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1907] STEVENS— CHRYSANTHEMUM RAY BLIGHT 257 



of the colony, the agar being full of old, dark, thick hyphae; exam- 

 ined December 8, all showed typical cases of disease. 



It seems apparent from this series that the mycelium from the 

 older central portions is capable of producing quicker infection than 

 that from the outer reg^ion of the colonv. 



RECOVERY OF FUNGUS FROM INOCULATED HEADS 



In many cases rays were taken from the heads which WTre made 

 diseased by inoculation and these rays were thrown upon Petri 

 dishes containing solidified pea agar, with the result that in each 

 case the petal was soon the center of the pure colony of a fungus 

 identical with that used in the inoculation. 



As a result of all of these inoculations it seems clear that the 

 fungus in question is actually the cause of the diseased condition of 

 the blossom; that it can gain entrance to the tissue of the blossom 

 much more easily than to the tissue of the leaves, petioles, and stems; 

 and that humidity at the time of inoculation favors the success of the 

 inoculation. 



I desire to acknowledge my indebtedness to Mr. J. G. Hall, 

 Assistant Pathologist, for the illustrations accompanying this article. 



MEDIA USED 



Cow pea agar: 500 grams of fresh cow pea pods and contents were 

 stewed in one liter of water for one half-hour, drained, i per cent, 

 agar added, autoclaved at 110°, and filtered- 



Cow pea leaf agar: 500 grams of cow pea leaves and petioles were 

 stew^ed in one liter of water for one half-hour, drained, i per cent, 

 agar added, autoclaved at no**, and filtered. 



Pea agar: ten garden peas were autoclaved with i liter of water 

 for one-half hour, drained, i per cent, agar added, autoclaved at 

 no"*, and filtered, 



Four per cent, pea agar: four per cent, by w*cight of dry peas w^re 

 stewed wnth i liter of w^ater for one-half hour, drained, i per cent, 

 agar added, autoclaved at 110°, and filtered. 



rules 



Health Association, 



