192 Ml'- A. Hancock on the Anatomy of the 



of the egg and the hatching of it, and the subsequent growth of 

 the young polype has been minutely investigated by Sir J. G. 

 Dalyell. But the generative organ remained unrecognised u^tll 

 it was pointed out by Professor Allman. The appendage to the 

 lower extremity of the stomach, considered by Trembley to be 

 muscular, Professor Allman believes to be an ovary : that it is 

 so there can be no doubt, as eggs may occasionally be seen in 

 connexion with it. Appendages of this kind exist in Alcr/onella, 

 Plumatella, Fredericella and Paludicellay and will probably be 

 found in all Ascidian polypes. In Plumatella and Fredericella 

 there are however three of these appendages or filaments, PI. III. 

 figs. 4/,^,^, & 5 e^e'yhjhy which are all attached to the lowest part 

 of the stomach, and passing down have their other ends attached 

 to the wall of the cell not far from the insertion of the polype-re- 

 tractors. It is difficult to say whether all three are connected with 

 the generative function, or whether some of them are not muscles 

 for the retraction of the stomach. A bundle of such retractors 

 has been described by Dr. Parre in the marine species, attaching 

 the inferior end of the stomach to the base of the cell ; but one 

 of them is generally thicker than the rest, and may probably be 

 connected with the reproductive system. Paludicella has two 

 such filaments ; one, PI. IV. figs. I k7 n,g, passing in the usual 

 manner from the lower end of the stomach ; the other, m, d, from 

 the upper. These two filaments are inserted upon the posterior 

 wall of the cell, one a considerable way above the other. When 

 the polype is retracted these insertions are found to be a little 

 above the gastric attachments, and the filaments, fig. 2 j, k, 

 doubled upon themselves. These are thick, cylindrical and ap- 

 parently tubular, and do not at all resemble muscles, and indeed, 

 from the relative position of their attachments, they seem ill 

 adapted for retraction. 



In Plumatella and Fredericella, one, PI. III. figs. 4 «?, c? & 5 ^, e', 

 of the filaments is generally stouter than the other two, and this 

 has frequently an egg, e,/, attached to it. When the ovum is 

 much developed, it is difficult to make out its relationship to the 

 filament or ovary ; but when quite young, it has all appearance 

 of originating from the interior. On one occasion I observed two 

 eggs in connexion with the ovary, one almost mature, the other 

 only forming. The former, fig. 5/, was attached rather below 

 the middle of the generative organ. When the polype was pro- 

 truded, this organ dragged forward the upper end of the ^^^ ; 

 the other end of it was then seen to be attached to the wall of 

 the cell by the continuation of the filamentous ovary e^. A little 

 below the egg there was a slight oval swelling, in the interior of 

 which was seen a nucleated cell, ff, undoubtedly an ovum in a 

 very early stage of development, and apparently in the interior 



