INTRODUCTION 



the Basidiomycetes three kinds of cells are met with, the ordinary 



barren cells of the hymenium, the basidia with the spores, and 



certain other large cells named cystidia. 



The last-named are sometimes very small 



or practically absent, as in C lav aria ; in 



other genera they are very large, as in 



Coprinus (fig. 5), Hymenochate (fig. 6) and 



Peniophora. 



The more highly developed Basidiomy- 

 cetes as a rule bear white or slightly tinted 

 spores -, the lower or dung-borne species 

 usually produce black spores. In most 

 instances the spore-colour is permanent, but 

 in some species it vanishes and leaves the 

 spores hyaline. The colour of the spores 

 is often used as a generic or subgeneric 

 character ; the tint often, but not invariably, 

 gives the distinctive hue to the mature 

 hymenial surface. It is readily seen by 

 placing examples with the hymenium down- 

 wards upon a piece of glass on which the 

 spores will be deposited. 



At maturity, the spores of the Hymeno- 

 mycetes drop from the sterigmata and are 

 free in the air, but in the Gasteromycetes 

 the outer coats become naturally ruptured 

 before the spores can escape. In the Phal- 

 loidacea the sporiferous surface is at first 

 enclosed in a veil (volva\ and even after the 

 elongation of the stem, the cap (pileus) is 

 covered by a very thin, almost invisible Fig. 

 membrane ; when the spores are ripe they Aj ascus ; B> 

 are enveloped in mucus which runs down 

 from the upper parts of the fungus to the lower, where there 

 is a gelatinous stratum; the spores may possibly germinate in the 

 decomposing gelatine. In the fetid species the odour attracts 

 swarms of flies and sometimes small beetles to the sporiferous 

 mucus, which they eagerly devour. On flying away the insects 

 disseminate the spores, which have been seen to germinate after 

 having passed through flies. In the Lycoperdacea the spores are at 

 first enclosed in a peridium, and it is only when this is ruptured 

 that they are set free. The Hymenogastracece are subterranean, or 

 nearly so, and the spores must either germinate in the decaying 

 substance of the mother plant or be carried away by larvse, 

 insects, etc. 



In germination the spores open at one or both ends ; a trans- 

 parent germinal tube emerges (fig. 7) and forms strands, threads 

 or hyphce of cellular mycelium. The strands branch and coalesce 



B 2 



