6 CONTENTS 



Inoculation after exposure to ether % 21 



Inoculations on oats , . 21 



Inoculations under ordinary conditions 21 



Inoculation after exposure to ether 22 



Inoculations on oats and rye after the use of barley as a 



"bridging form" 22 



Summary of experiments with Puccinia graminis tritici. ... 22 



Effect of the aecidial stage on biologic forms 23 



General statement 23 



Experiments in 1912 < 23 



Experiments in 1913 24 



Adaptation of biologic forms to new hosts 25 



Summary of Part 1 27 



Part II. Rust-resistant varieties of wheat 28 



Historical 28 



Forms which are resistant 29 



Field observations 29 



Experimental '. 30 



Greenhouse trials 30 



Inoculations on resistant forms 32 



Metabolism of the host and rust resistance 33 



Effect of water content of soil 34 



Effect of fertilizers - 36 



The nature of resistance 40 



Histological details of infection 42 



Infection of Minnesota No. 163 42 



Infection of Khapli 44 



The course of infection in other resistant forms 45 



Minnesota No. 163 inoculated with Puccinia graminis avenae 46 



Summary of Part II 48 



Bibliography ... * 50 



Explanation of Plates 55 



