30 NUTRITION OF FUNGI 



live on artificial media after the reserve within the spore has be- 

 come exhausted. Such species, in contrast, cannot be domesti- 

 cated. Strange diets, never encountered in their natural habitats, 

 are forced upon them in captivity in the test tube. Perhaps the 

 mycologist who attempts to study their physiology in artificial 

 media may actually be studying their pathology. 



Many published accounts dealing with the growth of a given 

 species on a wide variety of media are quite pointless and con- 

 tribute nothing fundamental to an understanding of the nutritional 

 requirements of the species. Similarly the compounding of nu- 

 trient formulae may be a misguided procedure, and the use of such 

 formulae may yield only sterile knowledge. The making and 

 using of formulae can be condoned only if their purpose is to 

 reveal the necessity of some factor that conditions a metabolic 

 activity of the fungus. 



In future studies more attention should be given to the utiliza- 

 tion of specific organic and inorganic materials in particular meta- 

 bolic activities. This necessity is indicated by the fact that some 

 substances do not support growth, although they are respired. It 

 is further indicated by the fact that many fungi grow well in the 

 presence of a given food but do not reproduce. Evidence shows 

 that some specific element, vitamin, or other growth factor is 

 essential for reproduction but may not necessarily limit any other 

 metabolic activity of the given fungus. 



More should be known regarding the mineral requirements of 

 fungi. Account should be taken in such studies of the ash content 

 of the fungus at the conclusion of the growth period, in com- 

 parison to the known ash content of the nutrient before the 

 fungus was allowed to grow upon it. It is indicated, furthermore, 

 that fungi may well be used in analytic procedures, especially in 

 the determination of trace elements [Niklas and Toursel (1941)1 

 or of vitamins. 



It appears that a more adequate understanding of the nutrition 

 of fungi would result if the terms parasitic (paratrophic) and 

 saprophytic (saprotrophic) largely disappeared from the teacher's 

 vocabulary. More emphasis would then be placed upon the abil- 

 ity of fungi to synthesize foods as well as a variety of other sub- 

 stances. As a consequence, the fact that fungi do not possess 

 chlorophyll would be of little concern to the teacher, and the 



