cancer cells corresponding to differences of the structures in which the carcinomatous exudation takes place.

Cancerous deposits are distinguished as primary and secondary. The first deposit which occurs is called primary, and any which may subsequently take place are called secondary. It is generally supposed that secondary cancers are dependent on the primary, the latter furnishing germs which gain admission into the circulation, and being deposited in other situations, become the point of departure for fresh manifestations of the disease. It has been already stated that, not only are the structures in immediate proximity to the deposit involved and destroyed, but the affection extends to the neighboring lymphatic glands. It may, however, be reasonably doubted whether secondary deposits more or less remote from the site of the primary cancer proceed from the latter; in other words, it is by no means certain that the system becomes infected by the introduction into the circulation of matter derived from an existing cancerous affection. Various facts go to show that a primary cancer involves an antecedent or underlying unknown special pathological condition called a cachexia, or, if it consist in a bloodchange, a crasis. A predisposition to this disease, or the cancerous diathesis, is undoubtedly in some cases inherent in the system from birth, and inherited. Now, it is perhaps more probable that secondary cancers are dependent on the general or constitutional condition which led to the primary affection than that they proceed from an infection by the latter. This view is consistent with a fact which clinical experience appears to teach, viz., that secondary cancers are more apt to occur after the extirpation of a part primarily affected, than if surgical interference had not been resorted to.

As regards the situation of the cancerous deposit, there is a preference (so to speak) for certain organs. Rokitansky gives the following list of parts which are liable to be the seat of this disease in the order of their enumeration: "First, the uterus, the female breast, the stomach, the large intestine, and especially the rectum; next comes the cancer of lymphatic glands, especially as retro-peritoneal cancer accumulation in front of the vertebral column; hepatic peritoneal cancer; bone-cancer; cancer of the skin, and of the lips; of the brain; of the globe of the eye; of the testis; of the ovary; of the kidneys; of the tongue; of the esophagus; of the salivary glands. and the parotid."

TYPHOID DEPOSIT.

The deposit which takes place in the Peyerian patches of the small intestine and the corresponding mesenteric glands in typhoid fever may be reckoned among the exudations. This deposit is characteristic of typhoid fever, and will be considered more fully in treating of the latter in the second part of this work. The typhous matter or substance, as it is called, is deposited during the early part of the disease in considerable quantity. The Peyerian patches and mesenteric glands become more or less enlarged. At first the substance has considerable density, but during the progress of the disease it softens, and is reduced to the consistence of a pulpy mass. In the Peyerian patches, generally, if not invariably, it sloughs away, carrying with it the glandular bodies which compose the patches, and leaving ulcerations which, if recovery take place, undergo cicatrization. In the mesenteric glands the deposit is absorbed. The typhous exudation consists of an amorphous material abounding in molecular granules; corpuscular bodies resembling the tuberculous corpuscles, but somewhat larger and acted on more rapidly by acetic acid; nucleated cells, highly granular, and free nuclei, the latter being granular and sometimes containing fatty granules.

The behavior of this deposit forms an important part of the natural history of typhoid fever. It is characteristic of typhoid fever as contrasted with typhus. The fact that the deposit is peculiar to the Peyerian patches and mesenteric glands goes to sustain the opinion now held by physiologists, viz., that the unknown function of the patches is identical with that of the glands, the former being the first row of glands spread out upon a plane surface.

The foregoing are the exudations important to be here noticed as entering into the morbid anatomy of a large number of individual diseases. It will be borne in mind that the term exudation is restricted to deposits which solidify by the progress of coagulation. Other solid deposits which are not strictly exudations will be noticed under the head of degenerations.

СНАРТER III.

ANATOMICAL CHANGES IN THE SOLID PARTS OF THE BODY-(Concluded.) Lesions of Composition continued-Transudations-Dropsies-Fluxes-Degenerations-Fatty Degeneration-Fatty Growth-Calcareous Degeneration-Lardaceous or Waxy Degeneration -New Formations or Morbid Growths-Pneumotoses-Animal and Vegetable Parasites.

TRANSUDATIONS-DROPSIES.

A MORBID condition, affecting the composition of parts, consists in an abnormal accumulation of liquid, exterior to the vessels, derived from the blood. Liquids escaping through the coats of vessels, devoid of coagulated fibrin or lymph, and holding in solution more or less of the constituents of the serum of the blood, are distinguished as transudations. Transudations preserve the liquid state, in this respect differing from exudations, the latter coagulating and thus giving rise to solid deposits. The act of transudation is purely physical, that is, it has no special relation to the vital endowments of the tissues, but only to their physical properties. The serous or watery portion of the blood percolates the walls of the vessels precisely as any liquid confined in artificial tubes of leather or some porous material may transude. Transudations generally do not even involve the principle of exosmosis, which is operative to a considerable extent in living organisms. They take place usually as a result either of a morbid attenuation of the blood-serum, or of undue hydraulic pressure, or of both these physical causes combined; other circumstances, also, may co-operate by rendering the sides of the vessels more permeable. In a true transudation there is no solution of continuity or rupture. Hemorrhage, therefore, is not a transudation unless it be admitted that the blood-corpuscles can pass through the pores of the vessels without the molecular coherence of the tissues being disturbed. Bloody serum, or serum colored with hæmatin, may transude, constituting what is called false hemorrhage.

Transudations may take place in different situations. Occurring in situations from which the liquid cannot escape, viz., within serous cavities and into the areolar tissue, they constitute dropsies. Occurring upon some internal surface whence the liquid is conveyed out of the body through an outlet, or, in other words, upon a mucous surface, they constitute fluxes. The latter do not now especially concern us, since they do not occasion

lesions affecting the composition of parts. The transudations which constitute dropsies are alone to be considered in this connection.

The distinctive feature of a dropsy is, that the liquid which escapes through the coats of the vessels is not liquor sanguinis, but water containing more or less of the constituents of blood-serum. When liquor sanguinis or bloodplasma escapes, the results are coagulated fibrin or lymph, and subsequently certain metamorphoses or developments which were noticed in the preceding chapter. Effused products which solidify by coagulation and become the seat of adventitious tissues, of pus-globules, etc., are exudations. On the other hand, liquid effusions devoid of coagulating material, undergoing no metamorphoses, not giving rise to new formations, in other words, in no sense blastemata or cytoblastemata, are transudations, and, if retained, such effusions constitute dropsies. It is proper to remark that this distinction is not always observed. Vogel, for example, applies the term "fibrinous dropsies" to accumulations of liquid which contain coagulated fibrin in greater or less abundance. According to the distinction just made, these are not correctly called dropsies. They are exudations, involving generally, if not always, inflammation. A true dropsy is not an effect of inflammation. Inflammation of serous membranes, it is true, frequently gives rise to more or less liquid effusion. But the effused liquid is turbid from the admixture of lymph, and contains more or less solid fibrin. In a dropsical accumulation, on the other hand, the liquid is generally clear, like the serum of the blood, and no solid fibrin or lymph is apparent. Again, while inflammatory effusion is due to a morbid condition (inflammation) of the serous membrane, in pure dropsy the morbid condition, on which the transudation depends, is situated elsewhere, the membrane itself being free from disease. Individual diseases exemplifying this contrast between inflammatory and dropsical effusions are pleuritis and hydrothorax, peritonitis and hydroperitoneum, true hydrocephalus and meningitis. The prefix hydro expresses the fact that the disease is dropsy.

In pure dropsy the effused liquid bears a resemblance, more or less close, to the serum of the blood. But it differs in different cases, owing to variations as regards the ingredients held in solution. It has usually an alkaline reaction. It generally contains albumen in greater or less quantity. According to Lehmann, transudations into the pleural sac are richer in albumen than those into the peritoneal; there is still less albumen in dropsy of the arachnoid than in hydroperitoneum, and effusions into the areolar tissue are the poorest in this constituent. When albumen is abundant, the liquid is viscid, and it may become so from the absorption of water. Dropsical effusions are sometimes red, from the presence of blood-pigment or hæmatin. Occasionally it is yellow or greenish, from the presence of bile-pigment. Fatty matter may be present in sufficient quantity to render the liquid opalescent or milky. Various of the saline ingredients of blood-serum are present, the chloride of sodium preponderating. Urea is occasionally found.

Dropsies receive different names according to their situation. Seated in the serous cavities, they are designated by prefixing hydro to the name of the membrane, as already stated. Dropsy of the areolar tissue of a part is called adema. This name is applied to effusions into the areolar tissue of internal organs as well as beneath the integument. An effusion into the pulmonary air-cells is called oedema of the lungs. When subcutaneous cedema is general, that is, extending over the body, it receives the name anasarca.

Dropsy is always dependent on some antecedent morbid condition. It is never a primary affection. It is, in fact, not a disease per se, but only a symptom of disease. It is produced by the affections which stand in a

cansative relation to it, in two ways: 1st, by increased pressure from an accumulation of blood in the veins; and, 2d, by diminishing the density of the blood-serum. These two physical conditions comprise the mechanism of dropsical transudations. In all instances either there is an increase of hydraulic pressure in the veins from obstruction, or the blood is abnormally aqueous; and both these physical conditions may be combined.

The terms general and local dropsy express an important distinction. In general dropsy, subcutaneous oedema is diffused to a greater or less extent; that is, anasarca exists, together with more or less effusion into certain of the serous cavities, the peritoneal and pleural especially. The oedema appears first either in the lower extremities, or on the face, or simultaneously in both these situations, and thence extends over the body. The anasarca may be accompanied with a small or a considerable accumulation in the serous cavities. Now, all cases of general dropsy involve either an obstruction seated at or near the central organ of the circulation, or a morbid condition of the blood, or both may be combined. General dropsy, due to obstruction, is nsnally a symptom of disease of the heart; occurring in this connection, it is distinguished as cardiac dropsy. The dropsy, under these circumstances, is generally associated with difficulty of breathing (dyspnoea) out of proportion to the amount of effusion into the pleural cavities; also, with disturbed action of the heart, and more or less congestion of the surface, giving to the skin frequently a dusky hue. On the other hand, general dropsy due to a morbid condition of the blood, in the majority of cases is connected with those affections of the kidneys embraced under the name of Bright's disease. Occurring in this connection, it is called renal dropsy. Cases of this variety of dropsy are characterized by the presence of albumen in the urine (albuminuria), by pallor of the surface, and, as a rule, a less amount of dyspnoea than in cardiac dropsy. Irrespective of disease of the kidneys, or albuminuria, the blood sometimes becomes attenuated so as to give rise to general dropsy. It is occasionally incidental to protracted intermittents. I have known anasarca to a great degree, with effusion into the cavities, to occur in connection with anæmia due to lactation, without either renal or cardiac disease.

In local dropsy the effusion is limited chiefly to one serous cavity, or, if in the areolar tissue, it is confined to one organ or to a part of the body. The most frequent of local dropsies is hydroperitoneum, which is dependent on obstruction of the vena portæ, generally as a result of hepatic disease, more especially the affection called cirrhosis. This, with other local dropsies, will be considered in connection with individual diseases; oedema of internal parts, when restricted to any organ or to a limited space, is due to hyperæmia or congestion which may occur under different circumstances. It may depend on venous obstruction, as when oedema of the lungs is produced by cardiac lesions which involve mitral obstruction. It is incidental to inflammation. The swelling in the neighborhood of an inflamed spot on the surface of the body is due to serous infiltration. This occurrence is generally of little moment, but it becomes an event of very grave importance when oedema of the glottis is incidental to pharyngitis; oedema of the lungs is incidental to the congestion distinguished as hypostatic, due to gravitation of blood to the dependent parts from impairment of the forces carrying on the circulation. It occurs in the last stage of fevers or other diseases characterized by adynamia or great depression of the powers of life.

Transudatious upon mucous surfaces, constituting fluxes, will be considered, as entering into certain individual diseases, in the second part of this work.

DEGENERATIONS-FATTY DEGENERATION.

The lesions of composition, which have been considered, do not involve alterations of structure or textural changes. Certain of the exudations, it is true, lead to the destruction of the tissues surrounding them. This occurs in the progress of cancer and tubercle, but the destructive effects of these exudations are due to pressure, to disruption from their accumulation, and to the inflammation which they excite. In transudations the tissues remain unaffected except that they may become attenuated from the distension occasioned by the liquid. But the lesions which are now to be noticed are characterized by the substitution of morbid deposits for the normal substance of the affected tissues; the change in composition consists in alterations of structure or textural changes. This is the distinctive feature of the lesions of composition which are commonly known as degenerations. And of these the most frequent in its occurrence is the substitution of fat for the normal substance of tissues, or fatty degeneration. To this lesion much attention has been directed of late years; and in elucidating it, the microscope has rendered valuable service to pathology.

Different structures in various situations are found to present, in the place of the substance peculiar to their normal composition, fatty granules or oil drops. Muscles are especially prone to this change. It is often observed in the muscular walls of the heart. Examined with the microscope the characters of the muscular fibre are more or less impaired or lost, and those of fatty matter are present. In proportion as this change has taken place, the tissue becomes softened, rupture is liable to occur, and instead of the healthy color the affected parts present a yellowish or tawny appearance. Of course, also, in proportion as the muscular substance is replaced by fat, the function proper to this structure is impaired; its power of contraction is diminished, and the affected organ is enfeebled.

An important distinction is between fatty growth and fatty degeneration. In fatty growth the adipose tissue is increased. This may take place beneath the integument and in any part of the body containing more or less of this tissue. Increased generally throughout the body beyond a certain extent the condition known as obesity or corpulency is produced. This may take place in a degree to constitute a disease. On the other hand, a decrease of the amount of adipose tissue which belongs to health occurs in emaciation produced by a deficiency of the alimentary supplies which contribute to fatty growth, and by various diseases. In obesity or corpulence there is, in fact, hypertrophy or abnormal growth of the adipose tissue, and in emaciation there is atrophy of this tissue.

Fatty growth may be limited to a particular organ. Thus, taking the heart for an illustration, this organ in health presents a certain amount of fatty tissue. Hypertrophy of this tissue, or, in other words, increase of the fat vesicles, may occur to such an extent that the whole surface of the organ is covered with a thick layer of fat. The fat vesicles may also penetrate, in greater or less quantity, between the muscular fibres. Nevertheless, the muscular structure of the organ may remain unchanged. The heart is affected with obesity; but this is not fatty degeneration. In fatty degeneration the fatty matter occupies the place of muscular substance; that is, fat is contained within the sarcolemma at the expense of the normal contents or the musculine.

An interesting pathological question here arises. Is the substance of muscle converted into fatty matter, or is this substance removed by absorp tion and its place occupied by fat? Does fatty degeneration, in other words,