dorsal tube arises in the manner described by Pizon, that is, 

 as an anteriorly directed endoder.-aal diverticulum, they give 

 a different account of the origin of tne ganglion. . In all 

 the species studied, tne ganglion is formed as a differen- 

 tiation of tne dorsal v/all of the hypophyseal tube, and has 

 therefore a comnon rudiment v/ith the latter. Their results 

 are in agreement v/ith vj-hat Hjort has found in Botryllus, ex- 

 cept that in all of the above-mentioned Ascidians the hypo- 

 physis lies belov; the ganglion, v/hereas in Botr yllus it is 

 above . 



Finally, Ritter (24) who has recently described the 

 bud-development of Goodseria, a genus in which budding had 

 not been observed before, finds a complete agreement, concern- 

 ing the origin of the neuro-hypophyseal system, with Hjort 's 

 work on Bot ryllus . 



In the same paper Ritter gives a preliminary ac- 

 count of some observations on the development of the buds of 

 Perophora anne^ctens (Ritter) and P. Iiis.tejM^- ^^^ both spe- 

 cies he derives the common rudiment of the hypophysis and 

 ganglion from cells which wander out from the dorsal wall of 

 the inner vesicle. 



After this short review of the state of our know- 

 ledge regarding this much confused subject , I shall now give 

 an account of my ov/n observations on the development of the 

 dorsal tube and ganglion in the buds of Perophora viridis_. 



My results, which are based on a study of an unin- 

 terrupted series of stages, have led me to believe that the 



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