Journal of Argicultural Research 
Vol. XXI, No. t 
114 
Table VIII. — Relation of seed-coat condition to paraformaldehyde injury, as indicated 
by germination 
Length of exposure to paraformaldehyde. 
Percentage of germination. 
Little Club. 
Early 
Baart, 
hand- 
thrashed. 
Hand- 
thrashed. 
Harvester- 
thrashed. 
1 day. 
IOO 
90 
70 
0 
50 
50 
0 
O 
IOO 
80 
30 
0 
2 days. 
6 days... 
14 days. 
In conclusion, mechanical injury to the seed in thrashing governs 
seed injury to wheat resulting from treatment with copper sulphate 
and from saprophytic fungi, in storage and in the soil. It has been 
shown (1) that perfect seed coats are an.absolute protection in ordinary 
exposures to copper sulphate of any strength, (2) that they are partial 
protection against injury which results when formaldehyde-treated seeds 
are dried, and (3) that they afford marked protection against sapro¬ 
phytic fungi in storage and in the soil. Better thrashing methods are 
the obvious remedy for the losses caused by seed treatment for smut 
and by molding of damp grain in storage or in cold, damp soil. 
SEMIPERMEABILITY OF BARLEY SEED COATS IN COPPER-SULPHATE 
SOLUTIONS 
It is often stated in agricultural bulletins, and farmers commonly 
believe, that barley is more sensitive to fungicides, notably copper sul¬ 
phate, than is wheat. But if, as Brown (j, 4) found, the seed coats 
are impermeable to copper sulphate, this should not be true. Experi¬ 
ments were undertaken, therefore, to determine whether there is any 
basis for this prevailing belief in the greater susceptibility of barley. 
The first variety experimented upon was Turkestan barley, of which 
there happened to be a supply of unthrashed seed in good condition in 
the laboratory. The hand-thrashed seed was soaked in a saturated 
solution of copper sulphate for 6, 8, and 10 hour intervals, as had been 
done with wheat (see Table V). To our great surprise, all were killed, 
not a single seed showing any sign of germination, although in later 
experiments occasional exceptions to this were found (Table IX). It 
had been noticed that barley, unlike wheat, had a more or less ragged 
hole on each kernel where it was broken from the rachis. It ap¬ 
peared that when barley was thrashed, even by hand, every seed coat 
was weakened or injured at this point. It was assumed from this fact 
that the kernels left attached to a piece of the rachis would be as imper¬ 
meable to copper sulphate as is wheat. Experiments proved this sup- 
