“Poisons, (says Dr. Girtanner) remedies, and, in general, all surrounding bodies, acting only on the irritable fibre, it follows that they act upon the system in a similar manner, and that every substance capable of producing the greatest possible effect upon the fibre, that is to say, every substance capable of exhausting all the irritability both of the fibre itself and of the system, in an instant, as for instance, laurel water, or white arsenic, is also capable of producing all the inferior degrees of action, either by acting on a fibre less irritable, or by acting upon the same fibre, but in a less quantity. Laurel water, opium, white arsenic, ammoniac, are of course both medicines and poisons capable of _healing_, as well as of _producing_, _all maladies whatsoever, without exception_.[93] And this is confirmed by a number of experiments which I have made upon different animals. This _truth_ seems to me _of the utmost importance_; and the Abbe Fontana, who made more than six hundred experiments to prove that ammoniac is no remedy against the bite of a viper, would have saved himself the trouble, had he known it. If, instead of applying the venom of the viper to so many animals, and afterwards applying ammoniac to the wound, he had made a single comparative experiment, and applied ammoniac to a wound made by a lancet that was not poisoned, he would have found that ammoniac itself, applied in this manner, would have produced a disease exactly analogous to that caused by the venom of the viper; and, consequently, so far from removing the malady, must necessarily increase it, by exhausting the irritability of the fibre in a much less time than the venom of the viper by itself was capable of doing. Mr. Fontana has made more than six thousand experiments upon the poison of the viper; he employed more than three thousand vipers, and caused to be bit more than four thousand animals; and the conclusion he drew after this truly enormous number of observations was, that the poison of the viper kills all animals, and produces the disease by its action on the blood. But why did Mr. Fontana neglect to make the decisive experiment, the _experimentum crucis_ of Bacon? It is well known that frogs, and many animals with cold blood, live a long time without the heart, and entirely deprived of blood. If therefore the poison of the viper kills animals by its action on the blood, it will not destroy frogs without blood. But experiment contradicts this reasoning. The poison of the viper will kill frogs without blood in as short a time as it kills those animals who have not lost their blood. It is not therefore by its action upon the blood that the venom of the viper destroys animals; and thus does it happen that a single experiment frequently overturns all that _six thousand_ other experiments have apparently established. According to my experiments, poisons operate upon the blood just as they do upon the muscular fibre,