Apr. 15 , 1921 
Susceptibility of Injured Seeds to Molds 
115 
position correct. Heads were broken into fragments so that from one 
to three kernels were attached to each piece of the rachis. These were 
treated with saturated copper sulphate for 6 hours and for 10 hours. 
The resulting germination was 90 and 80 per cent, respectively. (The 
control germinated only 85 per cent.) None of the seedlings showed 
any abnormality. The kernels stripped from the rachis and treated in 
the same way were all killed (PI. 21, B). The experiment shows the 
semipermeability of unbroken Turkestan barley kernels in saturated 
copper sulphate and the destruction of this semipermeability by mechan¬ 
ical injury at the hilum caused by breaking the kernel from the rachis. 
Even more marked results were obtained upon treating some well- 
thrashed Coast barley with saturated copper-sulphate solution, the 
kernels being similar in structure to those of the Turkestan variety. 
Only 28 per cent germination was obtained after an exposure of one 
hour. Exposures of five minutes were found not to be injurious. Coast 
barley is the same subvariety (Hordeum vtdgare var. coerulescens) ( 11) 
as the one used by Brown (4) and which he found to be impermeable to 
copper sulphate after three days in a 5 per cent solution. Similar results 
were obtained with Turkestan barley and are shown in Table IX, together 
with the germination percentages of Early Baart wheat obtained after 
the same treatments. The comparison brings out the greater suscepti¬ 
bility of this hand-thrashed barley to copper-sulphate injury, compared 
with hand-thrashed wheat. 
Table IX .—Comparative germination of hard-thrashed barley and wheat after treatment 
with saturated copper-sulphate solutions 
Turkestan barley. 
Early Baart wheat. 
Length of exposure. 
Germina¬ 
tion. 
Height of 
plumule. 
Germina- 
tioft. 
Height of 
plumule. 
5 minutes. 
Per cent. 
IOO 
IOO 
60 
O 
Cm. 
12 
12 
7 
Per cent. 
Ton 
Cm. 
8 
8 
8 
1 hour. 
X uu 
IOO 
6 hours. 
96 
CO 
24 hours. ..... 
Control, untreated. 
IOO 
12 
96 
Z 
8 
If it is the nature of the abscission of the barley kernel from the rachis 
which determines its resistance to copper-sulphate injury, it follows that 
those varieties which shatter easily in the field and in which a smoother, 
more natural break occurs between kernel and rachis should show more 
perfect semipermeability. The Nepal variety (White Hull-less) seemed 
to be of this type. On treating, however, our samples showed even 
greater injury than that sustained by the nonshattering Coast barley. It 
is to be regretted that lack of sufficient hand-thrashed material of these 
29669°—21 - 2 
