45 



B. In methylene-blue. After 25 minutes the numerous green 

 algae are not yet blue at all. Colourless algae, however, are no- 

 where to be found, all of them are blue: the few with structure 

 (they have no green chloroplast !) as well as the rather numerous 

 ones without structure. 



2. Colourless Spongilla material containing several green symbiotic 

 algae, a few colourless ones with structure and rather numerous 

 colourless ones without structure. 



A. In eosine. After 25 hours the (several) green algae are not 

 yet red at all. Colourless algae are but seldom to be found, al- 

 most all of them are red: the few with structure (without green 

 chloroplast), as well as the rather numerous ones without structure. 



B. In methylene-blue. After 35 minutes the (several) green 

 algae are not yet blue at all. Colourless algae, however, are 

 nowhere to be found, all of them are blue : the few with structure 

 (without green chloroplast) as well as the rather numerous ones 

 without structure. 



The same counts for the algae of Ephydatia. 



By these last experiments we have got the decisive proofs, 

 that all colourless symbiotic algae in sponges are dead, at least 

 are dying. So we have mcontestahly shown, that the green r,sym- 

 hiotw'' algae in the tissues of' the Spongillidae become colourless 

 exclusively by dying (of the algae, namely), in order to gradually 

 pass from colourless algae ivith clear structure into the successive 

 stages of „solutioti''\ colourless algae with shade of structure, co- 

 lourless ones ivithout structure, vague shades of colourless ones, and 

 to finally disappear. 



For completeness' sake I want to mention that the colourless 

 sponge algae, arisen from green ones in a culture infected by 

 diatoms (pag. 43), were also quicldy stained with methylene-blue. 

 This proves that they too were dying. 



