CHANGES IN THE MATERNAL ORGANISM 499 



absorbed by the human female in the last two weeks of 

 pregnancy, and Slemons l found 7 per cent, and 3 per cent, 

 in a primipara and a multipara respectively at the same 

 period. 



b. The Daily Requirement of Protein for the Foetus. The only 

 measure we possess of the extra protein required in pregnancy 

 is the amount deposited in the foetus and adnexa, the growing 

 uterus, and mammae. But this gives too low a figure, since one 

 gramme of tissue-protein requires more than one gramme of 

 food-protein for its manufacture. In addition, though we are 

 dealing with a period when anabolic processes are at a maximum 

 in the new organism, we are bound to assume that the cardiac, 

 hepatic, and other activities of the foetus, and the rhythmic con- 

 tractions of the uterus entail a certain loss of protein from wear 

 and tear. What these extra requirements amount to is un- 

 known, or whether protein substances play any part in the 

 provision of energy for the work of organisation. 2 



The amount of nitrogenous material deposited in the human 

 foetus during the last stages of pregnancy has been calculated. 

 Michel 3 estimates it at 56'69 grm. of nitrogen in two months, or 

 slightly under 1 grm. per day. Magnus-Levy 's figures are some- 

 what lower 50 grm. in the last hundred days, or 0'5 grm. per 

 day. This represents only 3 grm. of protein, and when added 

 to the daily deposition in the placenta, uterus, and mammae, 

 it still remains inconsiderable. 



c. The Nitrogen Balance in Pregnancy* According to the 

 earlier investigators, a special economy of protein exists during 

 pregnancy. As Repreff 5 puts it, anabolic processes are in- 



1 Siemens, "Metabolism during Pregnancy, Labour, and Puerperium," 

 Johns Hopkins Hosp. Rep., vol. xii., 1904. 



2 In so far as the work of organisation is carried out by the mammalian 

 foetus and not by the mother, the energy is probably supplied by the com- 

 bustion of carbohydrates alone (see p. 518). 



3 Michel, " Sur la composition chimique de 1'embryon et du foetus 

 humain, " Comp. Rend. Soc. Biol., vol. li. , 1899. 



4 See also v. Noorden's Metabolism and Practical Medicine, vol. i., 

 Sect. IV. D., English Translation, 1907. 



5 Repreff, " De 1'influence de la gestation sur les ^changes materiels," 

 Russ. Dissert., 1888. Quoted by Slemons, loc. cit. 



