1903.] On the Nematocysts of Solids. 463 



Royal Physical Society of Edinburgh, in which he maintained that 

 the cnidae, or thread cells of the ^Eolidse, were derived from the 

 Hydroids on which they fed. He mentions that the same idea had 

 previously occurred to Huxley and Gosse, and that the latter had 

 suggested the method of proving its correctness. The observations 

 which Wright brings forward in support of this view are as follows : 



1. An E. nana, found on a shell covered with Hydractinia, in a pool 



containing Campanularia Johnstoni, had nematocysts of two kinds 

 found in Hydractinia, and also large distinct nematocysts of 

 C. Johnstoni. 



2. An E. coronata, found on Coryne eximia, contained nematocysts 



like those of the latter. 



3. An E. Landsburgii, found on Eudendrium rameum, contained large 



bean-shaped nematocysts like those of the body of the polyps, 

 and very minute ones, like those of the tentacles. 



4. An E. Drummondii, found on Tubularia indivisa, had nematocysts 



of four kinds, found in the latter. Having fasted for " a long 

 time," this specimen was fed on Coryne eximia. Next morning 

 its papillae and alimentary canal were crowded with the cnidse 

 of Coryne mixed with those of Tubularia. 



He remarks that Joshua Alder was unconvinced, on account of the 

 improbability of such a thing being true, and asks for further 

 evidence. 



In 1861 R. Bergh published a paper in Danish, which was abstracted 



in the ' Microscopical Journal,'* in which he described these organs 



in several species and genera in which they had not previously been 



i observed. He considers them to be secreted in the cnidosac, and does 



[ not mention Strethill Wright's paper. 



This omission induced Strethill Wright to publish in the next volume 

 I of the same journal an abstract of his former paper, in which he says 

 [that further observations and experiments had fully confirmed his 

 view. 



Owing either to the absence of figures, or to the afore-mentioned 

 i improbability of the conclusions it contained, this abstract seems to 

 have been overlooked as completely as the original paper. I have not 

 found a single reference to it in subsequent literature, and nearly all 

 recent observers have taken for granted that the nematocysts develop 

 'within the ^Eolids themselves, and several have attempted to work 

 out this development. Bergh has, indeed, mentioned in several places 

 I the possibility of a different view; for instance, in a footnote on 

 jp. 16 of 'Die Cladohepatischen Nudibranchien,' in reference to the 

 'frequent presence of more than one kind of riematocyst in the same 

 I individual, he says: "Esistnoch fraglich ob nur eine Art Cnidse in 



Vol. 2. 2nd ser. 



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