462 MEDICAL MYCOLOGY 



of the glabrous skin with small but typical favic scutula. Achorion muris, A. 

 gallinae, and A. Schoenleini retain some of their suppurative character when 

 inoculated into another host from that on which they have become specialized. 

 The first two retain closterospores, chlamydospores, and aleurospores of the 

 Neomicrosporuni group, while A. Schoenleini has lost all spore forms, but arthro- 

 spores and chlamydospores which function as closterospores. 



Having considered tlie types of lesions and morphology of the group, let 

 us return to the problem of classification briefly mentioned on page 434. Prior 

 to the work of Sabouraud, some of the genera had been described, but little 

 attention had been paid to them either by botanists or by medical men. As 

 we have seen, Sabouraud separated his genera principally on the position of 

 arthrospores in the lesion and his species on the presence of various spore 

 forms and on the characters of the giant colony. On this basis, the name 

 Achorion was used for all organisms causing favic scutula and typical favic 

 hairs. Microsporum was used for all organisms producing a sheath of small 

 arthrospores around the hair and mycelium within it. This was divided into 

 the section Neomicrosporuni for those which infect domestic animals, often with 

 production of some suppuration. The species of this section grow much more 

 rapidly in culture and become pleomorphic. The second section contains those 

 species confined to man which grow slowly in culture and have no pleomor- 

 phism. Epidermophyfon was used to designate the organism of eczema mar- 

 ginatum, the only organism of that group to be clearly recognized at that time. 

 The residue was placed in Trichophyton, which was recognized to be somewhat 

 heterogeneous. Sabouraud, however, separated this genus into several sections 

 which make quite distinct groups and which were raised by Castellani & Chal- 

 mers to generic rank. The central group, which must retain the name Tricho- 

 phyton according to the International Rules of Botanical Nomenclature, com- 

 prises the organisms producing arthrospores inside the hair, typified by Tri- 

 chophyton tonsurans (T. craterifonne). The subsections were vaguely recog- 

 nized without being named, the group of species centering around T. tonsurans, 

 T. Sahouraudi (T. acuminatum), and T. violaceum ; the groups were separated 

 on the basis of giant colony characteristics and, somewhat, on morphology. A 

 transitional group was made a separate section, Neoendothrix, centering around 

 T. flavum (T. cerehriforme), in which the mycelium and spores persist in the 

 hair follicle for a long time although the arthrospores are also produced in the 

 hair as in T. tonsurans. Another section consisted of those species in which the 

 arthrospores were borne outside the hair, forming a sheath somewhat resembling 

 that of Microsporum but composed of both mycelium and arthrospores. This 

 section, called Ectothrix, was divided into three subsections which differ rather 

 more widely than the subsections of the Endothrix section. These were the 

 faviform subsection, with a morphology and cultural characteristics close to 

 Achorion, a megaspore subsection with large spores, and a microspore subsec- 

 tion called "microide, " comprising primarily the group producing kerions, 

 which has been considered as the most primitive in the foregoing discussion. 



Castellani & Chalmers (1919) followed the traditional procedure for large 

 unwieldy genera and designated the Neoendothrix section as Neotrichophyton, 



