Edgerton : Cotton Anthracnose 



117 



not seem in any way distinct from the one on apple, Glomerella 

 fructigena (Clinton) Sacc. Whether the shape of the ascospores 

 of the cotton anthracnose was due to environment is a question. 

 There is often considerable variation in the size of the ascospores 

 from the same host as developed on different substrata, the spores 

 developing on the host plant being as a rule smaller than those 

 developing on nutrient media, but I have not noticed a varia- 



Fig. I. Asci and ascospores of Glomerella. a, Glomerella Gossypii, asci and 

 ascospores; b, same, typical ascospore ; c, Glomerella from fruit of 

 Ficus carica, showing asci and ascospores. All magnified 750 diameters. 



tion in shape. As I have never seen ascospores of the cotton 

 anthracnose that have developed on artificial media, I cannot 

 compare them with those that developed naturally. But this 

 difference in shape seems noteworthy and may represent a 

 specific character. 



A third feature, and the most interesting, developed from a 

 study of the sterile threads which are now generally conceded 

 to be present in all perithecia in this genus. The genus has been 

 described at various times as (a) without paraphyses, (b) with 

 paraphyses, and (c) with periphyses. These threads were so 

 especially abundant in the perithecia from the cotton boll, that 

 a good opportunity was offered for settling the point beyond a 

 question. A large number of sections from 2 to 8 ^ in thick- 

 ness were made and studied. In many of the sections the sterile 



