IS THE TR(3PH0BLAST OF HYPOBLASTIC ORIGIN? 591 



affirmative, the so-called blastopore which van Beneden (1875) 

 described in the rabbit's morula-stage might correspond to 

 the spot referred to in the three figures (Test-fig. 3 B — D), 

 where the polar bodies lie. 



Having thus shown that Assheton's hypothesis of the 

 hypoblastic nature of the trophoblast is irreconcilable with 

 the phenomena in Galeopithecus, I emphatically repeat my 

 conclusion that we are not justified in accepting it for any 

 other vertebrate. He himself will admit that, such being 

 the case, the comparison of the trophoblast of mammals with 

 the " deckschicht " of fishes comes to the foreground with 

 increased validity, 



I have already stated above that it is not ray intention in 

 this paper to follow Assheton's criticism step by step. A 

 more extensive article on the ontogeny of Galeopithecus will 

 appear in the course of this year. I shall there find occasion 

 to reply more fully to other parts of Assheton's criticism. 

 There is, however, one point on which I feel bound to 

 apologise, viz. that I have not allowed enough space for the 

 recognition of the fact that my kephalo- and noLogenesis had 

 ah'eady been partly foi-estalled in several of Assheton's papers, 

 and had by him been termed proto- and deuteiogenesis. I 

 ought to have particularly mentioned these names in my 

 paper of 1908. Still, I must maintain my terminology now 

 th;it Assheton himself states (I.e., p. 240) that his and my 

 names " signify a different interpretation," and now that he 

 maintains that mine "does not represent the actual facts." 

 As matters stand I feel that the important issue which is at 

 the base of the whole question of gastrulation in vertebrates 

 (very fully treated in Keibel's contribution to vol. x of the 

 ' Ergebnisse der Anatomie und Entwickelungsgeschichte,' 

 but since then looked upon in a somewhat different light 

 after his and my own short papers in the ' Quart. Journ. Micr. 

 Sci.' [vol. 49] and in the ' Anat. Anzeiger' [vol. xsvi] had 

 appeared) renders any polemics about the nomenclature that 

 should be adhered to untimely. Very numerous investigations 



