3. The pressure developed by this secretion is more considerable than that of the blood itself in the glands; and, finally,

4. The nervous irritation does not determine any modification of the circulation that may be considered as a special source of mechanical force. As regards the influence of the nerves upon the movements of the lymph and the secretion of the lymphatic glands, Ludwig and Krause being satisfied that the quantity of lymph which escaped from the thoracic duct of a dog was the same whether the two carotids were tied or not, and not less after a fast of twenty-four hours, than immediately or some hours after a copious meal, observed a prompt acceleration of the discharge upon galvanizing the lingual branch of the trigeminus, either at its peripheral extremity or in its course along the lower jaw. The increase continued as long as the irritation of the nerve lasted, and the discharge was three or four times the normal amount. We have observed a considerable augmentation of the lachrymal secretion upon irritation of the gasserian ganglion. Eckard, on searching for the nerves which supply the mammary gland, recognized as such the glandular branches of the lateral thoracic nerve, which runs along the axillary border of the pectoralis major muscle, between the fourth and sixth intercostal space, and besides, one or two extremely delicate filaments, variable in their origin, which accompany the large vessels. Having divided all these nerves in a goat, he observed no modification in the lacteal secretion; but he lacked the more important experiment of irritating these nerves. The section of the glandular nervous trunks does not destroy the excitability of the peripheral nervous extremities for all causes of irritation, as long at least as these extremities are not atrophied.

It is believed, then, "that there are small ganglia in the midst of glandular substance designed to establish relations between the nerves of sensibility and those of secretion." As a proof of the influence of the nerves upon the secretion of the gastric juice, it has long been claimed that the gastric juice is never secreted except in consequence of some irritation. This idea has been confirmed by the experiments of Bernard, Blondlet, and Panum. Bernard, from his experiments, concludes that the pneumogastric serves only to transmit an irritation to the medulla, after receiving itself from the lung; that it is the medulla that really presides over saccharine secretion; and that the great sympathetic is the agent by which the medulla acts upon the liver.

Dr. Samuel says, among medicines, we have a great many having a specific action in augmenting and diminishing certain secretions. The well-known action of Mercury and Delphinine in salivation may be regarded as among the most generally acknowledged and best demonstrated facts in the whole of anthropology. May not the resolvent action

VOL. II.-17.

of Mercury (and also of Iodine) upon ganglionic lymphatic tumors be attributed by analogy, with what has been observed by Ludwig and Krause, to an irritation of the nerves which preside over the elaboration of the lymph, and to the movement of this fluid in the interior of the canals, &c.

1. HYDROPS.-DROPSY.

GENERAL DESCRIPTION.-Dropsy is generally but a mere symptom of some other affection. Its proximate cause consists in an inflammation, congestion, or exalted action of the capillary extremities of the arterial vessels of the serous and cellular membranes, and a torpor or inactivity of the venous absorbents of the same parts.

The remote and general causes of dropsy are excessive loss of blood and other animal fluids; general debility, resulting from disease, mechanical injuries, obstructions of the liver, spleen, kidneys, veins, lungs; abuse of drugs and stimulating drinks. At first view an inflammation or congestion of the serous exhalents would seem to be incompatible with general debility, arising from excessive loss of blood, and diseases of the liver, kidneys, lungs, spleen, &c., but the fact is now well established that these circumstances actually favor the formation of these very capillary inflammations and congestions.

Some writers maintain that serous effusions do not occur until the active inflammatory symptoms are passing off, and a state of sub-acute inflammation obtains; while others, like Laennec and Johnson, lay it down as a fundamental law of serous membranes, "that they begin to effuse the moment they become inflamed." It is true that acute inflammations of serous membranes often occur and subside without leaving any traces of effusion, but this is owing to the fact that, during the general febrile excitement, the venous absorbents of the affected cavities, being equally irritated with the exhalents, exercise their functions with preternatural activity, thus conveying off the fluid as fast as exhaled, and securing the equilibrium between exhalation and absorption. After the inflammatory symptoms have subsided, if the exhalents and absorbents both recover their tone, health returns; but, as frequently happens, if the latter remain feeble, while the former return to their normal state, the healthy balance is lost, and dropsy is the result. In health, "the cellular tissue, and all of those cavities lined by serous membranes, are continually lubricated by a fluid which exhales from capillary extremities of the arterial vessels." (Frank.) This fluid serves to render the parts soft, pliable, and mobile, and to prevent the adhesive inflammation which would otherwise occur from friction during the movements of the body. These exhalents give out nearly a given quantity of vapor, and a due equilibrium is established

between the amount secreted for the use of the organism and that which is afterwards taken up by the venous extremities, and thrown off by the skin, kidneys, salivary glands, and intestines. So long as this proportion is maintained, all goes on well; but whenever any of the serous membranes, like the peritoneum, the pleura, the pericardium, or the arachnoid, secrete more fluid than is required for the wants of the economy, or than can be absorbed by the venous extremities, then drafts are made upon other and healthy parts to supply the increased demand. On this account the perspiration becomes suppressed and the skin dry and husky, the saliva scanty and viscid, the urinary secretion small, high-colored, foetid, and sedimentitious, the stools scanty and difficult, and the functions generally deranged.

In cases of dropsy, arising from excessive loss of blood or starvation, the normal physical condition of this fluid is changed,-the impression it produces upon the structures is altered, and a superabundance of serum is poured out into the cavities and the cellular tissue. This increased exhalation may be due either to the greater affinity which the serous membranes exert upon the altered blood, or to an irritation of the capillary extremities which induces an exaltation of their exhaling function. The experiments of Matteucci teach us that different fluids pass through the animal membranes in definite quantities, and with certain degrees of rapidity, according to the character of fluids used, and the condition of the tissue operated upon. These different phenomena are termed endesmose and exosmose; and it is by no means improbable that some varieties of dropsy may be partially dependent upon this peculiar action.

Another very important circumstance connected with the formation of dropsies is alluded to by Eberle. "I have," says he, " already observed that immediately after a profuse loss of blood, absorption goes on with unusual activity. The blood-vessels are rapidly replenished with crude fluids: for the absorbents being extremely active, nearly all the aqueous fluids received into the stomach are speedily absorbed into the circulation; and, this is especially favored by the very great thirst which almost always occurs after excessive sanguineous losses. The blood being thus inordinately supplied with a crude and watery fluid, becomes more irritating to the heart and capillaries, and diluted to such a degree as to pass off more rapidly by the exhalents." (Practice of Medicine.)

Direct experiments on animals have proved that artificial dropsies may be produced by abstracting blood and drenching them with water. On the other hand, Magendie and Matteucci have equally demonstrated that a fullness of the blood-vessels very materially retards, and in some instances entirely suppresses, the function of absorption.

We think, then, it may be safely concluded that in every case of dropsy there are two simultaneous morbid conditions present, namely, increased exhalation and decreased absorption; and that, although irritation and congestion of the exhalents are generally indispensable conditions to this morbid action, yet that effusion may result in certain cases simply from an alteration in the character and quantity of the blood by endesmose.

Dropsies are acute or chronic, primitive or secondary, simple or complicated; and the character of the effusion is dependent upon the age, sex, and constitution of the patient, and the nature of each particular case. Generally, however, the fluid is composed of albuminous matter dissolved in more or less water, with different phosphates and carbonates and a little sulphur, (Frank,) of an oily character-of a citron, orange, or straw color; and of consistency semi-gelatinous, or like the white of eggs. But these appearances are sometimes subject to variations, as cases are reported in which the liquid was brown, white, green, purulent, bloody, saccharine, urinous, in some instances containing substances like hydatids and bits of membrane.

ance.

Much light is sometimes thrown upon the nature and causes of dropsy by an examination of the urine. In certain cases of anasarca, for example, it is found that the urine coagulates on the application of heat, and from this circumstance we may suspect the existence of the disease so ably described by Dr. Bright under the name of granulated kidney. The application of heat in these cases, first causes the urine to become milky, and afterwards to present a curdled or flaky appear "In hydrothorax following scarlatina, the urine is mixed with cruorine; in hydrothorax depending upon degeneration of the spleen and liver, the urine contains a large quantity of urea and uric-acid, rosic-acid and purpurate." (Hartmann.) In acute dropsies the effusion does not occur until the active inflammatory symptoms are passing off and a condition of sub-acute inflammation supervenes. In these cases, also, the exhalation takes place with more rapidity, and is attended with more painful symptoms, than in the chronic varieties. Now and then slight accumulations take place which remain stationary for years, when they entirely disappear, or the morbid condition of the exhalents returns, and the disease advances to its full development. Instances of this description are often observed in hydrocele, and in ovarian dropsy.

An excellent diagnostic arrangement of the dropsies has been made. by Marshall Hall, founded upon their causes, viz:

"1. INFLAMMATORY DROPSY.

"First. The History.-This form of dropsy generally takes place rather suddenly, and is to be traced to exposure to wet and cold."

"Second. The symptoms consist in the appearance of diffuse, tense anasarca, generally with dyspnoea, and frequently with the signs of effusion into the head, thorax, or abdomen, and with a coagulable, and occasionally a sanguineous condition of the urine."

"Third. The morbid anatomy varies according as the dropsy is confined to the cellular membrane, or extended to the serous membranes; in the latter case there is frequently the effusion of coagulable lymph, as well as of serum, from the serous surfaces. The kidneys, in protracted cases, become disorganized, granular, scabrous, &c."

"2. EXANTHEMATOUS DROPSY.

"First. The History.-This form of dropsy succeeds to some exanthematous diseases, but by far most frequently to scarlatina." "Second. The symptoms are similar to those just detailed as designating inflammatory dropsy; there is the same disposition to effusions into the brain, thorax, and abdomen."

"3. DROPSY FROM EXHAUSTION.

"First. The History and Symptoms.-This form of dropsy is known by being traced to the loss of blood. It occurs in the form of anasarca, and of effusion into the cavities. I do not know whether the urine be coagulable."

"Second. A similar form of dropsy is induced in cases of neglected chlorosis."

"4. DROPSY FROM DEBILITY.

"First. The history and symptoms sufficiently establish and distinguish this form of dropsy. The patient has frequently had returns of dropsical affections, and has a pale and cachectic appearance. The urine coagulates into brownish flakes by exposure to heat."

"5. DROPSY FROM OBSTRUCTION IN THE FLOW OF VENOUS BLOOD.

"This form of dropsy arises from—

"First. Diseases of the heart, especially of the valves. "Second. Disease of the lungs.

"Third. Disease of the liver, especially of the 'cirrhose. "Fourth. Pressure on, or disease of the veins themselves. "The History and Symptoms.-This kind of dropsy is distinguished by ascertaining the seat and nature of the original disease. Like the rest, it assumes the form of anasarca, and of effusion into the serous cavities, and into the cellular membrane of the internal organs, as the lungs, intestines. &c. The urine is not coagulable.”