The maximum and minimum pulse-rates, with differences, are shown at the bottom of table 80. Usually the maximum occurred during the first week, when the subject was on a normal diet. Certain exceptions to this are noted in the footnotes. In some instances the pulse-rate was reduced nearly one-half, notably so in the case of Yea and Kon. It should furthermore be noted that the maximum with Kon occurred immediately after his return from the Christmas holidays. The same is true for the absolute maximum for Can and Tom. The subsequent course of the pulse during January, however, with neither Kon nor Tom reached as low a level as was recorded earlier, although with Kon a subsequent value as low as 38 was obtained. In general, it may be stated that, from the data in table 81, the pulse-rate was reduced approximately one-fourth.

Such a striking change in pulse-rate is wholly inconceivable and, indeed, outside the experience of any clinicians with whom we have conferred. Furthermore, the literature rarely mentions pulse-rates as low as were frequently observed in these series, except with primarily pathological cases, and no study of general malnutrition or undernutrition with which we are familiar indicates such profound alterations. We evidently have to deal here with a distinct physiological level, with accompanying conservation of circulatory activity or, as subsequent discussion of the total metabolism will show, the low pulse level is the natural consequence of a lowered metabolism and hence shows a marked decrease in the circulatory activity. In any event, as indications of the pulse-rate of young men who are apparently normal, active and healthy, carrying out with no appreciable reduction in stamina or vigor their intellectual and physical collegiate activities, these values are, we believe, without comparison anywhere in physiological literature.

The tendency for the average minimum pulse-rate to coincide with the minimum food intake and minimum weight may be noted by comparing the dates of the average minimum pulse-rates, namely, November 17 to 25, with the body-weight curves and with the food intake at this time. The subsequent tendency to increase, which became marked during January, is undoubtedly due in part to the freedom allowed the men during the Christmas vacation. On the first day following the Christmas recess Can, Kon, and Tom showed their highest pulse-rates for the whole experiment, i. e., 68, 61, and 74, respectively. With all of the subjects except Moy and Bro, the first pulse-rates observed after the Christmas recess were markedly higher than the last rate registered prior to the recess. This increment in the case of Can was 18, Kon 20, Gar 11, Gul 9, Mon 6, Pea 9, Pec 5, Tom 25, and Yea 10. With Bro there was a decrease of 2 and with Moy of 3. As a prime indication of the increased metabolism, these increases in pulse-rate may be directly ascribed to the uncontrolled diet during the Christmas recess.

Average Daily Pulse-Rate, Squad A

Although the legitimacy may be questioned of comparing daily average values when the number of subjects used for averaging varied, as they do here, since Fre, Kon, and Spe did not serve for the whole period and the daily pulse records are not continuous, even with the other subjects, we have for purposes of comparison included the daily averages in table 80. It will be recalled that the pulse-rate was usually recorded for 9 subjects each morning and that on the few mornings following the experiments in the group respiration chamber in Boston, the pulse-rates for the entire squad were measured. Usually the averages given in the last column of table 80 are those for not less than 8 or 9 subjects. The maximum average daily value of 58 beats appears on September 27 (the first day of the experiment). This figure represents an average value for 9 subjects. The minimum average daily value of 38 beats is noted twice, first on November 19 and again on January 28. On the latter date, however, the average represents but 4 subjects, while on November 19 daily pulse-rates for 9 subjects are included in the average. Three italicized figures, i. e., 38, 40, and 40, appear in this column between November 19 to 24, and two appear in the last of January.

Beginning with October 7, that is, the third day after the reduced diet began, the average pulse-rate drops to 51 and continues to be reasonably uniform throughout October. There is a fall to 44 on October 31 and until November 19 the rate remains not far from 44. There is then a short period of low values, but throughout the month of December the average value of 44 or 45 beats is almost uniformly noted, the exceptions being December 9, 10, 11, and 13. A striking increase in the average value is noted on the first few days after the Christmas recess, January 7 to 9, when values of 54, 51, and 53 are found. There is then a progressive decrease, the lowest level occurring from about January 24 to 28, with a tendency for a slight rise thereafter. Apparently when these men are on their maintenance diet at the lower level, the average pulse-rate for the entire group is not far from 43 or 44 beats per minute. While, as we have stated, this method of averaging is open to criticism, the general influence of the reduced diet upon the squad as a whole is fairly well depicted by this series of daily averages. The daily records for each member of Squad A essentially correspond with the course of the general daily average. While certain of the men did not reach a particularly low level in pulse-rate, they nevertheless showed a general decrease in pulse-rate. With other men in Squad A extraordinarily low values were obtained. The profound influence of the reduced diet upon the pulse-rate is thus shown by inspection of the figures for the individual men, but it is shown by the daily averages more clearly and with less contamination by minor extraneous factors.

Save on a few days, all of the pulse records in table 80 were taken at Springfield. On certain of the Sundays in Boston pulse-rates were taken in the group chamber before the subjects rose in the morning. When compared, we find that the Boston values do not differ materially from those obtained on the day before and the day after in Springfield. For instance, on November 25, the average daily pulse-rate for the group obtained in Boston was 41, while the Springfield value for the day before was 40. That for the day following (47) is not unusual, and indicates the rise following the Sunday with uncontrolled diet.

On December 9 in Boston the pulse-rate averaged 47, the day before in Springfield 44, and the following day, also in Springfield, 50. On December 20 the rate obtained in Boston was 44 and the day before 43. On January 13 the rate in Boston was 48, the day before 52, and the following day 50. On January 27 the average rate in Boston was 42, the day before 42, but the following day, only 38. This last average is made up of values obtained from only 4 men, three of whom had consistently low pulse-rates. The final value for February 3 of 45 is the same as that for February 2 obtained in Springfield. The somewhat different conditions obtaining in the Boston experiments (see p. 491) were thus not sufficient to affect materially in either direction the average pulse-rates. It therefore seems perfectly justifiable to include them among the average pulse-rates in table 80.