The origin and histogenesis of the thymus in Raja batis. 445 



spaltenorgau ihren Anfang nimmt, ist für die ßeurtheilung des letztern 

 immerhin von Wichtigkeit" (! ?). 



The immediate eöect of Fkoriep's observations and conclusions 

 was to banish the branchial sense organs to the limbo of things non- 

 existent. Soon after then Ayeks (1892), although he had accepted my 

 work as correct in the earlier part of his memoir, in the latter 

 portion on p. 314 wrote as follows: "As Froeiep has shown the ecto- 

 dermal thickenings which Beard described as giving rise to the lateral 

 line organs have in fact another fate. The genuine lateral line or- 

 gans escaped Beard's observation^) (!), and in consequence Beard's 

 conclusions as to the homology of the vertebrate auditory organ are 

 incorrect" ^). 



Other writers, for so far as I am aware beyond Antipa, and, of 

 course, Dohrn, no-one else has troubled to look into the actual facts 

 for himself, have simply taken Froriep's errors as established facts, 

 and have used them to good purpose! Thus Goronowitsch. This 

 writer in an attack upon Miss Platt's ectodermal origin of cranial 

 cartilages, when referring to the ectodermal thickening behind the eye, 

 and identifying it as one of the "FRORiEP'schen Anlagen" (cui bono?), 

 dogmatically writes: "Die FRORiEP'schen Anlagen, welche wir von den 

 nicht existirenden 'branchial sense organs' von Beard scharf unter- 

 scheiden müssen, sind räthselhafte Gebilde, welche aber, wie es scheint, 

 eine grosse Rolle bei der Entwicklung wahrer Ganglien spielen müssen" 

 (1893, p. 255). The logic and the earnestness of this passage are quite 

 instructive. It contains the following statements of supposed fact: 

 Beard's branchial sense organs are non-existent, the FRORiEp'schen 

 Anlagen are problematical structures, and they must play an important 

 part in the development of true ganglia. 



It would be interesting to learn whence Goronowitsch got his 

 exact knowledge as to the non-existence of the branchial sense organs. 



1) This is, perhaps, intended by Ayeks to be an English version 

 of what he supposes rKORiEP to have said. It is anything but a fact. 

 The structures, dealt with in my work of 1885 upon the sense organs, 

 do become the lateral sense organs of the adult, and no-one with any 

 practical knowledge of Elasmobranch development can doubt it. 



2) A remarkably illogical statement for one to make, who had ac- 

 cepted my account in the earlier pages of his work, and who had 

 actually confirmed and extended the conclusion. If my conclusions as 

 to the homologies of auditory organ and lateral sense organs were in- 

 correct, the error would be fully shared in by the like ones of Ayees. 



