PLATE 30 



A. — Inoculated by means of artificial transfers of aphids from diseased plants- 

 Green Mountain variety. Transfers made February 26, March i, and March 15, 1919. 

 Distinct mottling and crinkling of younger leaves noted April i, 1919. Green- 

 house, Washington, D. C. 



B. — Plants inoculated in same way as those in A of this plate, but with aphids 

 taken from healthy plants. No mosaic April i, 1918. Greenhouse, Washington, 

 D. C. 



