FUNGI. 143 



sporophore, which in its simplest form, as seen in the genus 

 Mucor, consists of a single aseptate, erect hypha, bearing at 

 its apex the sporangium ; in the genus Stilbum we have an 

 erect bundle of similar hyphse, more or less agglutinated at 

 the lower stem-like portion, the tips being free and spread- 

 ing, each producing a spore ; in the Agaricus or mushroom 

 type the stem in like manner consists of a bundle of more 

 or less parallel hyphae, that radiate at the apex and form 

 the "flesh" of \h& pileus or cap, the latter being covered 

 in many species by a pellicle that can be separated when 

 moist. This external pellicle is formed from the superficial 

 hyphae, the walls of which become gelatinous and conse- 

 quently cemented together into a continuous film which 

 corresponds functionally to the epidermis of higher plants. 

 In a few of the mesopod or central-stemmed species of 

 Polyporus, a thin zone of hyphas, lying just within the peri- 

 pheral portion of the stem, becomes highly differentiated as 

 a mechanical sheath for giving rigidity to the stem ; the 

 hyphffi forming this zone are branched and interwoven, the 

 walls become very thick, so that the lumen or cavity is 

 nearly filled up, and by their partial gellification firmly 

 cemented together; at the apex of the stem this sheath 

 becomes broken up into spreading, frequently anastomosing 

 rays that pass into the pileus as a supporting framework. 

 The whole of this hard lignified framework often remains 

 intact when all the other portions of the fungus have decayed 

 or been destroyed by minute beetles. The above examples 

 of sporophore structure are characteristic of the group of 

 fungi called Basidiomycetes ; a second type, equally charac- 

 teristic of the Ascomycetes, consists of isodiametric cells that 

 form a pseudo-parenchyma ; in the genus Feztza, typical of 

 the Discomycetes, the tissue remains soft and colourless ; while 



