CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES.—SCLEROTINIA. 219 
peripheral mass the elements of which originate in the periphery of the primordium 
as branches of the stout medullary hyphae. The small central bundle is short, the 
peripheral hyphae are longer in proportion as they are nearer to the circumference, 
and, like the periphyses of the Pyrenomycetes, their extremities converge towards the 
median line, and thus a narrow depression is formed at the apex of the whole which has 
been noticed before on page 52. No other decided difference of structure isto be observed 
even at this time between the two kinds of hyphae, and during the subsequent growth 

FIG. 104. Sclerotinia Sclerotiorum. Thin ver- 
tical section through the periphery of a sclero- 


tium which has been kept moist and is ready FIG. 105. Sclerotinia Sclerotiorum. Mediansection through a 
to develope; beneath the black rind is the young p which is bursti 'hrough the rind. Magn. 90 
primordium of a sporocarp. The dark angular times, butcompleted from higher enlargements. 
bodiesare calcium oxalate. Magn 15otimes. See 
also Fig. 14. 
of the whole body all possibility of distinguishing them ceases. But it is not improbable 
that the difference reappears with the formation of the ascus, in other words, that the 
hyphae which have proceeded from the primordium are the ascogenous hyphae and 
the primordium is therefore an ascogonium, while the envelope-apparatus of the 
sporocarp with the paraphyses comes from the peripheral hyphae; and thus the 
young sporocarp contains from the first the two elements side by side, though they 
are not anatomically different. The original structure 
of the primordium is obscured after the emergence of 
the sporocarp, but its place usually continues to be 
distinctly marked by the brown colour of the walls of 
the medullary cells at its circumference; this however 
may often ultimately spread to the primordium also. 
The number of primordia in a sclerotium is always 
much larger than that of the sporocarps which are 
matured; many are obliterated by their peripheral cells 
turning brown or are destroyed by the emergence of 
neighbouring SPUREN FIG. 106. Sclerotinia Sclerotiorum. 
Sclerotinia Fuckeliana shows phenomena of a a ps of 
development quite similar to those which have been 
described; but there is one difference which adds greatly to the difficulty of obser- 
vation: the primordia are not formed inside, but on the surface of the sclerotium. 
A thin bundle of hyphae from the medullary tissue bursts through the rind and 
developes on its outer surface into a dense round coil, the central part of which 
is like the primordium of S. Sclerotiorum and is surrounded by the peripheral hyphae 

