308 MEACHAM, HOPFIELD AND ACREE 



CONCLUSIONS 



1. Malt extract and corn meal extract have been buffered with 

 phosphate-acetate mixtures and with phosphate-phthalate mix- 

 tures to straighten out the first phosphate inflection curve and 

 regulate the hydrogen ion concentration accurately between pH 



= 1 and pH = 8. By using asparaginic acid and other amino- 

 acids the acidity can be regulated accurately between pH = 1 

 and pH = 13. 



2. It is shown that Endothia parasitica (Murr.) Anders, grows 

 excellently on all of these media when regulated at optimum 

 values close to pH = 5.7, but that the phosphate-phthalate buffer 

 is somewhat (25 per cent) better. Furthermore the malt extract 

 seems to give slightly (10 per cent) better growth than a corre- 

 sponding corn meal medium containing the same buffers. 



3. It is suggested that biologists should study the influence of 

 all chemical species present, such as the activity of the nonion- 

 ized acids, bases and salts along with the various simple and com- 

 plex ions. 



