Journal of Agricultural Research 
Vol. XXI, No, a 
118 
The amount of injury to samples of hand-thrashed Early Baart wheat 
caused by long exposures to copper-sulphate solutions varies directly as 
the concentration of the solution—that is, the stronger the copper sul¬ 
phate the greater the percentage of injured seeds. Individual seeds vary 
in their resistance to penetration, some succumbing before others, so 
there is a gradual increase in germination with increased dilution of the 
solution. The data in Table XI illustrate this. 
Table: XI. —Relation of strength of copper-sulphate solution to seed injury after an 
8 -hour exposure as indicated by germination and seedling growth of Early Baart wheat 
Strength of solution. 
Germina¬ 
tion. 
Height of 
plumule. 
Saturated. 
Per cent. 
30 
55 
90 
85 
100 
100 
Cm. 
5 - 5 
6 - 5 
10. 0 
10. 0 
10. 0 
10. 0 
1 pound to 1 gallon. 
1 pound to 4 gallons. 
1 pound to 10 gallons. 
1 pound to 80 gallons. 
Control, untreated. 
The great variations in the length of time seeds from the same sample 
of wheat could be soaked in copper-sulphate solutions without injury 
have been very perplexing throughout our experiments. The preceding 
data bring out the fact that although, as a rule, penetration of the poison 
is first noticeable after about 6 hours and not decided until after 8 
hours, occasionally almost no germination was obtained after 6 hours, 
and injury appeared even sooner. In some experiments, no germination 
was obtained after 24 hours’ exposure, while in others there was only 
about 50 per cent. It was thought possible that these variations might 
be due, at least in part, to differences in temperature. Consequently, 
some experiments were planned to show the relation of temperature 
of the solution to the length of time hand-thrashed Early Baart wheat 
could remain in a saturated copper-sulphate solution without injury. 
Table XII gives the results of one of several experiments. 
Table XII. —The relation between temperature and the semipermeability of the seed 
coats of Early Baart wheat in a saturated copper-sulphate solution, as indicated by 
germination 
Germination when stored at — 
Length of exposure. 
9° C.. in 
refrig¬ 
erator. 
13.5° C., 
outride 
window 
ledge. 
17° C., in 
labora¬ 
tory. 
35° C.. in 
incu¬ 
bator. 
55°C..in 
incu¬ 
bator. 
2 hours.. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
95 
85 
95 
90 
85 
4 hours. 
90 
90 
85 
80 
65 
8 hours. 
95 
75 
80 
75 
55 
24 hours. 
70 
55 
35 
40 
30 
