10 



been isolated, used to settle down to the bottom in one day's 

 time , then forming, together with sponge-rests, a continuous 

 membrane rather firmly attached to the bottom. 



The cultures of colourless clilorophyll corpuscles (from colour- 

 less sponges) were obtained in the same manner. 



The culture-media were the following: 1. water from the con- 

 duit, 2. solution of inorganic food, 3. solution of organic food, 

 either diluted or concentrated, 4. liquid from a pressed sponge, 

 also diluted or concentrated. 



The following solutions of inorganic food were used: 

 I. Solution of Oehlmann (from Doflein (17)). 



999 Gr. water 



0.2 „ MgSO^ 



0.4 „ Na H^ PO4 



0.4 „ K N O3 



II. Solution of Beijerinck (from Gerneck (23) ). 



100 Gr. water 

 0.05 „ NH4NO., 

 0.02 „ KH, PO4 

 0.02 „ MgSO^ 

 0.01 „ Ca C\, 

 traces Fe SO4 



And the following solutions of organic food : 



I. Solution of Artari (2). 



0.5 7o peptone (Witte) 



1 „ glucose 



0.3 „ KH, PO4 



0.1 „ Mg SO4 



0.1 „ CaClj 



traces Fe.^, Cl^ 



II, The same, but containing 6°/^ glucose. 



III. ■ Diluted solution of organic food ; obtained by mixing 50 

 cM"* of the solution of inorganics I and 3 drops of the 

 following solution of organics (of Zumstein, from Dof- 

 lein 1. c.) ; 



