^§ 47, 48. 



THE POLYPI. 



53 



§ 47. 



I. With those polyps which are not sexless, and whose alimentary canal 

 hangs free in the cavity of the hotly, the sexual organs are situated in this 

 last. They often escape attention, since they are scarcely at all developed 

 except at the sexual epoch. Both ovaries and testicles frequently 

 appear as riband-like bodies, which, being attached by one extremity alone 

 to the stomach, move freely in the general cavity of the body. Sometimes, 

 however, they are attached longitudinally by one of their borders, like a 

 mesentery, the opposite border being free. In other cases, again, they are 

 attached directly to the sides of the body. 



The eggs and spermatic particles pass directly from the sexual organs 

 into the cavity of the body. In Coralla having individuals of both sexes, 

 fecundation takes place in the cavities of their bodies, which connect with 

 each other.*'* With the others, however, the individuals of which are of 

 one sex alone, the surrounding water is the medium of fecundation, by 

 transporting the spermatic particles unaffected to the eggs ; and this being 

 performed by the aqueous circulation before mentioned, impregnation takes 

 place in the cavity of the body. 



§ 48.* 



The variations of the internal genital organs in the different families are 

 as follows : 



1. With the Bryozoa, a riband-like ovary and testicle are suspended 

 from the extremity of the stomach. In these organs are developed only 

 two to four eggs or fasciculi of spermatic particles, from cells arranged like 

 a string of pearls. <'' 



The eggs, of which the germinative vesicle and dot disappear at a very 

 early period, are detached from the ovary before their shell is well formed, 

 and are set in motion by the cilia of the cavity of the body. Usually they 

 are flattened, and at first envelope,d by a thin and colorless membrane, 

 which soon becomes thicker and darker, and has upon its borders a clear, 



1 With Tendra zostericola, which is allied to 

 Flustra, the Polyps are contained in cells closely 

 bound to each other. But the cells of the males 

 communicate with those of the females by an open- 

 ing, through which the spermatic particles pass 

 into the cavity of the body of the female (see 

 Nordmann, Ann. d. Sc. Nat. XI. 1839, p. 191). 



1 See. for Alcyonella stagnornm. Met/en (Isis, 

 1828, Taf. XIV. fig. 1), ioT Plumatella cristata, 

 Dutnortier (loc. cit. pi. I. fig. 3, u, u) and for 

 Cellaria avicularia, Nord?nann (Obs. sur la 

 Fauue Pontique, p. 679, fig. 4, A. u).t 



and the particles themselves are the metamor- 

 phosed nuclei of these cells, exactly as in other and 

 higher animals. They have invariably, as far as I 

 am acquainted, a cercaria-form consisting of a solid 

 head, to which is attached a most delicate tail. 

 The shape of this head, when studied carefully with 

 the best powers, presents differences of zoological 

 import. Sometimes it is pyriform (Tubularia, 

 Actinia), sometimes conical (Astrangia), while 

 among the Bryozoa it is long-oblong with Alcyo- 

 ndla. I cannot therefore agree with Kolliker 

 (Cyclop. Anat. Art. Semen. 1849, p. 497) as to the 

 mode of development of these particles with these 

 animals. — Ed. 



5* 



* [§ 48.] In an emendatory note at the end of 

 the volume, the author remarks: " Sections 2d and 

 3d of this paragraph should be omitted, since the 

 genital organs, with all the Anthozoa, are attached 

 on the internal surface of the visceral cavity. See 

 Frey and Leuckart. Beitr. &c. p. 13." I have, 

 however, allowed them to remain, for the sake of 

 their notes. — Ed. 



t[§>48, note 1.] My own researches in 1851 

 have shown me that with Alcyonella the sexes are 

 separate. The testicles and ovaries consist of pedun- 

 culated sacs, closed at first, but which are rup- 

 tured on the mature development of their contents. 

 — Ed. 



