552 THE PHYSIOLOGY OF REPRODUCTION 



Biancardi 1 stated that cedemas in pregnancy were sometimes due 

 to the same cause, and might be cured by decreasing the chlorides 

 of the food. Next Cramer 2 affirmed that all cases of hydrops 

 graviditatis without albuminuria were due to a retention of sodium 

 chloride; and Boni, whose careful investigations of the urine in 

 pregnancy have already been referred to, found that the chlorine 

 excretion was decreased, and remained low during the puerperium. 

 Along with this there is a retention of water to maintain osmotic 

 balance. Normally 90 to 100 per cent, of the water taken in is 

 excreted in the urine, but the percentage fell to 72 per cent, in a 

 primipara, 53 per cent, in a multipara, and 48 per cent, in a twin 

 pregnancy (Siemens 3 ). Such a retention did not occur in a woman 

 who was later delivered of dead twins, 93 per cent, of the water 

 being excreted in the urine. 



Birnbaum's 4 results are not in agreement with the others. He 

 states that a retention of chlorides occurs only in the nephritis of 

 pregnancy, and not in normal pregnancy or in hydrops without 

 albuminuria. In the blood-serum the chlorides were 0'1740 per 

 cent, and 0'1775 per cent, in two cases, and 01733 per cent, in a 

 non-pregnant woman. 



H. Respiratory Exchange and Energy Metabolism during Pregnancy 



Modifications in the respiratory exchange arise from the altera- 

 tions in the maternal organism, and from the requirements of the 

 product of conception. To a certain extent diffusion of oxygen takes 

 place from mother to foetus, as it has been proved, by experiments 

 in asphyxia of the mother, that the direction in which oxygen goes 

 across the placenta depends on the tension. Whether there is also 

 a gas-secretion by the trophoblast is unknown. 



With regard to the foetus, Pfliiger argued on theoretical grounds 

 that the oxidation processes were inconsiderable, and the oxygen 

 intake small. Experimentally Cohnstein and N. Zuntz 5 arrived at 

 a similar conclusion. More recently, however, Bohr 6 has shown 

 that in the later stages of pregnancy the foetal guinea-pig has a 

 respiratory exchange at least as high as the mother. The actual 



1 Biancardi, " Sulla cura declorurante nelle nefriti e nelle albuminurie nel 

 campo ostetrico," Ann. di Ost. c Ginec., 1906. 



2 Cramer, " Chlornatrium-Entziehung bei Hydrops Graviditatis," Monats- 

 -ift f. Geburtsh. u. Gyniik., vol. xxiii. 



3 Siemens, "Metabolism during Pregnancy, Labour, and Puerperium," Johns 

 Hopkins Hasp. Rep., vol. xii., 1904. 



4 Birnbaum, "Excretion of Chlorides during Pregnancy," Arch. f. Gynak. y 

 vol. Ixxxiii., 1907. 



5 Cohnstein and Zuntz, " Untersuchungen iiber das Blut, den Kreislauf, und 

 die Atmung beim Saugetierfotus," Pflitgcr>s Arch., vol. xxxiv., 1884. 



6 Bohr, " Der Respiratorische Stoffwechsel des Saugetierembryos," Skandzn. 

 A, -c.lt. f. PhysioL, vol. x., 1900. 



