63 



ones hij culture in darkness and colourless sponges into green ones 

 hy culture in light, with the smallest number of active factors 

 possible. Consequently, we must succeed in explaining these plieno- 

 mena, the iiiterpr elation of which has been sought for ever so long 

 in quite a ivrong direction (pag. 36 — 41), as being caused by the 

 combined action of the multiplication and the mortality of the 

 green algae in the sponge tissues, in light and in darkness. See 

 Table 8, all n^s (all green and colourless Spongillae and Ephy- 

 datiae) ; generally of each sponge a piece was cultivated in light 

 and another piece under the same conditions in darkness. In each 

 piece the colour and mostly also the amount of algae in its 

 tissues was accurately examined at the beginning and at the end 

 of the experiment. 



In general we distinguish 3 types of sponges in respect to their 

 behaviour during the experiments. In type I the green colour, 

 so the number of green algae (as the experiments show), increases ; 

 in other words the increase of green algae surpasses the de- 

 crease. In type III the green colour and the number of green 

 algae decrease, in other words the increase of the green algae 

 is smaller than the decrease. In type II the green colour remains 

 constant as well as the number of green algae, or the green 

 colour or the number of green algae changes a little by increase 

 or decrease; in the last case but one we may speak of a type 

 Ilf; in the latter of a type 11"^. 



We see from the table: 



A. 1. From 92 Spongillae, cuj^tivated in light, behaved like 

 type I 60 

 „ Ih 3 

 „ II 22 = 22 = + 24% 



= 63 = + 68% 



II"i 2 

 III 5 



= 7 = + 8% 



If we consider, however, that under type II 21 already ori- 

 ginally green coloured sponges occur — in which some decrease 

 of the green colour could probably have been observed very well, 

 some increase but very difficultly ~ we are justified in neglecting 

 those 21 specimina. Than we would find: 



