34 JOURNAL OF THE 



The genus belongs to one of the great groups of fungi 

 known as the HypJioiiiycctes. Its members, along with 

 many others, are sometimes termed "imperfect fungi," 

 because they are not autoiwnious; i. e.^ they represent, as is 

 supposed, not complete individuals in themselves, but only 

 a transitory form, or stage, of a polymorphic fungus, the 

 perfect condition of the individual being some species of 

 SphcereUa or other ascomycetous fungus. Thus they stand 

 only as the conidial stage of more or less complex life 

 cycles. It is quite probable that in this respect they are 

 analogous to other conidial forms, of the nature of which 

 we have more positive knowledge, for example the Powdery 

 mildews (^nw_/^//^^). Downy mildews (Peronosporeae), etc., 

 so that the conidial stage can reproduce itself successively 

 for several generations without the intervention of the per- 

 fect, or ascigerous, stage. Therefore there is not a true, 

 or strictly obligate, alternation of generations such as 

 obtains in the Muscinc(S^ Filices^ etc. 



In but few of the species has the perfect stage been dis- 

 covered. The writer has given an account of the perfect 

 stage of Cercospora gossypina in the Bulletin of the Torrey 

 Botanical Club, Vol. XVIII, p. 300 {SphcereUa gossypina 

 Atkinson). Pammel (Bulletin No. 13, Iowa Agr. Exp. 

 Sta., May, 1891) is of the opinion that Cet^cospora angidata^ 

 on currants and gooseberries, is connected with SphcFrella 

 Grossularice^ and that Septoria Ribis is also connected 

 with the same perfect fungus. If this should be con- 

 firmed, then we have here a Cercospora forming one of the 

 stages of a trimorphic fungus possessing conidial, sper- 

 mogonial, and ascigerous stages. Cercospora arice Fkl. 

 is considered the conidial stage of SpJicercIla cincrascens 

 Fkl., and C. radiata Fkl. of S. Vitlncrue Fkl. (Sacc. Syl. 

 Fung., Vol. I, pp. 493, 503). Probably one reason why 

 the perfect stage of but few has been found lies in the 

 fact that in many cases this stage is only developed after 



