BUDDING OF THE DIDEMNIDAE AND THE DIPLOSOMIDAE. 



4(il 



what unsatisfactory statements of authors as to the way in which the 

 organs develop in this bud, but may mention thai peribranchial sacs 

 develop at the sides of the central enteric cavity, that gill-clefts break 

 through, ami that the ganglion, and the branchial and atrial apertures, 

 appear as rudiments. An oesophageal tube and a short rectum seem 

 also to appear. The former (Fig. l'-""'-' />, <i) now becomes connected 

 with the oesophagus of the parent (oe) near the point at which the 

 oesophageal tube of the abdominal bud (<t) enters it. At this one 

 point, therefore, three oesophageal tubes seem to be connected, viz., 

 that of the parent and those of the two buds. This is also the case 

 with the rectum, the short rudiment of that organ belonging to the 



R 



oe 



Fig. 232. — Budding in Trididemnum (alter I)ella Valle). A, intestinal loop of the 

 parent-individual with the rudiment of the abdominal (k), and thoracic {k') hud- ; 

 /,'. individual with the two buds at a later stage of development. ". oesophageal 

 rudiment of the bud k ; «', oesophageal rudiment of the bud&'; '>. rudiment of the 

 intestine in the bud k ; V, the same rudiment in the bud k' ; i. intestine of the parent- 

 individual ; /■. abdominal bud; /•'. thoracic bud; m, stomach; oe, oesophagus; x, 

 constricting ectoderm-ring. 



thoracic bud (©') entering the rectum of the parent (7) at the point 

 at which the rectum of the abdominal bud (b) joins it. If, now, the 

 oesophagus of the thoracic bud became more closely connected with 

 that of the abdominal bud, and such connection were also to be 

 established between the intestines of the two buds, the two halves of 

 the daughter organism would then at last be united. But although 

 the alimentary canal of the bud is now completed, it still, for a long- 

 period, remains connected with that of the parent, both in the 

 oesophageal region and through the rectum (Fig. 233).* 



* [For further details concerning the development of the complex buds of 

 the Diplosomidae and Didemnidae, see the recent works of Caulery (Nos. V.- 

 VII.) and Salensky (Nh. XXIX. i. Callery finds epicardial tubes in the 

 adults, and from these he derives the thoracic and abdominal buds. — Ed.] 



