MOVEMENTS OF RESPIRATION ON THE CIRCULATION OF THE BLOOD. 579 
Observation VI. — May 30th, 1865. 
The animal used was a large-sized male mongrel terrier. Eate of movement 1 inch 
in 3'3 seconds; arterial pressure 5 inches; respirations seventeen, pulsations seventy-six 
per minute. From the irregularity of the respiratory movements it is more difficult to 
make out the relation between the two tracings, which, however, is in conformity with 
previous observations. Those inspirations which were deepest and longest produced the 
most marked effect*. 
Observation VII. — June 20th, 1865. 
The animal used was of the same description as in the last experiment. Eate of 
movement 1 inch in 3’3 seconds ; arterial pressure 5 inches ; respirations twenty to 
twenty-two, pulsations sixty per minute. In this animal the variations of arterial 
pressure were very slight ; but as regards the diastolic intervals the facts of previous 
observations were confirmedf . 
Observation VIII. — June 17th, 1865. 
A female mongrel cur of moderate size was employed. Eate of movement 1 inch in 
three seconds ; arterial pressure 5 inches ; twenty-one respirations and fifty-eight pulsa- 
tions per minute. In this animal the respiratory movements were unusually frequent as 
compared with the contractions of the heart. Occasionally the cardiac and respiratory 
intervals are shown in the tracings to be nearly equal, in which case it is obvious that 
the thoracic movements could not produce any effect on the variations of arterial pres- 
sure. If, however, the respiration was retarded, the usual variations manifested them- 
selves, as is well seen in the second part of the tracing, where the frequency of the pulse 
happens to be twice as great as that of the breathing. The diastolic interval which 
follows inspiration is here found to be not more than half the length of that which 
coincides with it. Again, towards the end of the observation, where the animal is seen 
to have sighed deeply, a succession of short diastolic intervals with increasing arterial 
pressure is seen to follow the expansion of the chest, and to be of corresponding duration 
Observation IX.— June 24th, 1865. 
A male cur was employed in this experiment. Eate of movement 1 inch in three 
seconds ; arterial pressure 5 inches ; respirations nineteen, pulsations ninety-six per 
minute. The influence of the thoracic movements on the arterial pressure was not 
marked, excepting when the inspirations were deeper than usual. It is worthy of notice 
that there was a distinct pause between inspiration and expiration, as illustrated in the 
first part of the tracing, which serves to show that the expiratory act, unless it is unna- 
turally forcible, is without effect on the arterial pressure §. 
* The animal was further used for other experimental purposes. 
t The animal was subsequently used in an experiment as to the toxic effects of hydrocyanic acid. 
t This animal was further used for an experiment as to the influence of strychnia on the thoracic movements. 
§ The animal was subsequently employed for an experiment as to the toxic effects of hydrocyanic acid. 
MDCCCLXVII. 4 K 
