554 THE PHYSIOLOGY OF REPRODUCTION 



certainly no decrease in metabolism, the metabolic changes being at 

 least as active in the fostus as in the mother. 



L. Zuntz's 1 more recent and extended observations on women 

 before and during pregnancy showed a distinct increase in the 

 energy metabolism, which became progressively greater towards 

 the end of pregnancy. At the same time he observed, from the 

 middle of pregnancy on, as Magnus-Levy had before him, an 

 increased lung ventilation. This fact is of interest as it indicates 

 a stimulation of the respiratory centre by acid metabolites, in other 

 words, it is an expression of an acidosis (see p. 545). The increased 

 muscular work involved in this increased lung ventilation accounts 

 for at least part of the higher values obtained for the gaseous 

 exchange. If a corresponding amount is deducted there still remains 

 a slight increase in the gaseous metabolism which is on the whole 

 proportional to the increase in weight. In one case there was an 

 increase out of proportion to the increase in weight. Carpenter and 

 Murlin 2 have made very complete observations on pregnant women 

 during the last few days of pregnancy in a respiration calorimeter. 

 Unfortunately they could not obtain observations on the same 

 individuals in the non-pregnant state and were therefore restricted 

 to comparing their results on pregnant women with observations on 

 eight other normal women. They found an increase in the energy 

 exchange which was four per cent, higher than could be accounted 

 for by the increase in weight. Their measurements gave an energy 

 requirement for the resting pregnant woman during the end of 

 pregnancy of 24 cal. per day and per kilo. This must be regarded 

 as a minimum value. Hoffstrorn's case had an intake of 31 cal. per 

 day per kilo. 



In a dog pregnant with one puppy Murlin 3 found a very marked 

 increase in the total energy production amounting to nine per cent, 

 which became apparent in the sixth week and persisted till the end 

 of pregnancy (ninth week). The same dog became pregnant again 

 with five puppies. The increase then was much greater and was 

 exactly proportional to the greater weight of the offspring. In 

 comparing these results with those obtained in women the greater 

 weight of the puppy embryos in proportion to that of the mother 

 must be borne in mind. 



1 Zuntz (L.), " Respiratorische Stoffwechsel u. Atmung wahrend der 

 Graviditat," Arch. f. (Jynakol., vol. xc., 1910. 



2 Carpenter and Murlin, "The Energy Metabolism of Mother arid Child just 

 before and just after Birth," Arch, of Int. Med., vol. viL, 1911. 



3 Murlin, "Energy Metabolism of the Pregnant Dog," Ainer. Jour. PhysioL, 

 vol. xxvi., 1910. 



