IS THE TKOPHOBLASl' OF HYPOBLASTIC ORIGIN? 593 



reproduce the misnamed figure of this early Mauis, and 

 have since had the good fortune of obtaining sections of yet 

 earlier cleavage stages of the same animal. 



Sections of early blastocysts of two specimens of Manis ^re 



Text-pigs. 5a and b. 



Tig-. 5 80. 



Pig. 5 b. 



Two consecutive sections of very eai-ly blastocysts of Manis, which 

 show what is presunial )ly the earliest trophoblastic covering of 

 the mother-cells of the embryonic knob. 



reproduced here in Text-figs. 5 a, h, and G. The stage of Text- 

 fig. 5 is presumably a two-cell, the other (as far as I can follow 

 it up in the consecutive sections of the series) a four-cell 

 cleavage stage (purposely but incorrectly not counting the 



Text-fig. tJ. 



'^■i.:% 



Another section through another blastocyst of the same genus 



in the same stage. 



trophoblast cells as such). In both tlie differentiation between 

 the mother cells of the embryonic knob on the one hand, and 

 the already so much more numerous trophoblast cells, leads 

 to the inevitable conclusion that the phenomenon of the 

 separation of the larval trophoblast from the remaining 



