39 



2. in i'ich foediiig solutioii (water + salts + peptone + glu- 

 cose) vigorous growth of green algae takes place. 

 C. Chlorococcum infusionum froni the Lichen Xanthoria pa- 

 rietina. 



a. b. wlien cultivated in liglit or in darkness and in all kinds 

 of feeding solutions the algae rcniain green. 



Ho the algae proüe to hecome colourless under verij ((i/f'ereiU 

 conditions as to UgJd and food. Therefore we ougJit to exmnine, 

 if perhaps oiir symhiotic algae can lose their green colour and 

 2)((ss into the colourless form hg a combination of darkness (or 

 light) and a certain feeding miliea. And at the same time we 

 should examine, if the colourless form of the syinbiotic algae mag 

 in its turn pass into the green one hg a certain combination of 

 light (or darkness) and feeding milieu. 



For the present I will .treat the first question. We have to 

 examine then, to which of the foUowing types of algae — the 

 only ones possible and partly hypothetical — our symbiotic 

 alga belongs : 



A. when cultivated in darkness. 

 type I (Scenedesmus). 



in poorer feeding solution the algae remain green. 



in rich feeding solution the algae become colourless. 

 type II (Chlorella, Stichococcus). 



in poorer feeding solution the algae become colourless. 



in rich feeding solution the algae remain green. 



type III (Chlorococcum from Xanthoria). 



in poorer feeding solution ] 



. _ „ _ , . / the algae remam green, 



m rich leedmg solution ) 



type IV (hypothetical). 



in poorer feeding solution 1 , , , 



. , „ ,. , ,. the algae become colourless. 



in ricn teeding solution \ 



B. when cultivated in light. 

 type I (Scenedesmus). 



in poorer feeding solution the algae remain green, 

 in rich feeding solution the algae become colourless. 



