Origin,-A modification of secretion.
Locality,-1st, Tissues, systems, and organs;

a, In the substance and on the surface of
b. In the cavities of hollow organs.

2d, New formations.

Form,-1st, Punctiform,

2d, Tuberiform,

3d, Stratiform,

4th, Liquiform.

Seat,-1st, Molecular structure of organs,

2d, The blood.

organs,

As there are other morbid states of the system and products presenting distinctive characters, similar to those of melanosis, Dr. Carswell has also given us a tabular view of what he calls spurious melanosis, in distinction from the true. The following is his arrangement.

Origin,-A, Introduction of carbonaceous matter,

B, Action of chemical agents,

C, Stagnation of the blood.

Locality,-Of the first kind, the lungs.

Of the second kind, the digestive organs, the surface of serous and mucous membranes, the cavities of hollow organs, new formations.

Form, Of the first kind, uniform.

Of the second kind, 1st, punctiform, 2d, ramiform, 3d, stratiform, 4th, liquiform.

Of the third kind, 1st, punctiform, 2d, ramiform. Seat,-1st, The blood, contained in its proper vessels, or effused, 2d, Pulmonary tissue, cellular, and membranous.*

Persons, suffering this affection, sometimes discharge a dark and almost black secretion from the intestines, the stomach, and even the cystis. Under these circumstances, the old authors termed the disease melona-the black disease. The morbid secretions, in all these cases, are evidently melanotic; and, aside from the natural secretions with which they are mixed, are scentless and tasteless.

"See Cyclopedia of Practical Medicine, Volume 2d, Page 86th.

The pathology of this disease is not yet, it is true, fully understood. The melanotic discharge, however, so far as it has been analyzed, is found to contain the important elements of the blood, -fibrine, albumen, &c.; but, in addition, nearly one third of the quantity is a highly carbonized and abnormal substance.

That the disease is one producing general and decided debility will readily be inferred from the few hints given above, respecting its pathology. The depraved condition of the blood, of course, renders it, at best, an inadequate stimulant to the nervous system; but, especially, when the alvine and other discharges are melanotic, the nutrient and stimulating portions of the blood are abnormally removed, in such quantities, as greatly to exhaust the vital powers.

In conclusion, I will only add, that various new formations, such as tubercle, carcinoma, and melanosis, may exist simultaneously in the body and in the same organ; yet each is as distinct in its nature, as are the influences by which one organ is atrophied another hypertrophied, one indurated another softened, at the

same time.

CHAPTER XIV.

NON-MALIGNANT TUMORS.

Tumors in general differ from hypertrophy and euplastic deposits in the peculiarity of their structure, or their kind of vitality. They differ from cacoplastic and aplastic deposits in their possessing a higher degree of organization, that is, their degree of vitality. They are new structures; though some of them, in general characters, and most of them, in elementary composition, have a resemblance to healthy textures.

Tumors may be divided into malignant and non-malignant. The various forms of carcinoma, already generally considered, constitute essentially the class of malignant tumors. The nonmalignant may be sub-divided into different classes, though it is difficult or impossible to draw a clear line of demarcation between some of these classes.

NON-MALIGNANT TUMORS are, in general, those growths which occur in any part of the body without tending to infect other parts, which, though arising among, yet do not invade the healthy structures, and which prove injurious only by their bulk, their position, or their obstruction of the nourishment of the body. The principal portion of them may be included in one or the other of two classes.

The first of these classes is that of common encysted tumors. These tumors consist of a shut sac, containing either a liquid or a solid substance. The sac is formed so as to appear like areolar tissue condensed, or like serous or fibrous tissue. The liquid contents may be serum, blood, or pus, or a mixture of different ingredients. The solid contents may be either adipose, or fibrous, or sarcomatous, or cartilaginous matter; or they, too, may be of a mixed character, and may possess various kinds of structure. The solid contents, and the sacs of the tumors in the cases of both the solid and the liquid contents, are formed by altered vital properties in the cells, or primary granules, or some of the molecules of the textures, in some state of their progression. These molecules grow in modes more or less peculiar, and under influences more or less independent of the adjoining healthy parts.

The second of the two classes of non-malignant tumors referred to is that of hydatids. These, in character, approximate malignant tumors, in some respects. They are quite detached from healthy tissues, and are, perhaps, more peculiar, in structure and contents, than any other morbid growths. They seem to possess a vitality, in themselves and independent of the parts with which they are physically connected. That vitality, it is true, is of a low grade, but is real. They have a power of self-nutrition, manifest in the growth and structure of their walls;-a power of secretion, shown by the peculiarity of their limpid and colorless contents; and a power of reproduction by gemmation, the young being developed between the layers of the parent cyst, and thrown off, either internally or externally, according to the species. According to Professor Owen, the hydatid is "an organized being, consisting of a globular bag, which is composed of condensed albuminous matter, of a laminated texture, and containing a limpid colorless fluid, with a little albuminous, and a greater propor

tion of gelatinous substance." Whether, however, it is an animal or a vegetable, the Professor is slow to decide. But, surely, it can scarcely be considered an animal, as it neither feels nor moves. It has no contractile power, and is impassive under the application of stimuli. It evidently has nothing but organic or vegetable life; and it grows in the system, as the plant grows in the earth. It is, however, a nucleated cell, from the interior of which are developed nuclei and nucleoli, the germs of young cells; and, whether animal or vegetable, it would seem, that it must be, in its origin, an offset from healthy structure. Certain molecules, in a way not understood, must, at first, assume this abnormal form and detached life.

Hydatids are found in the lungs, liver, spleen, kidneys, uterus, and even in the mammæ. Their serous or protective cysts are formed much like those of common encysted tumors. Their existence supposes a state of cachexia or mal-nutrition in the system. They injure the system and destroy the health, by their bulk and position, by their compressing, displacing, and irritating some of the organs, and by the atrophy and inflammation of textures which they cause. Their cysts contain laminated matter more or less opaque, which is evidently the debris of collapsed hydatids; and, with this, sometimes a quantity of yellowish, opaque, pultaceous matter, consisting of granules, imperfect cells, fat, and other substances, deposited from the surface of the sac and degenerated so as to be aplastic.

Among non-malignant tumors have, also, been reckoned those which are vascular or erectile. These consist of a congeries of blood-vessels of considerable size, apparently enlarged capillaries, with more or less connecting filamentous tissue. Their structure, however, or their kind of vitality does not seem to be materially different from that of euplastic deposits. When they are supplied by large arteries, they are florid in color and pulsate, and, if themselves large, give a bellows or rasping sound with the pulsation, like what is heard in bronchocele or goitre. When the arterial communication is not free, they exhibit the darker hue of venous

blood.

There are various other modifications of non-malignant tumors, the consideration of which is not necessary to my present purpose.

DIVISION II.

DIAGNOSIS.

Diagnosis is originally a Greek term, diayvasis, signifying the art of distinguishing or discerning. Medically applied, however, it imports either a discriminating acquaintance with disease, or the science which gives that acquaintance.

As a science, diagnosis teaches the various methods of detecting existing pathological conditions. In other words, it illustrates the phenomena attendant on the different forms of disease. These phenomena may be general in their character, or special; they may be constitutional or local; they may disclose themselves only to the patient, or they may be manifest to the senses of another.

In what follows, I shall attempt an explanation of such topics as are important in understanding the nature of diseases, and yet are liable to fail of being accurately comprehended. My remarks will apply mainly to diseases of the thorax, though I shall develop the principles of physical diagnosis, in their application generally.

CHAPTER I.

SYMPTOMS.

The symptoms by which the knowledge of disease is gained, may be divided into rational and physical symptoms.

According to this division, the rational symptoms embrace those which we learn through the medium of the patient's mind. Thus, pain or any peculiar sensation, and its locality, are made known to us by the intellectual and communicating faculties of the patient. The physical symptoms, on the contrary, reveal themselves to us, through our own physical senses. By the eye, for instance, we perceive the form and the countenance of dis