CHAP, II.—DIFFERENTIATION OF THALLUS.—COMPOUND SPOROPHORES. 53 
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 gy, 2. Pestca (Sclerotinia, Fuckel) 
similar elements take place in it, and behind it in-  Scleretiorum. Lib. Sclerotium with emerg- 
tercalary additions (which however gradually cease u en 
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 ate 
tached, is generally an irregularly 
roundish flat disk, the larger part FIG. 23. Stereum hirsutum, Fr. Vertical radial section through the 
of which stands out at right angles margin of a fresh pileus slightly magnified and giving a partly 
. matic representation of the course of the hyphae; / the advancing 
from the substratum, whilethe other margin with two zones behind it, % the hymenial layer, » medulla, 
and often very small part is firmly ind. x covering of hairs. 
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. We 
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 


