588 



A. A. W . iniiK'KrHT. 



incredulity on van Beneden's part that this latter author in 

 tlie important article which appeared one year later than 

 Assheton's (' Anat. Anzeiger/ 1899, p. oO')), does not take 

 the slightest notice of the Euijlish autlior's view that the 

 trophoblast (van Beneden's '^couche enveloppate") should be 

 looked upon as an entoderin.Ml derivate. 



If we now return to Text-fig. 1 of this paper and inquire how 

 this stage in the ontogeny of Guleopithecus has been reached, 



Text-kh;. 1. 



Section of ;l blastocyst of Galeopitliecus with embiyonic knob 

 and enveloping trophol)last, jnst before the estal>lisliment of 

 the continuous hypoblast. 



we see that it has been preceded bv the stages of which 

 Text-figs. 2 and o are the repi'esentatives. 



In Text-fig. 2 the centre of the different sections is occupied 

 by comparatively large nuclei, evidently belonging to a central 

 group of cells — the mother cells of the embryonic knob. 

 Outside this embryonic knob and forming the peripheral 

 layer in these sections is protoplasm in which distinct cell- 

 boundaries are not visible, but in which a certain number of 

 nuclei (smaller than those of the embryonic knob) clearly 

 indicate that in the live blastocyst a peripheral cell-layer was 

 diflerentiated in addition to the embryonic knob. 



