6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 92 



2. Emerson's (1929) Solution 



Magnesium sulphate o.oi molar 



Potassium nitrate 0.0125 



Potassium acid phosphate 0.0090 



Calcium carbonate 0.000 1 



Iron a 



3. Johnston's (1929, 1932) Solution 



Calcium nitrate 0.005 volume molecular concentration 



Magnesium sulphate 0.002 



Potassium acid phosphate 0.002 



Distilled water made up to i liter 

 Iron ^ 



4- 

 Detmer i solution in which potassium chloride is replaced by .33 grams of 

 potassium acid carbonate which supplies the same amount of potassium. 



s. 



Detmer ^ solution in which potassium chloride is replaced by .6 grams of 

 potassium acid carbonate. 



6. 

 Detmer j solution in which potassium chloride is replaced by 1.2 grams of 

 potassium acid carbonate. 



7. 

 Detmer f, solution in which potassium chloride is replaced by 2.4 grams of 

 potassium acid carbonate. 



8. 

 Similar to i but with cotton plugs. 



9- 

 Similar to 2 but with cotton plugs. 



" All equal quantity of iron was added to all the solutions. 



Rtibber stoppers were used for all the Erlenmeyer flasks except in 

 8 and 9, duplicate cultures of Detmer ii and Emerson respectively, 

 which were plugged with cotton. The excess sulphur was removed 

 from the rubber stoppers with petroleum ether before they were 

 sterilized. One hundred cc of nutrient solutions was placed in each 

 300-CC Erlenmeyer flask and sterilized in an autoclave at 20 pounds 

 pressure for 20 minutes. 



Five cultures of each of the above solutions were inoculated with 

 Stichococcus hacillaris Naegeli. A similar number of cultures was 

 inoculated with Chlorclla vulgaris var. Four sets of each alga were 

 placed in the water baths, the fifth in a north window of the Smith- 

 sonian flag tower. 



