Page:Popular Science Monthly Volume 2.djvu/431

Rh of cold. Its action on the nervous centres, however, is only secondary and consequent on another phenomenon, studied by 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 circulation are so far restored as to permit the blood-globules, disorganized by cold, to be diffused throughout the vessels. Death occurs, therefore, 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 corrupting 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 surround 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. He has at least the consolation of knowing these laws, and guiding his existence so as to soften