181 



With the help of these data we got to the following conclu- 

 sion concerning this questión (p. 111 — 114): 



It is either the want of food of the sponge or (and) the „poi- 

 sonous" influence of harmful products of metabolisni of tlie 

 sponge (to be considored as a reaction of defence against a fo- 

 reign intruder), which continually destroys green „symbiotic" 

 algae in the amoebocytes ; and exactly those algae, the power of 

 resistance of which is already weak^ned for some or other reason 

 (p. 102—109). All algae killed in this way come to the benefit 

 of the nourishment of the sponge ; as this one digests and dis- 

 solves them entirely either free in the protoplasm of its amoebo- 

 cytes or in food vacuoles, keeps the products of the decomposi- 

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

 (p. 100). 



For the present no decision can be given about the exact signi- 

 ficance for the life of the sponge of the 0^, which the living 

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

 that this O2 is of much significance ; even so much, that the 

 katabolic phase of the process of metabolism in a green sponge 

 in light has quite another course by it — namely gives a rela- 

 tively much larger quantity of energy to the sponge — than in 

 the sponge in darkness (p. 98, 103, 109 — 110). Some indications 

 were found for this possibility. 



Direct transfer of products of photosynthesis from the living 

 green algae into the sponge tissue does, most probably, not take 

 place at all (p. 96, 87, 92). 



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

 sponge and green alga is, considered from the point of view of 

 the use to the sponge, we cannot very well answer that questión, 

 before the problem, mentioned above, about the significance for 

 the sponge of the O2 secreted by the green alga in the light, 

 has come to solution: 



