mikI others, finding that them conceptacles wrere borne on the same 



eliwn as the conidia and perithecia, naturally concluded thai fchej 



;nis of the Bame plant, and, from their analogy to certain 



na] reproductive bodies in allied groups of the Ascomycetes, called 



them pycnidia, and the minute l>odies they contain, stylospores or 



pycnidiospores. This is still the accepted belief of many botanists. 



De Barj (Morph.und Phys. der Pilze, III, pp. 53-75, Tafeln VI, VII), 



shows that tin 1 pycnidia instead of being reproductive organs of the 



Erymphe t are, in reality, the fructification of a fungus that is parasitic 



on the Ert/sipfie. llr calls it Cicinobolus Cesatii, and gives numerous 



figures Bhowing its delicate, septate mycelium, developing within the 



mycelial threads of the Erysiphe, and sending up branches which, by 



repeated division, form the cellular wall of the pycnidium. 



There is much confusion in regard to the nomenclature of this 

 group. The earlier authors, with poor magnifiers or none at all, made 

 meager descriptions of their supposed species, for which reason it is 

 often impossible to determine from their writings what they had in 

 hand. Host plants are not so much of a guide here as in most cases 

 for parasites, though many specific names have been proposed, it seems 

 solely upon the observed habitat of the fungus. In what follows, an 

 earnest endeavor has been made to identify and describe true species 

 wherever they grow. The Bulletin of the Illinois State Laboratory 

 of Natural History, Volume II, Article VI, Parasitic Fungi of 

 Illinois, part II, by T. J. Burrill and F. S. Earle, has been made the 

 !>asis of this work. This bulletin was founded upon collections made 

 in Illinois, mostly by A. B. Seymour who also made studies upon the 



ies. 



KEY TO THE GENERA. 



Appendages to the perithecia simple, and similar 



to the threads of the mycelium. 2, 



Appendages various, readily distinguished from the 



mycelium. 3. 



Only one ascus in a perithecium. - - Sphcerotheca. 

 ral asci in each perithecium. - - - Erysiphe. 



Appendages branched at their tips. 4, 



Appendages not branched. - - - . 5. 



Only one ascus in a perithecium. - - Podosphcera. 



Several asci in each perithecium. - - Microsphcera. 



Appendages swollen at base, tips straight. Phyllactinia. 





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