24 Nebraska Agricultural Exp. Station Research Bul. 16 
plasm beyond the critical water content. Maximow (1908) 
agrees with Miiller-Thurgau and Molisch in that the withdrawal 
of water during the freezing process is the killing factor. He 
concludes, however, that the withdrawal of water is limited to 
the plasma membrane, and that this membrane is the part of the 
cell which is injured and that as long as a film of water can 
be kept in contact with this membrane no injury takes place. 
Matruchot and Molliard (1901) also believed that water was 
drawn from the protoplasm and nuclear material of the cell in 
the process of freezing and that this continued until they con- 
tained less than the minimum required to maintain vitality. 
Protoplasm, in order to retain its vitality, according to Ewarts 
(1897). requires from 2 to 3 per cent of water. Adams (1905) 
contends that if these theories be true the same argument should 
hold for dry seeds which contain about 12 per cent of water. 
But dry seeds are not killed by freezing. Hence some other 
explanation must be found. 
PHYSICAL AND CHEMICAL DISORGANIZATION OF THE PROTOPLASM 
AND OTHER CELL CONTENTS 
Many who have sought to determine the cause of death by 
freezing have concluded that freezing produces certain physical 
and chemical changes in the protoplasm and other cell contents, 
and that these changes result in death of the living matter. In 
harmony with this view, Detmer (1893) states, “In consequence 
of the disorganization of the protoplasm the cellular fluids leave 
the plasma; at the same time the nature of the hyloplasmic 
layers undergoes a complete change and they are now pervious 
to many substances which in a normal condition they did not 
permit to pass. This is the cause of the discoloration of frozen 
plants and of the phenomenon that pieces of frozen red beet, 
if put into water, readily part with coloring matter and sugar, 
while the living cells tenaciously retain these substances.” 
Becquerel (1905), in studying the action of liquid air on the 
life of seeds, found that if sufficient moisture was present in the 
tissues the cold disorganized the protoplasm and nucleus, mak- 
ing germination impossible. Galloway (1895) also contributed 
to this same idea, for he concluded that a freezing temperature 
may be sufficiently low to cause a chemical disorganization of 
the living substance and that the part of the plant where this 
takes place dies. Gorke (1906) and Schaffnit (1912) both 
found that freezing precipitated certain proteids from the cell 
sap and that the ease with which these proteids are precipitated 
bears some relation to the hardiness of the plant. Precipitation 
of the proteids, therefore, according to their interpretations, is 
