Sketch of the Class Fungi. 



287 



clavate, or ending in a sharp or obtuse point. In Tremellce it is fo- 

 liaceous, decumbent, sinuous, plaited, or smooth and gelatinous. 



Having gone through the forms of the hymenophore, let us now 

 examine its structure. In general two different tissues enter into its 

 composition : one consists of cells which are at first spherical, but 

 which become polyhedral by mutual pressure ; the other of septate 

 filaments, generally of a very small diameter. The union, intermix- 

 ture and felting of these elementary tissues not only determine the 

 gelatinous, spongy, fleshy, or corky or woody nature of this organ, 

 but produce, moreover, the many forms which they present. We 

 must not forget that the central layer {trama) of the gills of Agarics, 

 of the prickles of Hydna, of the dissepiments of Polypori, &c, being 

 formed by prolongations of the tissue of the hymenophore, is conse- 

 quently, in the majority of cases, composed of the second order of 

 cells, that is to say, the elongated ; sometimes, nevertheless, covered 

 by another thin layer of globular cells, which separate it from the 

 sporigerous membrane ; and that in Russula and Lactaria, whose 

 trama is altogether composed of these cells, it is from these very 

 cells that those proceed, which, under the name of basidia, anthers, 

 paraphyses, &c, concur in the formation of the hymenium. There 

 is still a very important fact, should it be confirmed, and which, in 

 any case, I ought not to pass by in silence, viz. the presence of lati- 

 ciferous vessels in some species of this family. Their discovery is 

 due to M. Corda, who assures us that he has seen them in Russula 

 /ceteris. According to this mycologist, who has also figured (Ic. 

 Fung. iii. p. 42, t. 7. f. 106, g, i, k, I) this vascular system, whose 

 existence has never been suspected, the laticiferous vessels are con- 

 tinuous, pellucid, equal, generally flexuous, much branched, and fre- 

 quently anastomosing by means of collateral branches. They con- 

 tain (I am still speaking of Russula /ceteris) a milky, semitransparent, 

 opaline juice, filled with molecules, and which appears to move slowly 

 in different directions. These vessels are more numerous in the gills 

 of Russula /ceteris, and on the surface of the stem, than in the paren- 

 chym of the pileus or peduncle. They contribute, moreover, accord- 

 ing to Corda, to the formation of the hymenium in this Agaric, de- 

 scending between the basidia under the form of ceeciform tubes, at- 

 tenuated at first at the extremity, and then terminated by a globular 

 swelling (7. c. fig. 106, g, i)*. 



The parenchym of many Hymenomycetes presents the very curious 

 phenomenon of becoming blue when, after being torn or broken, it 

 is put in contact with the atmosphere (e. g. Boletus cyanescens). 



We have seen that in Discomycetes the hymenium consists of 

 cylindrical or claviform tubular cells, placed parallel to each other, 

 and each containing eight sporidia arranged in a single row ; in other 

 words, that it is composed of endosporous asci : that of Hymenomy- 

 cetes presents a structure almost similar as regards the cells and their 

 disposition, but instead of being included, the sporidia, most fre- 



* See moreover the ideas on this subject put forth by M. Morren, Acad. 

 Hoy. des Sc. Brux., 5 Janv. 1839. 



