The table, as Dr. West remarks, shows not only that the liability of certain organs to become the seat of tubercle, is different in childhood from what it is in the adult; but, also, that tubercle is simultaneously deposited in a greater number of organs in the young than in the old.

CANCER.

Malignant disease of the lungs is not a common disease. Mr. Adams's research has, however, shown that it occurs more frequently, both as a primary and as a secondary affection, than was supposed to be the case by Bayle, who, in 900 subjects examined, only once met with cancerous growths in these organs. Both Laennec and Bayle only found the medullary variety; other forms have since been met with, but the encephaloid is that which vastly preponderates. Hasse has seen an instance of colloid cancer; in the Reports of the Pathological Society of London for 1849-50, a case of primary fungus hæmatodes of the lung is Fig. 198.

Infiltrated cancer of the lung, with its microscopic elements. The lighter part is that containing the deposit; it was of a brownish-red tinge, and of greater density and hardness than the unaffected parts. It occurred in the right lung of a young woman, aged 34, whose right bronchus was surrounded with a mass of medullary cancer; the right kidney also contained a large growth of the same kind, and the 11th dorsal vertebra, especially its right side, was extensively destroyed by the same disease.

detailed by Mr. Adams. The only fact by which it appears that we may determine the primary or secondary character of the deposit, is the circumstance of the lungs either being the sole, or, at any rate, the

chief seat of the disease. It is stated by high authorities, that the former always assumes the infiltrated character, while the latter appears exclusively in nodules or isolated tumors scattered through the lungs. This distinction cannot, however, be rigidly maintained. The pulmonary texture entirely vanishes in the malignant growth, while the surrounding tissue is compressed and its functions interfered with. The neighboring lymphatic glands are invariably involved in the degenerative process. With regard to the parts of the body from which cancer spreads to the lungs, Hasse remarks "that the bones and testicles appear to furnish the most frequent starting-point; and numerous examples tend to show that surgical operations for the removal of cancer in those parts, are very speedily followed by its transition to internal organs. Many instances are adduced in which the skin and the mammary glands, the uterus, the liver, the membranes of the brain, were first assailed. I have seen a very remarkable instance consecutive to primary cancer of the submaxillary gland. On the other hand, cancer, in organs whose veins are tributary to the portal system, does not appear to spread to the lungs, although it is known to lead very often to corresponding disease of the liver." To this we would add that malignant disease, occurring in the mediastina, as it frequently does, does not appear to possess a great tendency to affect the lungs. We often see large masses of cancerous growth occupying these parts, and, perhaps, causing death, as well by suffocation as by exhaustion, without a trace of malignant disease in the lungs, although there is proximity of tissues as well as an intimate relation by the blood vessels. The only case of the pancreatic variety, to use Abernethy's apt designation, that has lately fallen under our observation, entirely filled the upper part of the anterior mediastinum, and infiltrating the pectoral muscles of the right side without affecting the lungs, otherwise than by pressure. A good instance of reticular carcinoma of the posterior mediastinum was exhibited by Dr. Jenner, at the Pathological Society of London,' which, however, slightly encroached upon the root of the lung; we had an opportunity of examining it, and could, therefore, confirm the fact of the reticular character. Neither of these varieties has been seen to occupy the pulmonary texture. Whether the peculiar functions of the lung influence the nature of the deposit, or whether this depends upon some other cause, there is no evidence to show.

A law universally adopted, and one that appears perfectly consistent with the inherent tendency to endogenous multiplication in cancer, and the absence of this character in tubercle, is, that the cancer does not coexist with tubercle. We do not wish to assert that there are no exceptions from the rule; but they are so rare, and in those instances on record the diagnosis generally admits a reasonable doubt, so that the law is in no way invalidated.

In connection with cancer, we have to allude again to an excessive deposit of carbonaceous matter in the lungs; when this is the case, we have to deal with what Carswell has termed melanoma. The excessive secretion from the blood of black pigment accompanies the normal pro

See Reports, 1851-52, p. 253.

cess of involution, tubercular disease and cancer; and, as we have already had occasion to observe, appears to be mainly due to the interference with the oxygenation of the blood. Carswell himself admits the complication of true melanosis with fibrous, carcinomatous, and erectile tissues, and since it does not in itself offer any characteristic features which would serve to establish its pathological identity as an independent formation, we are justified in regarding it rather as an accidental addition than as an essential constituent of a physiological or pathological tissue.

CYSTS.

The formation of cysts in the lungs is of rare occurrence and perfectly latent, so that they are not discovered until after death, unless they excite irritation; they may then find their way into the bronchi and be expectorated. They occupy the lower lobes of the organs; they consist themselves of a double membrane of a clear pellucid appearance, which, under the microscope, present an homogeneous, delicately laminated structure. The lamina form parallel lines, so as to resemble the pages of an open book. The pulmonary tissue adjoining the cyst is covered by a dense membrane, so that, although entirely surrounded by the pulmonary parenchyma, there is not in reality any real intimate relation with it. They generally contain a limpid fluid, and present an endogenous development of hydatids of the same character as the parent cyst. They vary in size, but an instance which occurred to us of an acephalocyst, sufficiently capacious to contain a hen's egg, must be looked upon as unusually large. It neither contained secondary hydatids nor echinococci. A unique case of cysts in the lungs, filled with air, is quoted by Hasse.1

1 Pathological Anatomy, Syd. Soc. Ed. p. 337.

28

CHAPTER XXXI.

PLEURITIS.

THE serous sac inclosing the lungs and serving to facilitate the movements of respiration, is more prone to morbid affections than any other serous membrane; of these, inflammation is the most frequent, and one that arrests the physician's attention very commonly both in the patient and in the dead subject. Some of the products of inflammation were formerly set down to physiological causes, owing to their being frequently met with in individuals whose histories did not give evidence of pleuritic inflammation having occurred in the course of their life. But the inference is not just, because even in severe pleurisies the symptoms are not necessarily of a character to attract the patient's attention, and most persons are familiar with the occurrence of occasional pains, of a not very enduring character, which may be accompanied by some effusion, though not of sufficient intensity to interfere with the function of respiration. The great frequency of the concurrent inflammation of the pulmonary tissue and its investing membrane, has given rise to a frequent misapplication of the term, and to a variety of theories in reference to the cause of pleurisy. So distinguished an author as Portal attempted to prove that pneumonia was not essentially different from pleuritis; but since the more careful prosecution of morbid anatomy, and the clearer distinction of symptoms during life which we owe to auscultation, no doubt exists that the two, though often associated, differ in their symptomatology as they do in their etiological and pathological relations.

The first stage of inflammation of the pleura is manifested by the appearances of greater or less congestion, causing a multitude of vessels, not visible in the perfectly healthy pleura to the naked eye, to become filled with blood; a marked distinction may sometimes be observed between the venous and arterial channels, as exhibited in the different colors of the two systems. The vessels form an irregular network, and the more intense the inflammatory condition, the more uniform the redness becomes. At times, we find the character of the congestion to be more punctiform, and to resemble, as Laennec has it, an attempt made to dot over the pleural surface with a paint-brush, with small spots of blood of an irregular shape, and closely approaching one another; it is probable that in many cases this appearance is due, not to the peculiarity of the disease, but to a partial emptying of some vessels as a postmortem effect. The membrane, at the parts most affected, soon loses its natural transparency and gloss, in consequence of a secretion from

the overcharged vessels investing its surface with a coating of lymph or fibrin, a straw-colored semi-gelatinous effusion which may be easily

Straw-colored lymph, coating the lower lobe of an inflamed lung, in recent pleurisy, before there was a trace of adhesion to the costal pleura. The outline represents one of two coils of new vessels, seen under the microscope in the fringe of lymph at the lower end.

Fig. 201.

stripped off from the serous membrane. The microscopic appearances of this fibrin are delicate linear fibrillæ, of a generally parallel direction, enveloping and entangling the granular and corpuscular forms observed in fibrinous exudation. We very rarely meet with cases of what Andral has termed dry pleurisy, as the effusion is a rapid sequel of the first stages of inflammation; but we frequently have an opportunity of observing a limited plastic exudation at one point, while the greater part of the remaining pleura or its fellow may exhibit the first stage of the disease. In the recent cases of sthenic inflammation, the effusion presents the appearance of a thin layer of thick cream, which, at the most dependent parts, seems to be dropping from the organ. The older the effusion, the more it assumes a membranous character, the friction and compression to which it is subject giving to it an irregularly the contact with the liquid, and there was honeycomb or cellular appearance, or causing it early to put on a filamentous or mossy form. The plasticity of the effusion is in a ratio with the plastic character of the blood; hence, it does not always present the characters just described, but varies much in cohesion, in color, and quantity, accord ing to the constitution of the individual attacked, and according to the

Portion of the lower lobe of the left lung

of a patient, compressed by turbid serum, occupying the pleural cavity. A thick

layer of lymph covered the hepatized portion of lung; it was perfectly smooth from

a free scalloped margin at some parts, of an inch in breadth. The exudation-matter consisted of filamentous matter, entangling corpuscular fibrin.