AGRICULTURE: L. R. JONES 
43 
of its progeny has since proved to be the best with the unselected control 
strains. 
Selected head strain 96% lived 80% headed 
Non-selected controls 36% lived 16% headed 
From the best of these heads, selected as the second generation survivors 
on sick soil in 1912, seed was grown in 1913 and like trials on the same in- 
fected soil made again in 1914. In order the better to show the significance 
of these results the following summary includes the averages of all of the 
head strains selected from the best strain in 1912 together with the results 
from the best head strain. Data are also here included as to the per cent 
of diseased plants in each strain at the end of the season, the average weight 
of the heads, and the computed yields in tons per acre. 
SECOND GENERAL TRIALS, 1914 
LIVED 
HEADED 
DISEASED 
WEIGHT 
PER HEAD 
YIELD 
PER ACRE 
per cent 
per cent 
Per tent 
pounds 
tons 
99.5 
94.0 
5.0 
4.0 
12.2 
100.0 
98.0 
1.5 
5.5 
18.8 
46.0 
24.5 
81.0 
2.7 
2.1 
A comparison of the 1914 results with each other and with those of 1912 
shows clearly certain encouraging things. First, the disease resistant char- 
acter, whatever may constitute it, is fixed and inheritable; second, there is a 
distinct improvement in the second generation as compared with the first; 
third, there is enough variation as between the selected head strains of the 
second generation to furnish a basis for further possible improvement by 
continued selection. Perhaps this last idea requires restatement in such a 
way as to lay the emphasis upon another fact. Since there is a considerable 
variation within the progeny of even the selected head strains it is necessary 
to continue the method of growing the seed strains on ' sick' soil for trial and 
selection in order to maintain the highest standards, and were this to be dis- 
continued there would probably be a tendency toward gradual reversion. 
Such selections and trials have since been continued in an intensive way 
by our department with further encouraging results while the more exten- 
sive work of seed growing and its distribution (under the name Wisconsin 
Hollander) has passed to the hands of a committee of practical cabbage 
growers organized for this purpose. 
In this way our own departmental activities, including the investigations 
of certain graduate students, have been freed for direction to some of the 
more fundamental questions involved. Among these the following may be 
defined. 
1. Wherein is the difference between the susceptible and the resistant 
plant? In other words, what constitutes disease resistance? 
