516 THE PHYSIOLOGY OF REPRODUCTION 



cytes can be produced by placental, extracts. As a result 

 of this, hsemoglobinsBmia may occur in pregnancy. WychgeP 

 observed it in eight out of twenty-three pregnancies, and the 

 condition occurs more frequently still in eclampsia. At present, 

 however, it is not yet generally accepted that an erythrotoxin is 

 formed by the syncytium, though Bonnet ^ has shown histo- 

 logically that a destruction of red cells probably takes place 

 during hfe. He noticed on the surface of the villi " perfect and 

 damaged erythrocytes in all stages of degeneration, clumping 

 and solution." So Hofbauer found, by adding neutral-red to 

 the chorionic vilh of two fresh two-months' placentae teased in 

 sahne, that many of the blood corpuscles showed red dots 

 indicating degeneration. 



6. Calcium. — The source of the foetal calcium is still un- 

 settled. According to Drennan,^ it is derived from the circulat- 

 ing blood and not from the tissues of the mother, but he adduces 

 no strong evidence. It is well known that the teeth are apt to 

 become brittle in pregnancy from a decrease m calcium fluoride * 

 and a deficiency in enamel formation. Evidence of a special 

 drain on calcium is also found in puerperal osteomalacia, 

 which occurs in poor people who presumably have an insufficient 

 supply of calcium in their diet. 



c. Phosphates and Sulphates. — It has been generally found 

 that the phosphoric acid excretion runs parallel to the nitrogen 

 (V. Eeke,^ Schrader *). Jagerroos,^ however, showed an equih- 

 brium between intake and output in a pregnant dog which 

 showed a distinct loss of nitrogen. According to Schrader, 

 the excretion of sulphates is parallel to that of nitrogen. 



' Wychgel, " Unteisuohungen iiber das Pigment der Haut und der Urin 

 wahrend der Schwangerschaft," Zeits. f. Oeburtsh. u. Oyncik., vol. xlvii. 



^ Bonnet, quoted by Hofbauer (Biologie der menschlichen Plazenta, Wien 

 und Leipzig, 1905). 



" Drennan, "The Abstraction of Calcium Salts from the Mother's Blood 

 by the Foetus," New York Medic. Joum., vol. Ixxxvii. 



' Terrier, " De I'lnfluence de la Grossesse sur les Dents," Thise de Paris, 

 1899. 



^ V. Eeke, Jagerroos ; see pp. 500 and 501 for references. 



^ Schrader, " StofEwechsel wahrend der Schwangerschaft," Arch. f. 

 Oyndk., vol. x., 1900. 



