22 2 Journal of Agricultural Research vou xxv no. s 
successful, whereas in reality over 120 separate infections had occurred. 
The failure to pick out the infected plants lay in the fact that it is not 
until the second year the rust has lived in the blackberry that the canes 
become so infected secondarily by invasion of mycelium from the peren- 
Fig. 5.—Root system of nursery stock of blackberry No. 134 planted May, 1020, dug May, 1922. lettering 
has same significance as that in Figure 4. Infected plants A, B, C, D, E, and F arise from roots con¬ 
nected with the original stock at three different levels. The roots shown here are entirely free from 
mycelium. See figure 4. Original root crown at X, present crown at Z. 
nial base that they show the peculiar features mentioned. Canes prima¬ 
rily infected remain for the most part quite normal and blossom as usual, 
since the upper parts are free from the parasite. The results of the 
infection experiments are given in Table I. 
