ORDO II.
Decreased Irritation.
GENUS [IV].
With Decreased Actions of other Cavities and Membranes.
Many of the diseases of this genus are attended with pain, and with cold extremities, both which cease on the exhibition of wine or opium; which shews, that they originate from deficient action of the affected organ. These pains are called nervous or spasmodic, are not attended with fever, but are frequently succeeded by convulsions and madness; both which belong to the class of volition. Some of them return at periods, and when these can be ascertained, a much less quantity of opium will prevent them, than is necessary to cure them, when they are begun; as the vessels are then torpid and inirritable from the want of sensorial power, till by their inaction it becomes again accumulated.
Our organs of sense properly so called are not liable to pain from the absence of their appropriated stimuli, as from darkness or silence; but the other senses, which may be more properly called appetites, as those by which we perceive heat, hunger, thirst, lust, want of fresh air, are affected with pain from the defect or absence of their accustomed stimuli, as well as with pleasure by the possession of them; it is probable that some of our glands, whose sense or appetite requires or receives something from the circulating blood, as the pancreas, liver, testes, prostate gland, may be affected with aching or pain, when they cannot acquire their appropriated fluid.
Wherever this defect of stimulus occurs, a torpor or inaction of the organ ensues, as in the capillaries of the skin, when exposed to cold; and in the glands, which secrete the gastric juice, when we are hungry. This torpor however, and concomitant pain, which is at first owing to defect of stimulus, is afterwards induced by other associations or catenations, and constitutes the beginning of ague fits.
It must be further observed, that in the diseases of pain without fever, the pain is frequently not felt in the part where the cause of the disease resides; but is induced by sympathy with a distant part, whose irritability or sensibility is greater or less than its own. Thus a stone at the neck of the bladder, if its stimulus is not very great, only induces the pain of strangury at the glans penis. If its stimulus be greater, it then induces pain at the neck of the bladder. The concretions of bile, which are protruded into the neck of the gall-bladder, when the disease is not very great, produce pain at the other extremity of the bile-duct, which enters the duodenum immediately under the pit of the stomach; but, when the disease is great from the largeness of the bile-stone, the pain is felt in the region of the liver at the neck of the gall-bladder.
It appears from hence, that the pains enumerated in this genus are consequences of the inactivity of the organ; and, as they do not occasion other diseases, should be classed according to their proximate cause, which is defective irritation; there are nevertheless other pains from defect of stimulus, which produce convulsions, and belong to Class [III. 1. 1].; and others, which produce pains of some distant part by association, and belong to Class [IV. 2. 2].