67 



green sponge in light: mu = mo 



V A 



green sponge transferred into darkness : mu < ^) mo 



; II V 



light-green sponge in darkness : mu < mo 



I II V 



colourless sponge in darkness: mu = mo 



Now the reverse : proceeding from a colourless sponge grown 

 in an aquarium in darkness (so : mu = mo). What happens when 

 we transfer this sponge into an aquarium in light? Then the 

 sponge will become green : 



colourless sponge in darkness: 

 colourless sponge transferred into light: 



I 



light-green sponge in light: 



I 



green sponge in light: 



I am not going to treat this question at large now, for I will 

 soon come back to it, when treating the behaviour of the sponges 

 in nature. 



Having examined the 6 factors^ ruling the number of sym- 

 biotic algae in sponge tissue^ as well as some of their chief com- 

 binations , we ivill try to answer the above (p. 48) mentioned 

 questions^ concerning Spongillidae in free nature^ by means of the 

 data we have obtained in the mean time. 



1) < is 8troHger than <, ^ is stronger thau <. 



