From what has been said, it is evident that all the phenomena, over which preside what are commonly called the tonic forces, viz. organic sensibility and insensible contractility, are completely independent of nervous action; and consequently that these properties would not, like those of animal life, require this action. Each kind of sensibility has its morbid phenomena over which it presides. Inflammations, suppurations, the formation of tumours, dropsies, sweating, hemorrhages, disorders of secretions, &c. &c. belong to the alterations of the organic sensibility, whilst every thing like spasm, convulsion, paralysis, trance, torpor, injury of the intellectual functions, &c. &c. every thing, in fact, which tends in diseases to destroy our relations with surrounding bodies, belongs to the alterations of animal sensibility or contractility, and implies a greater or less degree of disorder in the nervous system.
In general, the diseases that affect the functions of animal life are of a nature wholly different from those which destroy the harmony of organic life. They have not the same character, the same progress, and the same phenomena. Place on one side the injuries of the external senses, blindness, deafness, loss of taste, &c.; those of the internal senses, mania, epilepsy, apoplexy, catalepsy, &c.; those of the voluntary motions, &c.; on the other, fevers, hemorrhages, catarrhs, &c. and all the diseases that disturb digestion, circulation, respiration, secretion, exhalation, absorption, nutrition, &c.; we shall then see what an immense difference there is between them.
Physicians have used too vaguely the term nervous influence. If in medicine, as in physiology, we had accustomed ourselves to use those expressions only to which was attached a precise and definite meaning, this would have been employed much less frequently.
It appears that the nerves have some influence still unknown, in the production of animal heat. The following facts relate to this influence. 1st. In aneurism, the ligature of the nerve is often followed by a sensation of general torpor and coldness in the limb. 2d. Sometimes, in hemiplegia, the affected part is of a temperature below what is natural, though the pulse may be as strong in this side as the other. 3d. One of the characters of ataxic fevers, the principal seat of which is in the brain, is the remarkable irregularity in the temperature of the different parts of the body. 4th. Animals, with a strongly marked nervous system, as quadrupeds and birds, are those of all others, in whom the degree of natural heat is the highest. 5th. I knew a person that had had the cubital nerve divided by a piece of glass above the pisiform bone, and whose little and ring fingers of that hand uniformly remained colder than the rest. 6th. Often in luxations, the compression of the nerves by the heads of the bones, produces an analogous effect, &c. &c.