12 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 



doubtless had data for some periods in which the subjects were asleep, 

 but these were not published a fact to be regretted, for although the 

 data were contaminated by the fact that food had been taken previ- 

 ously, it is highly probable that the compensatory influence of sleep 

 would in large part offset the stimulus due to the food. Since these 

 results are not available, we are unable to use for comparison any of 

 the data obtained by Rubner in this important research. 



Rubner compares the values found with these children with those 

 reported by Sonden and Tigerstedt. In almost every instance he 

 finds that the carbon-dioxide production per square meter per hour 

 noted by Sonden and Tigerstedt was greater than that found by 

 himself. Rubner does not believe these differences can be entirely 

 accounted for by the restlessness of the subjects, although this must 

 play a considerable role. We find ourselves in full accord with Rub- 

 ner's severe criticism of the Sonden and Tigerstedt data, especially 

 as to their use for comparison; we likewise believe that values obtained 

 on this basis can not be used for a satisfactory demonstration of a 

 material alteration in the basal metabolism of youth as compared 

 with that in old age. It still remains a fact, however, that practically 

 all of the criticisms raised by Rubner against the experiments of Sonden 

 and Tigerstedt also apply to Rubner's own experiments. For instance, 

 Rubner criticizes the fact that Sonden and Tigerstedt's subjects 

 received food, but the process of digestion likewise had a part in his 

 own experiments, although not so great as in those of Sonden and 

 Tigerstedt. He furthermore takes exception to the fact that Sonden 

 and Tigerstedt's subjects moved about in the chamber or were restless, 

 but his subjects moved and indeed walked about in the chamber at 

 times. Rubner's criticisms make it especially clear that only data 

 obtained in the post-absorptive condition and in complete muscular 

 repose are ideally suitable for comparing the metabolism of individuals 

 of different ages. These conditions were not secured by either Sonden 

 and Tigerstedt or by Rubner, although the values obtained by the 

 Scandinavian investigators with the two boys studied throughout the 

 night approximate very closely the basal metabolism, i. e., very nearly 

 comply with basal conditions and prerequisites. 



Since Rubner wrote so late as 1902, it is somewhat surprising that 

 no mention was made of the research of Magnus-Levy and Falk pub- 

 lished in 1899, which met all of the objections raised by Rubner to 

 the Sonden and Tigerstedt experiments. These experiments of 

 Magnus-Levy and Falk were made, however, for the most part during 

 relatively short periods, and Rubner strongly objects to respiration 

 experiments made in short periods, an objection with which we can 

 not agree. Rubner's chief conclusion is that the metabolism of nursing 

 infants per square meter of body-surface is no larger than that of 

 adults, although he does find an increased value for young boys. 



