224 DIVISION II. COURSE OF DEVELOPMENT OF FUNGI. 



propagation not belonging to the sporocarp. This is the case in Eremascus albus, 

 Hypocopra fimicola, Ascobolus furfuraceus, Pyronema, Gymnoascus, species of 

 Collema, Endocarpum pusillum, Thelidium minutulum, and very many, if not 

 all, Lichen-fungi ; a similar course of development is the almost invariable rule in 

 Sclerotinia Sclerotiorum, where a filamentous mycelium grows from the germ-tube of 

 the spore, the mycelium producing sclerotia and the sclerotia sporocarps. Single 

 resting-cells, which occur accidentally in the mycelia and then resume active growth, 

 are no more to be taken into consideration in this connection than the soredia 

 of Lichens which will be described in section CXVII. More distinct formations 

 of gonidia have not been observed in this course of development. 



There is a second case in which the development may proceed as in the first ; 

 but it commonly happens that a formation of distinct gonidia is introduced, and the 

 products of their germination resemble those of the ascospores. A good example of 

 this kind is to be found in Sclerotinia Fuckeliana 1 . A primary mycelium grows from 

 the germinating ascospore, and may in the simplest case produce sporocarps directly 

 and without going through any intermediate state. I have observed this once and in 

 one specimen only cultivated artificially in grape-juice on a microscopic slide. The 

 sporocarp was produced directly from a tuft of mycelial branches resembling 

 in appearance the primordium of a sclerotium, but its initial states were not 

 further examined. The general rule is that sclerotia are formed (p. 34) on the 

 primary mycelium ; then either sporocarps alone proceed from the sclerotium, 

 as in Peziza Sclerotiorum, or filamentous gonidiophores, which are known under the 

 name of Botrytis cinerea, Pers. One only of the two forms appears on a sclerotium, 

 never both together or one after the other. These gonidiophores may also grow 

 directly from the mycelium which has proceeded from ascospores, without prejudice 

 to future formation of sclerotia, but this certainly does not very often occur. Finally, 

 the germinating gonidia produce a mycelium with all the characteristics of one that 

 has proceeded from the ascospore and giving rise to the same products, but with this 

 difference that it inclines much more to the formation of gonidiophores. To 

 these phenomena is to be added the occasional formation of special abortive gonidia 

 or doubtful spermatia, which must however be noticed again in section LXXIV. 



A third case is that of a number of species in which it must be allowed that the 

 course of development proper to the first category is possible, but is never actually 

 observed. More usually the primary mycelium or thallus formed from the ascospore 

 always produces gonidia. Strictly speaking, two subdivisions may here be dis- 

 tinguished : 



a. The primary mycelium which proceeds directly from the ascospore is 

 reduced to a promycelium (section XXXI) which produces sporidia; these give 

 rise to the definitive thallus, which then behaves as in the first category or as in 

 the cases placed under b. Of this kind is Polystigma rubrum and Rhytisma 

 Andromedae also, to judge from the germination of the ascospores. 



In this case also the formation of gonidia is as a rule a necessary part of the 

 development, for a perfect fertile thallus is not produced without its interposition. 



1 See Pirotta in N. Giorn. Bot. Ital. XIII, p. 130. 



