CHLOROPHYLL-CORPUSCLES AND AMYLOID DEPOSITS. 237' 



ino- crreen pigment (purple when acidified) obtained by Mr. 

 Moseley in great quantity from species of Pentacrinus 

 dredf'ed by H.M.S. " Challenger/' The banded absorption 

 spectrum of alcoholic solutions of this substance is figured 

 by Mr. Moseley in vol. xvii of this Journal^ in a memoir 

 containing a great number of very important observations, 

 which appear to have been overlooked by those who have 

 recently been studying the characters of animal pigments. 



Chloropliylloid pigment of Hydra viridis. — As to the 

 chlorophyll-like substance of Hydra viridis, it is to be ob- 

 served that there is very great difficulty in obtaining such 

 a quantity of it as will suffice for complete spectroscopic 

 study with reagents such as Sorby has carried out in the 

 case of Spongiila. Hence the general indication of chloro- 

 ])hylMike substances afforded by the single strong absorption 

 band in the red, acquires in this case importance. Still more 

 important is the physiological and morphological evidence 

 with regard to it which will be detailed below, and suffices 

 to render the identity of the pigment of the green corpuscles 

 of Hydra with that of the chlorophyll bodies of plants highly 

 probable. 



Physiological evidence as to the occurrence of chloro- 

 phyll in animals. — At present the attempt to prove the 

 identity of a green pigment occurring in an animal with 

 that of the chlorophyll bodies of plants, by proving the 

 green tissues of the animal to be capable of decomposing 

 COo in sunlight with liberation of oxygen gas, as the green 

 tissues of plants are known to do, has only been made with 

 success in one case. 



Mr. Geddes has shown that a green marine Planarian 

 worm {Convoluta Schultzii), when exposed to sunlight in 

 water containing COo in solution, evolves an appreciable 

 amount of oxygen gas. Supposing that the green pigment 

 of the chlorophyll bodies were itself the agent of the decom- 

 position which is associated with them, this observation 

 would be tolerably conclusive as to the presence of the same 

 green pigment in Convoluta Schultzii. But if Pringsheim's 

 theory that the chlorophyll acts only as a ''screen" be true, 

 and if the decomposition is actually effected by the proto- 

 plasm of the vegetable cell, then it seems not very unlikely 

 that one green pigment might act as a screen as effectually 

 as another, and the physiological evidence as to the identity 

 of the two pigments would have little value. Some value 

 must, however, be ascribed to it, for it is, on the whole, more 

 probable — even if we accept the screen theory — that only 

 substances belonging to Sorby's groups of chlorophylls, 



