It is only the ignorant who dare assert that experimentation on animals cannot be applied to man. There are of course differences which physiologists train themselves to perceive; for example, certain poisons are almost innocuous to some animals, and are very fatal to man. The alkaloid of belladonna, atropine, is a thousand times more toxic for a man than for a goat. It is difficult to kill a goat with morphia, whilst a drop of laudanum kills a new-born babe. Carbonic oxide is absolutely harmless for the invertebrata which have no blood. Crayfish and snails live with impunity in pure oxide of carbon. And I could cite a number of other facts which are described in detail in every treatise of physiology or pharmacology. But what does it matter to us if we know it?--and we can nearly always know it. There are functional differences between men and animals; and physiologists know these perfectly well by their training; but there are, above all things, much more striking resemblances. It would be, for instance, ridiculous to suppose that oxygen did not dissolve in our blood in about the same way in which it dissolves in the blood of a cat or a rabbit; that the pneumogastric nerve, which stops the heart of the cat and the rabbit, will not stop the heart of man; that the arterial pressure, which is 16 c.m. of mercury in the horse, the dog, and the cat, is 1 c.m. or 1.60 c.m. in man; that the transformation of albuminous matters into urea takes place differently in the dog and in man. On the contrary, everything goes to prove the general laws are the same, and that the physiology of man, whilst not rigorously identical in every respect with the physiology of the animal, is nevertheless sufficiently analogous to enable a _general physiology_ to comprise in its vast laws the functions of every living being, man, mammal, vertebrata, invertebrata, and even every living cell. CHAPTER VI MORALITY AND VIVISECTION If we took the assertions of anti-vivisectionists literally, we should arrive at the strange conclusion, that the victims of vivisection are immensely numerous, and that vivisection is one of the calamities of the century. As a matter of fact, the number of victims due to physiology is very low. Let us try to count them up. There are only about twenty laboratories in France where experiments on animals are made. Let us allow that there are twenty in England, twenty in Italy, forty in Germany, and fifty in other countries, making a total of 150 laboratories. If we suppose that a dog, a cat, and a rabbit are sacrificed every day in each of these laboratories, we should certainly exaggerate.