456 



TUNICATA. 



individual. The inner layer, the entoderm, arises as was first proved 

 by Kowalevsky (No. 60) for Perophora, as a diverticulum of the 

 stolonic septum (epicardial sac) with which it long remains connected. 

 Between the ectoderm and the entoderm, the primary body-cavity 



of the bud appears filled with 

 mesenchyme - cells. We shall 

 presently, following the accounts 

 of Kowalevsky (Xos. 60 and 

 61), Seeliger (No. 66), and 

 van Beneden and Julin (No. 

 10), describe more in detail the 

 further development of the bud. 

 We can here merely mention 

 that, in Clavelina, the connection 

 of the bud with the stolon, and 

 through the latter with the other 

 individuals of the colony, is 

 usually retained even in the adult. 



Not all the root-like processes of 

 Clavelina seem to be capable of pro- 

 ducing buds. Many of the ramifica- 

 tions seem intended merely for attach- 

 ment or to serve as reservoirs of blood 

 (Seeliger). The latter then have 

 no epicardial process extending into 

 them. A sharp distinction must be 

 made between these sterile body- 

 processes, which may be compared 

 with the mantle-vessels, and the 

 ramifications of the actual prolifer- 

 ating stolon. 



Among the Composite Ascidians 

 the family of the Distomidae 

 belongs to the type just described, 

 the entoderm-vesicle of the bud 

 here also becoming abstricted 

 from a process at the posterior end 

 of the endostyle. In the Botryllidae, the Did&mnidae, and the 

 Diplosomidae, on the contrary, budding of another type occurs. 



The family of the Distomidae seems to be distinguished by the fact 

 that its buds separate very early from the proliferating stolon. They 

 are then found within the common cellulose mantle scattered between 



Fig. 229. — Portion of a proliferating 

 stolon oiPerophora (after Kowalevsky). 

 ec, ectoderm of the bud ; en, entoderm 

 of the bud ; hn, buds ; s, stolonic 

 septum (epicardial lamella) ; v, ramifica- 

 tion of the stolon. 



