460 MEDICAL MYCOLOGY 



The final degeneration of this genus is reached in the E. gypseum group in 

 which closterospores are absent, and the lesions are confined to the soles of the 

 feet in man. In E. gypseum the colony is cafe-au-lait in color, crateriform and 

 powdery, and becomes pleomorphic in 5 weeks; in E. pedis, the colony is yel- 

 lowish cream color, disciform, with long velvet and becomes pleomorphic in 2-3 

 weeks; while in E. niveum, the colony is white, slightly elevated, with long 

 velvet, and never pleomorphic. 



The line of Epidermophyton is continued in Endodermophyton where prac- 

 tically only the chlamydospore and arthrospore are left and even these are 

 rather degenerate. The lesion has been highly specialized on the dry portions 

 of the epidermis without inflammation or even much pruritus. The epidermis 

 loosens in triangular scales with the points inward and attached at the base in 

 concentric circles ; the cerebriform colonies are more or less moist and yel- 

 lowish. The species of this genus are not easily inoculable into experimental 

 animals. 



Returning to the E. lacticolor line in Ectotricliophyton, where the nodular 

 organ was retained and the closterospore was absent, let us turn our attention 

 to FavotricJiophyton. Here we find increasing specialization to host although 

 the nature of the lesion is little changed from the milder types caused by Ect&- 

 trichophyton. Lesions on the nomial host are apt to be less inflammatory and 

 of longer duration than those produced on other hosts. As in Epidermophyton, 

 FavotricJiophyton may be polyphyletic in origin. The white species are perhaps 

 related to E. farinulentum since in F. singulare (F. alhum), Baudet reports 

 having seen closterospores in one colony on barley, and in a member of this group 

 on a goat. He (1932) reports abundant aleurospores on oleic acid medium, pota- 

 to and carrots; in F. Urenae, Ochoterena reports closterospores regularly pres- 

 ent. F. singulare is specialized on Bovidae as is also F. alhum of this group. F. 

 discoides has an umbonate rather than an umbilicate disc, is probably adapted 

 to the horse, and produces severe lesions in man. F. ahissimcum may belong 

 here or it may be an aberrant member of the F. violaceum group, but it was 

 too poorly described to place definitely. The lesions and host would suggest 

 relationship to F. violacea. 



The principal group of species of Favotrichophyton shows a gradual degen- 

 eration from F. halcaneum. in which there are traces of nodular organs through 

 F. flavivirens to the yellow and ochraceous brown species and to the F. violacea 

 group. The early members of this series, such as F. halcanea, are adapted to 

 man or normal host unknown ; the bulk of the yellow group to the Bovidae ; the 

 ochraceous group to the Equidae, and finally the F. violaceum group, producing 

 endothrix lesions in the hair of man, with or without some suppuration, are not 

 easily inoculable into the guinea pig. This group appears to be confined to the 

 Semitic and related races. With this degeneration has come the production of 

 moist colonies, often elaborately folded but of very circumscribed growth, as in 

 the genus Achorion, whence the name "faviform" is often applied to the group. 

 Descriptions of many of the species have been confined to the appearance of 

 the colony on Sabouraud agar, so that new data may easily alter the arrange- 

 ment adopted here. 



