37 



Oltmanns (47) supposes that in the colourless gemmules of the 

 fresh-water sponges the algae would be colourless for lack of light. 



But is it correct to suggest this analogy of algae to higher plants ; 

 is it not possible that the sijmbiotic algae do produce chlorophyll 

 in darkness? 



When comparing the amount of algae in green and colourless 

 sponges (p. 35, Table 6) one is inclined to declare, on account of 

 the presence of green algae in colourless sponges in darkness and 

 of colourless ones in green sponges in light, that evidently lack 

 of light can not be the cause of the algae being colourless. But 

 this conclusion would not be riglit ; for it is possible that it is 

 dark within the tissue of a green sponge in light — therefore 

 the colourless algae — ; and on the other hand we know, that a 

 sponge, c. q. a colourless one, is able to capture green chlorophyll 

 corpuscles from the surrounding water (pag. 27 — 28). 



In order to decide whether the symbiotic algae can produce 

 chlorophyll in darkness or not, we have to cultivate them isolated 

 from the sponge tissues. So I did on a large scale (see Table 4 B, 

 cultures in water, except column 6), with the following results : 

 1. During the first two months a rather vigorous multiplication of 

 the green material took place, together with an inrease of the 

 number of green chlorophyll corpuscles (and not caused by a pro- 

 pagation of other algae). 2. Even in cultures of 4 months and 

 older such multiplication occurred, or green stages of division 

 were to be found. 3. In old cultures the normal green corpuscles 

 were still present in a great number. 4. On the contrary, the 

 colourless corpuscles (with structure) in general did not increase, 

 but even decreased in number ; in this way : the original number 

 disappeared rather quickly, lateron some new ones might arise, 

 but also these disappeared after some time. 



So the fact known for higher plants, viz. that chlorophyll can not 

 be produced in darkness, proved not at all appliable to our sym- 

 biotic algae. On the contrary, these algae can produce chlorophyll 

 in darkness very ivell indeed. 



It proved then to me to be a well-known fact in botanical 

 literature since Schimfer (51) 1885, that algae can produce chloro- 



