$$ 95, 96. THE ECHINODERMATA. 95 
CHAPTER IX. 
ORGANS OF GENERATION. 
§ 95. 
Although most Echinoderms have extraordinary powers of reproduc- 
tion, yet this, apparently, is not for the multiplication of the individuals, 
for they do not reproduce either by fissuration or by buds. 
The Holothurioidea alone, perhaps, form the exception.” All propagate 
by the sexual organs of separate male and female individuals, and her- 
maphroditism is very rare. 
The eggs which are usually round, are covered by a thin chorion, and 
contain beside a little albumen, a variously colored vitellus with its germi- 
native vesicle and dot.” The sperm is always milky, and the spermatic 
particles which are unaffected by sea-water, are nearly always composed 
of Bound or oval, rigid body, to which is attached a delicate, very active 
tail. 
§ 96. 
Externally, the organs of both sexes exactly resemble each other, and 
especially during the interval of procreation; but at the sexual epoch they 
often differ in color. Their situation is very varied, and they are composed of 
simple or branched tubes, with proper excretory ducts. These last, however, 
are sometimes wanting, and then the contents of the former escape by rup- 
ture, and, falling into the cavity of the body, pass out through the respira- 
tory openings. 
Here, as in the Polyps and Acalephs, the copulatory organs being absent, 
the water is the medium of the fecundation of the eggs, by bringing the 
spermatic particles in contact with them. 
1 The Holothuria, which, when captured, dis- 
charge all their viscera through the mouth, can, 
according to Dalyell (Froriep’s neue Not. No. 
331, p. 1), not only reproduce all these. but also 
can divide spontaneously into two or more parts, 
each of which becomes a complete individual. This 
multiplication by fissuration occurs also, perhaps, 
with Synapta Duvernea; see Quatrefages, loc. 
cit. p. 26. 
2See the eggs of Comatula Europaea (Mil- 
er, Abhandl. d. Berl. Akad. 1841, Taf. V. fig. 17), 
of Asteracanthion violaceus (Wagner, Prodro- 
mus, &c., Tub. I. fig. 3, or Carus and Otto, Erlaute- 
rungstafeln, Hft. V. Taf. I. fig. 1), of Echinus ivi- 
dus and sphaera (Valentin Monogr. &c. fig. 167, 
169), of Holothuria tabulosa (Wagner, Icon. 
zoot. Tab. XXXII. fig. 12), and of Synapta Du- 
-vernaea (Quatrefages, loc. cit. Pl. V. fig. 1). 
* [§ 95, note 3.] The spermatic particles of the 
Echinoderms are developed, like those of the other 
Radiates, in special cells, and like them also have, 
I think, invariably a cercaria-form. The differ- 
ences in the shape of the head of these particles 
3 See, for the spermatic particles of Astera- 
canthion, Solaster, and Echinus (Kelliker, 
Beitrage, loc. cit. fig. 1-4, and Valentin, Monogr, 
&c. fig. 168), of, Holothuria and Synapta 
(Wagner, Icon. zoot. Tab. XXXII. fig. 18, and 
Quatrefages loc. cit. Pl. V. fig. 2). Those of sim- 
ilar form have been seen in Comatula by Muller 
(Monatsbericht d. Berl. Akad. 1841, p. 189, or the 
Abhandl. of the same, loc. cit. p. 235). Accord- 
ing to Valentin (Repertorium, 1841, p. 301), 
those of Spatangzus violaceus have an el ted 
body, pointed in front, with a very delicate hair-like 
tail. Those of Ophioderma longicauda, and 
Ophiothriz fragilis, according to my own obser- 
vation, have a round body, with an equally deli- 
cate hair-like tail.* 
are wide, and of zoological import. Thus it is 
sometimes round (Asterias, Urastes), sometimes 
pyrifornt (Echinocidaris), and sometimes longe 
conical (Medlita). — Ep. 
