200 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI. 
between the ascogenous cells distributed in the hypothecium and Woronin’s hypha. 
Considering the difficulty of getting at the young states of these sporocarps 
the data before us leave it open to possibility that both Polystigma and Xylaria 
do really behave like Collema, only certain initial and intermediate states being 
at present unknown, and that we shall at length discover organs in Xylaria equi- 
valent to spermatia. But if what we at present know is the full account of the 
matter, then Xylaria is distinguished from Polystigma, and of course still more 
from all the forms mentioned in number 2, by the fact that the ascogenous cells 
and hyphae do not spring from a distinct archicarp, but, like the paraphyses, 
from parts of the primordium, while the archicarp, unmistakeably present in form 
as Woronin’s hypha, perishes without taking part morphologically in the formation 
of asci. 
5. The difference from the first case is still more distinct in certain dis- 
cocarpous Lichen-fungi which have been examined by Krabbe (Sphyridium, 
Baeomyces, Cladonia), in Sclerotinia and in a number of Pyrenomycetes. , 
Ascogenous and envelope-hyphae are everywhere inserted between one another 
and are closely interwoven in the hypothecium of the long-stalked cup of Sclerotinia 
Sclerotiorum, but a direct genetic connection, an origin of the two from a common 
source, can nowhere be shown; the lowest extremities of both pass into the uniform 
sterile tissue which ascends from the stalk. It is nevertheless highly probable that 
the two kinds of elements have a separate origin from the commencement of the 
formation of the cup, for small round coils of very delicate hyphae are formed 
in the sclerotium beneath the rind before the cup emerges from it. The commence- 
ment of a cup always rises from above a coil of this kind as a comparatively thick 
bundle of hyphae, the innermost of which are branches of the hyphae of the coil, while - 
the much more numerous peripheral hyphae originate in the surrounding tissue of the 
sclerotium. It is probable that the latter represent the envelope-apparatus, and those 
from the coil the ascogenous portion of the cup, and that the coil therefore 
is a kind of ascogonium. But a distinct proof of this has never been forthcoming, 
because, as the stalk elongates, it is no longer possible to show a morphological 
distinction between the two elements and by this means to establish the connection 
between the later ascogenous hyphae and their: supposed primordia. Neither anthe- 
ridial branches nor spermatia were observed during these developments. 
In the Lichen-fungi mentioned above, the ascogenous hyphae may be seen, 
according to Krabbe, distinctly marked between the hyphae of the envelope- 
apparatus at a very early stage in the development of the sporocarp. But no 
initial organ has been observed from which they originated, and it must be presumed 
that they both have a common origin in the hyphae of the vegetative thallus or of 
the primordium of the sporocarp, and without the co-operation of spermatia or 
antheridia. 
In the Pyrenomycetes, Claviceps, Epichloe, Pleospora, and perhaps also 
Nectria, no co-operation of the above-named organs has been observed, and no 
distinct ascogonium. The young perithecium, as at present known, is a body 
consisting of similar hyphae or parenchymatous cells, and its elements are gradually 
fashioned and differentiated into the parts of the perithecium ; in this process a cell- 
group occupying the position of the hypothecium undertakes the formation of the asci, 
