Freezing Injury of Seed Corn 
27 
liquid hydrogen. According to Muller-Thurgau (188.6), apples 
lost 63.8 per cent of their moisture when frozen at — 1.5 degrees 
C. : 36.2 per cent of the total water, therefore, remained in the 
cells. Kernels of corn which contain a large percentage of 
water will freeze at this temperature and die. If the moisture 
content of the cells of a kernel of corn were reduced to 30 or 
even 20 per cent at this temperature, the vitality should remain 
uninjured, so far as moisture is concerned. Dry seeds contain 
only 10 to 12 per cent of moisture, yet they retain their vitality, 
and a still further reduction in the moisture content can be 
made without injury. Ewarts (1897) shows that the fatal 
minimum moisture content of protoplasm is 2 or 3 per cent. ‘ 
The theory is, then, that as the cooling goes on, more and more 
water is withdrawn until less than this amount remains in the 
cell, and death results. This should also hold true for dry 
seed which contain 10 or 12 per cent of water, but these are not 
injured by such freezing. An example may also be taken from 
Table 9, where corn containing 20.5 per cent of moisture was 
entirely kilDd, while corn containing 16.3 per cent of moisture 
showed no injury. The freezing evidently did not reduce the 
moisture content in the former case more than 2 or 3 per cent, 
yet the vitality was destroyed. It does not seem probable that 
the removal of so small an amount of water would cause death. 
It seems more probable, however, that the small difference in 
moisture content was sufficient to permit disorganization of the 
protoplasm in the one case, while in the other it remained 
unaffected. 
The rate of thawing and its relation to killing was not 
studied. The results which have been obtained and reported by 
Muller-Thurgau (1886), Molisch (1897), and Chandler (1913) 
seem to indicate quite clearly that it has very little to do with 
the amount of killing. It can hardly be considered, therefore, 
as an important factor in bringing about the death of frozen 
tissues. 
EFFECTS OF FREEZING UPON THE VIABILITY OF SEED CORN 
Ordinary freezing temperatures do not injure mature, dry 
corn, but it is always the immature or damp corn that is injured 
by freezing. It was proposed, therefore, to determine at what 
temperature freezing and loss of vitality take place in corn at 
different stages of maturity as indicated by differences in 
moisture content. 
The effect of freezing upon the germinative qualities of 
seed corn has been tested experimentally under two sorts of 
