PART I 



THE LOWER LIMIT OF VITAL 

 TEMPERATURES 



INTRODUCTION 

 DEFINITIONS AND PRELIMINARY REMARKS 



111 a study of the mechanism of cellular or of proto- 

 plasmic death by low temperatures, one needs to know, 

 first of all, at what low temperatures life is destroyed. 

 The following pages present a review of the literature on 

 this subject. 



According to the effects that they produce on living 

 matter, the temperatures are classified into rital, lethal, 

 survival and auahiotic. If the same effects are obtained 

 over a range of temperatures, there must be distinguished 

 a maximum and a minimum in each range; thus there 

 would be a maximal and a minimal lethal, a maximal and 

 a minimal survival temperature, and so on. The multiple 

 aspects originating from so many distinctions on one 

 hand, and the overlapping of the ranges on the other, have 

 resulted in some confusion. But more important mis- 

 understanding has arisen from the widely different senses 

 in which the various authors use the terms just mentioned, 

 and from the impossibility of defining clearly a death 

 temperature, in the present state of our knowledge of the 

 cause of death by cold. This will be illustrated by the 

 following analysis of the notion of lethal temperatures. 



The death point has sometimes been considered as a 

 definite temperature at which an organism passes from 

 the living to the dead state in somewhat the same manner 

 as, at the freezing point, a substance passes from the 

 liquid to the solid state. So understood, the death tem- 

 perature would be specific for each organism in the same 

 sense as the physical constants are specific for each sub- 



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