I am aware that as to this experiment, it may be asserted that the ligature of the artery, of itself, is capable of paralyzing the limb. In fact, such circumstance has happened twice with me, but I have also had occasion to observe, that it does not necessarily follow the ligature of this vessel, as it does the ligature of the aorta: when the latter vessel is tied, all movements cease at once; notwithstanding all which, the result of the injection of black blood, is almost constantly that which I have asserted it to be;--I say almost, 1st, Because I have once seen it fail in its effect, though done with the requisite precautions; 2dly, Because the debility, which is induced, both in duration and degree, will be according to the strength of the animal on which the experiment is made. There is also occasioned in this experiment, a manifest suspension of the sensibility of the animal; it is not indeed so ready to appear as the loss of motion; but it always comes on, especially if the injection of the black blood be repeated three or four times, with small intervals. A similar, but a more tardy effect may be produced by adapting to the canula, which has been placed in the crural artery of an animal, a tube which has been previously fixed to the carotid of another animal, and then by asphyxiating the latter.[96] The organs of the internal life are not dependent on the brain, and therefore are not affected by the suspension of the cerebral action in asphyxia. It is the influx of the black blood which is the immediate cause of their death. I have already demonstrated what the influence is of this blood upon the organs of the circulation. We have seen how the heart ceases to act, as soon as it is penetrated by it; it is owing in part to the injection of the arterial and venous parietes themselves, by the vasa vasorum, that the vessels are forced to suspend their actions. It will be always a difficult thing to prove, that the secretions, the exhalations, and the process of nutrition, could not be made from venous blood, because the circulation of this sort of blood in the arteries, does not continue for a sufficient time, to allow of observations, or the manner in which these functions would be affected by it. On this subject, however, I have made some essays. 1st, I exposed the inner surface of the bladder of a living animal, after having previously divided the symphysis pubis, and opened the lower belly, I then examined the oozing of the urine from the orifices of the ureters, while I asphyxiated the animal. 2dly, I divided the vas deferens, with the view of observing, whether the semen would flow or not, during such state.