BASIDIOMYCETES 399 



the breaking up of vegetative hyphae (Fig. 263, 1) or of hyphal branches; 

 in many forms, the latter are differentiated as fertile hyphae and then 

 may be recognized by their limited elongation and fasciculate arrange- 

 ment (Fig. 264, 3). In the Basidiomycetes, they are very frequent, and 

 in the higher orders represent the normal asexual form of multiplication. 

 In these they replace the conidia. Gemmae arise in the Basidiomycetes 

 in a manner and frequency similar to that in the Ascomycetes. 



In contrast to the extensive correspondence to the vegetative myce- 

 lium of the Ascomycetes, the haploid mycelium of the Basidiomycetes 

 produces no functional sexual organs. Recent investigations, however, 

 have shown that it is sexually differentiated, as in many Ascomycetes 

 and Phycomycetes, and is divided into monoecious (homothallic) and 

 dioecious (heterothallic) types. True homothallism is rare; it was 

 experimentally demonstrated for Corprinus narcoticus, C. sterquilinus, 

 C. stercorarius, C. lagopus, C. niveus (Lendner, 1920, Brunswick, 1924; 

 Mounce, 1921, 1922). They can pass through their complete life cycle 

 in single spore cultures. As in the heterothallic forms of Phycomycetes 

 and Ascomycetes, the single spore cultures of heterothallic forms, e.g., 

 C oprinus fimetarius , C. radians, C. papillatus,C.micaceus,Anellaria separata 

 (Panaeolus separatus) , P. campanulatus, Armillaria mucida, Schizophyllum 

 commune and Corticum polygonium (Aleurodiscus polygonius, Gloeocystid- 

 ium polygonium) (Bensaude, 1918, Kniep, 1919, 1923, Vandendries, 1923, 

 1925, 1925a, 1926; Brunswik, 1924, 1926; Hanna, 1925), may (with the 

 exception of a few cases of parthenogenesis to be discussed later) be culti- 

 vated indefinitely as haploid sterile mycelium. This forms only second- 

 ary spore forms and continues development only if brought together in 

 mixed culture with the dynamically opposite mycelium (often somewhat 

 differing morphologically in growth form). C oprinus Rostrupianus, 

 studied by Miss Newton (1926), is peculiar in that the spores and young 

 mycelia are typically heterothallic, while about half the mycelia, six 

 months or more in age, are homothallic. The mycelium becomes binu- 

 cleate in some unknown manner. Only the binucleate mycelia produce 

 sclerotia capable of forming fructifications. The sclerotia from uninu- 

 cleate mycelia germinate with only mycelium. In a few Basidiomycetes, 

 however, as in Corticium polygonium, Coprinus stercorarius, C. niveus, 

 C. lagopus and Schizophyllum commune, the sexual differentiation has 

 apparently gone still further than in the Phycomycetes and Ascomycetes 

 so far as known ; their mycelia are not differentiated into + and - strains 

 but into several strains. In Corticium and three species of Coprinus, 

 four sexually differentiated types have been noted; in Schizophyllum 

 there are still more types, e.g., A, B, C, D, E, etc., of which A may be 

 brought together with B and C, B with A and D not with C, C with A 

 and E but not with B and D. After a time secondary mycelium and 

 fructifications develop. In these forms, heterothallism appears to rest 



