100 



On p. 50 I have treated already, what an enormous quan- 

 tity of water a tiny sponge makes circulate through its canal- 

 system. This current of water is kept up by the flagellar-motion 

 of the choanocytes. Consequently in these choanocytes a very 

 strong transformation of energy takes' place; tJiose choanocytes, 

 therefore, must necessarily dispose of a great source of energy. 

 What is more evident than that this large mass of oildroplets and 

 of carbohydrate globules ivould serve as such! The more so, as 

 Ve know from general physiology, that in organisms labour, 

 the so called functional metabolism, exactly takes place at the 

 expense of N-free materials, so of carbohydrates and fats — 

 Verworn (58), Hammarsten (26). 



Next we can say that it is also very likely, that the oil- 

 droplets (and carbohydrate globules?) are used in great numbers 

 for the development of the gemmules ; for what we have given 

 an argument above. 



Let us just look over, what we have stated in the last pages 

 about the production and the consumption of fat in the sponge; 

 and let us try to make up in this way an explanation of the facts, 

 which we derived from Table 12 for colourless sponges from 

 darkness and green ones from light (point 5, 6, p. 87 — 89). 



This must be preceded however by another question. Namely : 

 does the great mass of fat, obtained by the sponge from the 

 digestion of the algae, occur in the sponge as oildroplets — the 

 number of which we can easily state by means of the micros- 

 cope — , or divided into glycerine and acid — which entirely 

 disappear from observation ? In other words : may we see in the 

 number of oildroplets, which has been experimentally stated, the 

 total quantity of fat present in the sponge tissues, or, if not 

 the entire, yet a proportional quantity — or may we not do 

 so at all? This is an important question. The (1st and) 2"'^ sup- 

 position sounds most probable; not the S'tl. This question will 

 soon find its solution in the following. 



Now return to our subject. We were going to try to make 

 up an explanation of the facts mentioned under point 5 and (>, 

 with the help of the data about production and consumption of 



