14 Ech. 
' ECHINODERMATA. 
(pp. 114, et seq .). Evolution of sexual elements (pp. 120, et. seq.) : after 
the spermatozoon is set free, its nucleolus travels to the periphery, pro- 
jects, and is cast out. The ovum has no follicle, and its zona radiata is 
secreted by its own activity. The sexual cells originate from the same 
primitive cells as blood corpuscles. Successive hermaphroditism in 
Asterina gibbosa (pp. 126 & 127). Asexual reproduction (p. 128): two 
methods — (1) by median division, as in Asterina wega ; (2) by radial 
division, as in LincJciadce, where the arms fall off, and each arm buds a 
new body, while the old body buds new arms. 
The author concludes his observations by arranging the Asterids he has 
studied in what appears to him to be their natural order (p. 131). He 
finds nothing in the anatomy of Asterids to support Perrier’s view that 
each starfish is a colony of six individuals, a central nutrient and five 
radial reproductive animals. 
CuisNOT (2) finds that the aboral nervous system of Crinoids is not 
an isolated formation, but that analogous, if not homologous, structures 
occur in Urchins, Ophiurids, and Asterids. In Asterids each arm is 
traversed on its aboral side by a strong muscular band ; these bands con- 
verge to the centre to form a star-shaped figure. Over these bands there 
is a great thickening, of nervous nature, of the peritoneal epithelium. 
The histology of these thickenings is quite similar to that of the ambu- 
lacral nervous system. No connection was found between this enterocoelic 
nervous system and the superficial nerve plexus. In the same category 
with the enterocoelic nervous system in Crinoids and Asteroids must be 
placed the genital nervous ring found by Prouho in Echinus acutus and 
Strongylocentrotus lividus , and occurring also in Arbacia pustulosa and 
Echinodiscus biforis. In Ophiurids there is a nerve ring placed exactly 
like that of Urchins, in the aboral ring which goes from the axial sinus to 
the genital organs. It perhaps communicates with the peripheral branches 
of the ectodermal nervous system, but it appears to be of mesodermic origin, 
developed at the base of the enterocoelic epithelium. 
Cu^not (3) disputes Hartog’s theory that the madreporic system 
represents a left nephridium : (1) for embryological reasons ; (2) because 
colouring matters injected into the body cavity do not escape by it, 
but by simple osmosis from the feet or lymphatic gills, and there is 
practically no communication between the body cavity and the exterior 
by the madreporite, from a physiological point of view ; (3) because the 
communication between the body cavity aud the exterior is frequently 
secondarily obliterated anatomically ; and (4) because Hartog’s experi- 
ments are not conclusive as to the presence of an outward current. The 
experiments of Perrier, Prouho, and Cuenot showed that no currents 
existed at all. [Vide Ludwig (2).] 
Fewkes (3) describes and figures a single stage in the development 
of Asterina gibbosa , slightly older than the oldest stage described by 
Ludwig, Asterina being selected as a type of the Asterice adambulacrarice , 
and also because pentagonal, and therefore nearer to the Echinoids than 
the stellate genera. A comparison is instituted between this form and 
