HEAT AND LIFE. 415 



enco of cold. Its action on the nervous centres, however, is only- 

 secondary and consequent on another phenomenon, studied hy Pouchet, 

 which reveals this as the secret of death. "When the temperature of 

 the interior of the body sinks to 10 or 12 below zero (cent.) the cold 

 freezes the blood more or less, thoroughly disorganizing its globules, 

 and it is this alteration which, either at once or when the blood becomes 

 fluid again, destroys all the vital functions. Larrey relates the case of 

 Sureau, chief apothecary of the French army in Russia, who, when chilled 

 to freezing by a painful march in the snow, did not die until the moment 

 they began to restore warmth. Experiments on animals show that 

 they keep themselves alive as long as they are maintained in a state 

 of half congelation, and die whenever their temperature and circula- 

 tion are so far restored as to permit the blood-globules, disorganized 

 by cold, to be diffused throughout the vessels. Death occurs, there- 

 fore, whenever the quantity of these globules is sufficient to produce a 

 considerable disturbance in the system, that is, whenever the frozen 

 part is at all extensive. An animal entirely frozen, and consequently 

 containing in its congealed blood no globules but those unfit for life, 

 is dead, without possibility of resurrection. Thawing it only restores 

 a soft flaccid, discolored body, with opaque eyes. If freezing only 

 attacks a limb, it becomes gangrenous, and is destroyed. Pouchet 

 deduced from these examinations a judicious, practical conclusion. 

 If it is true that, in cases of partial freezing, the death of the individual 

 is due to the disorganized globules reentering the circulation and cor- 

 rupting the blood, it is plain that, the more sudden the invasion of 

 these globules is, the more rapidly death will supervene. It follows, 

 that, by resisting this invasion, by means of ligatures, or extremely 

 slow thawing, we might succeed in preventing the poisoning. The 

 diseased globules which, pouring in a flood into the heart and lungs, 

 would imperil life by the sudden alteration of the blood, will apparently 

 disturb it merely in an unimportant way, if they are dropped into the 

 blood by slow degrees. 



Thus the late researches of experimental physiology explain for us 

 the effects of heat and cold, regarded as toxic agents. The former is a 

 poison of the muscular fibre, the latter a poison of the blood-globules. 

 The case is the same with heat as with the other elements of the 

 cosmic medium, in which the animated being lives. It enfolds the 

 most contradictory powers, like the tender flower, spoken of by Friar 

 Lawrence, in " Romeo and Juliet," from which may be distilled both 

 safety and danger. It can by turns support health, heal disease, or 

 inflict death. 



Man is, then, the weak plaything of all those silent forces that sur- 

 round and press upon him. In vain he enslaves them ; he cannot 

 escape the inflexible laws that subject the equilibrium of life to that of 

 the lowest physico-chemical conditions. lie has at least the consola- 

 tion of knowing these laws, and guiding his existence so as to soften 



