BUNT, OR STINKING SMUT, OF WHEAT. 
13 
sterilized soil. In changing to infested soil the original soil was 
readily shaken out down to the seed without disturbing the roots by 
inverting the pot. These plantings, made on November 6, were later 
transplanted to infested soil at a depth of 2 inches. 
Pots 3, 5, 7, 9, 10, and 11 (see Table 11) were placed out of doors 
when transplanted and allowed to remain there until November 17. 
They were then kept in the greenhouse until November 20, when they 
were transplanted to open ground, after which no further growth 
took place until spring. Pots 1, 2, 4, 6, 8, and 12 remained continu- 
ously in the greenhouse until November 20. 
Table 11. — Relation of age and stage of development of seedlings of Hybrid 148 to 
susceptibility to bunt infection at Pullman, Wash., November, 1915. 
Depth 
of 
cover. 
Date of 
change 
to in- 
fested 
soil. 
Length of 
pltmule 
when trans- 
planted. 
Condition at the time 
of transfer. 
Plants. 
Pot. 
Height 
above soil 
Nov. 17. 
Num- T „,- . 
ber har-: In ^ ct " 
vested. j c(l - 
No. 1 
Inches. 
0.25 
Nov. 9 
Nov. 10 
Inches. 
0.125 to 0.250 
9.."in tn ;snn 
Coleoptile unbroken.. . 
Inches. 
2.00 to 4.00 
3 00 to 4 00 
' Per ct. 
46 91-8 
No. 2 
No. 3.... 
.25 
.50 
.50 
.75 
.75 
1.00 
1.00 
1.50 
1.50 
39 
57 
49 
57 
21 
37 
19 
31 
52 
42 
43 
10 3 
...do j .625 to .875 
...do ! .750 to 1.000 
Nov. 11 1 -125 to 1.375 
do 
do 
do 
.50 
3.00 to 4.00 
.50 
3.00 to 4.00 
.25 to .50 
3.00 to 4.50 
.50 to 1.00 
1.25 to 1.50 
.25 to .50 
4.00 to 5.00 
1.8 
No.4 
No. 5 
4.1 
1 7 
No. 6 
...do 
...do 
Nov. 12 
...do 
Nov. 13 
1.250 to 1.500 
1.500 to 1.(25 
2.000 to 2.250 
2.000 to 2.250 
2.250 to 3.000 
2.000 to 2.250 
3.000 to 3.500 
do 
do 
In leaf; coleoptile 
broken. 
Coleoptile unbroken.. . 
4.8 

No. 7 
No.S 
No.9 
No. 10 
No. 11 
No. 12 

3.2 
3.9 
2.00 Nov. 12 
2.00 Nov. 13 
Colpoutile unbroken. . . 
In 1 -at; coleoptil 
split at height of 2 
inches. 

23.3 
It is a noteworthy fact that infection seems to have been inhibited 
to a considerable degree by transferring the plant to conditions of 
lower temperature. No temperature records were kept; but the 
nights were frosty, and practically no growth took place in the out- 
door pots. The mean temperature could not have been higher than 
5° C. Growth conditions in the greenhouse were optimum. The 
only explanation that can be offered is that the process of bunt in- 
fection may involve the work of an enzym the action of which is in- 
hibited by temperatures not sufficiently low to prevent spore germi- 
nation and growth of the bunt organism as a saprophyte. 
It should be noted that, regardless of whether the primary leaf is 
free from or inclosed by the coleoptile, infection can and does occur. 
This fact is shown in Table 11. 
The second of these experiments was made in the open field dur- 
ing the period from May 10 to 12, thus making possible the uninter- 
rupted growth of the plants. Early Wilbur, the most bunt-suscepti- 
ble variety of spring wheat known to the writers, was used. The 
seed was hand-threshed, free from bunt, and treated 90 minutes in a 
1 to 240 solution of formaldehyde. In brief, the experiment involved 
the sowing of wheat at different depths, with a stratum of infested 
soil prepared as before described at definite levels above the seed. 
The plats were protected from rainfall and surface drying by boards 
until the seedlings were in leaf. The field soil was assumed to be 
