'264 STRUCTURAL BOTANY 



TYPE XXIII 



THE MUSHROOM (Agaricus campestris) 



The Mushroom, which to most people is the best 

 known of all Fungi, represents a group of great 

 extent, including about ten thousand species. The 

 Mushroom and its near allies (most of which are 

 commonly called " Toadstools ") are among the most 

 highly organised of the Fungi. What is known in 

 ordinary language as the Mushroom is simply the 

 fructification ; for the vegetative part of the plant, or 

 mycelium, is very inconspicuous, and remains hidden in 

 the soil. What is called " mushroom spawn," from 

 which the Fungus is raised in cultivation, consists of blocks 

 of richly-manured soil permeated with the mycelium. 



The vegetative structure is simple enough, the 

 mycelium consisting of long, branched, multicellular 

 hyphae, which traverse the substratum in every direction. 

 The individual hyphee are usually not isolated, but woven 

 together into strands. Fusions of the cells are very 

 common, and take place both between neighbouring cells of 

 the same hyphae and between those of adjacent hyphae. 

 The way in which union takes place is much like the 

 monoecious and dioecious conjugation of Spirogyra, but in 

 the case of the Fungi the process has nothing to do with 

 reproduction, and so far as we know serves no other 

 purpose than to facilitate nutrition. Each cell contains 

 numerous small nuclei in its protoplasm. 



The matured fructification consists, as everyone knows, 

 of a thick stalk (the stipe) swollen at the base, support- 

 ing a hat-like expansion (the pilem), on the under-side 



