108 GASEOUS METABOLISM OF INFANTS. 



110. On one or two occasions the pulse-rate seemingly approximated 

 a minimum of 112 to 113. 



With Weldon, 8 days old, the maximum was 161, and the minimum 



111. Here again the curve, which is given in figure 14, is characterized 

 by rapid and sudden fluctuations of considerable extent, although at 

 times there is a tendency for the curve to reach a minimum of about 115. 



With Herbert W., 5 weeks old, the pulse records were obtained 

 throughout the night for a period of 12 hours and are given in figure 15. 

 The maximum record was 134 and the minimum 98. Several times 

 during the night, the pulse-rate reached a minimum of about 100. 



Another 12-hour observation was obtained with Rita McL., 3 months 

 old, giving a maximum pulse-rate of 140 and a minimum of 87 (see 

 figure 16) . A minimum average is shown at not far from 90. 



Paul, 3 months old, in the same period of time had a maximum pulse- 

 rate of 154 and a minimum of 97, with an average minimum of approxi- 

 mately 100. The curve is given in figure 17. 



Tremballe, 5 months old, gave a maximum of 147 and a minimum 

 of 83. During the latter part of the night, the minimum records showed 

 an average of not far from 90 (see figure 18). 



With Christine D., 7 months old, the maximum record was 139, while 

 the minimum pulse-rate was 90, with the curve (figure 19) seeking an 

 average minimum of 90 during the latter part of the night. 



While all the curves indicate a quick reaction to muscular activity 

 of any kind, it would appear that the younger the infant, the greater 

 these fluctuations were and the more sensitive the infant was to changes 

 in muscular activity. The average minimum record for infants 8 days 

 old or under was approximately 115, while infants of 3 months or over 

 showed an average minimum of about 90. After nursing, the pulse-rate 

 was always high, but would subsequently reach its normal level in about 

 30 minutes if the infant remained quiet. Although the difference was 

 not very great, the curves as a general rule show that the older the infant, 

 the more rapid was the return to the average pulse-rate after nursing. 



While the recent observations of Katzenberger 1 are of great impor- 

 tance in supplementing our previous scant knowledge regarding the 

 average pulse-rate of infants and hence make any extensive comparison 

 of our data on different infants entirely unnecessary, we believe that 

 our observations show for the first time the large variations in pulse- 

 rate of afebrile infants during the night when extraneous muscular 

 activity is presumably less than during the day. We may correctly 

 infer that the fluctuations in the pulse-rate shown in these records are 

 probably exceeded by variations during the day and, consequently, in 

 the ordinary daily life of infants we have to deal with very wide fluctu- 

 ations in pulse-rate. Comparative data for different infants, to be of 

 value, should therefore be obtained at the minimum. This can only be 

 secured during deep sleep. 



'Katzenberger, loc. cit. 



