ISOLATION, PURIFICATION, NUTRITION 33 



species obtained in pure culture, it was selected for the initial 

 detailed mineral nutrition studies. Chu No. lo solution was not 

 a suitable culture medium for this work, as each of several of 

 the salts used provides more than one of the elements essential 

 for plant growth, thus making it impossible to study the effect 

 of variations in the concentration of a single element. For this 



Table 2 — Composition of basic culture solutions used for mineral nutri- 

 tion experiments with Coccochloris Peniocystis. 



Grams per Ppm. of 



Compound liter essential elements 



NaNOg 0.0413 N 6 8 



Na2HP04 0082 P 18 



KCl 0.0086 K 4.5 



MgCls 6H2O 0.0209 Mg 2.5 



Na2S04 0.0146 S 3.3 



CaCla 2H2O 0359 Ca 9.8 



Ferric citrate 0.003 Fe 56 



Citric acid 



NaoCOg 



NaaSiOg 



Hoagland's A to Z solution is added to the culture solution at 1/25 

 the strength specified for higher plants. 



reason, the nutrient solution presented in Table 2 was developed. 

 Whereas the concentrations of the essential elements are the same 

 as in Chu's No. 10 solution, the cations are present as chloride 

 salts and the anions as sodium salts which permit independent 

 variation of each essential element. The sodium carbonate and 

 sodium silicate present in Chu No. 10, ferric citrate - citric acid 

 as an iron source, and Hoagland's A-Z solution of minor elements 

 are included. 



The culture vessels were 500 ml. Erlenmeyer flasks containing 

 200 ml. of the appropriate nutrient solution. Pyrex glassware 

 and pyrex glass - distilled water were used for all solutions and 



