578 
DE. SANDEESON ON THE INFLUENCE EXEECISED BY THE 
horizontal line denotes an arterial pressure of 5 inches. The rate of breathing was 
11-12 per minute, and of the heart’s contractions 94. It is to be noted that in this 
animal the time occupied by the thoracic movements was greater as compared with the 
duration of the pause. Hence probably the variations of the arterial tracing are less 
abrupt. It is further to be noted that the diastolic interval is shortest a little after the 
commencement of expiration, and longest immediately after its termination*. 
Observation III.— June 13th, 1865 (Plate XXIII. fig. 3). 
The animal employed was a small male English terrier. Experimental method as 
before ; rate of movement 1 inch in six seconds ; arterial pressure 5 inches ; eleven respi- 
rations and seventy pulsations per minute. From the relative length of the respiratory 
intervals and the great regularity of the arterial undulations, the precise relation between 
the two tracings can be determined with great exactitude. 
Observation IV.— May 31st, 1865 (Plate XXIII. fig. 4). 
Animal used, a smooth black male English terrier. In this case a T tube with a very 
wide aperture was employed ; hence the oscillations of the lever were so slight that the 
commencement of inspiration cannot be distinguished. The moment at which the expi- 
ratory act commences and terminates is, however, clearly indicated. Rate of movement 
1 inch in 3*3 seconds; arterial pressure 5 inches; the respirations were more frequent 
than in any of the previous cases, being 32 per minute ; as there were 100 pulsations in 
the same time, three occurred during each respiratory act. Notwithstanding this pecu- 
liarity the relation between the two remained the same ; the highest points in the 
arterial tracing corresponding to the end of expiration, and the diastolic interval imme- 
diately after that event being twice as long as the one preceding itf. 
Observation V. — June 21st, 1865 (Plate XXIII. fig. 5)l 
A male mongrel terrier of good size was employed. Arterial pressure 6 inches (indi- 
cated by horizontal line) ; rate of movement 1 inch in three seconds ; respirations 16, 
pulsations 102 per minute. The tracings exhibit the following peculiarities : — the respi- 
ratory movements were more irregular, and the time occupied by them was greater as 
compared with the pause ; so much so that it several times happened that there was no 
interval at all between expiration and inspiration. The effects of this mode of breathing 
are well seen in one part of the tracing, where two inspiratory descents succeed each 
other almost immediately, in consequence of which a high arterial pressure is maintained 
for several seconds. The irregularities of the respiratory tracing are, so to speak, 
reflected in the arterial, each respiratory undulation having the same duration as the 
arterial undulation which corresponds to it J. 
* The animal was used for other experimental purposes. 
f The animal was further used for an experiment relating to the poisonous effects of carbonic acid. 
+ This animal was subsequently used in an experiment on poisoning by hydrocyanic acid. 
