52 4 THE PHYSIOLOGY OF REPRODUCTION 



metabolism by the alteration in weight. Thus Bar and Daunay 1 

 discovered no increase of weight in a pregnant dog, though it had 

 retained 5'24 gm. nitrogen, equal to 170 gm. flesh. Similarly, 

 Hoffstrom, in a primigravida, found a total retention of 209 gm. 

 nitrogen during pregnancy which could not be accounted for by the 

 slight increase in weight. Such a discrepancy may perhaps be 

 explained, partly at any rate, by a loss of water. In Man the 

 physiological variation in the water-content is as much as 2 kilos. 

 And in Hoffstrom's case the slight increase in weight was accom- 

 panied by a loss of fat. In any case this unusual discrepancy 

 between weight and nitrogen retention, which requires further 

 explanation, indicates a remarkable alteration in the metabolism of 

 the maternal organism. Hence it is necessary to obtain a more 

 accurate measure, and for this purpose to investigate separately the 

 metabolism of various substances : proteins, carbohydrates, fats, 

 minerals, salts, and oxygen. 



C. The Protein Metabolism in Pregnuncy 



(a.) The Absorption of Proteins by the Mother. According to 

 Kehrer, 2 the gastric functions are slightly below normal in the 

 human female during pregnancy. Free hydrochloric acid and pepsin 

 are each decreased by a third. At the same time the intestinal 

 functions appear to be sufficiently active for the satisfactory absorp- 

 tion of nutriment. 



The absorption of flesh does not show any characteristic change 

 in the dog during pregnancy. If decreased, it is due to pathological 

 conditions, and diarrhoea and vomiting are present (Bar and Daunay). 

 Ver Eeke 3 states that the absorption of nitrogen decreases in the 

 sscond half of pregnancy in the rabbit, but he ascribes the change 

 to mechanical conditions. Maurel 4 is of opinion that a gradual 

 decrease in the nitrogen intake occurs throughout pregnancy in the 

 guinea-pig, but at the beginning the intake is above the non-pregnant 

 level. Zacharjevvsky found that only four to six per cent, of the 

 nitrogen was unabsorbed by the human female in the last two weeks 

 of pregnancy, and Slemons 5 found seven per cent, and three per cent, 

 in a primipara and a multipara respectively at the same period. The 



1 Bar and Daunay, " Bilan des echanges azotes pendant la grossesse," Jour. 

 de Phys. et de Path., vol. vii., 1905. 



2 Kehrer, Die physiologischen und patkologucheti Beziekungen der weiblichen 

 Sexualorgane zum Tractus intestinalis, Berlin, 1905. 



3 Ver Eeke, Lois des echanges nutritifs pendant la gestation, Bruxelles, 1901. 



* Maurel, "Des depenses albuminoides pendant la grossesse chez le cobaye," 

 Compt. Rend. Soc. Biol, vol. Ixi., 1907. 



6 Slemons, " Metabolism during Pregnancy, Labour, and Puerperium," Johns 

 Hopkins Hoxp. Rep., vol. xii., 1904. 



