1884-85-] Edinburgh Naturalists' Field Clit-b. 211 



v.— THE H YMENOM YGE TES. 



By Mr A. B. STEELE. 



(Read Dec. 26, 1SS4.) 



The Hymenomycetes, of which our common Mushroom may be 

 taken as a type, belong to the primary division Sporifen^e, or 

 spore-bearers, of the order Fungi. By their complexity of organi- 

 sation and economic value, they form the most important of the 

 six families of this order. Although they occupy a very humble 

 rank in the scale of organised existence, possessing none of the 

 foliaceous or floral appendages of the pha^nogams, yet they are 

 remarkable for their strangeness of form and beauty and variety 

 of colour. Their rapidity of growth, as well as their tendency 

 to a circular form, is extraordinary. The strange j^ower of lumin- 

 osity in the dark which some species possess still remains a mys- 

 tery, and must have been a fertile source of superstition in the past. 

 The change of colour produced when cut or bruised, and the man- 

 ner in which the wounds are healed, resembling more the char- 

 acter of animals than of plants, are striking phenomena among 

 species of this family. They germinate without cotyledons ; and 

 being without chlorophyll, they cannot decompose carbonic acid, and 

 accordingly take up their nourishment from organic compounds. 

 They exhale carbonic dioxide and inhale oxygen, like animals. 

 No sexual organs, however, have been definitively discovered in 

 these plants. Though comparatively simple in structure, they 

 possess organs more or less complex. Most of them are com- 

 posed of a mycelium or vegetative structure, a volva, ring, stem, 

 pileus, and hymenium or fructifying structure bearing spores. 

 Spores are to Fungi what the seed is in vegetables of a higher 

 order. They are the reproductive organs. They are so minute 

 that they cannot be seen with the naked eye ; and their number 

 is so vast at a certain period of a Mushroom's life, as to make 

 it appear as if their union formed the whole hymenium, which 

 is found then covered with a fine dust resembling the pollen 

 of flowers. The spores, so long as they are adherent to the 

 hymenium, are free, and supported by filaments which rest on 

 small projecting bodies called basidia. At maturity the basidia 

 project at the surface of the hymenium. Each basidium is 

 composed of a single cell, round, ovoid, or elongated, which 

 bears at its summit one or several filaments called spicules 

 or sterigmata, at the extremity of each of which is a single 

 spore. (This was discovered in the species Coprinus comatus 

 as far back as 1780.) Each basidium bears four filaments or sterig- 



