BASAL KATABOLISM. Ill 



metabolism of new-born infants. The problem now before us is to 

 determine approximately the influence of the various superimposed 

 factors which make up a day of ordinary activity. 



INFLUENCE OF ACTIVITY UPON THE BASAL KATABOLISM. 



As has already been pointed out, the minimum metabolism values 

 recorded in this report indicate only the metabolism when the infants 

 studied were in a condition of practically complete muscular repose. 

 As a matter of fact, infants are not in complete muscular repose during 

 the entire first week of life, and there are periods in which the activity 

 varies from a general restlessness and movement of the limbs to 

 paroxysms of severe crying. The probable maximum values for the 

 metabolism are therefore of interest. The maximum values observed 

 with 93 of our infants, i. e., the values found in the periods when the 

 maximum respiratory exchange took place, are given in table 17 and are 

 there compared with the minimum values previously recorded in table 

 12. The percentage increase found in the maximum periods as com- 

 pared with the minimum periods is also given in table 17. It should be 

 borne in mind that the values given in table 17 are not the highest values 

 possible as a result of muscular activity, but are the highest that were 

 observed for the individual infants in our study. It is probable, 

 however, that the 211 per cent increase shown by one of the infants 

 represents approximately the possible maximum. 



Before the measurements of the respiratory exchange were begun 

 most of the infants were naturally somewhat active as a result of bath- 

 ing and dressing and their transportation from the hospital to the obser- 

 vation room. A considerable proportion of the maximum values were 

 therefore found in the preliminary periods of the observations, but a 

 large number of these values w r ere also obtained in other periods. 

 With a few infants the increase shown in the maximum period was 

 hardly 4 per cent, but the average for the 93 subjects shows an 

 increase of 65 per cent in the maximum heat-production as compared 

 with the minimum. In some instances this average difference was very 

 greatly increased. Thus, values over 100 per cent were found in 10 

 instances, the highest value being that of infant No. 89, with which 

 an increase of 211 per cent was found in the maximum period. On 

 the other hand, a large majority of the subjects showed an increase of 

 only 40 to 80 per cent above the minimum. 



Since other writers have reported a very much smaller increment in 

 the basal metabolism as a result of crying and muscular activity, a 

 close analysis of our figures is essential. A possible criticism may be 

 raised that these computations were based entirely upon the carbon- 

 dioxide output, making due allowance for the variations in the respira- 

 tory quotients in computing the calories produced. We have there- 

 fore recomputed the increment in metabolism for a considerable number 



