Apr. 15, 192 
Susceptibility of Injured Seeds to Molds 
H 3 
with the germination obtained after treating them with 1 to 4 copper- 
sulphate solution (Table VII, PI. 21, A). 
Table VII .—Data showing relation of broken seed coats to injury from a 5-minute dip in 
I pound to 4 gallons copper-sulphate solution , as indicated by germination 
Nature of sample. 
Slightly 
broken 
seed coats. 
Badly 
broken 
seed coats. 
Germina¬ 
tion after 
treatment. 
t PI 11V1 h arvester-thrashed. 
Per cent. 
IO 
12 
O 
I 
0 
Per cent. 
30 
88 
0 
99 
0 
Per cent. 
84 
48 
IOO 
20 
ICO 
Do . 
t Pluh "hand-thrashed. 
Early Baart, harvester-thrashed and scoured for milling. 
TTnrlv Unnrt hand-thrashed. 
rVcil 1 y iJctcU l) iiaAivi • • • .. 
It is possible, therefore, by examining the wheat with a hand lens, to 
predict very closely the loss that will be caused by copper-sulphate treat¬ 
ment. If the seed is known to be infested with smut spores, as shown 
by the darkened brush or the presence of smut balls, it may become a 
problem as to which will do the greater damage, the copper sulphate or 
the smut. A way out of the difficulty may be found in the use of 1 to 
320 formaldehyde solution (1 pint commercial formaldehyde in 40 gal¬ 
lons). A dip of 10 minutes in this solution, or in a 1 to 160 solution, 
followed by a 10-minute drain, does not injure the embryo, no matter 
how extreme the mechanical injury to the seed coat. A 1 to 80 solution, 
however, causes extreme injury when the seed coat is broken over the 
embryo, and only when it is so broken, but this strength never is rec¬ 
ommended. It should be noted in explanation of these statements of 
the inability of the 1 to'320 and 1 to 160 strengths to injure even broken 
wheat that the so-called formaldehyde injury occasionally reported after 
the use of these strengths is caused by the formation of paraformaldehyde 
during the drying of the seed. If the seed is not dried but is sown moist 
in damp soil or kept in damp storage, no injury results from the treat¬ 
ment. Paraformaldehyde is very unstable and is constantly breaking 
down into formaldehyde gas. Thus the seed, unless well spread, is sur¬ 
rounded by this toxic vapor which penetrates the seed coat, probably by 
again going into solution in the presence of any moisture in the seed 
covering. 
Seed-coat condition is important, therefore, in connection with this 
formaldehyde injury after the drying of treated seeds. The data pre¬ 
sented in Table VIII show that, although a perfect seed coat delays 
injury from paraformaldehyde, it does not prevent it. The paraformal¬ 
dehyde was obtained by evaporating some commercial formaldehyde 
and powdering the white residue in a mortar. The seeds were then 
placed in Syracuse watch crystals and covered with the perfectly dry 
powder, which was packed around them. 
