Zoonomia; Or, the Laws of Organic Life, Vol. II

by Erasmus Darwin

There are nevertheless many modes by which these inverted motions of the stomach and œsophagus are induced, and which it is of consequence to distinguish from each other. The first is the mode above described, where an effort is made to dislodge something, which stimulates the stomach into disagreeable sensation; and which is returned by repeated exertions; as when a nauseous drug is taken into the mouth, or a bit of sand falls into the eye, or a drop of water into the wind-pipe. In this the peristaltic motions of the stomach are first stopped, and then reverted by painful sensation; and the abdominal muscles and diaphragm by repeated efforts become associated with them. Now as less sensorial power is expended on the retrograde actions of the stomach, and of the lymphatics, which open their mouths on its surface, than by their natural motions, an accumulation of sensorial power in the fibres of the stomach follows the exhibition of an emetic, and on that account an emetic will sometimes stop a spontaneous vomiting which was owing to sensorial deficiency. See Sect. XXXV. 1. 3. and Art. [V. 2. 1].

As bitters and metallic salts, exhibited in small doses, stimulate the stomach into greater action, as appears by their increasing the power of digestion, and yet become emetic, when given in larger doses; one might suspect, that they became emetic by inducing debility, and consequent retrograde actions of the stomach, by their previously exhausting the sensorial power by their great stimulus; which might be effected in a moment without producing pain, and in consequence without our perceiving it. But on the contrary, there does not in general appear on the exhibition of emetics to be any previous exhaustion of sensorial power; because there is evidently an accumulation of it during the sickness, as appears from the digestion being stronger afterwards; and from the increased action of the cellular and cutaneous absorbents during its operation. See Art. [V. 2. 1].

Another mode, by which vomiting is induced, is owing to debility or deficiency of sensorial power, from the previous exhaustion of it; as on the day after intoxication, or which occurs in people enfeebled with the gout, and in dropsy, and in some fevers with debility. In these, when the vomiting ceases, there is no appearance of accumulation of sensorial power, as the digestion still remains weak and imperfect.

Another mode by which sickness or vomiting is induced, is by defect of stimulus, as in great hunger; and in those, who have been habituated to spice and spirit with their meals, who are liable to be sick after taking food without these additional stimuli. Other means of inducing sickness by vertigo, or by nauseous ideas, will be mentioned below.

We shall only add, that the motions of the muscular fibres of the stomach are associated with those of the heart and arteries by direct sympathy, as appears by the weakness of the pulse during the exhibition of an emetic; and that the absorbents of the stomach are associated with the cellular and cutaneous absorbents by reverse sympathy, as is shewn by the great absorption of the mucus of the cells in anasarca during sickness; at the same time that the absorbents of the stomach invert their actions, and pour the mucus and water thus absorbed into that viscus.

In cold paroxysms of fever the stomach partakes of the general torpor, and vomiting is induced by its debility, either by its association with the torpid capillaries, or other torpid parts, or by its own torpor commencing first, and causing the cold fit. The disordered motions of the stomach frequently seem to be the cause or primary seat of fever, as where contagious miasmata are swallowed with the saliva, and where fever is produced by sea-sickness, which I once saw. Nevertheless a disorder of the stomach does not always induce fever, as in that case it should constantly attend indigestion, and vertigo, and sea-sickness; but is itself frequently induced by association with the disordered movements of other parts of the system, as when it arises from gravel in the ureter, or from a percussion on the head.

The connexion of the motions of the stomach with irritative ideas, or motions of the organs of sense, in vertigo, is shewn in Sect. XX. and thus it appears, that many circles of association are either directly or reversely associated, or catenated, with this viscus; which will much contribute to unfold some of the symptoms of fever.

K. Tertian Associations.

The third link of associate trains of motion is sometimes actuated by reverse sympathy, with the second link, and that by reverse sympathy with the first link; so that the first and third link may act by direct sympathy, and the intermediate one by reverse sympathy. Of this instances are given in the syngultus nephriticus, Class [IV. 1. 1. 7]. and [IV. 2. 1]. At other times the tertian or quartan links of associate motions are actuated by direct sympathy; and that sometimes forwards and sometimes backwards in respect to the usual order of those trains of associate motions, as in Class [IV. 1. 2. 1].