Jul. 279, Bureau of Plant Industry, U. S. Dept. of Agriculture. 



Plate IV. 



Fig. 1 .— Leaf Prints of Lettuce from Beds A and B at the End of 30 Days. 

 Shades as Numbered, Ranging from 2 (n/15 Light) to 6 (Normal). 



Fig. 2.— Leaf Prints of Mustard from Beds A and B at the End of 30 Days. 

 Shades as Numbered, Ranging from 2 (n/15 Light) to 6 (Normal). 



