VOL. IV 



MINNESOTA BOTANICAL STUDIES 



PART IV 



Figure. 1. Batteries of wheat, rye, and cockleburs used in determining the relative 

 transpiration of healthy and rust-infected plants. 



Fig. 2. Upper surface of rye leaves infected with Puccinia rubigo-vera secalis, and 

 an enlargement just ten times the original size of one of these leaves. 



PLATE XLI 



