70 THE ACALEPHAE. $$ 67, 68. 
duction by eggs, and consequently by the means of proper genital organs, 
has been observed in all the families. oe 
With the Ctenophora,® both sexes are combined in the same individual ; 
but with the Discophora, the individuals are of on2 sex alone. 
§ 67. 
The eggs are spherical, a. * ~urrounded 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 suffer no change in water. 
In some Siphonophora, they appear to have a linear form, and attain a 
yery 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. 
often exiizely 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 different 
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. 
contact with the eggs. 
2 Will, Froriep’s neue Not. No. 599, p. 66. 
8 Siebold, Froriep’s neue Not. No. 1081, 1836, 
. 33.* 
- 1 Wagner (Prodrom. loc. cit. Taf. I. fig. 2; and 
Icon. zoot. Tab. XX XIII. fig. 15-17) and Siebold 
(Beitrage z. Naturgesch. wirbelloser Thiere. loc. 
cit. Taf. I. fig. A. B.) have figured the eggs of Cy- 
anea pelagia, and of a Medusa. 
2The spermatic particles of Eucharis and Be- 
roé consist of a round body, having a delicate and 
very movable tail (Will, loc. cit. Taf. I. fig. 6, 24). 
In Cydippe they are similar (Krohn, Froriep’s 
neue Not. No. 356, 1841, p. 52). This is likewise 
true of those of the Discophora; see Siebold, 
Beitrige loc. cit. Taf. I. fig. c. (Medusa) ; Kélli- 
ker, Beitrage loc. cit. Taf. I. fig. 8, 9, 10; and 
Miine Edwards, Ann. d. Sc. Nat. XVI. Pl. I. fig. 
1, d. (Rhizostomum, Chrysaora and Aequorea) ; 
* (§ 66, note 3.] Reproduction by fissuration 
has been-observed with the Discophora by Kelli 
ker (Siebold and Kélliker’s Zeitsch. IV. p. 325) 5 
he wi d this ph with St brachi: 
mirabile. It does not appear, however, that he 
has observed this process with adult forms ; for he 
remarks that there is reason to believe that this 
Stomobrachium is only a young, imperfect form 
of his Mesonema coerulescens.— Ep. 
t [§ 67, note 2.] The spermatic parti les of the 
Acalephae have invariably, I think, + cercaria- 
In this way the unaffected spermatic particles are brought in direct. 
Wagner, Icon. zoot. Tab. XX XIII. fig. 20, and 
Will, Horz tergest. Tab. I. fig. 12 (Pelagia and 
Geryonia). ; : 
For the spermatic particles of the Discophora, 
see ua.» Kélliker in the Neue schweiz. Denkschr. 
VIII. p. 4., Taf. II. fig. 18 (Cassiopeia). t 
8 It may be that the stout linear and active 
bodies, seen by Will (loc. cit. p. 78, 81, Taf. II. fig. 
26) in the respiratory cavity, the stomach and the 
general cavity of the body of Diphyes and Ersaea, 
and which he was inclined to regard as Entozoa, 
are the spermatic particles of these animals, since 
they quite resemble those of Alcyonella and Cris- 
tatella. : 
According to Sars (Faun. littor. &c. p. 38), the 
spermatic particles of Agalmopsis have a cerca- 
ria-form. ¢ 
form, like those of the Polyps, and like which, also, 
they are developed in special daughter-cells. — Ep. 
¥ [§ 67, note 3.] These bodies mentioned by 
Will as spermatic particles have since been exam- 
ined by Hualey (loc. cit.), who thinks they are not 
of this nature, a view which is otherwise probable 
from the fact that he found no male generative sacs, 
and also because, as I have shown (see my note 
after § 46, note 5), these particles with Alcyonella, 
have a cercdria-form. — Ep. 
