Dec. 10, 1917 
Flaxwilt 
593 
generation according to Mendelian laws. Unless there is some possi¬ 
bility that these fruits were not subjected to uniformly favorable condi¬ 
tions for blossom endrot, this is apparently an unusual case of inheritance. 
Orton (20, p. 463) says, in writing on the resistance of farm crops to 
disease: 
When a disease-resistant variety is crossed with a nonresistant variety, the resulting 
offspring inherit resistance to a limited and varying extent. 
The writer found that in crosses between resistant and susceptible 
flax plants there was considerable difference in the results obtained 
from the different progenies. The results seemed to depend largely on 
the individual plants crossed. One of the most promising crosses made 
was one between the resistant strain No. 4 and the most susceptible 
strain, No. 3. The resistant plant was used as female parent, and the 
progeny was designated as 4D20, “4” referring to the strain, “D” to the 
plot where the female parent was grown, and “20” to the number of 
the female plant. With these data on the female parent it was easy to 
refer to the original records of the cross for the strain of the male parent. 
This system of recording was used throughout the work. From crosses 
between the 2 plants mentioned above 5 capsuls were obtained, and 
26 first-generation plants were grown on soil thoroughly infected with 
F. Uni (PI. 45, D, b). These plants were distributed among three 
flats, one containing 8 and the two others containing 9 plants each. 
The plants in one flat were growing at a lower temperature than those in 
the two other flats, the temperature of the former ranging from 14 0 to 
19° C., while that of the latter ranged from 18 0 to 21 0 . None of these 
Fi plants, however, were infected, although the controls of susceptible 
flax No. 3 wilted completely (23). They were grown to maturity and 
seed was obtained for a second generation by selfing. There was a segre¬ 
gation in the second generation into resistant and nonresistant plants. 
Table III gives the results obtained from the first and second generations 
and their controls. In this case selfed seed from the parent strains were 
grown as controls. In order to show the comparison between hybrid 
plants and plants of the susceptible strain, the number of plants wilted 
at the end of three weeks and the number killed by wilt at the end of the 
experiment were recorded. 
The second-generation plants, as indicated by the controls given in the 
table, were grown under somewhat more severe conditions than the first 
generation, as is shown by the fact that a number of the plants of the 
resistant parent strain were killed or infected by wilt. The F x plants 
were grown in pure North Dakota soil, while the plants of the second 
generation were grown in artificially infected soil. Bolley (9) says that 
a change in the type of soil may cause a weakening of the resistant 
character. There was also a difference of temperature under which 
these F t and F 2 plants were grown, which may have played some part. 
The F 2 plants were grown in the summer and autumn, while the F x plants 
