CHLOROPHYLL-CORPUSCLES AND AMYLOID DEPOSITS. 249 



Sometimes these are absent, and it seems that specimens 

 of Hydra viridis may be obtained, according to season and 

 state of nutrition, in which such internal granules are 

 present in all the corpuscles, or, on the other hand, absent 

 from all or nearly all of them. 



The corpuscles average about twice the diameter of the 

 chlorophyll-corpuscles of Spongilla, that is to say, from 

 g-^Voth to y^'^o th of an inch. Some are larger. The chief 

 difference between the corpuscles in the two animals is found 

 in the fact that the green substance forms a concavo-convex 

 cap upon its related protoplasmic base or corpuscle in Spon- 

 gilla, whereas in Hydra the coloured cap is extended on all 

 sides, so as to form a hollowsphere enclosing some protoplasm, 

 and additional granules are developed within the sphere. It 

 has been pointed out above that, as an exception, a green 

 corpuscle may be found in Spongilla having the form charac- 

 teristic of Hydra (see PI. XX, fig. 12); so, too, in Hydra 

 small green corpuscles may be found, which have the green 

 investment incomplete and cap-like (PI. XX, fig. 20 a,f, h). 

 Kleinenberg observed the staining of the colourless proto- 

 plasm within the green corpuscles of Hydra by iodine, car- 

 mine, and aniline. This I have also observed, but found 

 it to be much less intense than that of the cell-nucleus, so 

 that it is possible to obtain a staining of the nucleus whilst 

 the corpuscles remain unstained (PI. XX, fig. 15). 



Kleinenberg makes no mention of any nucleus-like body 

 within the green corpuscles, and I am in accord with him. 

 Dr. Brandt states (loc. cit.) that a cell-nucleus can be clearly 

 demonstrated in each chlorophyll-corpuscle, and makes this 

 his chief ground for regarding the corpuscles as parasitic 

 Algae. I have not found such a nucleus in Hydra any more 

 than in Spongilla, and find it difficult to believe that, if 

 present, it would have escaped the careful examination made 

 both by Kleinenberg and myself. 



Kleinenberg makes no mention of starch in connection 

 with the chlorophyll-corpuscles or other parts of the endo- 

 derm-cells of Hydra. I have also not succeeded in finding 

 starch in these bodies. I have, however, very rarely ob- 

 tained a blue coloration \v\ih iodine in the neighbouring 

 protoplasm, and in one specimen a few granules (not chlo- 



cblorophyll, and is usually in the form of a spherical shell, enclosing factor 

 No. 3, but may also occur as granules embedded in that third factor; the 

 chromophorous substance resists the action of staining agents. (3) Colour- 

 less homogeneous protoplasm, enclosed by the shell of chromophorous 

 substance, and capable of taking a stain with strong colouring agents, 

 but devoid of nucleus or nuclear matter. 



