340 PROFESSOR E. RAY LANKESTER. 



specimen of green-coloured Spongilla. But a valuable 

 method is that of teazing the piece of Spongilla in a drop of 

 dilute solution of osmic acid (| per cent.). Such prepara- 

 tions may be subsequently stained by picro-carmine, as 

 shown in PI. XX, fig. 13. When this treatment is adopted 

 it is noted that though the nucleus of the sponge-cell stains 

 very intensely no staining of the chlorophyll-corpuscle, or of 

 the protoplasm close to it, occurs. 



There is no evidence of any nucleus-like body, either 

 within the chlorophyll-corpuscle or in immediate relation 

 with it. 



When a piece of green Spongilla is decolorised by the 

 action of strong alcohol and subsequently teazed the concavo- 

 convex discs, which were before observed in a green state, 

 are still to be found, but now they are colourless.' 



When the amoeboid cells of Spongilla containing chlo- 

 phyll-corpuscles are broken up on the stage of the micro- 

 scope the corpuscles are set free, and are found to have a 

 considerable degree of resistance to the action of water and 

 a permanence of form, as is observed with the chlorophyll- 

 corpuscles of plants. 



Under such treatment it is further observed that the green 

 concavo-convex discs do not separate cleanly from the pro- 

 tojilasm, but each carries with it a little sphere of protoplasm, 

 upon which it rests as a cap (figs. 9 d, 10 b). The relation of 

 the green cap to the sphere is such as to suggest a one-sided 

 formation of green matter upon one hemisphere of the pro- 

 toplasmic particle. Were the formation of green matter 

 symmetrical we should have the protoplasmic sphere enclosed 

 in a complete shell of green substance, as in the abnormal 

 corpuscle of fig. VZ, and as in the normal green corpuscles of 

 Hydra viridis (figs. 17, 20). 



I could not discover in the unbroken amoeboid cell that 

 there was any differentiation of a protoplasmic sphere cor- 

 responding to each chlorophyll-corpuscle. It would seem 

 rather as though a piece of the surrounding protoplasm 

 simply adheres to the concavo-convex disc when the cell is 

 broken up. At the same time pieces of protoplasm may be 

 observed when such cells have been broken up which con- 

 nect two or more (as many as six) concavo-convex discs of 

 green colour (fig. 10 a), suggesting that the cap-like chloro- 

 phyll-corpuscles are grouped around a centre of growth, and 



' Accordingly we distinguish iu the concave chlorophyll-corpuscle of 

 Spongilla — (1) the chloropiiyll itself, (2) the chroniophoious substance . 

 which carries the chlorophyll. In Hydra, as will be seen subsequently, we 

 have to add to these two elements (3) colourless protoplasm, enclosed by 

 the chromophorous substance. 



