192 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
of tlie fact that Wierzejski in his monograph * * * § has shown that there is 
almost a complete chain of forms connecting Brachionus Balzeri and 
B. quadratics , which are therefore not of specific value, yet other 
authors are perpetually bringing forward links in this chain as new 
species. Similar groups of forms are found in the genera Anursea and 
Nothulca , and show the folly of introducing new names to designate 
mere varieties. 
Echinoderma. 
Lacunar System of Starfishes, j* — M. L. Cuenot finds in Asterias 
rubens and Asterina gibbosa that each radial caecum bears two efferent 
lacunae in the mesentery which binds it to the dorsal wall, and that 
these radial lacunae unite in a pentagonal lacuna around the stomach. 
He corroborates, what has been repeatedly observed, that the ovoid 
gland, towards its aboral end, gives off two apparently glandular pro- 
longations which stretch into the coelom towards the stomach, and 
accepts the interpretation which regards these as vessels or lacunas con- 
nected with the digestive tube. 
The nutritive fluid enters the ovoid gland, filters among its cells, 
and passes, on the one hand, into the lacunar aboral ring abutting on the 
gonads, and, on the other hand, into a lacunar oral ring which gives off 
radial and ambulacral branches. 
The longitudinal lacunae of the caeca and the pentagon around the 
stomach are large canals with delicate walls, and contain an albuminoid 
coagulum and blood-cells. The coelomic prolongations of the ovoid 
gland have the same structure as the gland itself. It is probable that 
the radial caeca are covered with fine lacunae which pass into the longi- 
tudinal vessels, as injections seem to show. 
Development of Dadocrinus gracilis v. Such, and Holocrinus 
Wagneri Ben.J — Herr A. von Koenen has investigated the development 
of these two forms with a view to determining their relationship to 
other Crinoids. His conclusion is that Dadocrinus gracilis is related to 
forms like Erisocrinus, which are older even than Encrinus, while Holo- 
crinus, , on the other hand, is related to more recent forms, such as those 
included in the Apiocrinidte. 
Coelentera. 
Structure, Action, and Development of NematocystsJ — Herr N. 
Iwanzoff has studied the nematocysts of many Coelentera. They may 
be spherical, oval or cylindrical ; the coiled thread is typically evagi- 
nated, but in Anthozoa it may simply burst the capsule. In most 
Siphonophora there are four or five kinds in one animal, and all 
Coelentera seem to have at least two kinds, if they have any. In 
Ctenophora, they were observed only in Euchlora rubra. 
The capsule wall consists of two layers, of which the inner is usually 
the thicker ; the wall of the thread is continuous only with the outer ; 
the opening of the capsule has usually a plasmic lid ; the interior con- 
* ‘Rotatoria Galicyi,’ Akad. d. Wissensch, Krakau, 1893.' 
t Comptes Rendus, cxxii. (1896) pp. 414-6. 
i Nachr. K. Gesellsch. Wiss. Gottingen, iii. (1895) pp. 283-93 (5 figs.). 
§ Anat. Anzeig.. xi. (1896) pp. 551-6. 
