•246 ZOOPHYTA ASCIDIOIDA. 



fence of an internal separate ovary probable ; and some have 

 asserted its discovery. Mr Thompson, for example, maintains 

 that the organ suspended from the bend of the body of the Ve- 

 siculariadge is " an ovum or ovarium," because it is " quite ana- 

 logous in situation with the same organ in the lately discovered 

 compound Ascidise ;"* and when treating of the Cellarise Milne- 

 Edwards assigns to this organ a similar function, -f- but in other 

 places he tells us that it is connected with the biliary secretion. I 

 Previously however to the researches of either Thompson or Ed- 

 wards, Professor Grant had told us that the ova were generated 

 exterior to the body of the polype and disjunct from it, pullulat- 

 ing from the common connecting medium, for the ova and gem- 

 mules have the same origin, but the ova sprout from its inner 

 surface, whereas the gemmules grew from the exterior side on- 

 ly, and in consequence are capable of being developed without 

 separation. The correctness of this opinion seems to be prov- 

 ed by the observations of Dr Grant on the Flustra, in which he 

 saw that the ova were developed from the sides of the cell, 

 which they gradually filled by their increase in size, the body of 

 the polype being at the same time absorbed ; by the observations 

 of Raspail on the Alcyonella in which no ovary could be de- 

 tected, and in which the ova are evidently the produce of a 

 part disconnected with the animal viewed abstractedly ; and by 

 the researches of Dr Farre, who has equally proved that there is 

 no ovary in the Vesiculariadse, the organ which had been so 

 considered being in fact the proper stomach. 



The following synopsis exhibits the genera arranged under 

 their respective families, but at the same time it ought to be re- 

 membered that as, of many of the species and of some genera, 

 the polype remains unknown, their true position in the class is 

 only conjectural. 



• Zool. Researches, p. 96. 



f " On remarque aussi au bas de I'anse, forme par I'intestin, un organe par- 

 ticulier qui pourrait bien etre un ovarie destine a produire des gemmes reproduc- 

 teurs." Lam. Anim. s. Vert. ii. p. 175. 2de edit. 



^ " — une anse a laquelle est comme suspendu im appendice ceecal gros et 

 court." Ibid. p. 214. This opinion is also that of Professor Grant. Outlines 

 of Comp. Anat. p. 314. 



1. 



