igoS] EDGERTON—ANTHRACNOSES 369 



substance is not soluble in Gilson's fixer and hence the spores are held 

 in place (see fig. 7). While this fixer has not proved very good for 

 nuclear phenomena, it has been very satisfactory for the results 

 desired in this work. 



The culture media that have been most used are bean agar, made 

 from an infusion of fresh bean pods; potato agar with 10 per cent, 

 of glucose added; Elfving's nutrient solution (a synthetic medium); 

 and bean pods in tubes. Various other media have been used to 

 some extent, as beef extract gelatin, potato agar plus various organic 

 and mineral substances, sterilized cornmeal, cassava plugs, etc, 

 but these seem to have Httle value. Some writers have been advising 

 the use of cornmeal for obtaining perithecial stages, but I have had 

 no better results with that than with various other media. Bean agar 

 has proved as satisfactory as any used, several of the forms producing 

 perithecia on it, although not all of them. 



Characters of the group 



The anthracnoses are recognized by the characters of the conid- 



very 



ial stage. The genera 



the spores are borne in the same way in the same sort of pustule. 

 Colletotrichum is supposed to be separated from Gloeosporium by the 

 presence of setae in the conidial pustule, but as this distinction is a 

 poor one, in the following discussion the name Gloeosporium will be 

 used for all species, except perhaps occasionally where another name 

 IS the one in common use. 



The spores are borne in pustules underneath the cuticle, Jhe 



epidermis 



spore-bearing stroma appears first as a weft of thickly woven myceUum, 



The 



bearmg 



spores in abundance on short conidiophores. The spores are two to 

 several times as long as broad, straight or fusoid, and hyaline. There 

 seems to be some confusion in the Uterature as to the color of the 

 spores. For some time it went without question that they were hya- 

 Hne, but in 1894 Alwood (i) described the spores of the bitter rot 

 fungus as slightly greenish. Later Spaulding and von Schrenk (33) 

 detected the same color, and since then other writers have almost 

 invariably seen the same tint. Spaulding and von Schrenk say: 



