The Molds 



43 



schonleini is highly pathogenic and will be described in the section 

 upon Favus. 



2. Tricophyton and Microsporon. — These names are appUed some- 

 what loosely to organisms affecting skin and hair follicles of men and 

 animals. They form tangled slender mycelia with many spores of 

 varying size. They occasion "ringworm," barber's itch, pityriasis, 

 and tinea. Further description of the organisms will be found in the 

 section upon Ringworm. 



3. Mucor. — The mucors, or "black molds," belong to the Phyco- 

 mycetes. They form a thick, tangled mycelium, in and above which 

 the rounded black sporangia can be seen with the naked eye. The 

 mycelium becomes divided at the time of reproduction. Multiplica- 

 tion takes place asexually through conidia-spores which develop 



Fig. 12. — Mucor mucedo: i, A sporangium in optical longitudinal section; 

 c, columella; m, wall o£ sporangium; sp, spores; 2, a ruptured sporangium with 

 only the columella (c) and a small portion of the wall {m) remaining; 3, two 

 smaller sporangia with only a few spores and no columella; 4, germinating spores; 

 5, ruptured sporangium of Mucor mucilaginus with deliquescing wall (m) and 

 swollen interstitial substance (z); sp, spores (After Brefeld). 



within sporangia, and sexually by the conjugation of specialized 

 terminal septate branches of the mycelium, which conjugate with 

 similar cells, belonging to other colonies, to form zygospores. 



The sporangia form upon the ends of aerial hypha and consist of a 

 smooth spherical capsule within which the spores develop, to become 

 liberated only when the membrane ruptures. The colonies, each of 

 which is unisexual, may be described as + and — . Colonies of the 

 + type will not conjugate; colonies of the — type will not conjugate, 

 but when terminal filaments of + and — come together, conjuga- 

 tion occurs and zygospore formation takes place. 



Mucors are not infrequent organisms of the atmosphere and 



