2 NUTRITION OF FUNGI 



cussion of this subject under two headings: (a) inorganic or 

 mineral nutrition of fungi, and (b) organic nutrition of fungi. 



MINERAL NUTRITION OF FUNGI 



Problems relating to the mineral nutrition of fungi appear at 

 first to have been approached wholly by empirical methods. The 

 experiences and techniques of bacteriologists constituted the 

 foundation for these early studies. The investigators seem to 

 have employed such chemical compounds and in such proportions 

 as had been found to promote the growth of bacteria. The proper 

 kind and amount of mineral elements were not sought by ex- 

 tended series of experiments in which ash analyses were correlated 

 with rate of growth or with amount of mycelial mat. 



Not only were these procedures employed with liquid media 

 but also mycologists followed the bacteriologist in quite the same 

 way in the use of the numerous kinds of semisolid media. It is 

 not unusual to find now that a particular medium, compounded 

 according to a certain formula, is a favorite with a given mycolo- 

 gist and that he attempts to cultivate all species in which he may 

 be interested on this particular medium. It will become apparent 

 in the discussion which follows that this procedure may lead to 

 erroneous conclusions regarding the nutrition of the fungi in- 

 volved. 



Investigations of the mineral nutrition of fungi may be said to 

 have beeun with the classical researches of Raulin (1869), a 

 pupil of Pasteur. He employed Aspergillus niger as a test organ- 

 ism and secured optimum growth in a medium, now known as 

 Raulin's solution, having the following composition: 



Ammonium nitrate 4 grams Iron sulphate 0.07 gram 



Ammonium phosphate 0.6 gram Potassium silicate 0.07 gram 



Magnesium carbonate 0.4 gram Sucrose 70 grams 



Potassium carbonate 0.6 gram Tartaric acid 4 grams 



Ammonium sulphate 0.25 gram Water 1500 ml 



Zinc sulphate 0.07 gram 



He concluded that none of the minerals contained in this medium 

 could be omitted if optimum growth was to be secured. 



Raulin's studies stimulated a series of investigations, the out- 

 standing of which were those of von Naegeli (1880), Benecke 



