233 



6. Changes in the viscosity of protoplasm; 



7. Changes in the adsorptive properties of some pro- 

 topUisniic constituents; 



8. Solidification of protoplasmic fats; 



9. Precipitation of some of the components of the liv- 

 ing structure; 



10. Coagulation processes. 



Belehradek discusses the interrelationship between sev- 

 eral of these mechanisms. Many of them might be in- 

 volved at the same time in causing death. 



The observations concerning deJiydration as a result of 

 the action of cold without ice formation call for a few 

 notes and remarks. 



According to Molisch (1897), when Tradescantia hair 

 cells are exposed to cold for a long time the protoplast 

 separates in some places from the cell wall, indicating 

 that water has been extruded, 



Greeley (1901) described the same phenomenon in 

 Spirogijra filaments cooled from 20 "^ to +1° and kept at 

 that temperature for 3 hours. When the filaments were 

 cooled while immersed in olive oil he could see water 

 droplets exuding from the cells into the oil. 



Klemm (1895) looked upon such a protoplasmic con- 

 traction as an initiation of a disorganization which grad- 

 ually will result in death. 



Chambers and Hale (1932), however, noted that main- 

 taining onion epidermis at - 10 in the unfrozen condi- 

 tion for several hours does not induce plasmolysis. The 

 apparent contradiction between this last observation and 

 those previously recorded might be due to the fact that 

 plasmolysis by cold is exhibited only by some types of 

 protoplasm and only under some particular conditions. 



Concerning the cause of dehydration, we wish to point 

 out that the rounding up of protoplasm in Tradescantia 

 hair, such as occurs under the action of cold, can also be 

 produced by various forms of more or less violent stim- 



