42 



INTRODUCTION TO THE STUDY OF FUNGI 



usually present, mixed with the basidia but rather larger, and 

 the sterile cells are smaller and almost of the nature of, or 

 analogous to, paraphyses (Fig. 22). De Seynes regards all 

 three forms as modifications of the same organ, -i.e. the 

 basidia, of which the spore-bearing 

 are the fertile basidia, the cystidia 

 are hypertrophied basidia, and the 

 sterile cells atrophied basidia. All 

 these cells are continuations and 

 terminations of the tissues of the 

 receptacle, sometimes with three or 

 four subspherical cells intervening. 

 The basidia are elongated clavate 

 cells, or sporophores, filled with a 

 granular fluid, surmounted by four 

 short slender tubes, or spicules, 

 each of which expands at the apex 

 and becomes a spore ; into which 

 FiQ. 22.-Ba,sidia (6) and cystidia t^g contents of the basidium pass, 

 leaving the basidium empty, so 

 are completed it collapses and 

 shrivels, then falls away. The spores thus formed by 

 budding or gemmation, as far as known at present, are 

 asexual and only gemmae. Many efforts have been made 

 to prove them otherwise, but none of these have been con- 

 firmed. The spores themselves are unicellular (except in the 

 Tremdlini), and may be colourless or coloured. Modifications 

 seem to take place in the cystidia, in different genera, inde- 

 pendent of any difference in size. In the genus Peniophora 

 they evidently become encrusted with lime and granular, so "as 

 to present quite a distinct appearance ; in this condition they 

 have been called "metuloids." In Hymenochaete and some 

 species of Fomes the normal cystidia are replaced by rigid 

 coloured setae, which may be modifications of cystidia. 

 Corda regarded these peculiar cells as representatives of 

 male organs, and called them antheridia ; and a similar 

 interpretation has been given to their functions by Worth- 

 ington Smith. Most mycologists coincide in the opinion 

 that a sexual apparatus has not yet been discovered in the 



(c) of Agaricus ; {a) jiaraphyses. 



that when its duties 



