78 



2. BiRXER AND LuCANUS's SOLUTION. 



MgSO, '. o.sg. 



Ca(NO,), 1.5 g. 



KH.PO^ i.og. 



FeClj trace. 



Distilled water ; . . . looo c.c. 



3. Knop's Solution. 



MgSOj 0.25 g. 



CaCNOs), i.oog. 



K,HPO, 0.25 g. 



KCl 0.12 g. 



FeClj trace. 



Distilled water 1000 c.c. 



4. Prantl's Solution. 



K.SOj 0.7 g. 



NaCl 0.23 g. 



CaSOi ; 0.7 g. 



MgSO, 0.5 g. 



NH4NO,, solution, 0.064 per cent 20 c.c. 



5. Sachs's Solution. 



KNO3 ' I 



NaCl ■. 0.5 



CaSOj 0.5 



MgSO, 0.5 



CaHNO^ o.sg 



Distilled water 1000 c.c 



Experience has shown that it is best to omit the ferric chloride 

 from the stock solutions and to add a drop of a i per cent solu- 

 tion of ferric chloride to the nutrient solution of each culture 

 before the spores are sown. 



It is best to make up a liter of the nutrient solution, being very 

 careful always to use only pure chemicals and distilled water. 

 "It is not necessary to sterihze the solutions, in fact cultures seem 

 to do better on unsterilized solutions, especially those containing 

 ammonium nitrate, probably because of chemical changes caused 

 by heating. 



Solutions should be kept in flasks or bottles well-stoppered 

 with cotton in a clean place. Great care must be exercised in 

 opening the flasks in the laboratory or the solutions will become 



