224 Mineral Nutrition of Fungi [Jan. 



diethylarsine identified by Gosio''' when arsenic was added to cul- 

 tures of this organism. 



A niimber of interesting investigations have lately been carried 

 out with reference to the effect of replacing the inorganic Clements 

 of Raulin's medium by other Clements in the same group of the 

 periodic System or by elcmcnts presenting other analogics. 



Potassium is of great importance in the nutrition of fungi. 

 Sauton^ obtained a yield of 0.165 g^^''- dry weight of fungus in the 

 abscnce of potassium, and a yield of 2.6 gm., or nearly 16 times as 

 much, in the presence of 0.003 P^'' ccnt. of potassium. In tne ab- 

 sence of potassium no spores appeared after eight days, but spores 

 soon resulted after addition of this dement. Substitution of rubid- 

 ium and caesium for potassium reduccd the dry weight 50 per cent. 

 Assuming that the rubidium and caesium salts used were entircly 

 free from potassium, which may be regardcd as somewhat doubt- 

 ful, it would appear that these Clements can replace potassium to a 

 certain extent, though not advantagcously. Benecke^^ states that 

 the Substitution of rubidium is attcnded by a diminution in spore 

 production. On account of the decided preference of Aspergillus 

 niger for potassium, Sauton^^ suggests this as a method for purify- 

 ing rubidium and caesium from potassium. Buromsky^- was un- 

 able to obtain normal cultures when the potassium was rcplaccd by 

 sodium. The addition of sodium salts to a potassium free medium 

 gave no bcttcr cultures than the control. 



Magnesium, like potassium, is indispensable for the normal de- 

 velopment of Aspergillus niger. Javillier and Sauton^^ find that 

 this dement cannot be rcplaccd by glucinum in the culture medium. 

 Frouin^^ used salts of cerium, lanthanum, neodymium, praesody- 

 mium, Samarium, thorium, and yttrium, and found that none of 

 these Clements could take the place of magnesium. Buromsky^^ 

 found that calcium could not replace magnesium. On the contrary, 



^ Gosio : Rivisia d'igiene e sanitä publica, 1892, 201. 

 ö Sauton: Compt. rend., 155, 1181-3 (1912). 

 ^'* Benecke: Jahrb. wiss. Bot., 37, 487 (1902). 

 ^1 Sauton: Lac. dt., 155, 1181-3 (1912). 

 ^^Buromsky: Centrbl. Bakt. II, 36, 54-66 (1912). 

 ^3 Javillier: Compt. rend., 156, 406-9 (1913). 

 ** Frouin : Compt. rend. soc. Hol., 73, 640-1 (1912). 

 *^ Buromsky : Loc. cit. 



