Part 2
From this it is seen, that the pathology of jaundice, according to Frerichs, is very different from what we were formerly taught. For while he has entirely laid aside the theory of jaundice as a result of suppressed secretion, he has introduced two perfectly new elements--namely, abnormal diffusion, and diminished consumption. The latter theory, being, of course, founded on the supposition that bile, after playing its part in the digestive process, is re-absorbed into the circulation, again to perform another function in the animal economy, before its final excretion from the organism as effete matter. The theory of jaundice, hitherto most favoured in England, and which found {7} such an able exponent in Dr. Budd, is, that the disease may arise in two ways--firstly, by a mechanical obstruction to the passage of bile into the intestines, and the consequent re-absorption of the detained fluid into the blood; and secondly, by a suppression of the biliary secretion arising from some morbid condition of the liver itself, whereby the biliary ingredients accumulate in the circulation. Now, although I am not prepared to admit the justice of the views held regarding the origin and function of bile, on which these opinions are based, I nevertheless believe that in the following pages I shall be able, by the aid of modern medical science, to prove the correctness of the conclusions themselves. In order to do this, however, it will be necessary for me to begin by making a few remarks on the nature of bile, and the physiology of its secretion.
ON THE NATURE OF BILE.
In a few words, bile may be said to be composed of the following substances:--
Firstly,--Biliverdine, a green nitrogenized, non-crystallizable colouring matter, analogous to the green colouring matter of plants, and like it, leaving on incineration a distinctly ferruginous ash. This colouring matter appears, like {8} urohæmatine, and all other animal pigments, to be a direct derivative of the colouring matter of the blood.[2]
[Footnote 2: _Vide_ papers by the author on the colouring matter of the urine, Pharm. Journ., November, 1852. "Urohæmatine, and its combination with animal resin." Verh. d. Phys.-Med. Gesellschaft zu Wurzburg, Bd. V. 1854.]
Secondly,--Two peculiar substances, named respectively, glycocholic, and taurocholic acid--the former yielding, when in combination with soda, a crystallizable, the latter a non-crystallizable salt. Taurocholic differs still further from glycocholic acid, in containing a large percentage of sulphur, {9} and being, under the influence of hydrochloric acid, convertible into taurine, a beautiful white crystalline substance.
Thirdly,--Cholesterine, a crystalline, fatty matter, not, however, peculiar to bile, but found in various tissues, and secretions of the body.
{10} Fourthly,--A brown resinous substance resembling, in appearance and consistence, shoemaker's wax.
Fifthly,--Among the constituents of the bile, I may mention sugar, for both in the normal bile of man, and of the lower animals, the ox, and the dog, I have detected that substance. On one occasion, I even found torulæ in the bile twenty-four hours after its removal from the gall-bladder of a healthy dog.
Sixthly, and lastly,--a quantity of inorganic matter, consisting chiefly of soda, potash, and iron.
The specific gravity of bile fluctuates, of course, with the percentage of solid matter it contains. From my own observations, I consider that healthy human bile has an average specific gravity of 1020, and contains about six per cent. of solid matter, five per cent. of which is organic, and one per cent. inorganic substance. When fresh, bile is almost neutral; but it rapidly undergoes decomposition, and becomes alkaline.
In colour, human bile is usually of a brownish yellow hue; the colour, however, varies with its degree of concentration, the kind of food taken, and the state of the system. As regards the effect of food, if we may be allowed to form an opinion from experiments on dogs, it may be said that, as a {11} rule, animal food tends to give bile a yellow, vegetable food a green, tint.
Next, as regards the manner in which bile is secreted. For a long time it was thought, and, indeed, some people still think, that bile exists pre-formed in the blood, and that the liver only excretes it, as the kidneys excrete the urinary ingredients. Another class, running to the opposite extreme, believe that the liver is not merely the excretive, but also the formative organ of the bile. It appears to me, however, that neither of these extreme views is correct, and that the truth lies between the two.
It is, in fact, not at all difficult to prove that the liver manufactures certain biliary constituents, while it merely excretes others. Thus, for example, the two substances glycocholic and taurocholic acids are never to be found either in the blood, tissues, or fluids of the healthy organism, with the single exception of those of the liver and gall-bladder; and after extirpation of the liver neither acid is to be found in the body at all. On the other hand, such substances as cholesterine and biliverdine, are not peculiar to the liver or its secretion, but are the products of several organs, and are always to be detected in the blood, independently of the presence or absence of the liver. These facts, therefore, clearly show that the liver {12} is both a formative and excretive organ to some, and an excretive only to others, of the biliary constituents.
Lastly, the general opinion is that the secretion intermits, and, like the gastric, and pancreatic juices, bile is only formed during digestion. Were it so, however, where would be the necessity for a gall-bladder? Is it not to store up the secretion formed in the intervals of digestion, and to retain it until it is required? No doubt there are several animals, such as the horse, and the deer, that possess no gall-bladders; but there is undoubtedly in them some special arrangement of the digestive apparatus, rendering the presence of a gall-bladder unnecessary. In fact, it is easily shown that the biliary secretion in ordinary cases is continuous; for if in an animal possessing a gall-bladder a biliary fistula be established, and the secretion of bile carefully watched, it will be found that at no period of the day does it entirely intermit, although it is more active at one time than at another, the minimum of its activity being during sleep--the maximum during active digestion. The absolute quantity of bile secreted in the twenty-four hours is tolerably uniform, although the daily amount is slightly influenced by the kind of food.[3]
[Footnote 3: Arnold found that dogs secreted more bile on a bread, than on an animal diet. "Zur Physiologie der Galle," Mannheim, 1854.]
{13} IS BILE ESSENTIAL TO LIFE?
Several physiologists have given it as their opinion that bile is not essential to life, for animals have lived for many months after the artificial establishment of a biliary fistula, through which the bile was allowed to flow away, and be lost to the animal. Now, although this is perfectly true, yet it is at the same time evident that the uses of the bile cannot altogether be dispensed with, for all the animals with a biliary fistula lose flesh, become emaciated, and weak; the hair has a tendency to fall off, the bowels to become irregular; and a great and an almost constant discharge of foul-smelling gases takes place from the intestinal canal. At length, after a shorter or longer period, the animal sinks, and dies. The fatal termination can, however, be retarded by allowing him an additional quantity of nourishing food, for death from want of bile, as is too often seen in the human subject, is nothing else than death from slow starvation. The fact just related regarding the beneficial effects of an additional quantity of food in prolonging life, should never be lost sight of in the treatment of cases of obstruction of the gall-ducts, for, by attending to this circumstance, it is often in the power of the medical man to keep his patient alive for a considerable length of time.
{14} It may perhaps not be out of place if I here briefly enumerate the chief uses of bile in the animal economy. In order to live, not only must the individual particles of our frames die, but they must be continually replaced by new materials of a similar kind; and for the accomplishment of this important end, nature has endowed animals with a digestive apparatus in which their food undergoes the various physical, and chemical changes necessary to its absorption, and assimilation. In the animal laboratory or digestive apparatus there are five important agents constantly at work--saliva, gastric juice, bile, pancreatic fluid, and intestinal secretion, and each of these agents has a special and definite office to perform in the elaboration of the food.[4] At present, however, I must limit myself entirely to the consideration of bile.
[Footnote 4: For an explanation of these offices, see the author's article on "The Chemistry of Digestion," in the "British and Foreign Quarterly Review," January, 1860.]
Bile is the first digestive agent with which the food comes in contact on leaving the stomach and entering the intestines, and immediately on the acid chyme mixing with the alkaline bile, a white flocculent emulsion is formed, which emulsion has been described by many writers as a precipitation of the albuminose (digested albumen). Later {15} researches by myself and others have, however, shown that it is not the bile which precipitates the albuminose, but the acid of the chyme, which in reality sets free certain ingredients of the alkaline bile. In the majority of cases there is not even a true precipitation, for on throwing the milky-looking mixture upon a filter, I found that almost nothing remained behind, and the filtrate was nearly as white as the original liquid. Further, if the albuminose be separated from the chyme, and the chyme then brought into contact with the bile, the same flocculent-looking milkiness still appears. Nay, more, on adding equal parts of sheep's bile (fresh) to gastric juice drawn from a dog's stomach in full digestion, the apparent flocculent precipitate still appeared, although the acidity of the gastric juice remained unneutralized; and on throwing the whole into a filter, I found that the liquid that drained through was as milky and flocculent-looking as the original. The office of bile in the digestive process is neither to act on the albuminous[5] nor amylaceous portions {16} of our food; its chief action being to assist in the absorption of fats. When bile is mixed with neutral fat, little change is observed, but when brought in contact with the fatty acids, an immediate emulsion takes place. Lenz and Marcet[6] pointed out how the neutral fats of our food are transformed into fatty acids during their sojourn in the stomach; and Bidder and Schmidt[7] illustrated by experiments on dogs the important part played by the bile in their absorption. A dog, which in its normal condition absorbed on an average 7 grains of fat for every 2 pounds of its weight, absorbed only 3, or even as little as 1 grain, after the bile was prevented entering the intestines, in consequence of a ligature being applied to the gall-duct.
[Footnote 5: In speaking of the properties of the bile, I may mention that, although bile has no digestive power (properly speaking) over albuminous substances, yet, when injected into the subcutaneous cellular tissue of a healthy animal, it eats its way out through the skin, just as gastric juice or lactic acid does under similar circumstances. Even the muscles with which it comes in contact appear to be eaten away.]
[Footnote 6: _Vide_ a Discourse on the Chemistry of Digestion, by Dr. Marcet. Journ. of the Chem. Soc., Oct. 1862.]
[Footnote 7: "Die Verdauungssaefte und der Stoffwechsel." Leipzig, 1852.]
Further, these last-named observers found that, while the chyle in the thoracic duct of a healthy dog contains 32 parts of fat per thousand, that in the thoracic duct of a dog with a ligatured gall-duct, contains only 2 parts per thousand. These facts clearly prove that bile plays an important part in the absorption of the fatty portion of our food. Next comes the question, "In what manner does bile aid in the absorption of fatty matter?" {17} As is well known, fats or oils have no tendency to mix with water, and hence diosmose between an aqueous and an oily fluid is next to impossible. Matteucci has, however, shown that if an animal membrane be moistened on both sides with a weak solution of potash, it allows oil to pass through it. It has also been observed, that when the intestine is moistened with bile, it allows oil to pass through, which would not otherwise be the case. To illustrate this property of bile, I performed the following experiments:--
Firstly,--A clean piece of duodenum was filled with oil, ligatured at both ends, and suspended in water, holding in solution a small quantity of albumen. (The albumen was added to the water merely to imitate slightly the albuminous blood.) On examination, twenty-four hours later, no oil was found to have escaped through the intestinal walls.
Secondly,--A second portion of intestine had its internal surface moistened with sheep's bile before the introduction of the oil. It was then treated in the same manner as the preceding, and on being examined after the lapse of twenty-four hours, a small quantity of the oil was found to have penetrated through the intestine.
Thirdly,--Into a third portion of intestine was poured equal parts of sheep's bile, and chyme obtained from a dog in full digestion, through a {18} fistulous opening into its stomach. After being treated for the same length of time, and in precisely the same manner as the others, evident signs of the oily matters of the chyme having passed through the walls of the intestine were obtained, for they were seen as a scum floating on the surface of the albuminous water. Moreover, the fatty matters were not in the form of pure oil, but of a soapy substance.
The bile is thus seen to possess one of the more remarkable properties of the pancreatic juice. There is this important difference between the action of these two secretions on fats, however, that while bile merely emulsions and saponifies that portion of our food which enters the duodenum in the form of fatty acids, pancreatic juice, on the other hand, possesses the power, not only of emulsioning and saponifying the fatty acids, but also the neutral fats; indeed, its power seems chiefly to be exerted upon the latter. Hence it appears that both secretions are in a measure necessary to the complete digestion and absorption of the oleaginous constituents of our food.
On one occasion, while experimenting with bile at University College, I was surprised to hear Minton, the servant who was assisting me, say, that while he was travelling with Sir Andrew Smith in South Africa, he had oftentimes seen the {19} Caffres drink bile direct from the gall-bladders of the animals killed by the European party, and that, while passing the gall-bladder round to each other, they would rub their stomachs and say,--"Mooé-ka-kolla," signifying thereby, that it was very good. It certainly seems very extraordinary that any human being should not only drink, but drink with pleasure, a liquid so bitter and nauseating as bile. Perhaps the poor Caffres, however, drank the sickening tasted bile for the same reasons as the cattle in Caffreland, at certain periods of the year, go thousands of miles to drink at the salt-springs. There being scarcely any chloride of sodium in the earth, there is insufficient for the animal requirements in the herbage on which they feed, and they are forced to supply the deficiency by artificial means. Bile contains a large percentage of soda, and perhaps the Caffres drink it in order to obtain that substance, just as the animals drink the brackish water of the salt licks, feeling that it agrees with them, without knowing why.
THE MECHANISM OF JAUNDICE.
As said in the beginning of this paper, I believe, the pathology of jaundice may be embodied under the two heads, jaundice from suppression {20} of the biliary functions, and jaundice from re-absorption of the secreted but retained bile. These are at best, however, but vague terms, and in order to make the pathology of jaundice somewhat more definite it will be necessary for me to subdivide these two great classes in the following manner:--
(CLASS A.)--JAUNDICE FROM SUPPRESSION. Arising from:-- (1) Enervation. (2) Disordered hepatic circulation. (3) Absence of secreting substance.
(CLASS B.)--JAUNDICE FROM RE-ABSORPTION. Arising from:-- (1) Congenital deficiency of bile-ducts. (2) Accidental obstruction of bile-ducts.
I shall now try to point out the pathology of these different states, and see how far they are able to explain the occurrence of jaundice under the various conditions already alluded to.
JAUNDICE FROM SUPPRESSION.
Although there can be no misunderstanding the meaning of the term "jaundice from suppression," there may, nevertheless, be some difficulty in comprehending how the skin becomes yellow, and the urine high coloured, when the secretion {21} of bile is arrested. In order to explain how this occurs, it will be necessary to recall to mind what was said regarding the nature of the biliary secretion. It will be remembered that I began by saying, that while some of the constituents of the bile are generated in the liver itself, there are others that exist, pre-formed in the blood.
If this view of the physiology of the biliary secretion be correct, it is perfectly evident that when the secretion of bile is arrested, those substances which the liver generates will be entirely wanting, while those which it merely excretes from the blood will accumulate there as soon as their excretion is prevented; just as urea accumulates in the circulation when its elimination by the kidneys is stopped. Hence it is that, as soon as the biliary secretion is in abeyance, biliverdine accumulates in the blood (until the serum is as it were completely saturated with the pigment), from which it exudes and stains the tissues, and produces the colour we term jaundice. At the same time, or even before the skin becomes yellow, the urine assumes a saffron tint in consequence of the elimination of the colouring matter by the kidneys.[8] From this it will be seen that I regard {22} the yellow skin and high-coloured urine of jaundice as simply due to the deranged secretion of biliverdine, quite independent of the presence or absence of the other constituents of the bile, the effects produced by which will be referred to elsewhere. Meanwhile we shall separately consider the further pathology of the three subdivisions of jaundice arising from suppression.
[Footnote 8: The true order of the occurrence of these changes is:--On the second day the urine becomes high-coloured; in a day or two later the skin assumes a yellow tint; and, in very severe cases, within the first week or two, the sweat, the milk, the tears, the sputa, and the serum in the thoracic and abdominal cavities, become of a more or less decided yellow hue.]
JAUNDICE AS A RESULT OF ENERVATION.
It is now a well-established fact that all secretions are under the direct influence of the nervous system. Stimulate a nerve supplying a gland, and secretion is accelerated; stop the nervous action, and secretion is as instantaneously arrested. Again, just in the same way as volition can produce or suspend muscular movement, mental influence can hasten or retard glandular secretion. As an illustration of this fact, I need only call to mind the influence the mere sight of food has in exciting the salivary secretion, and the effect of bad news in arresting it. Exactly the same influence as is here alluded to, is exerted by the mind over the biliary function. If, for example, {23} as Bernard first observed, a dog with a biliary fistula be caressed, the secretion of bile is actively continued; if, on the other hand, the animal be suddenly ill-used, the secretion of bile is instantly arrested. If he be again caressed, the secretion is re-established, and the bile flows drop by drop from the end of the cannula. Here the influence is entirely produced through the intervention of the nervous system; and if such effects as are above described occur in the dog, we can surely have little difficulty in understanding how the biliary secretion can be influenced in the highly-developed organization of the human being. Indeed, every one must have felt how quickly sad tidings received during a meal not only destroy the appetite and retard digestion, but occasionally alter the complexion. This effect, that all of us must have experienced in a slight degree in our own persons, several may have observed to a greater extent in the persons of others, even to the production of well-marked jaundice. At this very time I have under my care a young married lady, who during the last two years has twice suffered from an attack of jaundice induced by witnessing her child in convulsions, and this I regard as an example of jaundice from enervation.
One of the reasons, no doubt, why jaundice does not more frequently follow upon mental emotion is {24} simply on account of a certain amount of pigment being required in order to produce a visible tinging of the body, and it seldom happens that the emotional effect on the biliary secretion is sufficiently permanent to permit of the requisite amount of pigment accumulating in the blood. The reason, too, why mental emotion is more apt to cause jaundice immediately after a meal is, as will afterwards be better understood, on account of the congested state of the liver at that time favouring the stoppage of the secretion. A blow on the head, which is now and then observed to be suddenly followed by jaundice, acts, I believe, in the same way as fright, namely, by paralyzing the nerve force required for the continuance of the biliary secretion.
I now pass on to the consideration of the pathology of the second kind of jaundice from suppression, namely, jaundice resulting from hepatic congestion.
JAUNDICE ARISING FROM HEPATIC CONGESTION.
This is one of the most common causes of the disease; but as there are two kinds of hepatic congestion--active and passive--it will be necessary for me to make a further subdivision, and consider each of these separately.
{25} _Jaundice the Result of Active Congestion._
The mechanism of jaundice resulting from active congestion of the liver is readily explained on physiological grounds.