256 



4. The majority of investigators have found subcooling 

 innocuous. 5. AVlien subcooling is injurious, the impor- 

 tance of the time factor suggests tliat the mechanism of 

 action is the same as that of cold above zero. 6. In nature 

 the subcooled state represents probably a condition of 

 safetj^ against injury, though there are some arguments 

 in favor of the o])])osite view. 



7. The organisms Avhicli resist extreme cold belong to 

 three groups : a) some resist only in the dry state, b) some 

 with their full water content, c) of the latter, some sur- 

 vive only if si)ecial precautions of rapid cooling and re- 

 warming are taken. 8. In all these, the main cause of the 

 resistance seems to be the impossibility of freezing. The 

 formation of ice might be prevented by the bound state 

 of the water in the partially dried organisms, by capillary 

 forces, by a possible rapid exosmosis of water in the small 

 living forms or by a narrow range of freezing tempera- 

 tures. 



9. Studies on the resistance of living matter to extreme 

 cold indicate that: a) molecular rearrangements such 

 as take place in crystallization are lethal, while solidifi- 

 cation into the amorphous state is not; b) cold alone, that 

 is, a decrease in molecular motion, is innocuous ; c) water 

 plays an important role not only in the functional activity 

 of living matter but also in the structure of the living 

 units; d) life is probably conditioned by some special 

 structure which, at low temperatures, allows for a state 

 of latent life and at higher temperatures furnishes the 

 basic mechanism for vital activities; the destruction of 

 this structure would induce death. 



