58 OUTLINES OF BRITISH FUNGOLOGY. 



instance, of the spawn of different Polypori and Sphcerice, al- 

 tered by growing beneath the bark, free from the influence 

 of light, in such a way as to form rootlike often anastomosing 

 bodies, with a dark separable cuticle. Sclerotium, on the con- 

 trary, is formed by the concentration of threads into solid 

 wartlike bodies or nuggets, entirely devoid of fruit, but which 

 on occasion give rise to various kinds of Fungi, as Agarics, 

 Pistillarice, Pezizce, etc. In one instance I was enabled, in 

 company with INIr. Hoff'mann, to watch the progress of a thin 

 slice of the Sclerotium, which is so common in mildewed 

 onions, when placed in a drop of fluid in an air-tight cell, to 

 the development from its tissues of a perfect Alucor. In some 

 cases, the spawn merely collects earthy particles about it till 

 it forms a large solid mass, which, when placed in proper con- 

 ditions, produces fruit, as Pohjporus tuheraster, a species com- 

 monly eaten in Italy. It is obvious that such productions 

 cannot be admitted into a system,* except so long as their 

 nature is unknown. It is however feared that some of the 

 Fungi which figure under different genera amongst Conio- 

 mycetes and Hyphomycetes, are in scarcely a better condition, 

 though they have this difference, that they do produce a sort 

 of fruit. Occasionally, under deficiency of light. Fungi pos- 

 sess a stem only, without any pileus, or only a very imper- 

 fect one; and sometimes, where perfect pilei are produced in 

 one part, mere stems are formed in another, as if there were 

 not vigour enough for every demand. This latter is the case 

 to some extent with Marasmius Rotula (Plate 14, fig. 7), but 

 it is far more conspicuous in some foreign species, as also 



* The best general rule is to admit nothing as a real species of Fungus 

 which does not bear fruit. It is possible that sucli formations as Sclei-otium 

 durum may be due to half-a-dozen different Fiuigi. Sclerotium complanatum 

 and S. scutellahim both give rise to the same species of PistUlaria. As, how- 

 ever, some persons may wish to know wliat spoeies have been described, I sliall 

 give them in an appencUx. 



