THE BrONOM[CS OF OONVOLUTA ROSCOFFF-NSIS. 379 



corpuscles aud yellow cells (zooclilorellfe and zooxantliellse) 

 of Protozoa, Coelenterates, Turbellaria, etc.; (2) as pigment 

 in the digestive gland (enteroclilorophyll) of Crustacea and 

 Mollusca (MacMunn, etc.), and in the gut, blood, fat, skin, and 

 eggs of Lepidopterous larvfe and pupfe (Poulton) ; (3) as 

 diffused pigment in Vorticella campanula (Engelmanu, 

 1883). 



. Research has shown (1) that some zooxanthella3 and zoo- 

 chlorelliB are intrusive algal cells, and has rendered the same 

 conclusion probable for some other cases ; (2) that entero- 

 chlorophyll is a pigment derived from the food (Dastre and 

 Floresco, 1898, 1899; Poulton, 1893); (3) that the chlorophyll 

 of Vorticella campanula is probably formed by the animal 

 (Eugelmann, 1883). Decisive proof of the formation of true 

 chlorophyll by animals does not exist, but the discovei-y by 

 Schunck, Marchlewski and Neucki (1901) that chlorophyll 

 and heemoglobiu are closely allied substances removes any 

 a priori difficulty in accepting such proof. 



The view that the green corpuscles of Hydra aud Spon- 

 gilla are not cells, but chloroplasts belonging to these 

 animals, has been supported by Prof. Ray Lankester (1881, 

 1882). "There is no more and no less evidence for considering 

 the green corpuscles of Hydra viridis as parasitic algse than 

 there is for taking a similar view with regard to the green 

 corpuscles of an ordinary green plant" (Lankester, 1882, 

 p. 88). In support of this view, Prof. Lankester asserts the 

 absence of a nucleus and of a cell- wall in the green corpuscles, 

 and the presence of angular colourless and brown corpuscles, 

 which he regards as stages in the development of the green 

 ones. 



Since Prof. Lankester's papers on this subject, no really 

 convincing histological proof of the presence of a nucleus, no 

 experimental proof of a cellulose wall, have so far as we 

 know been adduced. Even Beyeriuck's paper (1890) gives 

 no figures of the nucleus. Nevertheless there is good ground 

 for believing that these green corpuscles are a phase in the 

 life-history of Chlorella vulgaris, since Beycrinck has 



