Apr. is, 1921 
Susceptibility of Injured Seeds to Molds 
117 
Table X .—Germination of hand-thrashed seed wheat treated for various periods in 
cop per-sulphate solutions 
Experi¬ 
ment No. 
Variety. 
Strength of solution. 
Length of treatments and germina¬ 
tion obtained. 
Germina¬ 
tion of 
control. 
Little Club.. 
Saturated. 
\]/i hours, 100 per cent; 16 
hours, 40 per cent. 
2 hours, 93 per cent; 6 hours, 
86 per cent; 24 hours, 0. 
16 hours, 5 per cent. 
Per cent. 
IOO 
? , - T - - 
.do. 
.do. 
IOO 
“3 . 
.do. 
.....do. 
IOO 
O . 
A . 
Karly Baart. 
.do. 
6 hours, 100 per cent; 8 
hours, 92 per cent; 10 
hours, 82 per cent. 
6 hours, 80 per cent; 10 
hours, 70 per cent. 
6 hours, 96 per cent; 24 
hours, 52 per cent. 
2 hours, 95 per cent; 4 
hours, 85 per cent; 8 hours, 
80 per cent; 24 hours, 35 
per cent. 
pi hour, 75 per cent; 8 hours, 
35 per cent; 24 hours, 10 
per cent. 
6 hours, 8 per cent. 
IOO 
. . 
C. 
.do. 
.do. 
IOO 
J. 
6. 
.do. 
.do. 
96 
*7 . 
.do. 
.do. 
/. 
8. 
.do. 
.do. 
.do. 
.do. 
84 
96 
IOO 
04 
10. 
.do. 
1 pound to 4 gallons. 
.do. 
6 hours, 96 per cent; 24 
hours, 72 per cent. 
8 hours, 90 per cent. 
TT. 
.... do. 
12. 
La Espiga... 
Cedar. 
Saturated. 
6 hours, 5 per cent. 
12. 
.do. 
6 hours, 50 per cent. 
98 
The data here reported on wheat indicate either (1) that the seed coat 
is not perfectly semipermeable in copper-sulphate solutions but allows a 
slow diffusion of the salt into the seed, or (2) that the semipermeability 
of the seed coat is destroyed after a limited exposure, either by chemical 
injury from the poison, by stretching due to the absorption of water, 
or by some other means. Reichard (16) and Bokorny (r) found barley 
testas not so perfectly semipermeable as is reported by Brown (j, 4). 
Von Tubeuf (21) and Falke (7) both report penetration of copper sulphate 
through apparently sound testas of wheat. Shull (20) says that ultra- 
microscopic defects in the seed coats of Xanthium make quantitative 
data approximations only. 
Since 60-80 per cent of the seeds show no penetration after prolonged soaking in 
CuSo 4 and since they retain their vitality perfectly ... it seems reasonably certain 
that C11S04 does not penetrate a sound testa. 
He seems to regard membranes as semipermeable when they exclude 
substances for days, weeks, and months, and as permeable when the 
exclusion is merely a matter of hours. On this basis the testa of wheat 
is not semipermeable, or at least its semipermeability has very narrow 
timelimits. 
