43 



the colourless ones with structure (p. 

 protoplasm of the amoebocytes ; so they are not lying in vacuoles. 

 Nevertheless, sometimes one may also find them in food vacuoles 

 (Chapt. VIII). 



It is very likely now, that the 3 last groups, the colourless 

 algae with shade of structure, the colourless ones without struc- 

 ture, and the vague shades of colourless ones, are only successive 

 stages of „solution" of the colourless ones with clearly marked 

 out structure; for this reason it would be rather evident, that 

 the latter are dying. 



II. I have been able to prove by numerous experiments, that 

 in fact the isolated green symbiotic algae can cliange in this way 

 only : first into colourless ones with clear structure, then into 

 colourless ones with shade of structure, next into colourless ones 

 without structure, then into vague shades of colourless algae, in 

 order to finally disappear. The green algae were killed 

 purposely in many of these experiments, for instance by 

 heating or more or less intense lighting. (Table 5, n''. 68, 94, 

 95, 290 n, 290 p, 3071, 3081, 318, a. o.) 



In this table also many cultures taken from Table 4 are recorded. 

 In them it is striking to notice, that through infection of mould, 

 common algae or diatoms the green symbiotic algae are changed 

 into colourless ones with structure, while the latter, passing via 

 the other colourless stages mentioned above, will disappear from 

 the culture (W\ 84, 851, 113, 141, 188, 189, 190, 194, a. o.). 

 Bacteria, on the contrary, don't seem to do any harm to these 

 green algae at all (Table 4). 



As, when purposely killing the isolated green algae, we get 

 a succession of quite the same stages of colourless algae which 

 we also meet in sponges, it is indeed very likely, that in the 

 latter too the colourless algae with structure arise in no other 

 way than by dying of the green ones, in order to pass also after 

 that into the various successive stages of „solution" — mentioned 

 above — to finally disappear entirely from the sponge tissues. 

 And the more so, because the same succession of stages can be 

 found in cultures infected by mould, common algae and diatoms. 



