6 2 The Botanical Gazette. [March, 



The fungi commonly present and which play an important 

 part in the disease are Cercospora Gossypina Cooke, a species 

 of Collctotrichium, x a Macrosporium, 2 an Altcrnaria, and fre- 

 quently a pycnidial stage of some sphreriaceous fungus, 8 and 

 a bacterial organism which produces a characteristic disease 

 of the leaves. 



The bacterial disease is often very widely spread even when 

 no evidences of the other fungi are to be found, but is men- 

 tioned here because frequently it is an accompaniment of the 

 "black rust" and contributes materially to the aggravation of 

 the disease. It is first manifested by a watery appearance in 

 definite areolate spots which are bounded by the veinlets of 

 the leaf. The spots are sometimes very numerous and fre- 

 quently conjoined; often the disease follows one or more of 

 the main ribs of the leaf being bounded on each side by an 

 irregularly zigzag line. As the disease ages the spots become 

 blackish and finally brown, frequently then bordered by a black- 

 ish color where the disease has extended somewhat centrifu- 

 gally. The disease hastens the falling off of the leaves. 



During the entire season, from July to the close of October, 

 of the thousands of leaves old and young that I have exam- 

 ined, Cercospora Gossypina has been an almost universal ac- 

 companiment, and has not been second in point of attack, ex- 

 cept perhaps in rare cases. In many cases parallel or imme- 

 diately succeeding attacks were made by the Colletotrichium. 

 The Macrosporium as a rule follows closely the attack of the 

 Cercospora. 4 indeed sometimes seeming to be the first to at- 

 tack. In such cases possibly it attacked the spots diseased 

 by Cercospora before the hyphae and conidia of the latter were 

 developed. 1 he Alternaria usually succeeds the Macrospo- 

 rium, though often seeming tp be parallel with it. By its 

 numerous clusters of hyphae and profusely developed concate- 



l C. Gossypii ' K. ,\ Sonthworth. 



l/2 h !*?W,!?,? 5 he M , undescr i!> ed species for which I have proposed the name 



«* 2 < r 7£ """i™ TUe hyph * are *™phigenous P subfasciculate or 

 scattered ^.,0^140 mm. longX.000-.0or mm. in diameter, nodulose septate olive 

 brown. Conuha .018-022 mm. X 036 ,050 mm. strong yconSfcted^bout the 

 mud e, stoutly rostrate at one side of the apex, smith, transversel longitu- 

 d nally and obliquely septal olive brown. The nodulose hypfce resemble those 

 of such species as M. parasiticum Thuem Yl res,emDie 



oentone te Shtffi *?£*'"'* f '«" «* & M. Some recent cultures in agar- 



ptptone broth and an infusion of cotton leaves seem to show that it is the pyciid- 



«tt&rf£rtS*%I S r r " which ! have found ° n «*•- ie -- 



i ossibl} iiso that of the Phyllosticta. 



