Dec. 22, 1933 
Cytology of Wheat Stem Rust 
593 
In Table V the data for forms III and XIX on Baart, Kanred, and 
Mindum are summarized. The two rusts differ markedly in their 
ability to attack these hosts. Baart is susceptible to both, Kanred is 
susceptible to form III and immune from form XIX, while in Mindum 
these relations are just reversed, Mindum being immune from form III and 
susceptible to form XIX. Stomata occupied by the fungi are divided 
into four classes: Those normal or not visibly affected, those with the 
central part of the guard cells more or less injured, those in which the 
guard cells are dead, and those in which not only the guard cells but ends 
of adjoining epidermal cells are affected. The time of year in which the 
material was grown, the age of the fungus (number of days after inocu¬ 
lating the plants), the total number of stomata counted, the percentage 
of the fungi that entered the host, and the percentage belonging to each 
of the four classes for each lot of material are shown in the table. Each 
lot represents a given age of the fungus, and the different lots, fixed from 
two to eight days after placing the spores on the leaf, show the progress 
of the reaction. 
Table V. —Data comparing specializedforms III and XIX on Baart and Kanred common 
wheats and Mindum durum wheat, with reference to effecting entry and causing injury 
Fungi. 
Condition of guard 
stomata. 
cells of 
Host variety. 
Type 
of infec¬ 
tion. 
Month when 
grown. 
Days 
after 
inocu¬ 
lation. 
Num¬ 
ber 
count¬ 
ed. 
Per¬ 
cent¬ 
age 
enter¬ 
ing. 
Not 
injured. 
Partly 
killed. 
Dead. 
Dead 
and 
adjoin- 
a 
injured. 
FORM XIX. 
Baart. 
December.... 
4 
! 24 
7c 
l IOO 
O 
O 
O 
4 
.do....... 
8 
| 60 
30 
j 92 
8 
0 
O 
Kanred. 
0 
April. 
2 
1 
209 
II 
IOO 
0 
0 
0 
.do. 
4 
200 
18 
21 
37 
42 
O 
.do. 
6 
108 
14 
O 
O / 
29 
55 
16 
Mindum. 
7 
.do. 
4 1 
co 
78 
| 
18 
26 
44 
12 
O 
July. 
6 ! 
41 
30 
12 
49 
32 
7 
March. 
7 ; 
39 
23 
2 
14 
46 
38 
