1914] Arthur W. Dox 223 



The precise röle of the inorganic nutrients of the medium was 

 not fully understood until comparatively recent years. It is now 

 generally believed that phosphorus and sulphur form an integral 

 part of the fungus, since they go to make up the nucleoproteins and 

 proteins; potassium and magnesium enter into the structural Cle- 

 ments of the plant, while iron and zinc act merely as catalysers 01* 

 stimulants. Until very recently iron was thought to enter into the 

 composition of the coloring matter^ of the spores, forming a sub- 

 stance analogous to the hematin of the blood of vertebrates. This 

 view has lately been refuted by Javillier and Sauton^ who showed 

 that iron is not indispensable f or the production of the black spores. 



The phosphorus assimilation of Aspergillus niger has been 

 studied by the writer.^ Both organic and inorganic Compounds of 

 phosphorus, including phytin, glycerophosphate, nucleic acid, leci- 

 thin, casein, ovovitellin, and ortho-, pyro- and metaphosphates were 

 available. On the other hand, trivalent forms of phosphorus, such 

 as phosphite and hypophosphite, though not appreciably toxic, could 

 not be utilized as the sole source of this dement. 



Sulphur likewise forms a great variety of Compounds, both 

 organic and inorganic, representing various stages of oxidation. 

 In Raulin's medium the sulphur is supplied entirely in the form of 

 sulphate. As yet, however, very little work appears to have been 

 done on the sulphur assimilation of fungi. Kossowicz and von 

 Groller^ f ound that thiosulphate and thiocyanate were available, but 

 the numerous other types of sulphur Compounds have not been 

 studied with reference to their availability in culture media. Sele- 

 nium and tellurium, though presenting many analogies to sulphur, 

 behave quite differently in culture media. Rosenheim''^ introduced 

 Compounds of selenium and tellurium into cultures of Penicillium 

 brevicattle and noted the formation of an offensive gas in each case. 

 Although the volatile substances were not indentified, they were 

 probably alkyl derivatives of these Clements, analogous to the 



^Linossier: Compf. rend., 112, 489-92 (1891). 

 * Javillier and Sauton: Ibid., 153, 1177-^ (1911). 



5 Dox: Journ. Biol. Chem., 10, 77-80 (1911). 



6 Kossowicz and von Groller: Z. Gärungsphysiol., 2, 59-65 (1912). 



7 Rosenheim: Proc. Chem. Soc, 18, 138-9 (1902). 



