20 



MEDICAL MYCOLOGY 



forms, blastospores, arthrospores, chlamydospores, conidia, etc., usually de- 

 velop on the liaplont (thallus of the haploid stage of the life cycle). A single 

 species which successively produces several spore forms is called polymorphic. 



The spores of a second type are connected with sexuality and develop 

 after fertilization or meiosis in the spore mother cell. These changes are 

 connected respectively with the beginning or the end of the diploid phase. 

 The spore forms following fertilization are recognizable morphologically since 

 they are encysted zyg-otes (the products of a sexual act) ; biologically they 

 usually develop as hypnospores or resting spores (e.g., the zygospores of the 

 Mucoraeeae) . 



The spore forms which follow meiosis are morphologically recognizable 

 because they form tetracytes (as daughter cells of gonotoconts, the organs in 



Fig. 2. — Oidial formation in i; S, Mucor racemosus ; S, Mucor Prainii. 



de Botanique.) 



(After Chodat, Principes 



which meiosis occurs). Apparently, since they are products of meiosis, they 

 have become constant in number, usually 8 (in the Ascomycetes) or 4 (in 

 the Basidiomycetes) ; biologically they are also hypnospores in the higher 

 fungi. When the sporogenous cells which serve as gonotoconts form their 

 spores internally through free cell formation, they are called asci and their 

 spores ascospores (whence the term Ascomycetes). When the spores are cut 

 off externally from the gonotoconts, they are called basidiospores and the 

 sporogenous cells basidia (whence the term Basidiomycetes, the saprophytic 

 mushrooms, puffballs, etc., and the parasitic rusts and smuts). 



As the conidiophores of the haplont, these gonotoconts are usually grouped 

 in a superficial layer of tissue, known as a h3nnenium. This tissue generally 



