GENERATIVE SYSTEM. 



B. Organs for the Preservation of the Species and the Anatomy and Development of the Bud. 



(1.) Ovary and Testis. 



True sexual organs have now been satisfactorily demonstrated in several of the genera of 

 Polyzoa, both fresh-water and marine. In Alcyonella and Paludicella, I have succeeded in 

 making a careful examination of the generative system. In each of these both ovary and 

 testis are found in the same cell.* During the months of July and August there may 

 frequently be seen in the interior of the cell of Alcyonella funyosa, a roundish mass (PI. Ill, 

 fio-. 7, ^) attached by a short peduncle to the endocyst at a little distance within the orifice, 

 and corresponding exactly in position to an ordinary bud, with the early stage of which it may 

 indeed be readily confounded. This body is the ovary. It is filled with spherical ova in 

 various stao-es of maturity. The testicle, which will be found at the same time and in the 

 same cell with the ovary, is developed in the form of an irregular roundish mass (x), upon 

 a peculiar appendage which is present in all the fresh-water polyzoa I have had an opportunity 

 of examining, and which is always in the form of a long cylindrical, flexible cord, attached 

 by one end to the fundus of the stomach, and by the other to the endocyst near the bottom of 

 the cell. We may, with Huxley, designate this appendage by the t^xm. funiculus. The testicle 

 is composed of a mass of spherical cells, each of which contains within it numerous secondary 

 cells, "vesicles of evolution." (PI. XI, fig. 17). The visible contents of the vesicles of evolution 

 consist, at first, of nothing more than a well-defined spherical nucleus, and this is subsequently 

 transformed into a spermatozoal filament, which finally escapes by the rupture of the containing 

 cells (fio-s. 17 — 23). The spermatozoal filaments, in this genus, are simple vibrioid bodies 

 (fig. 23) without any terminal enlargement. They present distinct though somewhat sluggish 

 undulatory motions. The distal portion of the testis is more developed than the portion which 

 lies nearer to the stomach of the polypide, and the former portion may generally be seen with 

 the undulating spermatozoa projecting from it on all sides, in the form of a dense villosity 

 (PI. Ill, fig. 7, x)' while some of these, already become free (£), may be seen carried about in 

 the fluid of the perigastric space, and thus brought in contact with the ovary. 



In Paludicella, the ovary occupies the same position as in Alcyonella, forming an irregularly 

 shaped body (PI. X, figs. 3, 4, i/-), adherent to the inner surface of the endocyst towards the 

 anterior part of the cell. About the end of June, when I discovered this organ, it was loaded 

 with ova of various sizes, some so small as to require for their detection considerable magnifying 

 powers, while others were almost visible to the naked eye, and seemed ready to burst the 



* Van Beneden at oue time maintained the unisexualism of Alcyonella^ believing that the testis 

 and ovary always occupy separate cells (Quelques observations sur les Polypes d'eau douce, ' Bull, de 

 I'Acad. Roy. de Bruxelles,' 1839). In a subsequent memoir (Dumortier and Van Beneden, Hist. 

 Nat. dea Pol. comp. d'eau douce, ' Mem. de I'Acad. Roy. de Bruxelles,' tome xvi. Complement) he 

 modifies this view, and comparing the polyzoon in question to plants belonging to the class Polygamia 

 of the Linnean system, he believes that among the different zooids of the same colony, there are some 

 in which the sexes are distinct, and others in which they are united. My own observations, however, 

 are opposed to both these views, and it seems to me evident that the eminent professor of Louvaiu 

 has not seen the true ovary at all. 



