366 



RESEARCHES ON FUNGI 



stipe, and the subpilear part the primordium of the base of 

 the stipe. 



The various j)rimordia are then related as follows : 



/the primordium of ) 



the gills together forming the 



primordium of the 



The primordium of 

 the fruit-body as a 

 whole producing : 



the primordium of 

 the pileus-flesh 



pileus 



, the primordium of 



the primordium of | the stipe-shaft 



the stipe pro--! , . t e 



- . I the primordium of 



\ ducmg : , . i 



^ \ the stipe- base. 



Now, when a fruit-body is produced on the surface of the sub- 

 stratum, the primordium of the base of the stipe gradually thickens 

 and elongates a little, the elongation taking place chiefly in its upper 

 part ; and that is all. The primordium of the shaft of the stipe, 

 however, elongates after a time enormously, and so carries the pileus 

 high into the air (Fig. 182, p. 362). 



When a fruit-body starts its development not at the surface 

 of the substratum, but at some distance below it, the primordia 

 originate in the same manner as that just described. But here the 

 primordium of the base of the stipe becomes especially important. 

 In its upper part, just below the annular furrow, the parallel hyphae 

 of which it is composed grow enormously in length by intercalary 

 growth. The result of this is that the primordium of the pileus 

 (flesh, gills, and veil), together with the primordium of the shaft cf 

 the stipe, is pushed upwards through the manure, and an elongating 

 root-like structure, the pseudorhiza, comes into existence. The 

 intercalary growth at the top of the pseudorhiza continues until 

 the primordia of the pileus and stipe-shaft have been carried up 

 to, or nearly up to, the surface of the substratum. It then ceases. 

 As the pileus is carried upwards, the pseudorhiza not only elongates 

 but, as a rule, gradually thickens, so that the diameter of the 

 youngest and highest part is often very much greater than that of 

 the oldest and lowest part {cf. Figs. 180 and 185, pp. 360 and 367). 



As the pileus approaches the loosest and uppermost layer of 



