ON THE SEXUALITY OF THE FUNGI. 297 



independently of any process of fertilisation, and my own 

 observations on Strigula complanata^ lead to the same 

 conclusion. It will be noted that in the beautiful case demon- 

 strated by Stahl/ the host is a blue-green Alga, and the 

 parasitism may well be considered as lower in many respects. 

 Moreover, it is by no means certain that the Lichens represent 

 one group. 



In Claviceps purpurea we have an excellent example 

 of the highly- developed parasitism referred to. The ravages 

 of the parasitic mycelium seem to be confined to one organ of 

 the host — the young fruit — and we have seen from Fisch's 

 researches that the asci arise in the stromata, developed later, 

 in a purely vegetative manner. 



Our knowledge of the large group of the simpler Pyrenomy- 

 cetes does not enable us to make a generalisation of very much 

 value; but it is significant for our present purpose that the 

 apogamous Pleospora, for instance, is parasitic during 

 the early stages of its life, and, like so many of its 

 allies, adapts its cycles to those of its host, producing 

 a large stock of asexual conidia on the living leaves, 

 and using up their contents before falling, to complete the 

 development of the asci, &c., on the ground. It is scarcely 

 necessary to remind the reader how great an advantage accrues 

 to these higher parasites, when they scatter immense quantities 

 of spores from leaf to leaf of the living tree. That their 

 perfect "fruits'^ should be formed later, when the mycelium 

 has gathered up all the material possible, is quite in accordance 

 with what occurs in the formation of stromata, sclerotia, and 

 masses of hyphae (often with haustoria) around the young 

 perithecia in other cases. 



The same is generally true for such Discomycetes as Peziza 

 sclerotioides,^ P. Fuckeliana, and other parasitic Pezizse; 

 and it will be remembered that it is in these forms that De 

 Bary and others failed to find any traces of sexuality, thus 



1 ' Linu. Trans./ ser. 2, ' Bot.,' vol. ii, 18S4. 



- Op. cit. 



3 Frank, ' Krankheiten der Pflanze,' p. 531, &c. 



