Let us stop for a moment to consider these figures, which seem mere abstractions to those who have not reflected. At the present time, about 300,000 children per annum in France are attacked by diphtheria; that makes 4,500,000 from 1892 to 1907. The proportion of 30 per cent. is therefore 1,350,000. The number of children who have been saved in France alone by serotherapy in fifteen years is therefore 1,350,000. Let us put it in round numbers at one million only; this would be sufficient to justify the death of the twenty-five dogs and the one hundred rabbits which I sacrificed, and of the two hundred horses which Behring and Roux used for the preparation of the anti-diphtheria serum. A million families in mourning, a million hopes mowed down in the bud! Only fanatics would dare to say this weighs for nought in the balance. Moreover--and why should I not say it aloud?--this so-called humanity of anti-vivisectionists seems to me the antithesis of humanity. To satisfy a conception which they have forged out of a certain hazy ideal, they make quick shrift of human life and suffering. A hundred weeping mothers, a hundred unfortunate children with gaping throats, suffocating, gasping, the death-rattle at hand--that is what these sensitive souls declare is nothing beside one rabbit which has had to receive a little blood of a dog into its abdomen! These philanthropists are creatures of a fixed idea! Let humanity suffer, weep and die! What does that matter, provided that their fixed idea, driven right up to the hilt of delirium, triumphs! After all, if they persist in believing that the faint and uncertain suffering of a sick rabbit is not worth the certain and excruciating suffering of a thousand human creatures, I can say but one thing: I pity them from the very bottom of my heart. * * * * * These examples--antisepsis, tuberculosis, and serotherapy--will suffice perhaps to justify experimental pathology. There is now another experimental science which I am going to try to justify also. This is _Therapeutics_.