REPORT OF THE SOCIETY 125 



6. Colletotrichiim atrovirens. 



Culture sent by Dr. N. J. Giddings of the Laboratory of Plant Patho- 

 logy of the West Virginia Agricultural Experiment Station at Morgan- 

 town, W. Va. The writer has not been able to find any published 

 technical description of this organism. 



Media used. 



Since one ot the main objects of this investigation has been a carefull 

 study of the cultural variations of the above organism, as large and as vaned 

 a number of media as time warranted were used. The media falls, naturally, 

 into two classes solid and liquid. The first class consists for the most p art 

 of plant media and nutrient media made with agar. In the second group 

 is a number of well-known nutrient solutions. 



Cultures were grown in tubes of different sizes, in 150 cc. Pyrex Erlen- 

 me3'"er flasks and in petri dishes. All glassware was thoroughly washed in tap 

 water, rinsed in distilled water and autoclaved for twenty minutes at fifteen 

 pounds pressure before it was used. This method proved satisfactory and 

 very little contamination resulted. 



Of the solid and liquid media used the following were found to be the 

 most suitable: — 



Solid 1. Potato-dextrose agar. 



2. Czapek's synthetic agar. 



3. Oatmeal agar. 



4. Cornmeal agar. 



Liquid 1. Currie's solution. 



2. Pfeffer's solution. 



3. Czapek's synthetic solution. 



4. Duggar's synthetic solution. 



''Merck" chemicals were used entirely in the preparations of the liquid 

 media. 



Observation on type and rate of growth. 



On solid media. 



On the sohd media used growth characteristics were so similar that the 

 writer will not give individual descriptions. With the exception of the Saltation, 

 the general type of growth was as follows : 



The first indication on the medium was the production of a white downy 

 to downy silky, superficial mycelium. Xo coloration was observed until about 

 the end of the fourth day when a distinct amethyst color, most prominent in the 

 centre of the culture, began to appear. This amethyst coloration is a striking 

 general characteristic of all the cultures. In a few plates a yellow coloration 

 was also noted. At the end of the si?:th day black sclerotia appeared on the sur- 

 face of the agar and the white superficial mycelial growth began to disappear. The 

 sclerotia are almost invariably produced in concentric rings in petri dish cultu- 



