In order to estimate correctly the sensible organic contractility, it is necessary to destroy the animal contractility. So long as these two clash, interrupt and counterbalance each other, we cannot properly estimate them, and determine what belongs to each and what is common to both. Now we destroy animal contractility in the living subject, by cutting all the nerves of a muscle or an extremity, which then become paralyzed. The brain can no longer act upon them, and the results we obtain from stimuli, belong to the sensible organic contractility. The duration of this last property, after the experiment I mentioned, proves completely that the nerves are wholly foreign to it, that it resides essentially in the muscular texture, that it is, as Haller said, inherent in it. Thus whilst in the different paralyses the muscles lose the power of obeying the cerebral influence, or rather this influence becomes nothing, they preserve that of contracting in an evident manner when stimulated. This contraction of the muscles of animal life by stimulants, appears under two very different modes. 1st. The whole of the muscle can contract and shorten so as to approximate the two points of insertion. This happens in general when death is recent, when the muscle is still fully possessed of life. 2d. There are oftentimes numerous oscillations of the fibres; all are in action at the same time; now this action is not a contraction, but a real vibration, a fluttering, which has not a sensible effect upon the whole of the muscle, which not contracting cannot approximate its moveable points. When life is about abandoning entirely the muscle, it is thus that it moves. The diversity of the stimuli occasions also this double mode of contraction. Carry a scalpel over a living muscle, a contraction of the whole will be the consequence; afterwards sprinkle the same muscle with a neutral salt, sometimes there is an analogous contraction; but frequently there are only oscillations, vibrations similar to those of a muscle which life abandons. During the life of the animal, its sensible organic contractility is rarely in action, because the muscles have not agents that act upon them in a sensible manner at least. Why then is this property so developed in them? I cannot determine.