65 



pass the decrease. Accordingly, we saw that in light: a. most 

 colourless to light-green Ephydatiae (15) became greener (or at 

 least increased in number of green algae), that but few specimina 

 remained colourless (3) or even decreased in number of green 

 algae (3), while others became greener in the beginning in order 

 to lose their colour entirely afterwards (4); b. the green Ephy- 

 datiae sometimes kept up (3), sometimes even increased (2), 

 several times however considerably decreased (4) their green 

 colour. So it proves that in general Ephydatia in light behaves 

 like Spongilla; but that even under these circumstances it pos- 

 sesses a strong tendency to become colourless. 



2. From 37 Ephydatiae cultivated in darkness behaved like 



II 13 =13 = + 35% 



: m 9J = i« = ±^^°/» 

 , I, III 4 = 4= + ir/„ 



If we consider, however, that under type II 12 already origin- 

 ally colourless sponges occur — in which some increase of the 

 green colour could probably have been observed very well, but 

 no decrease can possibly have been observed — we are justified 

 in neglecting those 1 2 specimina. Then we would find : 



From 25 (= 37 — 12) sponges in darkness behaved like 



type I + IIi 2= 8% 



.II 1 = 4% 



„ II"i + III 18 = 72% 

 „ I, III 4 = 16% 



Consequently , in the greater majority of Ephydatiae, when 

 cultivated in darkness, the increase of the green algae proves 

 smaller than the decrease. Accordingly, we saw that in dark- 

 ness : a. most green to light-green Ephydatiae (11) lost their 

 green colour, but 1 kept it up; h. the colourless Ephydatiae ge- 

 nerally remained colourless (12) or even lost green algae (7); 



