within live minutes, and the cat not only continued to breathe, in profoundest sleep, for forty-five minutes, but would have been recoverable by simple removal from the vapor into fresh air if it had been removed while yet one act of breathing continued. This, however, was exceptional, because the cat in the same lethal atmosphere as the dog does not, as a rule, live more than thrice as long; i. e., if the dog ceases to breathe in four minutes, the cat will cease in from ten to twelve minutes after falling asleep.
The character of the vapor used does not make any difference, relatively. Carbonic oxide, carbonic acid, chloroform-vapor, carbon bisulphide vapor, yield the same relative results. Pure carbonic oxide kills with intense rapidity, but it kills the cat less quickly than the dog. If instead of a lethal vapor prussic acid be used, in administration by the mouth, the cat dies more slowly than the dog. The same is true in respect to death by drowning.
Still more curiously, recovery from apparent death is much more frequent in the cat than in other domestic animals. Mr. Warrington once observed a cat recover from apparent absolute death by prussic acid, eight hours after it had lain as if dead. I once saw a young cat come back to life after two hours of immersion under cold water.
I do not know many facts bearing on tenacity of life in other animals, but I have observed that sheep in a lethal atmosphere die very rapidly, goats much less rapidly, and pigeons more rapidly than common fowls. There is, apparently, a specific tenacity in all species.
In animals of the same species there are distinctions determinable by peculiarities in the animal itself. In one instance where a large number of dogs were put to sleep in the lethal chamber, one was found in deepest sleep, but still breathing, side by side and partly covered by another that was not only dead but cold and rigid. A similar fact occurred last year in the human subject in a mine. A father and son killed by fire-damp lay together, the father dead, the son living, though he, the son, had come first under the influence of the lethal gas. In all the fatal accidents to the human subject from the administration of chloroform or other narcotic vapor we see the same illustration. I doubt whether in any one of these unhappy events the death has been induced by what would be, under the common run of administrations, a fatal dose. But some die from a dose that would not so much as narcotize others. An analogous series of facts is met with in relation to the effects of physical and mental shocks and to surgical operations.
The variation of measure of tenacity of life is unquestionable. What is the reason of it? What is there in one species of animal that gives a measure of tenacity over another? Why, for instance, is the cat more tenacious of life than the dog?
The only answer as yet is, that the cat is endowed with more vitality. But this is no answer as to details. Is the endowment of the
