177 



4. The green chlorophyll corpuscles of the fresh-water sponges 

 are round or oval, 1.7 — 3.8 [y. in diameter, surrounded by a cell- 

 wall and consisting of protoplasm and a chloroplast; while perhaps 

 a nucleus is present, but a pyrenoide is absent. They enclose 

 oildrops, but carbohydrates were never to be found within them 

 (p. 21—27, Fig. 5, 40, 41, 6—11). 



5. These green chlorophyll corpuscles, isolated from the sponge 

 tissues, remain normal and alive for 6 months and even longer, 

 and multiply (p. 27, Table 4). They also occur free in nature, 

 in the waters in which the sponges are living, where they also , 

 multiply (p. 27—28). 



It proved possible to me to durably transmute colourless Spon- 

 gillidae into the green form, by infecting them with isolated 

 green chlorophyll corpuscles (p. 28, Table 7, 8). 



So the green, chlorophyll corpuscles prove to be organisms, on 

 the one hand capable of living by themselves without the sponge 

 body, on the other hand of accommodating themselves to the life 

 within the sponge tissues, when taken from the surrounding water 

 by the sponge. This result together with that of 4, mentioned 

 above, justifies the conclusion, that the green chlorophyll corpuscles 

 are algae, associated to the sponge in „symbiosis" (p. 21 — 24, 29). 



6. This green „symbiotic" alga of the Spongillidae multiplies 

 by simple, vegetative division of the whole mother cell, not by 

 „freie Zellbildung" (p. 30—33, Fig. 5, 12—34). Thus the alga 

 does not at all answer the definition of a Chlorella (p. 29 — 30, 

 84), but — in connection also with its structure (p.- 24 — 27) — 

 that of a Pleurococcus (p. 34). 



7. Grenerally speaking, green Spongillidae grow in light, colour- 

 less ones in darkness or in twilight (p. 35) ; while green sponges 

 grow colourless in darkness, and colourless ones grow green in 

 light (p. 35, Table 8). 



8. In the green sponges in light as well as in the colourless 

 ones in darkness green as well as colourless „symbiotic" algae 

 occur (p. 35, 46, 48, Table 6). 



9. Several of those colourless algae have exactly the same 

 structure as the green ones (p. 36, Fig. 35). 



12 



