PLECTASCALES 429 



its juvenile stage it forms hyaline hypliae which abjoint laterally numerous 

 ovoid, hyaline aleurospores (Fig. 74, 3). The hyphal cells are 1-4 nucleate, 

 while the conidia are generally uninucleate. The conidiophores occasionally 

 form a structure resembling a pycnium whose central cavity may be filled with 

 the slimj^ mass of conidia. 



The young copulation branches (Fig. 74, 4, 6) are 1-3 nucleate, the 

 antheridium is a clavate, vertical structure which finally contains 10-12 nuclei. 

 The ascogonium, which coils around the antheridium six or seven times, finally 

 contains about 20 nuclei. Cytoplasmic fusion and nuclear migration have not 

 yet been reported. The ascogonium divides directly into binucleate, almost 

 isodiametric cells; whence arise ascogenous hypliae which again coil helically 

 around the original helix. From this confused mass, the 8-spored asci develop. 

 Meanwhile the whole knot is closely surrounded by sterile hyphae which, with 

 a considerable thickening of their walls, become moniliform and develop short, 

 peculiar processes on one side (Fig. 74, 7). Besides these perithecia, light 

 brown sclerotia are formed on the feathers. There are also unusual pectinate, 

 falcate or setiform hyphae, all of whose unguiform processes are turned in the 

 same direction. Possibly these serve to disseminate the sclerotia by clinging 

 to animals. Some of these structures appear very similar to those found in 

 the imperfect genera Tridiophyton, Micro sporum, etc. 



The most compact rind apparently is found in Ateleothylax, a very im- 

 perfectly known genus, originally described from tinea capitis in Soudan. 

 Nothing is known of its cytology and very little of its morphology. A second 

 species probably belonging here has been described from tinea cruris in India. 

 It seems quite possible that the black perithecia described in these species may 

 belong to a contaminant. The cultural characters and imperfect stages would 

 place them in Trichophyton and Epiclermophyton respectively. 



The systematic position of the ascogenous stage of Microsporum japonicum, 

 producing tinea capitis in the yellow race, is very doubtful. It may represent 

 a very degenerate stage with a complete loss of sexuality (Kambayashi 1932, 

 see p. 547). 



Key to Genera 



Peridium of very thin-walled undifferentiated hyphae. 



Spore walls hyaline, yellow or red. Arachniotus. 



Spore walls brown or brownish violet. Amauroascus. 



Peridium of thick-walled, much branched hyphae forming a lattice. 



Tips of branches ending in spines. Gymnoascus. 



Tips of branches ending in spirals or helices. Myxotrichv/m. 



Tips of branches with many short side branches giving appearance of combs or saw- 

 teeth. Ctenomyces. 

 Peridium of thick-walled, greenish black hyphae, closely interwoven, suggesting perithecia of 

 Aspergillaceae. Ateleothylax. 



Ctenomyces serratus Eidam, Beitr. Biol. Pfl. [Cohn] 3: 377-433. Ph. 19- 

 23, 1883; Matruchot & Dassonville, Bull. Soc. Myc. France 15: 305-310, 1899. 



