Pulse Eate. 319 



here some examples of that increasing irritability of the heart observed in 

 Sucei (4) and Cetti (7) during their longer fasts. In all cases sudden 

 changes in muscular activity, even though slight, noticeably affected the rate. 



It should be noted that there was an increase in the pulse rate in all experi- 

 ments in which food was ingested. 



The relation between pulse rate and internal muscular work is more fully 

 discussed in a succeeding paragraph/ 2 where it is pointed out that the pulse 

 rate is a remarkably good index of the degree of internal muscular activity. 

 This is especially true when comparing different days of the same experiment 

 with the same subject. It still remains a fact, however, that some subjects, 

 notably A. H. M. (experiment No. 81), have an unusually low pulse rate, while 

 others, as for example, S. A. B. (experiment No. 77), have a very much 

 higher pulse, although it should be borne in mind that all the subjects were 

 living under conditions assuring approximately the same muscular activity. 



The study of the pulse rate, especially with the Fitz pneumograph, shows 

 marked variations when the sleeping and waking hours are compared. But as 

 this study of the pulse rate was only secondary to the securing of the heat 

 measurements and of chemical data, the records are not sufficiently complete 

 to permit careful consideration of the fluctuations in pulse rate from hour to 

 hour and day to day. In subsequent experiments it is hoped that observations 

 may be taken at sufficiently frequent intervals to show the relationship between 

 the pulse rate, respiration rate, and body temperature, and thus permit of a 

 strict comparison of the three factors. 



An examination of the changes in the pulse rate as the experiment progresses 

 shows that in the longer experiments, especially those with S. A. B., the pulse 

 rate almost invariably decreased as the fast progressed. In the majority of the 

 short experiments on the contrary, the pulse rate was greatest on the second 

 day of the experiment. From the observations during the 3 nights the 

 deduction may be made that there was a marked tendency for the rate to 

 increase from day to day. 



The pulse rates, then, are of specific value in this discussion only as 

 indicating the varying degrees of muscular activity on the different days of the 

 same experiment. 



There was no opportunity to study the character of the pulse in the experi- 

 ments made in this laboratory other than the occasional observations of the 

 attending physician. 



22 See p. 487. 



