109 



When we look over the residta ohtaineJ, we migld conclude the 

 foUowing cmises for the dijing of the algae in the sponge tissue: 

 A. In light in fact only „killing froin want of food'^ (point 1,1^, 

 and such of the (few) algae, the poiver of resistance of tvhich is 

 somewhat weaketied already for some or other reason; but not 

 „poisoning" by products of metabolism (point I, 2) nor lack of 

 food, lack of 0.^, and accumulation of CO^ in the algae them- 

 selves (point I, 3, 4). B. In darkness either ^killing from want 

 of food^' (point I, \) — perhaps even stronger 7iow — or (and) 

 „poisoning''^ hg products of metabolism (as reaction of defence of 

 the sponge against a foreign intruder) (point I, 2^, and such 

 again of algae, the power of resistance of wkich has certainly 

 weakened noiv niifch more, in consequence of lack of food or of 

 0.^ and accwmulation of CO.^ (point I, 3, ■i). 



For the present a more detailed conclusion cannot be given; 

 more data are required for that, among others about the problem 

 if there is really question about lack of 0^ — with all its con- 

 sequences, as for instance increased want of food — in the tis- 

 sues of a sponge in darkness. 



Let us now pay attention to the two points {oc, (3, p. 108), re- 

 garding this last problem and which are so important, because 

 they give us an insight into the sigtiificance, which the 0^, se- 

 creted hg the green algae in light within the sponge tissue, might 

 have for the life of the spo?ige. One cannot say, that the con- 

 clusion, made in connection with those points o. and /3, quite 

 satisfies us. 



The hypothesis, that in lack of 0.^ the kataholic phase of the 

 metabolism will have quite another course (than in abundance of 

 O.J and consequently will cause an increased want of food — 

 as is given on p. 98 and 103 sub I, 1 — may be right in general, 

 it seems a bit far-fetched to consider this hypothesis applicable 

 to our case of a sponge in darkness. Certainly, the sponge in 

 darkness will possess a much smaller quantity of 0.^ in its tis- 

 sues than the green sponge in light. But is there really lack of 

 0^, while sponges have even an extremely strong circulation of 



