i9o8] EDGERTON—ANTHRACNOSES 395 



colony. The medium on which the fungus had been growing did 

 not seem to he the cause of the variations, for cultures on the same 

 medium would vary in entirely opposite directions, or cultures from 

 very unhke media would vary in the same way. The characters in 

 which there was considerable variation were as follows: amount of 

 aerial mycelium, some very matted, some entirely strict; color of 

 substratum, from pure white to a dark greenish black; presence or 

 absence of pustules; presence or absence of pink color in the aerial 

 mycelium. 



However, the most striking variation that was obtained was with 

 the true bitter rot fungus, the culture being obtained from apples 

 sent from Missouri. The fungus had been grown in the incubator 

 for two or three months, having produced perithecia several times 

 on bean agar, and nothing unusual had been noticed; but very 

 suddenly remarkable variation was seen. A dilution culture was 

 made to obtain singie colonies for transplanting, but instead of 

 having one kind of colony in the plate, there were two, and they 

 were very distinct. At first the plate looked as if it had been 

 contaminated, but a study of the two forms showed that it had not. 

 Both forms produced typical bitter rot conidia. Cultures were made 

 of the new form and it was studied carefully with the following 

 results : 



On bean agar, for the first day or two, the colony characters were 

 identical with the typical form on apple. At that time the perithecia 

 began to develop, and from that time the differences were remarkable- 

 The typical form produced perithecia in nodules scattered over the 

 media as was mentioned above; but the new form produced them 



singly^ or occasionally in 



plat 



They were produced in such great abundance that the whole surface 

 of the plate was black with them. They began to form as small tufts 

 of pseudo-parenchymatous tissue on mycelium two to three days old, 

 and developed in such great abundance that all of the nutrient material 

 was used up before they could mature. Mature perithecia were not 

 seen, although they were looked for carefully; it is doubtful whether 

 any of them came to full maturity. The perithecia, however, so far 

 as they could be studied, were identical with the typical form. Conidia 

 formed abundantly, scattered over the surface of the agar, but they 



