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 viUi 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, hsemoglobin and its derivatives, de- 

 generated leucocytes and " Stabchen " 

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

 caUy 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 

 leucocytes, but no proteolytic or 

 lipolytic enzyme is contained in 

 glycerin extracts of the maternal 

 or foetal part of the cotyledon. 



After their absorption, the disin- 

 tegration of the cellular constituents 

 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. 



Lemuroidea. — Many of the lemurs have a simple aviUous 

 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. Vilh develop over the whole of the 



^ Turner, " On the Placentatlon of the Lemurs," Phil. Trans. Boy. Soc, 

 London, vol. clxvi., 1876. 



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

 Internal. Congr. of Zool., Cambridge, 1898. 



^ Hubrecht, " Spolia Nemoris," Qvxir. Jour. Micr. Sci., vol. xxxvi., 1895. 



Fig. 94. — Ingestion and dis- 

 integration of red blood 

 corpuscles by the tropho- 

 blast of the sheep. (From 

 Jenkinson's " Notes on the 

 Histology and Physiology 

 of the Placenta in Ungu- 

 lata," Proc. Zool. Soc., 

 London, vol. i., 1906.) 



