128 



MEDICAL MYCOLOGY 



Ashbyaceae. — This family has been little studied cytologically. In Pied- 

 raia Hortai, forming hard nodules on human hair, the mycelium is thick-walled, 

 septate, and more or less agglutinated into a solid mass surrounding the repro- 

 ductive structures (Fig. 15, 1, 2, 12). Young cells contain up to 8 nuclei, but 

 mature cells are mostly uninucleate, although one cell figured by Horta (1911) 

 suggests a binucleate condition. The functions of gametangium and ascus, 

 performed by distinct structures in the Spermophthoraceae, are performed by 

 a single stinicture, usually called the ascus, which arises as the terminal cell 

 of a hypha. The gametes are differentiated within this structure but unite 

 in pairs without being set free (Fig. 15, 3-11). The resulting zygotes then 



Fig. 14. — Spermophthora Gossypii. 1, gametangium showing immature gametes within ; 

 Z-%, stages of copulation of gametes, ascogenous filament with young ascus ; 8, asci showing as- 

 cospores ; 9, germinating ascospores. (After Guilliermond 1928.) 



elongate to produce the 8 uninucleate, fusiform, or crescent-shaped ascospores 

 with 2 (rarely 3) filiform appendages (Fig. 15, 13-16). The details of the 

 cytology have not yet been reported. The ascospores germinate directly to 

 mycelium which penetrates beneath the cuticle of the hair, forming a pseudo- 

 parenchymatous palisade which eventually ruptures the cuticle and expands 

 to produce the typical nodule. In Pieclraia veneznelensis, little is known of its 

 life history, but the ascospore number is reduced to four and the filiform ap- 

 pendages practically disappear. Langeron (1929) and Brumpt & Langeron 

 (1934) suggest that Piedraia is related to the sooty molds which it resembles 

 slightly in general appearance, but in the curious development of gametes and 



