ON BUDDING IN POLYZOA. 517 



most of the empty zooecia which had been previously inhabited, 

 a brown body was observed situated towards its lower end, 

 this was surrounded by funicular tissue (" endosarc," Joliet), 

 which sent out irregular strands to the walls of the zooecium, 

 some of them being connected with the band of flexible endocyst 

 which stretched across the mouth of the zooecium. In the centre 

 of this band, and therefore connected with the endocyst on the 

 one hand and with the funicular tissue on the other, was 

 situated, in the earliest observed stages, a small rounded mass of 

 cells yellowish in colour, surrounded by a sheath of transparent 

 cells, which together constitute the nascent bud. 



The bud soon acquires a well marked central cavity (PI. 

 XXXVII, fig. l),then becomes oval in form, and depends from 

 the anterior band of endocyst. A further elongation next takes 

 place, this process being more rapid above than below, result- 

 ing in a pyriform body, of which the upper and narrower part 

 consists of a thin double walled sac, the outer wall being the 

 sheath and the inner one the attenuated internal layer. The 

 lower and wider portion consists of the thin outer sheath 

 enclosing the active internal cells (PI. XXXVII, fig. 2). To 

 anticipate — the inner cells will form the external layer of the 

 tentacular sheath, the external epithelium of the tentacles, and 

 the internal epithelium of the alimentary canal of the new 

 polypide, while the outer layer or " sheath " will form the 

 inner layer of the tentacular sheath, the inner epithelium of 

 the tentacles and the tissue which surrounds the digestive tract. 



A series of somewhat complicated changes now takes place 

 in the lower moiety of the inner layer. (It should here be 

 premised that the outer layer is perfectly passive throughout, 

 merely adapting itself in such a manner as to wrap itself round 

 the active inner layer.) One side of this portion of the bud 

 protrudes, the protrusion becomes constricted off in such a 

 manner as to produce a blind sac, depending by the side of the 

 remainder of the bud, the constriction is quite complete except 

 at the uppermost point, this being the spot where the rectum 

 will be connected with the lophophore ; fig. o, PI. XXXVII, 

 which is drawn from a preparation, illustrates the commence- 



VOL. XXIII. NEW SEiv. M M 



