The Circulation 
OF THE 
Blood in the Orbit 
STUDIED BY MEANS OF THE 
Plethysmograph. 
By F. W. ELLIS, M. D., 
Springfield, Mass. 
Reprinted from the Boston Medical and Surgical Journal 
of April 21st, iSSj. 
BOSTON : 
CUPPLES & COMPANY, Pum.iSHERP; 
No. 94 Boylston Street, 
1887. THE CIRCULATION OF THE BLOOD IN THE 
ORBIT STUDIED BY MEANS OF THE PLE- 
THYSMOGRAPH. 
The vascular system of the orbit may be consid- 
ered as an appendage of that of the cranial cavity. 
The ophthalmic artery is given off at the base of the 
brain, and the ophthalmic vein may be regarded as 
the commencement of the cavernous sinus. The cir- 
culation in the orbit is, therefore, intimately con- 
nected with that of the brain. 
The circulation of the blood in the brain is sub- 
jected to peculiar conditions. The cranial cavity of 
the adult is inextensible, and practically filled with 
fluid. A certain amount of this fluid must be ex- 
pressed from the cavity at the time when a new supply 
of blood enters it. The blood finds a sudden obstacle 
to its free propulsion when it passes into the cranium. 
This increased resistance that the blood encounters 
expresses itself in a very marked manner in the 
pulse-tracing of the brain. 
Mosso 1 made an elaborate series of experiments 
with individuals who had lost portions of the skull 
either from accident or disease. He employed the 
graphic method in these investigations, and was 
thereby enabled to obtain permanent records of the 
circulation of the brain. Upon inspecting the numer- 
ous tracings published by him one is forcibly struck 
by the peculiar form of the pulse-curve, which is very 
dissimilar to that of ordinary sphygmograms obtained 
BY F. W. ELLIS, M.D., SPRINGFIELD, MASS. 
1 Sulla Oircolazione del Sangue nel Cervello dell’Uomo. 2 
from peripheral arteries. In many of Mosso’s exper- 
iments, the circulation of the arm was recorded at the 
same time as that of the brain. The arm was enclosed 
in a plethysmographic apparatus, which Mosso calls a 
hydrosphygmograph, and has been extensively em- 
ployed by him in studying the local variations of the 
pulse.2 
Fig. l. 
Figure 1 is a reproduction of a portion of one of the 
illustrations in Mosso’s work, “ The Circulation of the 
Blood in the Brain.” The upper tracing is that of the 
arm obtained with the hydrosphygmograph, the lower 
that of the brain. The striking differences in the char- 
acters of the two tracings are very apparent. In the 
plethysmogram of the arm, the secondary undulations 
all occur in the descending portion of the pulse-curve, 
and the pulse is, according to Landois, catacrotic. In 
the brain-tracing, however, the secondary undulations, 
all occur in the ascending portion of the pulse-curve ; 
the pulse is, therefore, anacrotic. In many of Mosso’s 
2 Die Diagnostik des Pulses, Leipzig, 1879. 3 
illustrations, the projecting point between the two 
notches in the pulse-curve of the brain occupies a 
higher level than the remaining portions of the curve. 
Mosso calls this the tricuspid form. 
The apparatus employed by Mosso to record the 
circulatory changes within the skull was a simple one. 
A piece of gutta-percha was made to cover the part of 
the skull where there was a loss of substance. The 
centre of the piece was perforated with a glass-tube 
connected by means of rubber-tubing with a Marey’s 
drum. The lever of the drum recorded the circula- 
tory changes upon smoked paper covering a revolving 
cylinder. By means of this simple apparatus used in 
conjunction with the arm plethysmograph, a series of 
very interesting experiments were made upon the 
effects of different psychical conditions upon the circu- 
lation of the brain. 
Several investigators have endeavored to record the 
intracranial circulation in animals, removing a portion 
of the skull of the animal experimented upon by 
means of the trephine. The experiments of Fredericq8 
are among the latest and most successful in this direc- 
tion. He obtained pulse-curves, in experimenting 
with dogs, quite comparable to those recorded in 
Mosso’s experiments with the human subject. 
It occurred to the writer that it would be of consid- 
erable interest to record the circulation of the orbit. 
The physiological importance of the subject is appar- 
ent. The circulation of the orbit is so intimately con- 
nected with that of the brain that there would seem 
to be great liability of circulatory changes in the 
larger cavity affecting the blood-supply of the smaller. 
If it could be proven that psychical changes affect the 
circulation of the orbit in the same way as they have 
3 La Courbe pletbysmograpliique dn Cerveau du Oliien, Travanx du 
Laboratoire, TJniv. de Liegfe, Tome 1, 1885 and 1886. 4 
been shown by Mosso to express themselves in the 
records of the circulation in the cranial cavity, then a 
very important advance in the means of investigating 
the physiology of the cranial circulation in the human 
subject would be made. Direct investigation of the 
cranial circulation can only be made in the adult upon 
persons who have lost portions of the skull. Such 
subjects are rare, and opportunities to utilize them for 
experimental purposes rarer. The orbit, however, is 
always accessible. 
For the purposes of this investigation, it was neces- 
sary to have apparatus much more delicate than that 
employed by Mosso. The blood-supply of the orbit is 
brought through an artery only a millimetre in diam- 
eter. I therefore employed some forms of apparatus 
that I had devised for very delicate physiological 
work.4 This apparatus is the piston-recorder for air 
connections, and the ether piston-recorder. For the 
purposes of this article it is not necessary to give a 
minute description of this exquisitely delicate appara- 
tus. I hope to do this in a future article, treating of 
the finger plethysmograph and its applicability to 
clinical research. 
The experiments were performed as follows: A 
piece of gutta-percha, five millimetres in thickness, was 
accurately moulded to the portion of face surrounding 
the orbit, after previous softening in warm water. A 
hole was made in this in a part corresponding to the 
centre of the orbit. A short glass-tube was fixed her- 
metically to this aperture. The gutta-percha shield 
was securely bandaged over the orbit, and the glass- 
tube in its centre was put in communication with the 
piston-recorder by means of a rubber-tube. If there 
is no leakage of air beneath the shield, which, with 
proper care, may be obviated, it is easy to obtain a 
4 Journal of Physiology, Vol. VII, p. 309. 5 
record upon smoked paper of the circulatory changes 
in the orbit. The most striking feature of these 
records is the peculiar shape of the pulse-curve. The 
curve is anacrotic, the secondary undulations appear- 
ing in the ascending portion and vertex. In order to 
greatly magnify these curves, I employed the ether 
piston instead of the ordinary form, and recorded its 
excursions by photography according to the method 
Fig. 2. 
described by me in the Journal of Physiology.6 Fig- 
ure 2 is a somewhat reduced reproduction of the out- 
line of one of the records obtained. The very marked 
similarity of the form of the pulse-curves in this 
record to that of the brain-tracing in Figure 1, is 
very apparent. This tracing is entirely different from 
one taken from the carotid in the neck or from any 
peripheral bloodvessel. It shows very clearly how 
intimately the circulation of the orbit is related to 
that of the cranial cavity. The peculiar form of the 
5 Vol. VII, p. 314. 6 
pulse-curve may also contribute in a measure toward 
the advancement of our knowledge of vascular physi- 
ology in general. The purpose of this preliminary 
account of these researches is to call attention to the 
exceeding delicacy of the methods employed, and to 
record the interesting fact that the pulse-curve of the 
orbit is very similar to that of the brain. The subject 
should be of interest to ophthalmologists as well as 
physiologists. The researches to be made with the 
apparatus and methods employed in these experiments 
will naturally tend in two directions : first, to gain, so 
far as possible, information of the cerebral circula- 
tion ; secondly, to ascertain to what extent the condi- 
tion of the circulation of the eye is indicated in the 
general record of the orbital tracing.