In the rectum, in which the excrements have not a long canal, but only a simple opening to pass, this is furnished with a sphincter which is wanting in the urethra. This sphincter habitually closed must be dilated by the impulse communicated to the excrements. When they are in the rectum a short time and in small quantity, the sensible organic contractility is not brought into action with sufficient power to expel them; it requires the action of the neighbouring voluntary muscles. If this action is not determined by the influx from the brain, the excrements remain in the intestines; hence how, for some time, we retain them at will. But as they increase in quantity, and become more acrid by remaining and consequently more irritating, then the sensible organic contractility strongly brought into action, empties the intestine involuntarily. If the sphincter, which is voluntary, is paralyzed, there will be incontinence, because no resistance is opposed to the tendency of the rectum to contract, a tendency which though feeble as long as it is but partly filled, is however always real. From what we have said, it appears evidently that the bladder and rectum, though receiving cerebral nerves, are yet less influenced by the brain than it at first view appears, and that there is evidently between them and the voluntary muscles a very great difference. They are not mixt, as it is called; they approach the organic muscles infinitely nearer than the others; I doubt even whether if no accessory power acted with and compressed them, the mind could by the nerves which come from the sacral plexuses, make them contract at will. I have never seen an animal void his excrements when the abdomen was open. Let us conclude from all that has been thus far said, that the cerebral nerves which go to the organic muscles have upon them an influence which by no means resembles that of the cerebral nerves going to the muscles of animal life. I am ignorant moreover of the nature of this influence. All the organic muscles receive nerves from the ganglions, both the preceding ones which are also penetrated by the cerebral nerves, and the small intestines, and the cœcum, colour, &c. which are exclusively pervaded by them. Now by cutting, tying or irritating in any manner these nerves, by stimulating the ganglions from which they go, by destroying or burning them with a concentrated acid or alkali, the muscle remains in its natural state; its contractions are neither accelerated nor retarded. I have not been contented with ordinary agents in convincing myself of the deficiency of real action of the nerves upon the organic muscles; a fact, which all good physiologists have always admitted, notwithstanding the opinions hazarded by some physicians who apply the vague term of nervous influence to organs which are not susceptible of it.