74 
Journal of Agricultural Research 
Vol. XXV, No. 3 
TavlE XV .—Symptoms of inoculated hills of rows i-o and i-H of Table XIV, on 
August 23 
In connection with the preceding experiment, duplicates of many of 
the leaf-mutilation inoculations were made with capillary glass tubes. 
From three to five of these tubes were filled with the juice and inserted 
into each shoot in the leaf axils (PI. 13, B). This method was effective 
only in the rows corresponding to i-O, 2-0, and i-J (Table XIV), and 
there only in a few hills, with symptoms appearing later than in the case 
of leaf mutilation. Apparently, transmission is too difficult with this 
method to be dependable, at least in comparison with the leaf-mutilation 
method. 
Corresponding inoculations of caged Green Mountains and Irish 
Cobblers with potato aphids, with contact of roots and foliage, were 
made in 1921. Six tubers of each variety were quartered. The quarters 
from each tuber were grown, respectively, in cages of four series—with 
no inoculation, with inoculation from mosaic Green Mountain hills, 
with inoculation from curly dwarf hills, and with inoculation from prog¬ 
eny of streak hills. In the first series there were three healthy plants 
in a cage, in the second there were two healthy and one diseased in a 
cage, and in the two others one healthy and two diseased. The aphids 
were transferred to the diseased plants and in turn reached the healthy 
plants in the same cages. The latter were planted somewhat later than 
the former so that they were still small when aphids were numerous 
enough to disperse and to be transferred artificially. Some of the 
diseased plants in the streak series were removed on account of the ap¬ 
pearance of mottling and the cages used for other experiments. This 
experiment is described further in Table XVI. 
