36 



As mentioned in the Introduction, Lankester (35) already has 

 found in colourless sponges the otherwise green amoebocytes now 

 overladen with colourless grains, which appeared to be chlorophyll 

 corpuscles in a somewhat abnormal condition, viz. irregular and 

 angular. Lankester concluded that there had to be some relation 

 between those two (green and colourless) forms. 



I have examined this more exactly and it proved to be the 

 case. But I must not only declare that — contrary to Lankester's 

 observations — the colourless chlorophyll corpuscles may be per- 

 fectly similar to the green ones as to their structure, but also 

 that their mutual relation is quite different from what Lankester 

 thought (Introduction pag. 4). On account of its great importance, 

 I will treat this question in a new chapter. 



VI. The structure of the colourless „symbiotic" algae ; how 

 they arise from the green ones. 



I will treat now only the pure structure of the colourless chloro- 

 phyll, corpuscles^ as we can observe it from the well preserved speci- 

 mina in which it is still clearly showing. This structure is per- 

 fectly similar to that of the green ones, as shown in the illustra- 

 tion (Fig. 35) ; the diameter is the same. The colourless corpuscles 

 may also contain an oildrop and generally occur free in the proto- 

 plasm of the amoebocytes, just as the green ones do. 



What then is the relation between these colourless symbiotic algae 

 and the green ones? Did the former arise from the latter or the 

 latter from the former? 



In relation to the facts, that green sponges occur in light and 

 colourless ones in darkness (p. 35); that green sponges grow 

 colourless in darkness and colourless ones grow green in light 

 (p. 35) ; and to the fact, that we know the same to be the case 

 for the higher plants, one might be inclined to conclude that all 

 these facts are based on one ^axaQ pheyiomenon, known for the higher 

 plants, viz. that chlorophyll can not be produced in darkness. 

 Lankester and Brandt (I.e.), indeed, did explain these facts in this 

 way, as I mentioned in the Introduction (pag. 4). And also 



