Bui. 40, U. S. Dept. of Agriculture. 



Plate VII. 



Healthy and Mosaic Plants of Nicotiana rustica. A, Healthy Plant; B, Diseased 

 Plant of Nicotiana rustica Produced by Artificial Inoculation from a Dis- 

 eased Plant of Nicotiana tabacum. 



(Greatly reduced.) 



