Table 3. Culture Medium for Volvox globator and V_- tertius 



1 ml . of PIV metals contains: 

 HOEDTA ^^^ 1 mg. 



Fe (as Cl~) 0.04 mg . 



Mn (as CI") 0.01 mg . 



Zn (as CI') 0.005 mg . 



Co (as C1-) 

 Mo (as Na+) 



0.001 mg, 

 0.005 mg. 



(1) see note Table 5 



media (Table 3) when glycylglycine is used as a pH 

 buffer in place of TEA. Not only could good growth 

 be obtained with the same trace metal mixture be- 

 tween pH 7 and pH 8, but we could also employ a 

 wide range of concentrations (1-4 ml ./1 00) . 



During our work with Phacus pyrum and Wolo - 

 szynskia limnetica , we designed suitable media for 

 the alkaline and acid region, with the hope of eli- 



citing more growth by changing the penetrability of 

 the substrates . With TEA and succinic or malic 

 acids as buffers, we had to vary the media and the 

 chelation to suit the pH and the buffer system. The 

 resultant acid and basic media gave less or no 

 growth when the pH was changed. After suspecting 

 that the choice of the pH buffer affected chelation, 

 we tried both the acid and alkaline media at 



90 



