tual observation, and his arguments, which are far from sat- 

 isfactory, fail to convince. He avers that a constriction 

 of the ganglion from the wall of tne dorsal tube does not 

 take place, but, on the contrary, the figures of Kjort (8: 

 Botryllus) prove fairly conclusively that such a constriction 

 does actually occur. Kjort 's contention that the ganglion 

 is formed from the thickened ventral wall of tne hypophyseal 

 tube, is based on a study of an unbroken series of stages and 

 is clearly borne out by his figures. In a short note""" on 

 the budding of Botryllus, v/hich was published recently, I 

 added additional evidence in support of Hjort's view, and re- 

 produced a drav/ing v/hich showed beyond a doubt that the 

 thickened ventral v/all of the dorsal tube is pinched off to 

 form the ganglion. The account given by Oka is entirely 

 different. According to this observer, cells wander out 

 from the ectoderm, fasten themselves to the ventral wall of 

 the dorsal tube, and there form tne ganglion. These wander- 

 ing ectodermal cells were also observed by Pizon, who descri- 

 bed them as giving rise to a portion of the genital gland, to 

 muscular fibres, and to certain cells of the blood. The 

 principal difference, then, bet'.veen the three authors is, 

 that whereas Pizon and Oka hold to an independent origin of 

 hypophysis and ganglion, Hjort maintains that there is a com- 

 mon rudiment for the tv/o structures. 



The results of Salensky (27) on the bud-development 



Johns Hopkins University Circulars, No. 119, June, 1895. 

 -44- 



