STRUCTURE OF AOARIC8. 9 



the Agarics, as the remarkable researches of Leveille have demon- 

 strated it,* and removed all doubts on the subject. In his recent 

 work (" Selecta Fungorum Carpologia," p. 107), M. Tnlasne gives 

 a rather instructive history of Sclerotium, which appears to be most 

 complete on the subject. 



M. Leveille has indicated the mode of sclerotial formation, which 

 has greater analogy with the rhizome, as is remarked in Agaricus 

 ftisipes ; the base of the pedicel is permanent, and produces tho 

 following year some new Agarics, becoming more or less branched. 

 The mycelioid nature of the Sclerotium, and its assimilation to the 

 organs which, in the Phanerogams, take the place of veritable 

 stems, is a proof more in favour of the theory, first noticed by 

 Palissot de Beauvois, and then by Dutrochet, of the identity of the 

 mycelium with a stem or thallus. 



The hymenophore, which is only the condensed mycelium, par- 

 ticipates in the vegetative function, but in a more especial manner, 

 to elaborate the reproductive bodies. It is cellular, membranaceous 

 or parenchymatous, formed of a pedicel and a cap, at times reduced 

 to a cap, which spreads into a membrane, and is clothed with a 

 hymenium, reposing upon a smooth surface (Thelephora) ; at other 

 times the inferior surface is folded, forming plates, pores, spines, 

 &C, upon which are the organs of fructification (Poli/ponts, Hyd- 

 num, &c.) 



The collected cells which form the stipe, and which afterwards 

 expand in the cap, are generally rather uniform, long, fibrous, often 

 much separated, rarely ramified, presenting at times in their dis- 

 tance from each other, at others in their dimensions, differences 

 which on the fissure of the stipe, present an aspect either fibrous, 

 granulated, spongy, or woolly. The cellular fibres are always 

 closer and more compact at the cortical part. The volva and ring, 

 which give excellent characters for classification, ought always to 

 be studied in their structure in each type. The cells of the paren- 

 chyma of the cap are more ramified than those of the stipe. One 

 sees them form by anastomosing and crossing each other, some 

 polygonous trellis-work. In the meshes so formed, there is a second 

 system of larger cells. These two systems have been described by 

 Corda, especially amongst Russula. lt These two forms," says this 

 author, "are not always neatly separated, but pass, as the organ 

 requires, more or less rapidly one into the other, or, what is more 

 rare, they arc substituted one for the other. These two forms of 

 tissue taking part, generally both together, in the structure of the 

 hymenium, each giving birth, or both together, to one or many 

 organs of the hymenium. "f 



Amongst the Lactarii some lacticiferous vessels may be seen, 

 often of a larger calibre, running over the meshes of the paren- 

 chyma, and forming a new system of organs. Why give them the 



* Ann. des. Sci. Nat., ser. ii., t. xx. (1843), p. 218-248. 

 t Corda, Iccmes Funjjoruoi. 



