408 THE PHYSIOLOGY OF REPRODUCTION 



foetal vessels are related to the orifices of the glands, and appear 

 to be concerned principally with the absorption of their secre- 

 tion. As already mentioned, the villi may also be concerned 

 with the excretion of waste products of haemoglobin. 



Bonnet was the first to show that the trophoblast in 

 Ruminants was actively phagocytic and absorbed the consti- 

 tuents of the uterine milk (Fig. 94). He demonstrated the 

 presence of fat-globules, haemoglobin and its derivatives, de- 

 generated leucocytes and " Stabchen " 

 (Fig. 95) — in short, all the histologi- 

 cally demonstrable constituents of the 

 embryotrophe — in the trophoblast. 

 Many, if not all, of the cellular ele- 

 ments are partially degenerated before 

 absorption. The appearances suggest 

 an enzyme action on the part of the 

 trophoblast, and perhaps also the 

 Fig. 94.— Ingestion and dis- leucocytes, but no proteolytic or 

 integration of red blood lipolytic enzyme is contained in 

 corpuscles by the tropho- , • 



blast of the sheep. (From gljcerm extracts of the maternal 

 Jenkinson's " Notes on the or fcEtal part of the cotyledon. 

 Histology and Physiology After their absorption, the disin- 



of the Placenta in Ungu- . ■• j ii n i . -. . 



lata," Proc. Zool. Soc, tegration of the ceUular constituents 



London, vol. i., 1906.) is completed in the trophoblast, and 

 they are no longer recognisable as 

 individual elements. Their products are transmitted to the 

 foetal vessels, though they may first be elaborated in the 

 trophoblast into a form or forms suitable for the use of 

 the embryo in the development of its various organs. 



Lemueoidea. — Many of the lemurs have a simple avillous 

 diffuse placenta, as Turner ^ first pointed out in specimens 

 from Madagascar. Hubrecht has investigated two others found 

 in the East Indies — Tarsius ^ and Nycticebus.^ The latter has 

 also a diffuse placenta. ViUi develop over the whole of the 



' Turner, " On the Placentation of the Lemurs," Phil. Trans. Boy. Soc, 

 London, vol. clxvi., 1876. 



^ Hubrecht, "Ueber die Entwicklung des Placenta von Tarsius," &c., 

 Intemat. Oongr. of Zool., Cambridge, 1898. 



^ Hubrecht, " Spolia Nemoris," Quar. Jour. Micr. 3ci., vol. xxxvi., 1895. 



