TRICHOPHYTONEAB 457 



as belonging' to a new species. Since the pleomorphic mycelia of different 

 species resemble each other much more than the normal mycelia of those 

 cultures, some have thought that different species were identical where their 

 pleomorphic mycelia were the same, and that the differences in the normal 

 mycelium were more or less accidental variations produced by environment. 

 However, many species never become pleomorphic, and even the time of ap- 

 pearance of such mycelium under standard conditions seems to be a definite 

 specific character. 



Sabouraud (1910) raised the interesting question whether some of his 

 species which show considerable degeneration, with loss of some spore forms 

 without exhibiting further pleomorphism, may already be pleomorphic mycelia 

 of other species which have become fixed and are producing lesions in animals 

 without ever returning to their original form. Some of the recent work of 

 Catanei and of Langeron & Talice would tend to confirm this hypothesis. 

 Grigorakis elaborated this in his doctoral thesis in 1925, and based his classi- 

 fication largely upon this hypothesis, without producing experimental evi- 

 dence bej^ond the isolation of pleomorphic mycelium of Microsporum felineum 

 from lesions on a cat. He would arrange the species in genera on the basis of 

 the stage of degradation shown in primary cultures without regard to the 

 lesion provoked or organs produced on other media than Sabouraud test agarT 

 It is possible that the future will see reductions of some of our present species 

 to synonymy on the basis of Sabouraud 's hypothesis, but this should be done 

 only after a verj^ careful study of the life history and cytology of both or- 

 ganisms, the nature of the lesions produced by normal and pleomorphic my- 

 celium of both organisms on their normal hosts as well as on the usual guinea 

 pig, and their microscopic morphology in and configuration of their giant colo- 

 nies on a great variety of media, including both, some of the animal products 

 proposed by Nannizzi and the higher carbohydrate and dung media revived 

 by Langeron & Milochevitch, as well as the usual laboratory media. 



Phylog^eny. — Perhaps the most primitive group of the dermatophytes is 

 that represented by the genus PinoyeUa, whose taxonomic position is not yet 

 altogether clear. It has only been found on the glabrous skin of old world 

 monkeys but is inoculable to guinea pigs where it causes an inflammatory 

 lesion of the ectoendothrix type. The closterospores are incompletely 4-6 locu- 

 lar, coenocytic, germinating by a single uninucleate hypha from each locule, 

 or each locule may form a separate uninucleate endospore which is ejected 

 from the end of the closterospore, producing on germination uninucleate sec- 

 ondarj^ mycelium with uninucleate aleurospores. The incompletely divided 

 closterospore may represent a gametangium (ascus) of the general type of the 

 Ascoideaceae in which the spore number is reduced, or the spore may even 

 germinate before forming its wall. The resulting mycelium would then be 

 homologous with uninucleate diploid ascogenous hyphae and the aleurospores 

 with asci which are no longer functional. On the other hand, although less 

 probable, the closterospore may represent an ascus and the aleurospore a 

 uninucleate haploid conidium. 



