Ill 



selves with the general formulating of the answer given on p. 109. 



The final result of our research into the use of the „symbiotic'^ 

 associatioti {of sponge and green alga) to the sponge is therefore: 



It is either the want of food of the sponge — which might be 

 strongly increased in darkness — or {and) the j^'poisonous'" influence 

 of harmful products of metabolism of the sponge {to be considered 

 as a reaction of defence against a foreign intruder) which 

 continually destroys green symbiotic algae in the amoebocytes • 

 and exactly those cdgae^ the power of resistance of which is already 

 weakened for some or other reason — ■ for instance by having been 

 in darkness — (p. 102 — 109). All algae killed in this way come 

 to the benefit of the nourishment of the sponge ; as this one digests 

 and dissolves them entirely either free in the protoplasm of its 

 amoebocytes or in food vacuoles^ keeps the products of the decom- 

 position (p. 96 — 97) and rebuilds its own cell parts with them., 

 namely for instance the oildroplets and carbohydrate globules 

 (p. 98 — 102). These oildroplets and carbohydrate globules in their 

 turn are, among others, the source of the great quantity of energy^ 

 which the sponge transforms in the flagellar motion of its choano- 

 cytes (p. 100). 



For the p)r^sent no decision can be given about the exact signi- 

 ficance for the life of the spmnge of the 0.,, which the living green 

 algae in light secrete within its tissues (p. 93). It may be, that this 

 0.^ is of much significance ; even so much, that the kataboUc phase 

 of the process of metabolism in a green sponge in light has quite 

 another course by it — namely gives a relatively much larger 

 quantity of energy to the spo7ige — than in the sponge in darkness 

 {p. 98, 103, 109 — 110). Some indications were found for this; but 

 this importayit question requires quite a sejjerate research, before 

 anything can be said for certain. 



As we saw {p. 96, 87, 92) it is very likely, that direct transfer 

 of products of photosynthesis from the living green algae into 

 the sponge tissue does not take place at all. 



When next we ask, what in fact the „symbiotic'" relation of 



