498 THE PHYSIOLOGY OF REPRODUCTION 



total metabolism by the alteration -in weight. Thus Bar and 

 Daunay ^ discovered no increase of weight in a pregnant dog, 

 though it had retained 5"24 grammes nitrogen, equal to 

 170 grammes flesh. Sach a discrepancy may be easily ex- 

 plained, for example, by a loss of water. In Man the physio- 

 logical variation in the water-content is as much as 2 kilo. 

 Hence it is necessary to obtain a more accurate measure, and 

 for this purpose to investigate separately the metabohsm of 

 various substances, proteins, carbohydrates, fats, minerals, salts, 

 and oxygen. The available data are as yet too meagre to 

 demonstrate the good and the bad conditions of nutrition, but 

 they indicate the paths along which future investigations may 

 prove of value. 



C. The Protein Metabolism in Pregnancy 



a. The Absorption of Proteins by the Mother. — According 

 to Kehrer,^ 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 absorption 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 * states that the absorption of 

 nitrogen decreases in the second half of pregnancy in the rabbit, 

 but he ascribes the change to mechanical conditions. Maurel * 

 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. Zacharjewsky 

 found that only 4 to 6 per cent, of the nitrogen was un- 



' Bar and Daunay, "Bilan des ^changes azotes pendant la grossesse," 

 Joum. de Phye. et de Path., vol. vii., 1905. 



^ Kehrer, Die physiologischen und pathologischen Beziehungen der weib- 

 lichen Sexualorgane zum Tractua intestinalis, Berlin, 1905. 



' Ver Eeke, Loia des echanges nutritifs pendant la gestation, Bruxelles, 

 1901. 



* Maurel, " Des d^peuses albuminoides pendant la grossesse chez le 

 cobaye," Comp. Bend. Soc. Biol., vol. Ixi., 1907. 



