a little to the left of the median dorsal line. '■:rnen the 

 displacement of the vesicle is completed, the rudiment lies 

 in the Tiedian plane; it then acquires a lumen, which is put 

 into communication anteriorly v/ith the cavity of the pharynx. 

 The ganglion has a double origin, and is formed by prolifer- 

 ation of the upper wall of the dorsal tube and also from free 

 mesodermal cells. 



8. The sexual organs have a comiaon mesodermal or- 

 igin, both testis and ovary arising from one and the same 

 spherical rudiment. 



C ONCLUD I NG REMARKS . 



The results which I have obtained from the study 

 of the budding of P_erophora viridis furnish additional evi- 

 dence in support of the viev/ that the development of the bud 

 and that of the larva do not proceed along parallel lines. 

 The attempts which have been made to harmof||inise the facts 

 of budding with the germ layer theory, have benn totally fu- 

 tile in the cuse of Ascidians, and ariy hypofiasis "Jhi':'\ ex- 

 plains budding in the Ascidians as a procesr. of regeneration , 

 by which the organs of the parent, or their-layers , give rise 

 to sim.ilar organs in the bud, must, in the light of known 

 fc.'Cts, be ruled out. 



The rudiment of the bud in all groups of Compound 

 Ascidians is composed of two vesicles, one wi*:hin the other, 

 enclosing between them free mesodermal cells. The outer 



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