106 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 



dioxide production in the preliminary period was 8.73 grams, 1 while 

 the lowest during the subsequent periods was but 9.09 grams, even 

 when the child was asleep. But this case is exceptional. 



In the first observation with No. 145, that of June 15, 1916, the 

 carbon dioxide produced in the first three periods varied only from 

 4.71 to 4.94 grams per hour. This is an astonishingly good agreement 

 between periods and is in large part explained by the fact that the 

 relative activity (indicated on an arbitrary scale) was I in all three of 

 the periods and the child was probably asleep the entire time. Since 

 the carbon dioxide values agreed so well, as a natural consequence the 

 values for the computed heat for these three periods likewise agree 

 well with each other. The carbon-dioxide production and heat for 

 the fourth period were somewhat lower than for the other periods 

 and thus represent the absolute minimum as determined for this day. 



Before further consideration of the data in table 25, the possible 

 errors entering into the measurements for any given period should be 

 pointed out. For example, the measurement of the carbon-dioxide 

 production for the individual periods is based upon the increase in 

 weight of a set of absorbing bottles containing soda-lime and sulphuric 

 acid. This requires the weighing of the bottles at the beginning 

 and the end of each period. While all such weighings are verified 

 by a second observer, an error in either one of these weights will 

 obviously affect the value for the carbon-dioxide production for that 

 period. Such a method does not admit of duplicate determinations for 

 any period a palpable defect. While this is true of practically all 

 modern methods in which a respiration chamber is used, i. e., either 

 the total amount of carbon dioxide is measured only by one absorbing 

 train or, if duplicate gas-analyses are made of samples taken from an 

 air-current, but one main meter or spirometer measures the air-current, 

 still, in considering the carbon-dioxide production for any individual 

 period, such possibility of error must be borne in mind. 



On June 15 the minimum heat production of 315 calories per 24 

 hours found in the fourth period is reasonably well confirmed by the 

 second period with 332 calories per 24 hours, which is about 5 per cent 

 higher. An average of these two figures would therefore give the 

 most probable basal value for the child on this day. Since, however, 

 we have an actually determined value of 315 calories, it is clear that, 

 aside from technical errors, this heat production must be the basal 

 or minimum heat production. In general, it may be said that the 

 minimum basal metabolism is that actually observed, barring tech- 

 nical errors. We are then specially interested in evidence to prove 

 the probability of a low value. Specifically, is 315 calories the real 

 minimum value, or shall we tacitly admit the probability of technical 



1 In table 25 it seems desirable for purposes of comparison to represent the carbon-dioxide 

 production on the basis of one hour rather than for the actual time of observation. 



