626 JOHN R. MUKLIN" 



with the metabolism of the normal, non-pregnant woman, so far as the 

 former has yet been studied. 



It is surprising how close is the agreement between the results obtained 

 with the respiration calorimeter and those obtained by the Zuntz-Geppert 

 method. For example, Zuntz's case 3, agrees perfectly as far as the O 2 ab- 

 eorption is concerned with Carpenter and Murlin's cases 1 and 3. The 

 mean oxygen absorption per kilogram and minute in the non-pregnant 

 woman before conception is 3.45 c.c., for the eight normal women 3.48 c.c., 

 but for the three cases taken during the puerperium it is 3.65 c.c., an 

 increase of 5.8 per cent. The mean result for all non-pregnant women 

 is 3.49 c.c. O 2 kilogram and minute. For the pregnant woman the result 

 is 3.57 c.c. or 3.5 per cent more than the amount obtained for all the cases 

 taken in complete sexual rest, and 2.2 per cent less than the average for 

 the puerperium. 



For the heat production Carpenter and Murlin found 1.03 Cal. pei* 

 kgm. and hour for the pregnant cases as against 1.02 Cal. per kilogram and 

 hour for all the non-pregnant subjects. For the woman in complete sexual 

 rest, however, the mean result for the eight cases is 0.99 Cal. per kilo- 

 gram and hour, i. e., about 4 per cent less than for the pregnant woman. 

 The agreement between the oxygen difference and the total energy differ- 

 ence is very satisfactory. The conclusion which may be drawn with entire 

 confidence is, that the basal energy metabolism expressed per 'kilogram and 

 hour, of the pregnant woman in the last month of her pregnancy, is but little 

 larger (4 per cent) than for the woman in complete sexual rest. 



While we have but little data as to the depth of respiration or as to 

 the increased labor of respiration in pregnancy, one may be inclined to 

 think that so slight a difference might be attributable entirely to such a 

 cause, instead of only partly so, as L. Zuntz believed. In fact, according 

 to Zuntz's own estimate of the increased labor of respiration in his Case 

 B the difference in oxygen absorption between the pregnant and the non- 

 pregnant condition is exactly accounted for in this way. This conclusion 

 would mean, very clearly, that the metabolism of the fetus, together with 

 all accessory structures, is the same as so much maternal tissue. If the 

 metabolism of the fetus itself were slightly higher in the human, as it 

 seems, from Bohr's experiments, to be in the guinea pig, this factor would 

 be counterbalanced by the fact that the liquor amnii (and possibly the 

 membranes) takes no part in the metabolism. 



On the other hand, the heat production in the puerperium is dis- 

 tinctly higher than that for complete sexual rest or for the pregnant con- 

 dition the average for Carpenter and Murlin's three cases being 1.10 cal- 

 ories per kilogram and hour, or 11 per cent higher than the average for 

 the former and 7 per cent higher than the average for the latter. 



What is the explanation of this higher energy production of the puer- 

 perient mother ? That it was not fever is apparent from the very accurate 



