CHAPTER XIII 



PSALLIOTA CAMPESTRIS 



Introductory Remarks Occurrence of the Fruit-bodies Fairy Rings External 

 Appearance of a Fruit-body Evolution of Ammonia from Dead Fruit-bodies 

 General Organisation of the Fruit-body for the Production and Liberation 

 of Spores The Radial Arrangement of the Gills The Number of the GiUs 

 The Depth of the GiUs The Thickness of the Gills The Ends of the Gills 

 The Gill-chamber and the Annulus Conditions for the Origin of Fruit-bodies 

 The Fate of Rudimentary Fruit-bodies Effect of Dry Weather on Develop- 

 ment The Spore-discharge Period and the Number of Spores The Mushroom 

 and the Panaeolus Sub-type Text-book Illustrations of the Hymenium 

 The Mottling of the Gill Surface Methods for Examining the Hymenium 

 in Surface View The Number and Size of the Spores on Individual Basidia 

 Rate and Mode of Development of the Spores of an Individual Basidium 

 An Analysis of the Hymenium of the Cultivated Mushroom The Hymenium 

 of the Wild Mushroom Camera-lucida Studies of the Young Hymenium 

 Camera-lucida Studies of a Nearly Exhausted Hymenium Camera-lucida 

 Studies of a Completely Exhausted Hymenium Secotium agaricoides 



Introductory Remarks. The present Chapter will treat of the 

 production and liberation of spores in Psalliota campestris, the 

 Common Mushroom (Fig. 129). The fruit-body of this fungus 

 belongs to the Panaeolus Sub-type, and its hymenium is organised 

 in all essentials exactly like that of Panaeolus campanulatus and 

 Stropharia semiglobata. Since the Panaeolus Sub -type was described 

 in great detail in connection with the two last-named species, it 

 may seem superfluous that it should be dealt with any further. 

 However, the Common Mushroom is so widely known all over the 

 world as a familiar plant, is so celebrated as an article of food, and 

 is so much employed in laboratory instruction, that it occupies .a 

 unique place among the Hymenomycetes. Moreover its structure, 

 particularly in regard to the hymenium, has been described hitherto 

 but very imperfectly. For all these reasons I have thought it 

 desirable that I should give as full an account of the organisation 



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