PULSE-RATE. 415 



records for this position obtained in connection with the portable 

 respiration apparatus. These values, which are entered in column d 

 of table 93, are more irregular than the others in that they were not 

 secured for all the men. As a matter of fact, the average values found 

 with the squads by the two methods are strikingly uniform on February 

 3 and January 6, but on January 28 an average pulse-rate of 61 was 

 secured in the standing experiments with the portable respiration 

 apparatus, as compared with an average of 54 for the standing values 

 obtained before the walking experiment. Somewhat wide variations 

 are noted in individual cases, particularly with Ham on January 6, 

 when the pulse-rate standing with the portable apparatus was 80 and 

 just prior to walking on the treadmill was 95, and with Sne on the same 

 day with pulse-rates of 89 and 69. 



While the increment due to standing over lying is practically the 

 same, both with the normal diet and with the reduced diet, a much 

 lower pulse-rate prevails with Squad B on the reduced diet than with 

 the normal diet. In other words, the general depressing effect on the 

 heart action of the reduced diet obtains even with the moderate strain 

 of the standing position prior to walking. 



In footnotes with table 93 values are recorded which were obtained 

 with McM on the normal diet day (January 6) and for Lon on the day 

 with reduced diet (January 28). It is perhaps of significance that the 

 increment due to standing over lying is with these two men the average 

 of practically all the others. The standing values with McM were 

 obtained under both conditions and agree fairly well, the values being 

 80 and 84, respectively. They represent, however, distinctly frag- 

 mentary evidence and are not included in the general averages. 



CHANGES IN PULSE-RATE OCCASIONED BY SHORT PERIODS OF EXERTION. 



The ability for adaptive increase in heart rate following exercise is 

 of prime importance to the organism. In normal persons the circula- 

 tion adjusts itself very rapidly to the muscular demand. The cardio- 

 inhibitory center is very sensitive. Investigators have observed that 

 with subjects sitting quietly the pulse-rate changes in the next one or 

 two cycles following the movement of the arm or any slight change 

 in the bodily position. The quickness with which the change occurs 

 from the resting pulse to the rate for exercise, provided the exercise 

 begins promptly, is a measure of vagus tone. In certain physiological 

 conditions, notably that of heart block, the adaptive increase in heart 

 rate during exercise will not take place. It is stated by Wiggers^ 

 that this is even more characteristic of incomplete heart block. 



Since it therefore happens that with many individuals showing a 

 slow radial pulse-rate, the circulation is adequate for conditions of 

 muscular repose but decidedly inefficient during exertion, and since 



^ Wiggers, Circulation in health and disease, Philadelphia, 1915, p. 279. 



