552 THE PHYSIOLOGY OF REPRODUCTION 



Biancardi 1 stated that wdemas 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, 5-'> per cent, in a multipara, and 48 per cent, in a twin 

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

 who was later delivered of dead twins, 9-' per cent, of the water 

 being excreted in the tirine. 



Birnbaiim'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-serimi the chlorides were 0'1740 per 

 cent, and O'lTTo per cent, in two cases, and 0'173.'! per cent, in a 

 non-pregnant woman. 



H. Rt'xphntory E.i'clm nt/i n ml Enrryy Metabolism <l mint/ 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 fcetus, 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 1 ' 1 has shown 

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

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



1 Kian< -anil, "Sulla eura declorurante nelle nefriti e nelle albuminurie nel 

 c-anijx) ostetrico." Aim. <li (M. < <!<,'<., ]!io:. 



2 Ci-aimT, "Chlornatrium-Entziehung bei Hydrops (Jraviditatis," Monats- 

 .*<!, ,-i ft f. <;<-l>n,i*li. //. (Jyitrii:, vol. xxiii. 



Siemens, "Metabolism during Pregnancy, Lalxnir, and Puerperium," John* 

 //../,////. //,,./,. A',/,., vol. xii., 1904. 



4 Birnbauin. " K. \cret ion of Chlorides during Pregnancv." A ,<!,. f. (iiim'ik., 

 vol. Ixxxiii., Ht<>7. 



' Cohnstein and Zuntz, " [Jntersuchungen iiber das Blut, den Kreislauf, und 

 die Atraung beim Saugetierfr.tus,' Pftftger* A, -<!,., vol. xxxiv., 1884. 



r, "Der Respiratorischc StotfVeclisel des Saugetierembryos," >'//'/"////. 

 iii/., vol. x.. 1!KK. 



