253 PROFESSOR E. RAY LANKESTER. 



green bodies having the form of spherical corpuscles, they 

 formed irregular angular masses, as shown in PI. XX, fig. 18. 

 Also, I was able to obtain, by squeezing from one and the 

 same endoderm-cell, groups of angular granules arranged 

 symmetrically as parts of a sphere, of which some were 

 colourless, whilst others were green (PI. XX, fig. 22). 



I consider this strong evidence in favour of the view that 

 the colourless angular bodies of H. fusca are potentially 

 chlorophyll-corpuscles ; that is to say, under certain cir- 

 cumstances they may develop in themselves chlorophyll. 

 What the conditions are precisely, we are as yet unable to 

 say. 



It is noteworthy that both in Spongilla and in Hydra, 

 when the pigment bodies remain in an abortive condition, 

 they are irregular and angular ; when they develop chloro- 

 phyll green on the other hand by peripheral activity, they 

 tend to the spherical condition. This may, it seems, be 

 connected with the fact that the formation of the chloro- 

 phyll is essentially a surface activity probably dependent on 

 the access of sunlight, and this surface activity would, if 

 perfectly symmetrical, necessarily result in the production 

 of a sphere. 



Dr. Brandt's conclusions with regard to the chlorophyll- 

 corpuscles of Hydra viridis. — The summary given a few 

 pages back of Dr. Brandt's statements in reference to the 

 corpuscles of Spongilla applies equally to those of Hydra. 



I am unable to see that he has adduced any facts, except- 

 ing the presence of a nucleus, which I doubt, which tend to 

 the conclusion which he has so definitely formulated by 

 assigning to the green corpuscles of Hydra the name Zoo- 

 chlorella conductrix. 



There is in all that is known of the structure of the 

 chlorophyll-corpuscles of Hydra, as of Spongilla, nothing 

 which separates them in character from the known chloro- 

 phyll bodies of plants. On the other hand, it is not only 

 impossible to characterise Dr. Brandt's genus '' Zoochlo- 

 rella " in botanical language, but there are a variety of 

 facts known both as to the objects called by him Zoochlorella 

 conductrix and as to those called Zoochlorella parasitica, 

 which lead to the conclusion that in thus dogmatically 

 asserting the parasitic and algoid nature of those objects. 

 Dr. Karl Brandt has wandered very far from the legitimate 

 inferences warranted by the facts. 



No distinct wall, either of cellulose or of other substance, 

 exists external to the green-coloured cap or shell of the 

 chlorophyll-corpuscles of Hydra and Spongilla. Their 



