140 



MORTIER F. BARRUS 



was planned with this end in view. In these experiments the beans 

 were planted in soil in ordinary greenhouse flats. Each flat was numbered, 

 and the conditions involved in the case of each are given herewith. Seeds 

 from healthy pods were used for planting each flat except flat 2, for which 

 seeds spotted with anthracnose were used. 



Flat 



Description 



1 



2 

 3 

 4 

 5 



6 



7 



8. 



Clean soil 



Clean soil. Seeds spotted with anthracnose used in planting 



Contaminated soil 



Contaminated soil sifted to remove particles of bean tissue 



Clean soil. Diseased vines and pods from crop of 1915 obtained from disease 



garden, broken up and mixed with soil in flat 

 Clean soil. Diseased vines and pods from crop of 1915 obtained from disease 



garden, placed on surface of soil and removed as seedlings were appearing 

 Clean soil. Diseased vines and pods from crop of 1915 obtained from disease 



garden, placed on surface of soil and left there 

 Clean soil. Diseased vines and pods from crop of 1915 kept in seed house, 



placed on surface of soil and left there 

 Clean soil. Diseased pods from crop of 1916 kept in seed house, placed on 



surface of soil and left there 



The clean soil (uncontaminated by C. lindemuthianum) used was taken 

 from a field where no beans had ever been grown so far as was known, 

 but it was not sterilized except in the last experiment, when it was thought 

 to be contaminated with spores. The flats, unless new, were sterilized 

 with steam. The contaminated soil came from places in the disease garden 

 where bean plants badly affected with anthracnose had grown in 1915. 

 Only the surface soil to a depth of from two to four inches was used. 

 In the first experiment both sifted and unsifted soil was used, but there- 

 after all contaminated soil was passed through a rather fine sieve in order 

 to remove particles of bean-plant tissue as far as possible. 



The healthy seed used was selected from clean pods, and in all but two 

 experiments (II and III) it was immersed for three minutes in a 1-1000 

 mercuric chloride solution and afterward washed in tap water. This was 

 done to destroy any spores of C. lindemuthianum that might possibly be 

 present. The affected seed was disinfected in the same way as was the 

 healthy seed. Seed so badly diseased that it could not germinate was 

 not used. The affected seed used in each experiment was of the same 



