(29: Clavelina) , 7Jilley (35: Ciena ) , Salen.sky (28: Diploso- 

 aa, Didemn-on) , and Caullery (1: Dlstaplla,Tjeptoellnum, Qlos- 

 sophorum, CircinaliujTi) , agree in their statements that the 

 peribranchial sacs arise in t"ne manner described by Kowalew- 

 sky, and are therefore purely ectodermal. It is fairly safe 

 to assume that Pizon is v.frong, and tnat in Botryllus, as in 

 all other Ascidians studied, the sacs are ectodermal. Tf 

 triis be the case, as the inner vesicle of the bud-rudiment 

 is directly cut off from the outer peribranchial wall in both 

 larva and buds, it follov;s that all the organs, including the 

 peribranchial sacs, derived from this inner vesicle through- 

 out the entire series of buds proceeding from the larva, are 

 ultimately of ectodermal origin. 



After this brief review of tne state of our knov;- 

 ledge concerning trie origin of tne bud-rudiment in the Asci- 

 dians, I shall now describe the process, as I have found it 

 to occur in Perophora v irid is . 



The buds arise in a single rov/ along the course of 

 the delicate stolons, which branch profusely and adhere on 

 one side to the surface over which they creep. The branches 

 come off approximately at right angles to the stems, from 

 which they proceed, but aside from this char;icteris tic there 

 is no regularity whatever in the method of branching; they 

 arise at unequal intervals, and as each grows out, it gives 

 off in its turn still younger shoots, the whole system be- 

 coming much tangled and twisted to form a loose felt-work. 



Proceeding towards the growing tips of the stolons, 

 both buds and branches are seen to become successively young- 



-7- 



