MINERAL NUTRITION OF FUNGI 3 



(1895), Molisch (1892, 1894), and Wehmer (1895). Von 

 Naegeli believed that sulphur and phosphorus are indispensable 

 for all molds and that potassium and calcium are replaceable, 

 potassium by rubidium or caesium, and calcium by magnesium, 

 barium, or strontium. The experiments of Benecke and Molisch 

 led them to conclude that magnesium is not replaceable by any 

 other mineral element. Benecke secured luxuriant growth of 

 many species of Aspergillus and Penicillium on a synthetic agar 

 medium, the inorganic salts of which were ammonium phosphate, 

 potassium chloride, and magnesium sulphate. Wehmer consid- 

 ered especially the essentiality of iron and zinc, each of which 

 was regarded as indispensable by Raulin (1869). 



Under the stimulus of studies on the mineral nutrition of green 

 plants several other mineral nutrient solutions were compounded 

 and employed not only with green plants but also with fungi. 

 These included the following: 



