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, 



