In the present day, we have all learnt that "something much more than a general tendency to form fat, or a general excess of fat in the blood is necessary to produce a local fatty degeneration." - (Sir James Paget's Lectures, Vol. I., p. 112.)

Every year throws new light on the physiology of the process by which this change is brought about; but of this it is not within the province of these Lectures to treat. I wish, however, to point out to you that the pathological condition termed fatty degeneration is to be regarded as a vestige of disease - a vestige of perverted assimilation, either local or general, and hence a vestige also of any diseases by which such perverted assimilation is produced. In the third series of Guy's Hospital Reports (Vol. III., 1857), Dr. Wilks has related a number of interesting cases of fatty degeneration, of which the only appreciable and probable causes were haemorrhage, diarrhoea, miasmata. In these cases the subjects were comparatively young, the heart was the organ in which the diseased change was most marked, and the body generally was neither fat nor wasted.

Fatty degeneration appears to be especially prone to occur in tissues which have passed from a condition of active assimilation to one of comparatively inactive or feeble nutrition, by whatever cause this change may have been brought about. Thus, the muscular tissue is particularly subject to fatty degeneration; it is also peculiar for the vigour of its normal assimilation, and it is when this is rendered feeble that degeneration occurs. This appears to be the case whether the vigorous assimilation is hindered by arrest of function in the muscles, as in the case of paralyzed limbs, or by deficient supply of blood, as in disease of the nutrient arteries of a part, or by a depraved condition of the blood supplied to the part, as in the case of persons who, after having led active muscular lives, gradually become anaemiated by passive haemorrhages. I have seen many instances of strong men, accustomed to vigorous country occupations, who, having become the subjects of bleeding haemorrhoids, by which the blood lost its red globules, and nutrition became enfeebled, suffered from degeneration of their previously strong and vigorous hearts. Many other examples might be adduced of the degeneration of tissues when their assimilation is changed from a vigorous to a feeble state. Thus we find, in watching the course of diseases of the heart, that the heart which has become hypertrophied in opposing some obstruction to the circulation during the active life of the individual, becomes degenerated when, in the further progress of the case, the patient is forced to relinquish active pursuits, and thus ceases to call upon the hypertrophied organ for the full exercise of its muscular power. Thus also, parts which have been inflamed are especially liable to degenerate, and fatty degeneration frequently takes place in organs deprived of their proper functions by disease, as in kidneys spoilt by Bright's disease. Thus, also the products of inflammation, when they have no further functions to perform, are peculiarly subject to fatty degeneration. Without pressing the subject further, I think we shall all agree that fatty degeneration must be regarded as a vestige of disease, not as a disease in itself, and that in thus regarding it, we must often look beyond the defect in assimilation to the causes of that defect, in order to find the disease of which the degeneration is truly a vestige.

I must now proceed to show to what a wide extent this vestige of disease acts as a cause of those deaths classed in the Registrar's reports under the heads of a variety of diseases.

"The most interesting examples (of fatty degeneration)," says Sir James Paget, "are those of primary degeneration of blood vessels. This has long been known in the atheromatous disease, as it was called, of the larger arteries, the true nature of which, as a fatty and calcareous degeneration of the inner and, consecutively, of the middle arterial coat, was discovered by Mr. Gulliver (See Med. Chir. Transactions, Vol. XXVI.). The descriptions of this complaint by him and by Rokitansky have left nothing unsaid that is yet known; but the observations are each year becoming more numerous and more interesting of similar changes in the minutest blood vessels. Such changes are especially observable in the minutest cerebral vessels, and their importance in relation to apoplexy, of which they seem to be the most frequent precedent, cannot be overstated." - (Ibid., Vol. I., p. 139.)

Dr. Wilks' experience has taught him that, "In the majority of cases of sanguineous apoplexy, disease of the blood-vessels exists." - (Lectures on Pathological Anatomy, 1859.)

Dr. Kirkes has shown (Med. Chir. Transactions, Vol. XXXV.) that paralysis, consequent upon arrested circulation in some portion of brain, is frequently the result of the obstruction of healthy cerebral arteries by masses of fibrine carried into them, after being dislodged from the valves of the left side of the heart, or from some part of the arterial system.

And Dr. Ormerod has pointed out that it is in the cachetic subjects, with feeble circulations, that such masses are likely to form in the heart, in the very persons, in fact, who are likely to be the subjects of fatty degeneration of this organ. - ("Observations on the Clinical History and Pathology of one form of Fatty Degeneration of the Heart," by E. L. Ormerod, M.D. Medical Gazette, 1849.)

And although Dr. Ormerod was not prepared at that time (1849) to consider the occurrence of fibrinous clots in the subjects of fatty degeneration to be more than a frequent coincidence, we do not now doubt that the languid circulation, and the inefficient contractions of the heart in the subjects of fatty degeneration, act, together with other circumstances, in causing these deposits of fibrine from the blood.

Describing the appearances after death in fatal cases of delirium tremens, Dr. Wilks says, "The body, as a rule, presents many degenerative changes, brought about by the intemperate habits. It is this alteration of the viscera, I think, to which death is owing. Delirium tremens is a recoverable affection until such changes have occurred in the tissues that improvement is no longer possible; and we then find in the body various morbid changes. These are mostly of the fatty kind, as all alcoholic drinks tend to this condition." - (Ibid.)