Note 103 — CHAP. I.

I have in the whole of this work been extremely cautious in reasoning concerning causes, from an opinion that they are very obscure, and that the theoretical part of physic is very imperfect and fallacious. This is perhaps in no instance more remarkable than in those opinions that prevail concerning the nature and influence of bile in producing diseases. An increased secretion of bile commonly attends the feverish complaints of hot climates, and those of the hot seasons of temperate and cold climates. It is not unnatural, therefore, to impute the disease then prevailing to this redundancy of bile: but, upon considering the matter more closely, it will appear to be rather a concomitant symptom, or effect, than a cause of those fevers; for, in the first place, in those cases in which there is the greatest secretion of bile, as in the cholera morbus, there is no fever. The only danger in this disease arises from the violent irritation produced in the bowels by such an extraordinary quantity of this secretion which commonly passes downwards; though I have seen it prove fatal when it flowed into the stomach, and produced perpetual retching and excoriation of the fauces; but in this case also without any fever. Secondly, in the most fatal of all fevers, in the West Indies, there are no marks of an increased secretion of bile, but, on the contrary, a preternatural defect of it, as appears by its not being evacuated either by stool or vomiting, by the white stools which sometimes attend the yellow fever, and by its not appearing in the first passages, nor in its own receptacles after death. Perhaps also that state of the bowels which renders it so difficult to procure stools may be in part owing to the want of this natural stimulus. It is nevertheless true, that in the intermitting and remitting fevers of hot climates and seasons there is perhaps always an accumulation of bile at the beginning, and an increased secretion of it during their course. It is farther true, that this adds to the patient’s uneasiness, and aggravates the symptoms, and that the cure consists partly in the evacuation of the bile. But it is also true, that in the very worst sort of fevers in hot climates it is a favourable symptom where the secretion of the liver is restored and increased, a bilious diarrhœa being one of the most auspicious symptoms that can occur in a yellow fever; and in those that are protracted and afford hopes of recovery, there is generally a gush of bile from time to time.—We may therefore lay down the following positions: 1. That in cases in which bile is most freely and copiously secreted no fever exists, as in cholera morbus. 2. That in the worst sort of fevers there is no preternatural secretion of bile, but, on the contrary, a defect of it. 3. That nevertheless there is an uncommon quantity of bile secreted in most of the fevers of hot climates, and that part of the cure consists in evacuating it.

I am extremely diffident, as I have said, in all matters depending on our supposed knowledge of the animal œconomy; but the preceding circumstances seem to countenance the following reasoning:—The bile, according to Dr. Maclurg, who has given one of the best dissertations on its nature and properties, is composed of two parts; the gross part, which is coagulable by acids, and that part in which the bitter principle resides. The first constitutes the principal part in point of quantity, and seems to be that portion of the mass of fluids which loses the property of sound healthy blood, by a tendency to putrefaction, and is thrown out by this secretion. I will not undertake to vouch for the truth of this, but shall assume it as true in the following reasoning:—According to this theory, therefore, the greater part of the bile is what may be called the effete part of the circulating mass, or perhaps only of the red globules or gluten, the watery and saline part, which passes off by urine being the corrupted part of the serum. This part of the bile being very liable to putrefaction, the bitter part is considered by Dr. Maclurg as intended to correct this, and also to answer some good purpose in digestion. One of the effects of the bile in this operation is to extinguish acidity, whether proceeding from substances taken in, or generated in the stomach. The blood in all climates, and in all situations of life, is subject to have part of it thus corrupted, which, being separated from the common mass by the liver, is mingled and discharged with the common feces; but external heat continued for any length of time tends to augment this corruption of the fluids, and therefore to increase the secretion of bile; and it has been observed both by myself and others, that the bile found in those bodies that have been inspected after death, in consequence of fevers in hot climates, is less bitter, and not so penetrating to the fingers, being therefore deficient in the antiseptic principle. But since external heat makes no alteration in the degree of temperature of the fluids themselves, this effect must take place through the medium of the solids, in consequence of that general languor and want of energy which too much external heat induces in the functions, particularly in that power by which the living body preserves itself from putrefaction. Now if this portion of the blood, thus altered and depraved, is readily secreted and speedily thrown out, as in cholera morbus, no harm befals the constitution, nor any inconvenience but what arises from the irritation of the primæ viæ. But this may not take place if the body should be otherwise deranged; for the removal of this noxious matter from the mass of blood depends upon a due irritability of the blood vessels, the liver, and the bowels, whereby they are stimulated to contract, and thereby expel it. According to the principle of Mr. John Hunter, (whose deep and industrious researches into the animal œconomy place him high in the list of those few on whom nature has bestowed real genius, and who are capable of adding something new to the stock of human knowledge,) there is in a state of health a relative habitude or mutual harmony existing between the solids and fluids, whereby they stimulate and produce actions in each other, in which the healthy state of the functions consists, whether employed in the formation of what is found, or the expulsion of what is noxious: so that where it happens that the solids have a morbid insensibility to the impressions of corrupted and acrimonious fluids, the retention of these adds still more to the general derangement. To illustrate this, it may be observed, that the stomach and bowels, when they are endowed, as it were, with their natural perception, immediately expel any preternatural accumulations of bile that may take place; but when they are insensible to this stimulus through disease, no effort is made to relieve nature till it is excited by medicine. The same reasoning may be applied to the various vessels and ducts. Thus when we see the liver gorged with bile, without any free excretion of it into the gall bladder, as I have sometimes found to be the case upon inspecting the body in some of the worst cases of fever, would it not appear that the gall ducts have lost that natural irritability whereby the bile is expelled? Or, in consequence of a depraved state of action, connected with febrile affection, may it not happen that the absorbents, which, in their natural state, only absorb particular substances, and in a given quantity, will suffer a change in this natural action, and absorb whatever happens to be applied to their orifices? In case of jaundice, the bile, which is perhaps not at all absorbed in a state of health, is taken up in large quantities, and mingled with the mass of blood, which proves a seasonable relief in the state of accumulation and distension occasioned by the obstruction. This may happen in cases of fever, not indeed as a relief to nature, but from a depraved state of irritability in the lymphatics, induced by disease. Though no increased quantity of bile, therefore, is found in the gall bladder, there may have been an increased excretion of it, a preternatural absorption having been excited. So that it may admit of a question whether the colour of the skin, in the yellow fever, is owing to this, or if the idea of it given in the text104 is more just; but in either case it seems probable that the extreme tendency to putrefaction in the whole body is owing either to the presence of bile, in consequence of absorption, or the retention of something in the blood from a defect of its secretion.

This reasoning concerning the bile in hot climates may, in some sort, be illustrated by what happens to the urine in cold climates. The urine is the vehicle of an excrementitious part of the blood, of which an increased proportion is generated in certain fevers, and if it is thrown out in the form of high-coloured, turbid urine, the fever will most probably be slight and short; but if it becomes pellucid, or crude, as it is called, the general derangement will be increased, the fever will be more violent and dangerous, and the first sign of returning health will be a turbid appearance and sediment.

If the reasoning in the above discussion should appear to some readers unsatisfactory, or ill connected, I can only say that if it is deserving of this character, I am willing to have it considered not only as an illustration, but an example of the nicety and fallacy of theoretical disquisitions.