CHANGES DURING PREGNANCY 525 



observations of Hoifstrom in a primipara during the last six months 

 of pregnancy showed an absorption of protein, and indeed of all the 

 food-stuffs, as good as in the normal person. It was in fact slightly 

 better than the standard given by Atwater. 



(6.) The Daily Requirement of Protein for the Fcetus. — 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 mammfe. But this gives too low a figure, since 1 gm. of tissue- 

 protein requires more than 1 gm. 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 contractions of the uterus, entail a certain loss of 

 protein from wear and tear. Whether protein substance^ play any 

 part in the provision of energy for the work of organisation is not 

 known. 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 combustion of carbohydrates alone (see p. 553). 

 Murlin has calculated in dogs the total energy requirements of the 

 foetus. He finds the total metabolism per unit of weight of the 

 embryos three days before birth equal to three times the metabolism 

 of the mother dog. 



The amount of nitrogenous material deposited in the human 

 fcetus during the last stages of pregnancy has been calculated. 

 Michel! estimates it at 56'69 gm. of nitrogen in two months, or 

 slightly under 1 gm. per day. Similar figures were obtained by 

 Fehling.^ Magnus-Levy's figures are somewhat lower — 50 gm. in the 

 last hundred days, or 0'5 gm. per day. This represents only 3 gm. 

 of protein, and when added to the daily deposition in the placenta, 

 uterus, and mammse, it still remains relatively inconsiderable. The 

 calculations of Bar and of Hoffstrom have already been given in 

 tabular forin (see p. 519). t 



(c.) The Nitrogen Balance wCPregnanvy? — According to the earlier 

 investigators, a special economy of protein exists during pregnancy. 

 As Eepreff* puts it, anabolic processes are increased and katabolic 

 processes decreased in pregnancy in dogs, rabbits, and guinea-pigs. 



1 Michel, " Sur la composition chimique de I'embryon et du fcetus humain," 

 Compt. Rend. Soc. Biol., vol. 11., 1899. 



2 Fehling, "Beitrage zur Physiologie des placentaren Stoffwechsels," Arch, 

 f. Ch/nak., vol. xi., 1877. 



3 See also Magnus-Levy in v. Noorden's Metabolism and Practical Medicine, 

 vol. i., Sect. IV. D., English. Translation, 1907 ; and Leo Zuntz in Oppenheimer'.s 

 Handhuch d. Biochemie, Erganzungsband, 1913. 



* Eepreff, " De I'influence de la gestation sur les echanges materials,'' R%iss. 

 Dissert., 1888. Quoted by Slemons, loc. dt. 



