8 STRUCTURE AND CLASSIFICATION OF FUNGI 



Vuillcmin recognized two further types of conidia. Hemispores 

 were considered to be transitional between arthrospores and true 

 conidia. Aleuriospores (in French, "aleuries") w^ere differentiated 

 from true conidia by the fact that they are not set free when mature, 

 but are only liberated upon the disintegration of the mycelium that 

 forms them. They are analogous to lateral chlamydospores. Recent 

 workers have not recognized either of these as valid distinctions 

 from true conidia. 



Fungi may form more than one type of conidiura from a single 

 thallus. Thus in the dermatophytes some species form small uni- 

 cellular conidia of the type which Vuillemin called aleuriospores, and 

 large multicellular fusiform conidia which have been called spindle- 

 spores. See Fig. 79. Certain other fungi may produce apparently 

 the same kinds of conidia from different types of conidiophores. 

 Some of the fungi isolated from cases of chromoblastomycosis have 

 been found to form conidia from such different types of conidiophores. 

 See Fig. 103. Since the classification of the molds is largely depend- 

 ent upon the characters of the sporophores and the spores, such mul- 

 tiple types of conidia and conidiophores lead to a great deal of 

 confusion. 



In recent literature dealing with fungi which produce two sorts 

 of conidia, they have often been classified according to size, as micro- 

 conidia and macroconidia. Thus the bodies formerly referred to as 

 aleuriospores in the dermatophytes are now often called microconidia 

 or simply conidia ; the spindle-spores are referred to as macroconidia. 

 In some fungi it has been shown that the microconidia are sex cells 

 or spermatia, but this is not generally true. There are also so-called 

 "conidia" which are actually sporangia containing one or only a few 

 sporangiospores. They are seen singly or in chains and resemble 

 closely true exogenous conidia. Actually their method of formation 

 and the fact that the spores themselves, or small groups of them, are 

 surrounded each by a membrane, show their true nature of sporangia. 

 They are usually called conidia but sporangiola is a better term for 

 them (Fig. 42). 



Sexual Spores. Spores resulting from the fusion of nuclei and 

 subsequent reduction division are produced in most of the lower 

 fungi less frequently and less abundantly than are the asexual spores. 

 Here the functions of sex, concerned with heredity and variation, are 

 to some extent separa.ted from the functions of multiplication and 

 distribution of the species, which is carried on mainly by the conidia 

 or sporangiospores. Often these "sexual spores" may be produced 



