494 THE PHYSIOLOGY OF REPRODUCTION 



At present it is only a speculation, as Veit himself is 

 careful to explain, but its far-reaching possibihties have already 

 given rise to many investigations.-' It must be clearly under- 

 stood, however, that biologists have at present no proof of 

 the formation of an anti-body consequent on the introduc- 

 tion of any protein of the same individual, or one of the same 

 species. 



From time to time evidence of hiemopoiesis in the placenta 

 has been brought forward. Mention of it was first made by 

 Masquelin and Swaen ^ in the rabbit, and later by Frommel ^ in 

 the mouse and bat. Hubrecht* strongly upholds the occur- 

 rence of blood formation in the placentae of Tarsivs and 

 Tupaia. The new erythrocytes arise as products of the frag- 

 mentation of nuclei of the trophoblast in Tarsius (see p. 410), 

 and of the trophoblast, and probably also trophospongia, in 

 Tupaia (see p. 457). They are later set free by solution of the 

 surrounding protoplasm. Such a process is beneficial both to 

 mother and embryo. The erythrocytes are increased at the 

 expense of the ovum, and they in turn increase the supply 

 of oxygen to the foetus. 



H. Changes in the Metabolism of the Mother 

 DURING Pregnancy 



A. The Source of the Materials transferred to the New 

 Organism 



The question is discussed in another chapter (see p. 484) 

 whether the materials that go to the formation of the new 

 organism are entirely elaborated in the ovum itself, or are partly 



^ See KoUmann, "Kreislauf der Plazeuta, Chorionzotteu und Telegonie," 

 Zeitschr.f. Biol., toI. xlii., 1901. 



^ Masquelin and Swaen, " Di5veloppement du placenta maternal chez 

 le lapin," Bull, de I'Acad. Roy. de Belgique, 1879. 



^ Frommel, Ueber die Entwiohlung der Placenta von Myotus murinus, 

 Wiesbaden, 1888. 



^ Placental hzemopoiesis is denied by many authorities, including Duval, 

 Maximow, Nasius, and Nolf. For a complete review of the subject, see 

 Hubrecht, " Ueber die Entwicklung der Placenta von Tarsius und Tv/poja, 

 nebst Bemerkungen iiber deren Bedeutung als hsematopoietische Organe," 

 Internal. Oongr. of Zool., Cambridge, 1898. 



