PART III 



THE MECHANISM OF INJURY AND DEATH RY 

 LOW TEMPERATURE 



Some confusion in the study of death arises from the 

 faihire to distinguish between organismal, systemic, cel- 

 lular and protoplasmic death. It is evident that a theory 

 which hokls that the death of a frog results from the de- 

 struction of the red cells in the frozen blood refers to 

 organismal death; a theory, according to which the leaves 

 of a tree die after a layer of ice has been formed at their 

 point of attachment and severed their connection with 

 the stem, considers systemic death ; a theory stating that 

 the death of a tissue results from a tearing of the cellu- 

 lar membranes by ice crystals is concerned with cellular 

 death ; finally, a theory which considers the fundamental 

 physico-chemical processes involved in the destruction of 

 living matter, such as the precipitation of colloids by con- 

 gelation, regards protoplasmic death. In this work we 

 are not concerned with organismal nor with systemic 

 death by cold, though occasionally reference will be made 

 to these; we are concerned primarily with protoplasmic 

 death. But the investigators, in general, do not distin- 

 guish between cellular and protoplasmic death, their 

 theories and their experiments concerning the two phe- 

 nomena are so intimately related that we shall treat these 

 two subjects together. 



There is some evidence that the mechanism of injury 

 and death b}^ cold is different when death is accompanied 

 by ice formation and when it is not. These two cases 

 will, therefore, be discussed in separate chapters, 



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