674 
PROFESSOR H. N. MARTIN ON THE INFLUENCE OF VARIATIONS 
As regards this temperature, the question arose which thermometer to use; that, 
p, in the inflow tube, or that pushed down the left subclavian to the aortic arch. The 
former gave the temperature of the blood flowing through the cavity of the right 
heart; the latter the temperature of the blood in the left auricle and ventricle and 
aorta, and accordingly in the coronary arteries supplying the cardiac capillaries. 
A priori, there seemed little doubt that it would be the temperature of this latter 
blood, brought as it was into close relation with every muscle fibre and ganglion cell 
in the heart, which would exert an influence on the cardiac rhythm, if any did. 
Experiment soon confirmed this. Both thermometers were read in several experi¬ 
ments, and it was always found that the pulse-rate changes followed much more closely 
the variations of temperature indicated by the instrument in the subclavian. In 
most cases, accordingly, only the reading of this thermometer was undertaken, as 
it was very desirable to reduce to a minimum the time during which the door of the 
warm chamber was open. 
The temperature observed was written on the kymograph paper over the tracing, 
along with the time at which the latter had been taken. After a pause, another 
tracing was taken, time and temperature noted as before, and so on throughout the 
experiment, which was usually continued until the heart began to show symptoms of 
weakened or abnormal action. 
The roll of tracings was subsequently gone over carefully, and on the graphic 
record of each observation periods of twenty seconds marked out; the pulses during 
that time were counted, and the mean arterial pressure measured. The results 
were then put in tabular form, the actual pulses counted being multiplied by three, 
so as to give the rate per minute instead of the number of beats in twenty seconds. 
In the “detailed results” given below, six such tables are printed; as curves 
present very quickly and accurately to the apprehension the general outcome of long 
columns of figures, charts have also been constructed (Plate 49) giving the 
curves of temperature variation and pulse-rate change during two of these experi¬ 
ments. 
Detailed results of experiments. 
Before proceeding to the following tables, which give the actual figures as to pulse- 
rate and temperature for several experiments, a few words of explanation are desirable 
with reference to some three or four points. 
First, it will be noted that for normal temperatures (38-39° C. in the left 
ventricle of the Dog, according to Claude Bernard) (10) the pulse is very fast. This 
is undoubtedly due to the section of both pneumogastrics, cutting off the heart from 
control by the extrinsic cardio-inhibitory centre, which is normally very active in the 
heart of the Dog. Upon atropin paralysis of the peripheral pneumogastric connexions 
with the heart V. Bezold and Blcebaum (5) found in this animal the pulse-rate 
