Page:Encyclopædia Britannica, Ninth Edition, v. 18.djvu/411

 PATHOLOGY 389 k uey. I .tic i I us in gyel. B- t ue. 1 esity, alkaline treatment) that there may be some analogous acidity intro duced into the blood and lymph in the form of organic acids (pro duced in the course of faulty digestion), which would cause the uric acid to be deposited from the blood as it circulates generally. It is in the cartilages of the joints that the deposition usually takes place, the great -toe joint (nietatarso-phalangeal) having a quite remarkable and inexplicable liability. The surface of the cartilage is crusted with patches of a whitish opaque substance, which proves to be needle-shaped crystals of urate of soda ; the deposition ex tends deeper and affects the fibrous structures of the joint ; it may be so extensive in other fibrous structures as to amount to tophi or chalk-stones. In some rare cases of gout such organs as the parotid glands may be completely disorganized by the chalky de posit, or there may be numerous centres of its deposition in the membranes of the spinal cord. Albuminuria and Eczema of Gout. Two morbid conditions are so frequently associated with gout as to be part of its natural history, namely, eczema of some regions of the skin (eyelids, back of neck, &c. ) and albuminuria. We have absolutely no clue to the connexion between the skin-disease and the uratic diathesis ; for the albuminuria a connexion may be suggested. The albumen will at first be absent in the intervals of gouty attacks, showing itself during the attack, or for a few days previously ; its appear ance in the urine thus coincides, so far as it goes, with the decrease of uric acid in the urine. It is impossible to exclude the possibility that the albumen is here an error of the renal metabolism. All the facts of the gouty constitution point to a far-reaching disturb ance of the metabolic functions, which may be induced by causes so different as lead-poisoning and a luxurious life ; uric acid is not the only metabolic product concerned, although it is the chief, for there is even an occasional implication of the glycogenic metabolism, as shown by the presence of sugar in the urine, and there is the much more common albuminuria. It is impossible to believe that there are structural changes in the kidney to account for the earliest occurrences of albumen in the urine in gout, for the urinary secretion may be normal for long intervals ; and it is by no means certain that the albumen is a leakage from the glomeruli owing to the altered pressure of congestion. The kidney in chronic gout may bo affected in obvious characters ; it will show, on section, streaks of white opaque substance within or between the tubules, that which is between them being composed of crystals of urate soda often in fan-shaped bundles, while that which is within them is an amorphous mixture of urates of ammonia and soda and uric acid. The so-called gouty kidney may and often does assume the progressive structural changes which lead to the state of contraction and puckering. (There are other renal deposits of uric acid, as in new-born children, which are transitory.) The uric-acid diathesis may manifest itself, not in gout, but in gravel. In this case the excess of uric acid is thrown into the tubules of the kidney, where it forms concretions ; these may either be washed out by the urine as fine grains, or may remain for a time to increase by accretion, forming renal and vesical calculus. Obesity, Local Formations of Fat. The significance of fat under all circumstances in the animal body is by no means well under stood, but it may be conveniently approached from the side of metabolism. Adipose tissue is a somewhat special development of mesoblastic tissue, and most usually of the common binding tissue. The embryonic cell transforms the greater part of its protoplasm into an oily fluid which contains no nitrogen, the nucleus being retained on one side along with a narrow fringe of cell-substance ; a fat-cell in its early stage thus resembles a signet-ring, and in its later development it becomes a thin -walled vesicle which may be distended by its oily contents much beyond the limits of even the largest cells of other tissues.- This transformation may happen to the cells of the connective tissue in almost any part of the body ; but in the ordinary course of development it has certain scats of election, such as the stratum of gelatinous tissue underlying the kidney and the subcutaneous tissue. All synovial and serous membranes, except those of the liver and lungs, are favourite seats of fat-formation. In the subcutaneous tissue the first formation of fat appears to be associated with local formation of blood, the same mesoblastic elements being at one stage hremato- blasts and afterwards, in their vesiculated state, fat -cells. It cannot be doubted that there is a close adaptation to the needs of the economy in the vicissitudes of the fat-tissue ; but it must be admitted at the same time that the adaptation is often singularly obscure. In many cases the changes in the fat-tissue seem rather to be a correlated necessity. One of the earliest facts that w r e meet with in this connexion is the gradual replacement of the thymus gland by fat, the fluid being absorbed in its turn, and the mass of tissue shrinking. Another fact of the same kind is the change into fat -cells of &quot;lymphoid&quot; cells elsewhere, as the change of red marrow into yellow marrow in the central canals of the long bones. Both of these changes have a prototype or an analogy in the transition that one sees in groups of the subcutaneous spindle-shaped cells from a hoematoblastic activity to a fat-making activity. The season of puberty is a time of active fat-formation, more especially in women, and notably in the breast-region. A still more remarkable develop ment of fat occurs in many cases of sterility, and in many women after the child-bearing period has ceased in ordinary. Such in stances of a greater or less degree of obesity are so clearly associated with the obsolescence of an important function that they may be called physiological. Other instances of obesity have no such obvious or uniform association. Thus, an obese habit may follow one or more attacks of malarial fever ; it sometimes occurs as one of the lifelong changes induced by an attack of typhoid fever. There is often a great degree of plumpness along with the extreme ill health of chlorosis. Idiocy and some forms of insanity are apt to be associated with fatness ; in the pseudo-hypertrophic muscular paralysis of boys the connective-tissue cells between the muscular bundles become so active in fat-making that they usurp the place of the muscle. As an effect of dietetic errors obesity usually follows the inordinate consumption of starchy and saccharine substances, and especially the drinking of much beer, stout, and even other forms of alcohol. As a racial character obesity is found among the negro populations in some parts of Africa (South Africa and the Upper Nile). Among the most extraordinary developments of true fat are those Local cases where it develops locally in association with cancers or other fat-for- malignant tumours. Thus, in a boy who had suffered amputation mations. of the leg for a malignant tumour of the tibia there was a recur rence of the disease in the stump and in the ilium ; he died in a state of extreme emaciation of all the body except the thigh of the affected side, which was enveloped in a layer of ordinary sub cutaneous fat half an inch thick all round, contrasting strangely with the wasted limb of the other side. To take another unambigu ous case, an extensive development of fat through all its embryonic phases can actually be traced in the serous covering of the rectum in a case of cancerous stricture of the part. There is usually much local development of fat round the sac of an old hernia. In certain glandular organs, such as the pancreas, the supporting connective tissue sometimes takes on an extensive fat-forming activity, so that the organ is half transformed into adipose tissue ; the same may be found around the pelvis of the kidney in old age. Lipomatous Tumours. It is not always possible to say whether Lipoma. a local development of fat should be called a lipoma or not ; thus, the fat around an old hernia may be so circumscribed as practically to amount to a fatty tumour, and that may be the case also with the fat around the breast or behind the eyeball. On the intestine, notably the transverse colon, the masses of fat do becoriie pendulous fatty tumours (much more often in the domestic quadrupeds than in man) of a uniform or lobulated structure, which may hang by a long and slender vascular stem, like an apple or a cherry on its. stalk ; when the vascular supply is kept up with difficulty these pen dulous masses of fat tend to become calcified or otherwise sclerosed, and to fall off into the abdominal cavity as &quot;loose bodies.&quot; The loose bodies of the joints originate sometimes in the same manner from the pendulous masses of subsynovial fat. On the peritoneal surface the pendulous growth of fat may have a short stem and abundant blood-vessels, and go on to form a large lobulated tumour ; but more usually in that situation the tumour-habit is established at a number of points, leading to the condition of multiple lipo- mata. The lipomata of the subcutaneous tissue may be single or multiple ; if they are not congenital they are most often associated with a general obese habit ; and they may grow to an enormous size. The submucous tissue of the stomach or intestine is a com paratively rare seat of fatty tumour. The most inexplicable lipo mata are those which form, under very rare circumstances, as circumscribed nodular masses in the interstitial connective tissue of the cortex of the kidney, and in the subarachnoid tissue of the brain and spinal cord. It is convenient to place these occurrences of obesity, of local Of fat- overgrowths of fat, and of lipomatous tumours under the head of making errors of metabolism, but it is difficult to find one physiological in gen- rationale for them all. Where obesity is due to dietetic errors we eral. may say that the carbohydrates supplied to the body have been more than the combustion could overtake, and that the residue is &quot; stored up &quot; as fat. Where there is a degree of embonpoint in such a malady as chlorosis we may say that the feeble oxygen-carrying capacity of the red-blood corpuscles has led to an inadequate combustion of the carbohydrates supplied in due quantity, and that the residue has been stored up in that case also. In the unhealthy fattening that sometimes follows malarial or typhoid fever it does not appear why there should be the residue requiring to be stored up. Again, there are persons of an obese habit (probably con genital) who avoid a diet of carbohydrates, but turn even their meat diet to fat, just as there are confirmed diabetics who turn everything to sugar. Still further, we have the very remarkable tendency to make fat when the reproductive functions have ceased either prematurely or in the ordinary course ; and that is a fre quently occurring case which can hardly be brought into the doctrine of inadequate combustion of carbohydrates. The peculiar liability of the connective tissue between or upon the bundles of