PHYSIOLOGICAL EFFECTS 
153 
after each experiment showed that there was a sufficient supply of oxygen 
to meet the needs of the subject. 
The observations of the pulse-rate in the experiments in which this 
collapse occurred are particularly noteworthy, the pulse rising in at least 
one experiment from 124 to 184 per minute inside of 2 minutes. Although 
the unusual conditions under which these pulse-rates were obtained do not 
make for the highest degree of accuracy, the records are not far from the actual 
values at the time the observations were made, as special care was taken to 
secure accurate records. 
PULSE-RATE. 
The intimate relationship between the pulse-rate and the muscular ac- 
tivity, or the degree of muscular rest, which has been observed so frequently 
in this laboratory not only with normal individuals but with pathological 
cases, with athletes and, indeed, with infants, emphasizes the importance of 
securing accurate records of the pulse-rate as an integral part of each experi- 
ment. When the subject is lying quietly on the couch, this may readily be 
done by means of a Bowles stethoscope lightly attached to the chest. During 
severe muscular work, however, these records were much more difficult 
to secure, and counts were therefore made of the radial pulse. When the 
subject rode at a high rate of speed with considerable lateral motion, accurate 
records even of the radial pulse were difficult to make so that only an experi- 
enced observer could be relied upon for these; accordingly, the records of 
the radial pulse were almost invariably taken by one of us (E. P. C). Un- 
fortunately, while the values obtained for the rest periods and subsequent to 
the work give admirable indications of the pulse-rate of the subject when at 
150 
140 
130 
120 
110 
100 
90 
80 
70 
60 
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10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 
Fig. 6. — Curves showing the pulse-rate when the external muscular work was 
equivalent to 1.05 calories per minute. 
rest, those taken during work, especially if the work were of a high intensity, 
were of necessity more intermittent and can only be looked upon as general 
indices of the rate of the heart-beat. It soon became apparent that the pulse- 
