THE SEXUALITY OP THE FUNGI. 53 



monstrated by Stahl, 1 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 my- 

 celium 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 Pyrenomycetes 

 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 

 hyphee (often with haustoria) around the young perithecia in other 

 cases. 



The same is generally true for such Discomycetes as Peziza sclero- 

 tioides, 2 P. FueJceliana, and other parasitic Pezizae ; and it will be 

 remembered that it is in these forms that De Bary and others failed 

 to find any traces of sexuality, thus placing them in strong contrast 

 to such as Ascobohcs (according to Janckzewski's researches), unless 

 intermediate forms like Pyronema and the saprophytic Pezizas are 

 compared also. 



Enough has now been said to show that there is at least strong- 

 reason for believing that a connection exists between the mode of life 

 of a given fungus and the extent to which it is apogamous. It will 

 no doubt be suggested that there are still cases where this view seems 

 at variance with the facts. Without wishing in any way to strain 

 matters at this point, it may be noted that we really know very little 

 of the mode of life of very many fungi, and that the terms saprophyte 



1 Op.cit 



2 Prank, * Krankheiten der Pflanzen,' p. 531, &c. 



