116 



Mycologia 



anthracnose, while the other half was perfectly green and healthy. 

 Two days later, six bolls picked at random in different parts 

 of the same field were examined, and three of them were found 

 to contain perithecia. In only one case did the anthracnose cover 

 the whole boll. On August 8, after a few days of comparatively 

 dry weather, over a hundred bolls were brought in from the 

 same field, but only two of these contained perithecia and they 

 were small withered bolls. Again, on August 25, after another 

 wet spell, fifty bolls were brought in from the same field and 

 the perfect stage was found on four of these. In another field 

 about a mile distant from the first one, bolls were also examined 

 but with less success. Forty bolls picked August 4 showed no 

 perithecia. However, toward the latter part of August, several 

 bolls out of a considerable number were found to contain the 

 perfect stage. From the conditions of temperature and humidity 

 at the time, it seems possible that moisture and heat may be 

 important factors in perithecial development in this species. 



The study of the perithecia showed several interesting things. 

 The perithecia were, as a rule, entirely embedded in the host 

 tissue and only the more or less well-developed beaks extended 

 through the epidermis of the boll. In only one instance {pi. 8, 

 f. 2) were the perithecia observed on the surface of the boll. 

 They were not collected together surrounding a nodule of fungus 

 tissue as is commonly the case in this genus, but were more or 

 less distinct and separate. Often they were so numerous that 

 they crowded one another, but only rarely did they seem to 

 have any connection with a common fungus stroma; often, also, 

 the perithecia were entirely separate, each one being entirely 

 surrounded by host tissue {pi. 8, f. 5). 



A second interesting feature was the shape of the ascospores. 

 Glomerella spores are generally more or less curved and elon- 

 gate, while these were rarely curved and more elliptical (fig. 

 1, a, b). I have had the opportunity of studying spores from 

 a number of different host plants, but I have seen in no other 

 form, the short, thick, elliptical spores like those which occurred 

 on the cotton. I have shown as a comparison, in fig. 1, c, 

 ascospores that developed on the fig, Ficus carica. The perfect 

 stage of this form has not hitherto been reported, but it does 



