116 THE FUNGI WHICH CAUSE PLANT DISEASE 



in the great majority of Ascomy- 

 cetes has not been investigated; 

 but in some species fertilization is 

 known to occur; in many species, 

 at least in form similar to that 

 shown by the Phycomycetes, it is 

 absent, probably having been lost 

 by degeneration or else very much 

 modified. 



In some of the Discomycetes 

 , . . there is one or more carpogonia 



Fig. 77.— Later stage showing asci . , . 



and ascophores. After ciaussen. and fertuization IS througn a tn- 

 chogyne by spermatia; a mode often met ambng the lichens. 



InPyronema,^Fig. 78, the carpogonium is multi-nucleate and it is 

 f ertiUzed by a multi-nucleate antheridium through a trichogyne. Fu- 



D ^ 



Fig. 78. — ^Pyronema confluens. A. the sex organs, og = oogonium, t= trichogyne. 

 B. fertilization stage in section through young apothecium, asc^asci, asf=as- 

 cogenous filament. After Harpet. 



sion of nuclei is probably in pairs as in Albugo bliti of the Phycomy- 

 cetes. In Boudiera ^ a very similar relation is found. Figs. 76, 77. 



In some Perisporiales ' an uninucleate oogonium is fertilized by 

 an uninucleate antheridium. Fig. 75. 



