If one scratches the skin of a dog with a poisoned arrow, like those used in war by certain savage tribes of America, the animal succumbs in less than a quarter of an hour. This terrible poison, called _curari_, destroys the motor nerves, but produces no change in the intelligence, and the functions of the sensory nerves. The dog scarcely notices the slight puncture on the skin and continues to walk about the room; but in a short time the hind-legs become stiff, one can see that they no longer obey the will; the posterior part of the body sways and falls. The animal rises and stumbles; then the fore-legs fail and the dog stands still. If we call him, or pat him, he responds with movements of the head, the ears, the eyes, and by wagging his tail. Soon however he cannot lift his head and lies stretched out, breathing quietly, as though reposing at his ease. On being called, he moves his eyes and feebly wags his tail, without any manifestation of pain. At last the respiratory muscles cease to act and life ebbs out without a single convulsive movement, and for a few moments sensibility and intelligence are still distinguishable in the fixed and glassy eye. It is like a corpse that perceives and understands everything going on around it, without being able to move, retaining sentiment and will but having no means of manifesting them. II In an investigation which I made with Professor E. Guareschi[5] into the effect of cadaveric venom, we found that all substances which slowly destroy the organism must produce phenomena analogous to those of curari, since the motor nerves, according to our researches, have less vitality than the sensory. [5] 'Les Ptomaïnes.’ _Archives italiennes de Biologie_, ii. p. 367; iii. p. 241. In order to be convinced of this fact, it suffices to take a rabbit and stop the circulation in its hind-legs. Placed on the ground, after a few seconds the animal cannot move its hind-legs, but if one presses them it squeaks and tries to escape with the aid of its fore-legs, dragging after it the hinder part of its body, which remains paralysed for a few moments. A sudden anæmia can therefore destroy motility but leave sensibility uninjured. When life is slowly ebbing, when the circulation gradually slackens and the death-agony is prolonged, I believe that there is always a point of time in which, with the exception of the respiratory and cardiac muscles, all others are already paralysed, in which all is dead but the sensory nerves. The hand, which with a last effort has been laid in blessing on our head, has sunk back on the coverlet never to be raised again, never to move the fingers which still feel the pressure of the farewell clasp; but the fixed eye still sees the shadows of the loved ones bending down to press tearful kisses on the brow, and when the last breath has fled, the mother still hears the despairing cry of her children and can no longer respond even by a look. III