CHAPTEE XVI 



SUBTERRANEAN FUNGI TUBERACEAE 



Two very similar small groups of Fungi resemble each other 

 very much in habit and in external appearance, but differ 

 considerably in their internal structure. These are the some- 

 what globose balls which are produced under the surface of 

 the soil, and called Tuberaceous or Subterranean Fungi. One 

 group has the spores developed in asci, belonging therefore 

 to the Ascomycetes, and the other has the spores naked on 

 basidia, and so belong to the Basidiomycetes, or that section 

 called Gastromycetes. The former are represented by the true 

 Truffles, and the latter by the false Truffles or Hypogaei. 



To begin with the simplest forms, we encounter struc- 

 tures which resemble small underground species of Scleroderma. 

 They are mostly somewhat globose in form, of a 

 dirty colour, with a thick outer coat or peridium. 

 In one or two genera the outer coat is thin or 

 obsolete ; when mature, if cut through the centre, 

 they are seen to be filled with a powdery mass of 

 dark -coloured spores, but if cut when young 

 the interior is streaked and mottled, at length 

 full of small cavities, in which the spores are 

 produced. The spores themselves are sometimes 

 elliptical or almond-shaped, with either a rough Odaviana. 

 or smooth surface, or they are globose and warted (Fig. 77). 

 It may well be said that these Fungi are underground 

 puff-balls, which are united to the terrestrial Gastro- 

 mycetes through the species of Scleroderma, one of which has 

 often a modified subterranean habit. In former times a species 

 of Melanogaster was sold and used, under the name of Eed 



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