It is somewhat unfortunate that graphic tracings of the exact respiratory ventilation could not have been obtained, such as are usually secured with the universal respiration apparatus in this Laboratory. Subsequent experience with the portable respiration apparatus has shown that such graphic records are possible, but since they were not obtained in this research, we must rely solely upon the pictures given by the pneumograph about the chest. It is impracticable to reproduce here the many pneumograph records obtained in connection with these experiments. Careful inspection of the records, however, shows no obvious alteration in the character of the respiration. There is no tendency towards apnoea or dyspnea, nor, so far as the pneumograph tracings indicate, any alteration in the character or type of respiration.

Average Respiration Rate

Since the reduced diet had but a slight effect upon the respiration rate, the fact that the average rate with these men was perceptibly lower than that ascribed to normal subjects of their age1 has no special significance other than to indicate that in all probability the men were well trained, were very little disturbed by the experimenting, and had fullest confidence in the observers. The average respiration rate, even before the reduced diet began, was not far from 14 per minute, a rate which agrees with that found in this Laboratory for men studied under the same normal conditions in an extensive comparison of respiration apparatus, i. e., 14.4 per minute.2 Subsequent discussion will show that the amount of carbon dioxide to be removed per minute by the ventilating current of air passing through the lungs was lowered nearly one-third as a result of the experimental conditions, and it may at first sight seem rather significant that the respiration rate was not lowered more than 1 or at most 2 respirations per minute with the average subject.

The respiration rate of the man who fasted 31 days3 had a distinct tendency to rise during the prolonged period of fast. The only other data we have which are at all comparable are those reported by Loewy and Zuntz.4 The extraordinarily low respiration rate of Zuntz, which averaged 5.4 respirations per minute in 5 experimental periods on three different days, can be compared with his respiration rate as noted in earlier experiments. A careful examination of these experiments shows that there was a tendency for his respiration rate prior to the war to be perceptibly above 7, although occasional instances of 5.5 are noted. The average respiration rate reported for Loewy during the war of 10.6 per minute is perceptibly lower than most of those noted with our subjects, and, indeed, than the occasional ante-bellum rates for Loewy found in his earlier experiments. It is fairly clear that in all cases, including not only our experiments in this research but those of Zuntz and Loewy, there is a tendency for the respiration rate to be somewhat lower with a low diet. This is in direct contrast with the tendency to an increased respiration rate noted with the fasting man.

1 See Quetelet, Tigerstedt's Lehrbuch der Physiologic des Menschen, Leipsic, 1913, 1, 7th ed., p. 451.

2 Carpenter, Carnegie Inst. Wash. Pub. No. 216, 1915; also Carpenter, Proc. Nat. Acad. Sci.,

1915. 1, p. 602.

3 Benedict, Carnegie Inst. Wash. Pub. No. 203, 1915, p. 163.

4 Loewy and Zunti, Berl. klin. Wochenachr., 1916, S3, pp. 826 and 828.

Respiration Rate With The Standing Position

Aside from the regular records of the respiration rates made in the morning respiration experiments on either the respiratory-valve apparatus or the portable respiration apparatus, a few observations were obtained with the men in the standing position. These were with Squad A on February 3, prior to walking, and with Squad B on both January 6 and 28, prior to walking, and are given in table 109. The values for Squad A for February 3 prior to walking range from 10 with Vea to 19 with Mon. If one compares these with the values obtained in the morning experiments, with the subject lying, on the last three days of the research (see table 108), it will be seen that occasionally the respiration rate for standing differed considerably from that for lying on the previous days. In certain cases, notably with Can and Mon, decided increases were observed for the standing position. The general average respiration rate for the morning of February 3 is 13.3 per minute for the 11 men.

For Squad B we have two sets of observations, with, however, no observations in the lying position for comparison. (See table 109).

Table 109. - Respiration Rate Of Subjects, Post-Absorptive And In Standing Position

Portable respiration apparatus.

Here we must confine ourselves to a comparison between the respiration rate for the normal and for the reduced diet. The respiration rates are, in a number of instances, considerably higher than usual. Thus on the day with normal diet we have rates of 21 or over with Ham, Sne, and Wil. On the day with reduced diet the respiration rate had a tendency in a majority of instances to be somewhat lower than it was on the normal day. Thus with all but Ham, Liv, and Sne, slight falls in the respiration rate occur at the end of the reduced-diet period. The three subjects named show positive rises, particularly Liv. Since Lon was not at the Laboratory on the normal day (January 6) we have for him only a record for reduced diet. The respiration rate on this day was not far from the average found with Squad A, but distinctly lower than that found with most of the other men in Squad B. The three very low rates of 9, 9, and 8 with Fis, Har, and Tho at the end of the reduced-diet period have special interest. These are lower than any rates observed with Squad A in the standing position and even lower than those observed with the men of Squad A in the lying position at the end of the research. No explanation for these low values is at hand other than changes in diet.