Feb. 16, 1924 
Flag Smut of Wheat 
461 
It was thought possible that small quantities of volatile oils were the 
effective constituents of the wheat-plant distillates. A series of rather 
empirical tests then were designed to test the action of a number of 
volatile oils on the germination of the spores of Urocystis tritici. 
The spores were sown on the surface of from 5 to 7 cc. of distilled water 
at from 18 0 to 22° C., as in the ordinary germination tests. A minute 
quantity of each substance was then applied on the point of a needle to 
each dish of spores. A film formed on the surface of each dish, although 
slightly different amounts of oil were added in each instance. 
The materials which stimulated germination of the spores are shown 
in Table II. Similar tests also were made with salicylaldehyde, butyric 
acid, acetone, benzol, oil of thyme, ethyl alcohol, methyl acetate, phenol, 
benzoic acid, lactic acid, acetic acid, and citric acid. After 24 hours at 
22 0 C., from 80 to 90 per cent of the spores treated with the first three 
substances had germinated. Less than 1 per cent of the spores treated 
with the other substances germinated. 
Several other essential oils, namely, oil of hemlock (bornyl acetate 30 
per cent), oil of lemon (d-limonene and citral), eucalyptus (cineol 50 per 
cent), and eugenol failed to stimulate germination. 
No spores germinated in the control dishes. It thus appeared that a 
large number of substances, in appropriate concentrations, might furnish 
the necessary stimulus for germination of spores of Urocystis tritici . 
It is obvious that under the conditions of the experiment (in which 
the Syracuse dishes are packed in the form of a nest, each dish forming a 
cover for the one immediately below it), the containers are not air-tight 
and there might be considerable volatilization of certain of the oils dur¬ 
ing the period in which the spores might be expected to germinate. 
TablF II .—The effect of surface films of volatile oils on the germination of spores of 
Urocystis tritici presoaked on surface of distilled water seven days at from 18 0 to 2 2° C. 
and oil applied on December 6 
Num¬ 
ber of 
dish. 
.Oil. 
Percentage of germination on— 
Dec. 7. 
Dec. 8. 
Dec. 9. 
26 
Balsam peru (cinnamein, 50—65 per cent). 
67 
29 
15 
Trace. 
28 
Oil of tansy (thuyl alcohol, 17 per cent). 
33 
Oil of cassia (cinnamic aldehyde, 75 per cent; 
trace lead and copper). 
34 
35 
Oil of verbena (citral, 50 per cent). 
Oil of bitter almonds (benzaldehyde, 85 per 
cent). 
9 1 
Trace. 
3 6 
37 
38 
39 
40 
41 
Oil of camphor (safrol, eugenol). 
Oil of bergamot. 
Trace. 
Oil of lavender. 
Trace. 
Oil of pine needles (30 per cent bornyl acetate). 
Control of distilled water. 
Trace. 
0 
0 
O 
.do. 
0 
0 
O 
A study was then made of solutions of certain of the above activating 
substances to determine the optimum concentrations. Certain of these 
organic substances are quite soluble in water but are highly volatile 
(e. g., acetone B. P. 56.48° C., alcohol 64°, ethyl acetate 77 0 ); others 
again are only slightly soluble, while still others are definitely soluble, 
even though only in slight amounts and less volatile. 
