ON THL] SEXUALITY OF THE FUNGI. 273 



Podosphsera^ be compared with the Peronosporeae, it is, 

 as De Bavy states, evident that the antheridia correspond in 

 both cases; while the '' archecarpium '' (i.e. the cell which 

 produces the ascus, and to which the antheridium applies 

 itself) of Podosphsera is homologous with the oogonium of 

 the Peronosporese. It is a remarkable fact that, as De Bary 

 noticed long ago,^ the antheridium of Podosphsera only 

 applies itself closely to the archecarpium, and does not pierce 

 it; it appears highly probable, moreover, that no passage of 

 substance from one to the other takes place — that the ascus, in 

 fact, arises without a sexual process, though the sexual organs 

 are present. 



Now a whole series of forms are known leading us up from 

 Podosphsera and the other Erysiphese through the Pyre- 

 nomycetes and Discomycetes, and it is remarkable that 

 (apart from some peculiar forms to be referred to shortly) 

 the best investigations lead us to conclude that while the 

 sexual organs are present, but functionless, in the lowest 

 forms, they disappear entirely in the higher Ascomy- 

 cetes. 



These facts may be put shortly in the form of a diagram as 

 annexed, where attention is only paid to the points referred to. 



Other Ascomycetes 



I 

 Erysipliese 



Podosphaera 



I 



Other Peronosporese 



I 

 Phvtophthora 



i 



Pythium. 



If we now turn to the Saprolegnise, we may note that De 

 Bary finds that, between the typical cases where the antheridia 

 pierce the oogomium wall, but do not empty any proto- 



' De Bary, ' Beitr. zur Morph. und Phys.,' R. iii. 

 2 De Bary, op. cit. 



