CHAPTER V. COMPARATIVE REVIEW. HYMENOMrCETES. 



301 



tissue of the sporophore, and closely interwoven and united with one another. In 

 more simple forms, as Hypochnus centrifugus, Tul. (Fig. 137) and the Tremellineae, 

 they may still be separated from one another for considerable 'distances; but they 

 usually form a delicate tissue very difficult to 

 unravel, which is distinguished by the name of 

 the subhymenial layer or subhymenial tissue. 



Where the hymenial surface is furnished 

 with projections of definite forms, these pro- 

 jections and the spaces between them are covered 

 uniformly by the hymenium and the subhymenial 

 tissue. Only the outermost free margin of the 

 projections, the edge therefore of the lamellae, the 

 orifice of the pores, the tip of the spikes, is in 

 many species not covered by the hymenium. The 

 inner portion of the projections which bears the 



. , ... . / i j- FIG. 137- Hypochnuf centrifugus, TuL *, b young 



SUbhymemal layer IS named the trama (alSO dlS- basidla. the terminal ceUs of the ramifications of a hy. 



..... _,. . pha, the branches of which form a tuft; at x an H- 



sepiment or intralamellar tissue). I he trama in shaped anastomosis. Magn. 390 times. 



by far the largest number of cases is distinctly 



hyphal in structure, and consists of a hyphal mass of the form of the projection, 



in which the hyphae arise as branches of those of the sporophore along the 



whole line of insertion of the projection, enter 



it at its base in a straight or curved line, 



and run from thence to its free margin in a 



course parallel to the surface. The trama there- 



fore usually exhibits a distinctly marked fibril- 



lation running from the line of insertion to the 



free margin, as in many Agarici (Fig. 138), 



Lenzites, species of Polyporus, Trametes Pini, 



Hydnum zonatum, H. cirrhatum, H. gelatinosum, 



and in Boletus edulis. The separate hyphae in 



the trama pursue a straighter or more undulating 



and winding course according to the species. It 



is more unusual for the trama to be composed 



of a tangled hyphal-weft without definitely di- 



rected fibrillation, as in Polyporus hirsutus and 



P. annosus (see on page 57). The structure, 



consistence, colour, &c. of the constituents of the 



trama are either the same as those of the rest 



of the sporophore or they may be different from E^ t Ztt%ff&5%5 



tVipm ac n o-lcmrp at thp crpnprir rVnrarfprs in hyphae, c subhymenial layer, h hymenium. t trama of 



tnem, as a glance at tne gem i thelameUa . Magn . ?0 timcs _ 



the Hymenomycetes is sufficient to show. Sub- 



hymenial tissue and hymenium spring from the trama in the manner specified 



above ; the elements of the hymenium are everywhere perpendicular to its surface. 



The trama of the lamellae in the group or genus Lactarius shows the structure just 

 described, at least in the case of L. subdulcis and L. chrysorrhoeus which I have 

 myself examined. The groups of large-celled tissue become suddenly fewer and 



FIG Ij8 Agariaa mlgarftf A 



