294 Journal of Agricultural Research voi.xx.No.-, 



Out of 3,203 plantings, all but 161 of which were from discolored tissues, 

 1,352 gave no growth. 



The field trials indicate that neither vascular discoloration nor fungus 

 invasion of the tissues of the mother tuber is a guarantee of disease in 

 the resulting plants, nor is their absence a guarantee of health. The soil 

 and not the tuber appeared to have been the more potent source of 

 disease. 



Stem-end seed pieces yielded slightly higher percentages of disease 

 than eye-end pieces, evidently because the stem end is endowed with 

 less physiological resistance. 



The plants showed a marked capacity for recuperation, which varied 

 with the variety, with the environment, and with the interaction of 

 the two. 



