extraordinary properties of this organism 
is the variation in its virulence when tested upon animals. All who have 
experimented with cultures of the diplococcus pneumoniaj have called 
attention to its rapid loss of virulence when cultivated in artificial media. 
It is important to note that a progressive diminution of virulence may occur 
likewise in the lungs and other organs where the pneumo-coccus is present 
in cases of croupous pneumonia. In one case of croupous pneumonia dying 
in the stage of grey hepatization Dr. Welch found very numerous colonies 
of the diplococcus pneumoniae, mixed with a few colonies of the staphylo- 
coccus aureus in agar plate cultures from the consolidated lung. A rabbit 
inoculated with a piece of the lung died on the fifth day with extensive local 
reaction and large spleen. The pneumo-cocci were abundant near the seat 
of inoculation, and were found in considerable number, although fewer than 
usual, in the blood. Plate cultures (agar) made from the swollen spleen (after burning thoroughly the surface) of this patient showed in very large 
number, colonies of the pneumo-coccus. No other species of organism was 
present in these cultures from the spleen. The same pneumo-coccus was 
likewise observed in cover-glass preparations from the fresh spleen. The 
organism isolated from the spleen conformed in every particular as regards 
its morphology, its behavior in artificial culture media, its short vitality, its 
color-reactions to the pneumo-coccus found in the lung, the so-called 
Fraenkel-Weichseljaaum pneumo-coccus. Nevertheless it was devoid of its 
customary virulence, for a mouse and a rabbit inoculated subcutaneously 
with a bit of the spleen survived, and mice and rabbits inoculated with pure 
cultures of the organism likewise survived, the only reaction being a small 
abscess or purulent infiltration of the tissues at the point of inoculation. In 
this case, therefore, the diplococcus pneumoniae was present in large numbers 
in the hepatized lung in a weakened state as regards its virulence, and 
in the spleen in a condition incapable of killing rabbits and even mice. 
Every grade of virulence was observed in the pneumo-cocci found in the 
different cases, from the degree just described as incapable of killing mice 
and rabbits up to the degree in which rabbits were killed in 36 to 48 hours 
by an acute septicaemia. In two cases the pneumo-coccus did not kill rab- 
bits but it did kill mice, so that the latter animals are more susceptible and 
are to be preferred for inoculating tissues in cases of croupous pneumonia. 
In three cases rabbits survived the inoculation for more than five days, the 
longest duration being twelve days. Inoculation of rabbits with exudation 
present in the bronchi or in the trachea sometimes caused a rapidly fatal 
sputum-septicaemia even when the pneumo-coccus present in the hepatized 
lung showed weakened virulence. In general the impression was obtained 
that the most virulent forms of pneumo-cocci are to be found in the sputum, 
in the freshly hepatized lung or at the margin of an advancing pneumonia, 
whereas the pneumo-cocci present in advanced stages of hepatization and in 
the spleen are likely to be less virulent. This progressive diminution in 
virulence, as tested upon animals, of the pneumo-coccus in the consolidated 
lung and other organs in cases of croupous pneumonia is surely a significant 
circumstance. In no instance had Dr. Welch as yet been able to isolate 
the pneumo-coccus in a state capable of producing pneumonia in dogs, 
although not less than 5 cc. of a bouillon culture 24 hours old (in the ther- 
mostat at 37° C.) of the pneumo-coccus, obtained from a rabbit dead 40 hours 
after inoculation, had been injected directly into the lung. Other observers, 
however, had obtained positive results by this method of inoculation. 
Others have found pneumo-cocci producing more rapidly fatal septicaemia 
in rabbits than resulted from any of the cultures obtained from the cases 
examined by Dr. Welch. 
In six of the ten cases the diplococcus pneumoniae was found in pure culture 
in the hepatized lung as determined by microscopical examination and by 
plate or roll agar cultures; in two cases it was present in combination with 
the Staphylococcus pyogenes aureus; in one case, in addition to the pus sta phy- 
lococci, the streptococcus pyogenes was present in considerable number; 
and in one case with gangrenous foci there were present, besides the diplo- 
coccus pneumoniae and the pus staphylococci, a short oval bacillus and a long slender bacillus not developing in plate cultures (aerobic cultures). In one 
of the cases in which the staphylococcus pyogenes aureus was present, sev- 
eral small abscesses had formed in the hepatized lung. In four cases the 
diplococcus pneumoniae was found in pure culture in the spleen, which in 
all of these instances was swollen and soft; in one case it was isolated from the 
kidney and in one from the heart’s blood. Tn all instances (five) in which the 
pleuritic exudate accompanying acute croupous pneumonia was examined 
by culture methods, the diplococcus pneumoniae was found in this exudate. 
In three cases of empyaema following acute croupous pneumonia (these do 
not belong to the ten cases now under consideration) the diplococcus pneu- 
moniae was found ; in two in pure culture, in one in combination with staphy- 
lococcus pyogenes aureus and albus. The pneumo-bacillus of Fried lander 
was not found in any case. 
Dr. Welch described the morphology and behavior in culture media of 
the diplococcus pneumoniae. He had found that a convenient way of staining 
the capsules was to treat the cover glass specimens, dried and treated in the 
usual way, with glacial acetic acid and then without washing off the acid to 
drop on the cover glass aniline-oil gentian-violet, which can be allowed to 
drain off and can be renewed two or three times. Attention was called to broad 
pale rods corresponding to empty capsules sometimes found in the fluid of 
empyaema following pneumonia. These may be 10-30 mm. long and 2-3 mm. 
broad. They stain faintly, may be entirely empty or may contain one or more 
deeply stained pneumo-cocci. They correspond to the capsular substance 
abound rows of pneumo-cocci, the cocci having partly or wholly disappeared. 
For staining sections, Weigert’s fibrin stain had given most excellent 
results. A method which had yielded good and quick results was to dry 
thin frozen sections from the fresh organs upon the slide and then to heat 
them for half an hour at a temperature of 110° to 115° C. These can then 
be stained like cover-glass specimens. This method is often employed in 
the laboratory for staining fresh tissues in general for micro-organisms. 
The statements of Fraenkel and others were confirmed as to the behavior 
of the diplococcus pneumoniae in artificial culture media, its susceptibility 
to slight changes in the reaction and composition of the medium, its brief 
vitality, etc. As already mentioned, Guarnieri’s gelatine-agar medium was 
found to be particularly suitable. 
The history of our knowledge of this organism from its discovery by 
Sternberg in September, 1880, up to the present time and the results and 
conclusions reached by the various investigators of its relation to croupous 
pneumonia were briefly reviewed. The frequent presence of the pneumo- 
coccus in the saliva of healthy persons is upon the whole an assistance to us 
in the explanation of the various factors concerned in the causation of 
croupous pneumonia.