Freezing Injury of Seed Corn 
81 
are obtained. Where less mature corn has been subjected to 
severe freezing, as high as 10 or 15 per cent may germinate 
imperfectly. Such seed may have either the plumule or the 
primary root killed, while the other end of the sprout may 
develop normally. If the plumule has been killed a viable 
root can never grow a new plumule. But if the primary root 
only is dead, the secondary roots may, under favorable ger- 
mination conditions, develop at the base of the plumule and a 
normal plant result. Such imperfect sprouts may be seen in 
Figure 20. 
Germination tests are often reported as so many strong, 
weak, or dead kernels. It would probably be quite as well to 
report perfect and imperfect germination and dead kernels. 
Since proper development of imperfect germs is doubtful, a 
classification into perfect and dead seed should suffice. Perfect 
kernels reported as weak are often relatively backward merely 
because of inherent slower germination or because of ununi- 
form, unfavorable germinating conditions which act as sources 
of experimental error in testing. 
