6oo 
Journal of Agricultural Research 
Vol, XI, No. ii 
Table VIII shows the results of crosses in which the first generation 
was entirely or almost entirely susceptible. The second generation in 
these cases behaved about as did the second generation from crosses 
which have been given above. There seems to be no common explana¬ 
tion for segregation in this case, which, of course, is to be expected when 
the first generation segregates irregularly, as was true with these crosses. 
Table VIII .—Resistance to flax wilt of crosses between resistant and susceptible strains of 
flax in which the first generation plants were entirely or almost entirely susceptible 
RESISTANT NO. 4 9 X SUSCEPTIBLE NO. 5 $ 
Parent strain. 
Date of 
planting. 
Num¬ 
ber of 
plants 
grown. 
Ratio at end of 
three weeks. 
Ratio at end of 
experiment. 
Num¬ 
ber of 
plants 
killed 
by 
wilt. 
Wilted. 
Not 
wilted. 
Wilted. 
Resist¬ 
ant. 
19x6. 
4Eijj (F,). 
Feb. 2 
14 
4 
IO 
12 
2 
3 
Resistant No. 4. 
.. .do.... 
18 
0 
18 
O 
18 
0 
Susceptible No. 5. 
12 
6 
6 
12 
O 
12 
F, generation: 
4E13-1. 
Sept. 23 
I27 
82 
45 
126 
I 
125 
Resistant No. 4. 
.. .do.... 
26 
4 
22 
7 
IQ 
C 
Susceptible No. 5. 
2 
2 
0 
2 
7 
0 
D 
2 
RESISTANT NO. 4 9 X SUSCEPTIBLE NO. 5 <$ 
4K12 ('F,'). 
Oct. 18 
11 
c 
6 
11 
0 
8 
Resistant No. 4. 
...do.... 
79 
5 1 
123 
0 
7 
76 
61 
6 
73 
0 
7 
Susceptible No. 5. 
...do.... 
O 
36 
62 
5 1 
106 
O 
5 ° 
F 3 generation: 0 4E12-1. 
... do.... 
17 
Sx 
0 
a Control same as for Fi. 
A large number of first-generation plants have been grown from dif¬ 
ferent crosses from which no second-generation plants have been grown. 
The first generations from these crosses vary from those which are 
entirely resistant to those which are entirely susceptible, as have been 
given in the previous tables. Table IX will show these results. 
DISCUSSION OF RESULTS 
The inspection of Tables III to IX reveals no common explanation for 
the results obtained. Except for one case (Table III), no definite ratios 
could be detected. However, there are a number of possible reasons 
for these results: (i) The plants were grown under abnormal green¬ 
house conditions. (2) The temperature was too high in some cases, as 
previously emphasized. (3) A different type of soil was used for some 
of the tests, which, according to Bolley (9), is likely to cause a breaking 
down of the resistant character. (4) There is a great variation among 
individual plants within a strain. 
