70 THE ACALEPHAE. *§>§ 67, 68. 



duction by eggs, and consequently by the means of proper genital organs, 

 has been observed in all the families. 



With the Ctenophora/-' both sexes are combin -d in the same individual; 

 but with the Discophora, the individuals are of oi. sex alone. '"^ 



§ 67. ■' 



The e"-o-s are spherical, ... ' -'^i-rounded by an exceedingly thin envelope. 

 The vitellus is of a whitish violet or yellow color, and contains a germina- 

 tive vesicle, and germinative dot.'^> 



The spermatic particles, which have generally the form of Cercaria (that 

 is, a head and a filiform tail), are very active, and suifer no change in water. ^-' 



In some Siphouophora, they appear to have a linear form, and attain a 

 very great size.^'^' 



§68. 



The genital organs are not developed except at the epoch of procrea- 

 tion, and this period is very brief On this account, their existence has 

 oftcii ^...L:'y escaped the notice of observers. 



The male and female organs so closely resemble each other, as to color, 

 form and position, that they are easily confounded. They consist either of 

 elongated pouches, or of riband-like bands, which are situated in difi"erent 

 parts of the body. In the first case, the sperm and eggs escape through 

 particular excretory canals ; in the second, they escape directly outwards 

 from the ovaries or testicles, or pass first through large cavities which com- 

 municate externally. 



As they have no copulatory organs, the water is the medium of fecunda- 

 tion. In this way the unaflected spermatic particles are brought in direct 

 contact with the eggs. 



2 fVill, Froriep^s neue Not. No. 599, p. 66. Wagner, Icon. zoot. Tab. XXXIII. fig. 20, and 



3 Siebold, Froriep^s neue Not. No. 1081, 1836, Will, Horae tergest. Tab. II. fig. 12 {Pelagia and 

 p. 33.* Geryonia). 



1 Wagner (Prodrom. loc. cit. Taf. I. fig. 2 ; and " '■ the spermatic particles of the Discophora, 

 Icon. zoot. Tab. XXXIII. fig. 15-17) and Siebold see ^■'■illiker in the Neue schweiz. Denlischr. 

 (Beitrilge z. Naturgesch. wirbelloser Tliiere. loc. VIU. p. -. Taf. II. fig. 18 (Cansiopeia). t 



cit. Taf. I. fig. A. B.) have figured the eggs of Cy- '■> It may be that the stout linear and active 



anea pelagia, and of a MeMusa. bodies, seen by Will (loc. cit. p. 78, 81, Taf. II. fig. 



2 The spermatic particles of Eucharis and Be- 26) in the respiratory cavity, the stomach and the 

 roe consist of a round body, having a delicate and general cavity of the body of Diphyes and Ersaea, 

 very movable tail (fTiW, loc. cit. Taf. I. fig. 6, 24). and which he was inclined to regard as Ento? ':i 

 In Cydippe they are similar {Krolin, Froriep's are the spermatic particles of these animals, since 

 neue Not. No. 356, 1841, p. 52). This is hkewise they quite resemble those of Alcyonella and Cris- 

 true of those of the Discophora ; see Siebold, tatella. 



Beitrage loc. cit. Taf. I. fig. c. (Medusa) ; Ktilli- According to Sars (Faun, littor. &c. p. 38), the 



ker, Beitrage loc. cit. Taf. I. fig. 8, 9, 10 ; and spermatic particles of Agalmopsis have a cerca- 



Milne Edwards, Ann. d. Sc. Nat. XVI. PI. I. fig. ria-form. | 

 1, d. (Rliizostomum, Clirysaora and Aequorea) ; 



* [ 5> 66, note 3.] Reproduction by fissuration form, like those of the Polyps, and like which, also, 



has been observed with the Discophora by Kblli they are developed in special daughter-cells. — Ed. 



ker (Siebold and Kdlliker^s Zeitsch. IV. p. 325) ; J [§ 67, note 3.] Tliese bodies mentioned by 



he witnessed this phenomena with Stomobrachium Will as spermatic particles have since been exam- 



mirabile. It does not appear, however, that he ined by Huxley (loc. cit.), who thinks they are not 



has observed this process with adult forms ; for he of this nature, a view which is otherwise probable 



remarks that there is reason to beUeve that this from the fact that he found no male generative sacs, 



Stomobrachium is only a young, imperfect form and also because, as I have shown (see my note 



of his Mesonema coerulescens. — ED. after § 46, note 5), these particles with Alcyonella 



t [§ 67, note 2.] The spermatic particles of the have a cercaria-form. — Ed. 

 Acalephae have invari.ably, I think, a cercaria- 



