314 ARTHUR WILLEY. 



Van Beneden and Julin say (loc. cit., p. 353), " Le cerveau 

 de Padulte precede du cul-de-sac cerebral." But their "cul-de- 

 sac cerebral," which they suppose to be entirely transformed 

 into the adult ganglion, is no other than my neuro-hypophysial 

 canal; and although, as we have seen, the brain of the adult 

 does proceed from the same epithelial tract as the latter 

 structure, yet it is perfectly distinct from it to the extent that 

 the lumen of the "cul-de-sac cerebral" is and continues to be 

 throughout the lumen of the neuro-hypophysial canal. Evi- 

 dently the true origin of the ganglion of the adult escaped the 

 attention of the Belgian authors. For the rest, I may repeat 

 that their fig. 11, planche xvii, which would appear to be clear 

 enough to dispel any doubt as to the origin of the hypophysis, 

 is to me, in that regard, quite unintelligible, and I have been 

 unable to duplicate it in any of my preparations. Possibly in 

 the figure in question it is merely the funnel-shaped anterior 

 dilatation of the hypophysis which has been drawn, its posterior 

 narrower continuation having eluded observation. 



In face of the above statements I was much surprised to 

 read in an interesting note on the eyes and subneural gland of 

 Salpa, communicated to a recent number of the 'Zoologischer 

 Anzeiger' (No. 409, Jan., 1893) by Maynard M. Metcalf, the 

 following lines: — " The ganglion of Salpa is homologous with 

 the visceral portion of the larval Ascidian nervous system. 

 Van Beneden and Julin have shown that the dorsal wall of 

 this portion of the Ascidian tadpole's neural tube proliferates 

 cells which become the ganglion of the adult, while the thick- 

 ened ventral wall of the same region gives rise to the subneural 

 gland." It is sufficiently clear from what I have said above 

 that this statement must rest upon a complete misapprehension 

 on the part of the author as to the results arrived at by van 

 Beneden and Julin. This is what they say about the subneural 

 gland (loc. cit., p. 350) : — " En un point de son trajet [i. e. of 

 the caecum hypophysaire] sur un petit nombre de coupes et 

 seulement dans sa partie anterieure on constate que le plancher 

 du tube epithelial [i. e. the hypophysis-tube which for them is 

 derived entirely from an evagination of the wall of the 



