156 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 



this phenomenon with adults has been that with the heavy individuals 

 there is a large proportion of inactive fat, which does not materially 

 contribute to the heat production. This explanation, while reasonably 

 clear for adults, does not, we believe, hold true with children, for on 

 this basis we should expect the children with the higher weights to 

 have a much larger proportion of inactive body-fat than the smaller 

 younger children, and in consequence their heat production per kilo- 

 gram of body-weight would be lower. As a matter of fact, physical 

 examination has shown that young children usually have a much 

 larger proportion of fat than older children, so that the phenomenon 

 exhibited in figures 35 and 36 is exactly contrary to wiiat would be 

 expected if one considered solely the proportion of fat in the body. 

 At this point a note of caution must be sounded. In our discussion 

 of the conditions laid down by us as the basal requirements, we have 

 stressed considerably the fact that with young children one of the pre- 

 requisites for basal measurements can not be satisfactorily met, i. e., 

 the post-absorptive condition. With adults, measurements are made 

 approximately 12 hours after the last meal, when, it has been experi- 

 mentally demonstrated, the stimulus of the previously ingested food 

 has practically disappeared. Our observations show that the younger 

 the children, the more difficult it is to secure long periods without food. 

 Furthermore, with young children, particularly, it is difficult to deter- 

 mine exactly at what hour the stimulus of the previously ingested 

 food ceases and the point at which the stimulus of the ever-occurring 

 incipient acidosis begins. Since the influence of the previously 

 ingested food is in inverse proportion to the age of the children in- 

 cluded in this study, one must bear in mind that the high portion 

 shown in both curves in the two figures 35 and 36 is undoubtedly in 

 part influenced by the previous ingestion of food. We believe, how- 

 ever, that if a correction were possible for the influence of food, on 

 the percentage basis this part would still lie somewhat above that 

 for the older and heavier children. Furthermore, we have every 

 reason to believe that the values observed at the earlier weights (from 

 3 to 5 kg.) were fully as much affected by the previous food as those 

 between 6 and 8 kg., and there is clear evidence of a somewhat lower 

 metabolism at these weights. While, therefore, the previous ingestion 

 of food unquestionably raises somewhat the level of the curve showing 

 the general trend of metabolism per kilogram of body-weight, probably 

 no theoretical correction could remove all of this difference, especially 

 as we have likewise a somewhat compensatory effect due to the fact 

 that many of our younger children were in deep sleep, a condition 

 that we believe definitely lowers the metabolism. So while our 

 children could not be compared on the basis of a "post-absorptive 

 condition" with adults, for the most part they were asleep and had 

 a somewhat lower metabolism due to the specific effect of sleep than 

 did the adults, who were for the most part awake. 



