and Laboratory Methods. 2311 



Ammonium nitrate - - - - - - - -5 gr. 



Potassium phosphate --..-. .2 " 



Magnesium sulphate ------- .2 " 



Calcium chloride ------- .1 " 



Distilled water .-.--. lOOO. cc. 



Iron sulphate -------- trace 



For blue greens the amount of ammonium nitrate should be doubled and 



the addition of from 1 to 2 per cent, glucose is often of benefit. 



The solution used by Chodat and Grintzesco (Congres International de 



Botanique, Paris, 1900) is as follows : 



Calcium nitrate ------- l.Q gr. 



Potassium chloride ------ .25 " 



Magnesium sulphate _--.-- .25 " 



Potassium phosphate - _ . . - .25 " 



Distilled water ----..- IQOO. cc. 



This used in various dilutions from .5 to .1 per cent., gives good results with a 



number of the Protococcoidae. It does not, however, produce anything like as 



abundant growth as the modified Beyerinck solution, particularly when used 



with agar or gelatine. 



Another combination of mineral salts, recommended by Molisch, is : 



Potassium nitrate - - - - - - - .2 gr. 



Calcium phosphate ------- .2 " 



Magnesium sulphate - - . - - - - .2 " 



Calcium sulphate ------- .2 " 



Iron suphate -------- trace 



Water ----.-.-. lOoO. cc. 



The potassium nitrate in this solution does not seem to be any better than 

 the calcium nitrate in Knop's and the alg^e grow but little more luxuriantly 

 upon this medium. Blue green forms can scarcely establish themselves and 

 many unicellular grass greens appear starved or abnormal. The length of time 

 necessary for growth in this solution is also longer than where ammonium 

 nitrate and sugar are added. 



The following rather elaborate solution was devised by Miquel for use in 

 cultivating fresh water diatoms. Although it has proven satisfactory, it does 

 not present any marked advantages over the formulae already given. Diatoms 

 seem to require a plentiful supply of oxygen, but will grow well on solid media 

 rich in organic matter. 



A. Magnesium sulphate - - - - - - 10. gr. 



Calcium chloride ------ 10. " 



Sodium sulphate ------ 5. " 



Ammonium nitrate - - _ - _ 1. " 



Potassium nitrate ------ 2. " 



Sodium nitrate ------ 2. " 



Potassium bromide ------ 0.2 " 



Distilled water ------ ]()0. cc. 



B. Sodium phosphate ------ 4. gr. 



Calcium chloride - - - - - - - 4. " 



Hydrochloric acid ------ 2. cc. 



Iron perchloride - - - - - - - 2. " 



Distilled water ------ 80. " 



