Therapeutic Applications. Cod-liver oil has recently taken a place among the most valuable articles of the Materia Medica. Used from time immemorial, in the maritime districts of Holland, Germany, and the northern parts of Great Britain, as a popular remedy in rheumatism and rickets, it was first brought to the notice of the medical profession, in the year 1782, by Dr. T. Percival, of England, and was afterwards referred to by Dr. Bardsley, in his Hospital Reports, in 1807; but gained little attention until the publication of a paper by Schenck, in 1822, in Hufeland's Journal, containing a series of observations upon its efficacy in chronic rheumatism, particularly sciatica and lumbago. After this time, its employment was much extended in Germany, and other parts of the continent of Europe; and numerous communications in the medical journals set forth its claims to high consideration, not only in the complaints above mentioned, but in others, and especially in the different forms of scrofula and tuberculosis. In 1841, it was brought to the notice of the medical profession in Great Britain, as a remedy in phthisis, by Dr. J. Hughes Bennett) of Edinburgh; his reports in its favour were confirmed by the ample experience of Dr. C. B. Williams, of London, and subsequently by that of Dr. Walshe; and, both in that country and in our own, the use of it extended rapidly, until it became almost universal, in the complaint referred to, and in other forms of scrofulous disease.

Cod-liver oil is indicated generally in cases of chronic debility, with impoverished blood, and defective nutrition or assimilation, not connected with inflammation of the stomach. The class of affections in which it has obtained most reputation are those included under the term scrofulous; and, in many of these, it has exhibited powers beyond those of all other remedies. To understand its effects, it is necessary to discriminate between these affections.

The name scrofulosis may be applied to a condition of system, essentially connected with a low state of the vital forces and defective or depraved nutrition, which exhibits itself under two aspects. In one of these, there is a tendency to the production, in various parts of the body, sometimes in one part, sometimes in another, and sometimes in several parts at once, of a feeble, protracted, obstinate kind of inflammation, strongly tending to the suppurative and ulcerative state, and indisposed to a spontaneous cure, which is usually designated by writers as scrofulous inflammation. In the other, there is a disposition to deposit, in the various tissues, a peculiar matter called tubercle, which, at first solid, either remains in this condition, irritating the neighbouring parts like foreign matter, or gradually softens, and is ultimately discharged through the inflammation, suppuration, and ulceration of the contiguous structure. These two different local expressions of the constitutional affection may exist quite separately, or may be conjoined in the same case. Now cod-liver oil has an extraordinary influence over the state of system referred to, generally controlling it in a considerable degree, often suspending it for a time when not completely eradicable, and sometimes curing it wholly and permanently.

In the set of cases belonging to the first category above mentioned, those, namely, in which the local affection is simply scrofulous inflammation, the oil will often effect complete cures; because, the morbid condition of system being corrected, and the strength improved, the local lesions are no longer produced, and those already existing are allowed to heal; and life may in general be saved, if the disorganization has not proceeded too far before the application of the remedy.

In the second set, or that characterized by the tuberculous deposit, the diathesis may be in like manner modified or corrected; but the remedy has no influence whatever over the tubercle when already formed, which will exercise its influence upon neighbouring parts, or pursue its own regular course of degeneration, quite independently of any corrective that can be applied. In such cases, it is obvious that the oil can prove curative only when employed, either before the tuberculous deposit has taken place, or when it has occurred in situations, or in quantities, not necessarily destructive of life, through the disorganization of the tissue affected. Thus, when the tubercles are situated in the brain, or the arachnoid membrane, there is scarcely a chance of safety; because, being irremovable, they will ultimately incapacitate, by their irritant influence, this vital organ for the performance of its functions. When, on the contrary, they are deposited in the external lymphatic glands, in the subcutaneous areolar tissue, and even in the bones, there is reasonable hope of a cure; as the parts are less essential to life, and the irritation can generally be supported until the offending matter has been discharged. Again, when such an organ as the lungs is the seat of the deposition, as there is a possibility that the tuberculous matter may be thrown off, it follows that, if the quantity is not so large as fatally to overwhelm the lung by irritation, as in diffused miliary tubercle, or to destroy the organ by ulcerative inflammation in the course of its discharge, or to exhaust the system by the profuse suppuration, and the irritative influence of the local disease, one of which events generally happens in ordinary phthisis, there may be good hope of ultimate recovery. Upon these principles may, I think, be explained the frequent success complete or partial, and the frequent failure also, of the remedy in scrofulous diseases. It will be proper, now, to treat specially of the several affections of this kind in which the oil is used.

External Scrofula. In all the forms of external scrofula, unattended with tuberculous deposition, much good may be expected from cod-liver oil; and, united with other measures calculated to improve the blood, and give vigour to the system at large, a cure may generally be expected. Its effects are peculiarly obvious in the suppurative and ulcerative stage of the affection, whether the lymphatic glands, the subcutaneous tissue, or the skin itself be the special seat of the disease. Scrofulous ulcers and abscesses of the neck, axilla, and groin, or of the skin and the areolar tissue, in any part of the body, often rapidly improve, and ultimately get well under its use. I have seen large and exhausting abscesses of the lower extremities, which have reduced the patient, during months of suppuration, to the lowest condition of emaciation and debility compatible with life, recover slowly but steadily. from the period at which the system was put under the use of the remedy.