202 Proceedings of the 



or irregular cells. The endoderm of the tentacles possesses a 

 similar variety in structure. I have not been able to satisfy 

 myself of the existence of a canal in their interior. 



The internal surface of the endoderm has the function of 

 nutrition ; its external surface that of reproduction. 



23. The Reproductive Polypoid Organs (fig. 1. 5), male and 

 female, are always situated on separate unisexual polyparies. 



24. The Male Polyp is smaller than the alimentary 

 polyp. The buccal cavity and mouth appear to be absent; 

 but I have occasionally seen the place of the latter marked 

 by a whitish spot, through which I have succeeded in forcing 

 the contents of the intestine. The tentacles are merely small 

 protuberances, thickly studded with the larger thread-cells, 

 which bodies also occur over the whole surface of the polyp. 

 The parietes of the body consist of the same three elements 

 as that of the alimentary polyp. Their middle third is 

 dilated into a sac, from which numerous diverticula protrude, 

 to form spermatic capsules (fig. 5). The endoderm of the sac 

 and capsules is richly ciliated, and loaded with brown granular 

 matter ; and between all the communicating cavities a con- 

 stant circulation of fluid, charged with globules of sarcode, 

 takes place with a powerful rotatory turmoil. At first, all the 

 coats of the capsules are in close apposition to each other ; 

 but, as they increase in size, the endoderm (c) becomes widely 

 separated from the other coats, by the secretion from its outer 

 surface of a dense transparent gelatinous matter. The trans- 

 parency of this matter, after a time, becomes obscured by the 

 formation within it of innumerable minute cells, from each of 

 which a single spermatozoon is presently developed. After a 

 time, the endodermic layer of the capsules having been re- 

 duced by absorption to a mere linear core of brown matter 

 occupying the axis of the capsule, and the spermatic mass 

 having become liquid and white, the latter is at last evacu- 

 ated from an opening in the summit of the capsule, and 

 descends through the water as an expanding cloud. 



25. The Female Polyp resembles the male in its form and 

 the development of its generative capsules. But at an early 

 stage of the development of the capsule, from four to nine ova 

 make their appearance between the endoderm and the other 



