CHAP. II. — DIFFERENTIATION OF THALLUS. — COMPOUND SPOROPHORES. $$ 



FIG. 22. Pcziza [Sclerotinia, Fuckel) 

 Sc/erotiorum, Lib. Sclerotium with emerg- 

 ing sporophores of different ages. Nat. 

 size. 



are in the apex of the structure and form its growing point, in which growth in length 

 continues, while it dies out in the parts below it as these become successively further 

 removed from it and the cells of the hyphae have grown longer and thicker. The parallel 

 arrangement of the hyphae is not everywhere maintained ; firstly, a number of short 

 hyphal branches bend round obliquely upwards and outwards close below the apex, 

 and terminate in the free lateral surface, where they form a cortical layer to 

 the compound sporophore ; and secondly, in the first stages of the develop- 

 ment, when the sporophore is scarcely visible to the naked eye, the hyphae surrounding 

 the longitudinal axis are somewhat more loosely united 

 together than in the periphery and have their extremi- 

 ties slightly curved towards the axis. In this state 

 the primordial sporophore grows to a certain length by 

 continued apical growth in a straight line. Then the 

 growth in length of the axile hyphae is retarded while 

 that of the peripheral hyphae advances rapidly. In 

 this way a narrow canal, which can only be seen 

 under the microscope, is formed in the apex of the 

 cylindrical sporophore with its upper margin bounded 

 by the slightly incurved extremities of the hyphae. 

 And while growth constantly proceeds in the direc- 

 tion of this margin, successive formations of new and 

 similar elements take place in it, and behind it in- 

 tercalary additions (which however gradually cease 

 to appear), together with the first formation and 



development of the hymenium and other parts : thus the cylindrical body gradually 

 assumes the form of the stalked funnel. The final growth in thickness of the stipe, 

 which is however only slight, occurs chiefly in the periphery, and as the axile hyphae 

 share but little in it, a narrow canal is formed which traverses its length. 



In other species of stalked Peziza, P. nivea for instance, I have not myself observed 

 the first stages in the formation of the cups ; they are not however difficult of obser- 

 vation, and several accounts have been given of the way in which they grow for 

 a time by formation of new elements in their originally involute margin, and 

 at length assume their final form 

 by an expansion of their tissue- 

 elements advancing in the direction 

 of the margin. 



3. The sporophore of Stereum 

 hirsutum (Fig. 23), which is de- 

 scribed as a pileus divided in half 

 without a stalk and laterally at- 

 tached, is generally an irregularly 

 roundish flat disk, the larger part 

 of which stands out at right angles 

 from the substratum, while the other 

 and often very small part is firmly 

 fastened to it ; if the substratum 



is vertical, the projecting part of the Fungus has a horizontal direction, its upper 

 surface is thickly covered with hairs, and on its under surface is the hymenium. \\ e 

 need not here take notice of other and more irregular forms which are of frequent 

 occurrence. 



The sporophores first appear in the form of semicircular gray tufts of hyphae 

 1-2 mm. in breadth. These are formed on stout mycelial filaments which spread 

 in large numbers through the dead wood inhabited by the Fungus. The tufts are 

 formed of numerous hyphae, which spread from a central point with tolerable regularity 



^Miuli. 



FIG. 23. Stereum hirsutum. Ft. Vertical radial section through the 

 margin of a fresh pileus slightly magnified and giving a partly diagram- 

 matic representation of the course of the hyphae; p the advancing 

 margin with two zones behind it, h the liymenial layer, m medulla. 

 r rind, z covering of hairs. 



