CYTOLOGY 159 



In Epiclermophyton no conidia are produced and the macroconidia 

 are clavate or egg-shaped, rounded instead of pointed at the tip, with 

 no septa or only a few, and the walls are thick and smooth. 



In Trichophyton the macroconidia, when produced, are long 

 clavate spores with rounded end, one or several cells formed by cross 

 septa, and the walls are smooth and thinner than in the other genera. 



The macroconidia thus serve to identify the genus of dermatophyte. 

 Macroconidia are produced in each of the three genera (although not 

 in every strain of every species), but the type of macroconidium in 

 each genus is distinctive.^ 



Taxonomy. Some of the dermatophytes occasionally form peculiar 

 knots and twisted masses of hyphae which resemble the ascogonia 

 of some Ascomycetes. These have been interpreted as abortive at- 

 tempts to form asci. They have been referred to by the French 

 authors as nodular organs. Matruchot and Dassonville ^- noted a 

 similarity between certain of the dermatophytes and some species 

 of Gymnoascaceae, and claimed to have produced experimentally a 

 ringworm with a species belonging to this family of the Ascomycetes, 

 Ctenomyces serratus. The Gymnoascaceae are characterized by the 

 formation of asci, not in a compact and well-defined perithecium, 

 but in masses surrounded by a rather loose network of protective 

 mycelium. The clusters of conidia and specialized hyphae produced 

 by some strains of Trichophyton resemble the loose poorly organized 

 ascocarp of the Gymnoascaceae in a superficial way, and several 

 authorities have therefore considered that the dermatophytes are 

 ascomycetes. We do not believe that this point has yet been proved, 

 and prefer to consider the dermatophytes as Fungi Imperfecti, with- 

 out however denying the probability of a relationship to the Asco- 

 mycetes. The variety and variability of the spores formed by the 

 dermatophytes has made it difficult to assign them a position in Sac- 

 cardo's classification. Vuillemin groups them with his Arthrospo- 

 rineae, Ota and Langeron ^^ with the Conidiosporales of Vuillemin's 

 classification. 



In the hair and skin the dermatophytes sporulate only by a frag- 

 mentation of the mycelium into its component cells. The so-called 

 spores found in the lesions are therefore to be looked upon as oidia 

 or arthrospores. The size and arrangement of these arthrospores 

 give some information about the identity of the fungus, but for 

 specific identification pure cultures must be studied. 



Cytology. Grigorakis studied the cytology of the ringworm fungi. 

 The cells of the vegetative hyphae and of the macroconidia, chlam- 

 ydospores, and arthrospores are multinucleate. The conidia are uni- 



