It is also to the different changes of these properties, that must be referred the more or less copious sweats and the various exudations of which the skin is the seat. In fact, the exhalant vessels remain always the same in relation to their structure. Why then do they admit a greater or less quantity of fluids? Why at certain times do they allow of the passage of substances, which they repel at others? It is because the modifications of their organic forces are changed. These forces are often weakened in an evident manner in diseases; they become languid and are prostrated. Then blisters are applied in vain; the organic sensibility no longer answers to the excitement that is made upon it. This is a striking phenomenon in ataxic fevers, and proves the independence of the phenomena of cutaneous exhalation, capillary circulation, &c. in regard to the cerebral nerves. In fact, whilst during the paroxysm the brain is in extreme excitement, the voluntary muscles are put by this excitement into a violent state of convulsion, and the energy of the whole of the animal life seems to be doubled before it ceases to exist, the organic is already in part exhausted; the functions of the portion of the skin which belongs to this life have already ceased. The stimuli of cutaneous organic sensibility vary remarkably in their degree of intensity. 1st. The strongest are fire, cantharides, the alkalies, the acids sufficiently diluted by water not to act but upon the vital forces and not to alter the dermoid texture by the horny hardening, the juices of many acrid and corrosive plants, certain fluids even produced in the economy, as those of cancers, &c. All these stimuli redden the skin when they are applied to it. 2d. Most of the same stimuli, diminished in intensity, stimulate it but slightly. 3d. Finally, aqueous fluids, cataplasms and emollient fomentations seem to produce this excitement the least; they even rather weaken the cutaneous organic sensibility; they seem to act upon it like sedatives and moderate the kind of excitement it produces in inflammations. The same is true of most of the fatty substances; thus oils, butter, grease, &c. are in general not calculated to keep up the suppuration of blisters. It is requisite, in order to keep the skin at the degree of organic sensibility, necessary for the purulent exudation that then takes place, to mix cantharides with fatty substances.