The Animal OrcjauisJti and its Germ-Layers 63 



are interesting in the highest degree. It would be impossible, 

 even were it desirable, to review the memoir exhaustively. 

 As to the most general aspect of it, it will suffice to say that 

 Goette takes issue with nearly every one of Weismann's most 

 important conceptions. The hypothesis that the gonophores 

 are in all cases degenerate medusse; the hypothesis of Mar- 

 schroute (of liard and fast germ tracks); the hypothesis 

 of entirely independent activity of the sex-cells in migration 

 supported by the suggestion that the cells migrate by virtue 

 of a "homing instinct" something like that supposed by 

 some naturalists to be possessed by migratory birds ; and 

 finally and most relevant to the present discussion, the hy- 

 pothesis which denies the actual origin of the germ cells in 

 the endoderm : all these hypotheses and others which could 

 be mentioned, Goette holds to be either in positive opposition 

 to the observed facts or not necessitated by them. 



It would be contended on the Weismannian mode of theor- 

 izing that since the issue is mainly one of interpreting facts, 

 and not of what the facts are, Goette's views are entitled 

 to no more weight than are Weismann's, and so do not con- 

 stitute a disproof of the hypotheses in question. As this con- 

 tention comes very near to the center of Weissmann's logical 

 procedure, we must look at it attentively. Assuming that 

 Weismann and Goette are equally endowed by nature and by 

 training as observational biologists (and I have no doubt 

 the great majority of unbiased zoologists who know the 

 work of the two men would allow this), it must be granted 

 that Goette as pitted against Weismann does not constitute 

 a disproof of the latter's hypotheses. But does this admis- 

 sion leave these hypotheses just where they were before 

 Goette's attack upon them? By no means. We may state 

 the case this way : Weismann observes a long series of facts 

 concerning the structure and development of a particular 

 group of animals, and on the basis of these and in the 

 interest of a theory of still more general scope, and of pre- 



