384 



MEDICAL MYCOLOGY 



with cultures and becomes more and more familiar with them in 

 the laboratory routine. 



Studies of the type conducted by Conant (1936, 1936a, and 

 1937), in which the investigator has at his disposal a large number 

 of species and strains, offers the best means of solving the confus- 

 ing taxonomic problems of the Trichophytoneae. Conant made 

 biometric studies but may not have had a sufficient number of 

 strains of each species to become familiar with the extremes of 

 variation within a given species. In criticizing these studies, Em- 

 mons (1940) pointed out that, if Conant had examined more 

 strains of Micros porinn fulvum and M. gypseum, he probably 

 would have regarded them as specifically identical. At any rate 

 it must be emphasized that the inherent tendency of all species to 

 vary must never be lost sight of by students of this group nor of 

 any other group of fungi. 



The difficulties attendant on making specific identification by 

 clinical aspects are illustrated by the experiments of Dowding and 

 Orr (1937). They isolated Trichophyton gypsevm from three 

 clinically distinct diseases, namely kerion, tinea circinata, and vesi- 

 cular lesions on feet. 



