250 



THALLOPHYTES. 



piece of the greatly extended reticulately anastomosing mycelium {m), from which 

 sprout a number of receptacles ; these are at first solid pear-shaped bodies («) composed 

 of young hyphae all similar to one another. At an early stage the tissue of hyphai gives 

 way beneath tJie apex, leaving an annular air-cavity (//, /), the upper wall of which forms 

 the under-side of the pileus ; and from this the radial hymenial lamellae grow downwards 

 (7/7, /), filling up the air-cavity. The hyphae run from the base of the whole receptacle 

 to the margin of the pileus, forming the outer wall of the air-cavity ; the tissue lying in 

 the centre elongates into the stalk {IV, st), while the distance from it of the margin of 

 the pileus constantly increases; the hyphae which lie beneath the air-cavity that coJi- 

 tains the lamellae become stretched in consequence, and separate from the stem from 

 below upwards, forming a membrane {F, 'v), running from the upper part of the stem 



Fig. iT2.—As(iriciis variecolor. I mycelium m, with young 

 receptacles a b (natural size) ; c longitudinal section of one of the 

 latter (magnified); //an older receptacle, with commencement 

 of the formation of the pileus ; /// the same in longitudinal sec- 

 tion ; IV a more mature pileus, v the veil. The lines in the 

 sections indicate the course of the hyphae. 



Fig. \T>,.—Agaricus cainjrestris (natural size). 



beneath the lamellae to the margin of the pileus, into which their hyphae are continued. 

 When at length the pileus' extends horizontally from the elongation of the tissues, the 

 membrane (volva) becomes detached from its margin, and hangs from the stem like a 

 ruffle. (Compare also Fig. 68, p. 8i, Boletus Jlavidus .^ 



The hymenium, as has already been mentioned, covers the surface of the lamellae- 

 form peg-shaped or tubular projections of the under-side of the pileus. A trans- 

 verse section of the latter across the hymenium gives, in all three cases, nearly the same 

 figure, as is seen in Fig. 174, drawn from ylgaricus campestrh. ^ shows a piece of the 

 disc of the pileus cut transversely, b the substance of the pileus, / the lamellae ; in 5 a 

 piece of a lamella is more strongly magnified to show the course of the hyphae. The 

 substance of the lamella, called the Trama (/), consists of rows of long cells, which 



