REVIEW III. 1. Etudes sur la Tuberculose. Par J. A. VILLEMIN. Observations on Tuberculosis. By J. A. VILLEMIN. Paris. 1868. Pp. 610. 2. Die Krankhaften Geschwülste. Von RUDOLPH VIRCHOW. Einundzwanzigste Vorlesung. Band. II. Hälfte II. On Tumours. By RUDOLPH VIRCHOW. Twenty-first Lecture. Vol. II. Part II. Berlin. 1864. Pp. 555-749. 3. The Nature and Affinities of Tubercle; being the Gulstonian Lectures for the Year 1867. By REGINALD SOUTHEY, M.D. London, 1867. Pp. 118. 4. Sulla Struttura dei Tubercoli prodotti per Inoculazione. Nota del Dottor Giulio Bizzozero. Remarks on the Structure of Tubercle produced by Inoculation. By Dr. JULIUS BIZZOZERO. Milan. 1867. Pp. 10. 5. Beiträge zur Experimental-Pathologie. Von Dr. LEBERT und Dr. OSCAR WYSS. Contributions to Experimental Pathology. By Dr. LEBERT and Dr. OSCAR WYss. Virch., Archiv., 1867. Pp. 142-170; and 532-580. 6. Lecture on the Artificial Production of Tubercle, at the Royal College of Physicians. By WILSON FOX, M.D. THE history of tuberculosis has been so recently and so fully related in the pages of this Journal, that a renewal of the subject might, for the present, well seem to be unnecessary and superfluous: but the original observations by Virchow on the anatomy of tubercle, and the close affinity that it has to other kindred discases; above all, the remarkable views concerning its causes and nature lately put forth by Villemin, and endorsed by other trustworthy observers, furnish abundant and most important material for another review. That which will chiefly force itself upon the attention of any one who will refer to the list of books here introduced to notice, is the fact that the very groundwork of our pathology is rapidly undergoing a complete transformation. It requires no prophetic spirit to predict the extinction of those humoralistic doctrines of plastic exudation and crasis with which we were as students imbued, so completely are they becoming supplanted by the teachings of the new cell-pathology. We see a pathologist of Lebert's fame enunciating cellular doctrines as a matter of course. Southey, an ardent admirer of Virchow, puts forth in an agreeable English dress for English readers the teachings of the great Berlin master. Bizzozero's writing breathes of them from the first to the last page of his pamphlet. But, most remarkable of all, a Frenchman, Villemin, and the French have been notoriously the last and the least inclined to accept Prussian authority-not only builds up the first part of his excellent book on the strictest precepts of cellular pathology, but shows by his writing that he has been led by a contemplation of this new pathology to the discovery that he has made. We purpose first to give a short account of tubercle, its birth, life, and death; secondly, to inquire into the marks of relationship that it bears to other kindred diseases, as scrofula, glanders, syphilis, typhoid fever, cancer; thirdly, to discuss the influence of supposed causes in its production; fourthly, to make mention of the lower animals in which it is naturally met with; fifthly, to enumerate the experiments that have been made to show its capability of communication from man to the lower animals, and from one animal to another, by means of inoculation; sixthly, to examine the arguments that have been drawn from these experiments, and from other facts, in favour of its communical lity by contagion from man to man, and to endeavour to show how far we are justified, in the present state of our knowledge, in accepting any such conclusions on this most engrossing subject, all-important as it is for the welfare of mankind. It may, perhaps, be well, before proceeding with our subject, to say a few words against the tendency, which has long and much prevailed, to regard diseases as strange entities, or to confound disease itself a complication of effects produced by certain causes in the tissues of the body-with the causes of disease. Thus fallaciously guided, the student of biology, instead of being led step by step up a gradual ascent from the study of physiological to that of pathological processes, is made to spring over a wide gulf into a new and strange land. The truth is, that we pass by a scarcely perceptible transition from the phenomena of healthy nutrition to hypertrophy, inflammation, tubercle, tumours, fevers, and other forms of perverted nutrition or disease. A hypertrophy may be an excess of healthy nutrition, or it may be what we call disease; this distinction being not one whit founded on intrinsic differences, but being an arbitrary distinction of our own according to the usefulness or harmfulness, as observed by us, of the changes which take place. We see a blacksmith's arm enlarge as he works at his forge, and we see a thyroid or a cervical gland enlarge from some cause which we cannot so clearly appreciate. We examine the condition of the tissues in both, and we find in both alike what we call hypertrophy or hyperplasia. The ele mental increase in both is identical, but we call the one "healthy action," because we see why it occurs and what a useful purpose it subserves; while we denominate the other "disease," because we cannot see its purpose in the economy, and therefore regard it as hurtful. From hypertrophies to tumours is but another mere step or shade of gradation. Between certain tumours, in their early stage, and products of inflammation, no distinction can be made and we shall hereafter see how identical in their structure are tubercles with products of inflammation on the one hand and certain tumours on the other. Hence, from the merest hypertrophy up to the most aberrant form of tumour, disease is nothing more than an unusual activity or perversion of the very changes which are ceaselessly going on in the nutrition of the body, and which constitute what we understand by the life of the individual. Perhaps nowhere is the birth of tubercle better studied than in the pia mater of a person who has died of acute tubercular meningitis. A piece of this membrane, spread out and examined under a moderately high power of the microscope, is found to be the seat of an extraordinary cellular increase. The cells and nuclei which mark this increase or proliferation are seen part scattered profusely and at random through the membrane, giving it the well-known milky appearance that it offers to the naked eye, part clustered into little whitish or grayish knots or particles-the individual tubercles. A close scrutiny of these latter will show that they are especially abundant along the smaller branches of the cerebral arteries, and seem here to take their origin in the cells of the connective tissue which composes the adventitia or outer coat of these blood-vessels. So markedly is this the case that, although the tubercle cells must be allowed to arise from the connective-tissue-cells of the membrane generally, yet the adventitia appears to be certainly the part most actively concerned in their development. The tubercle-cells generally are rather smaller than a white blood-cell, have faintly granular contents, and are very brittle, so as very readily to rupture and set free their shining nucleus. Towards the border of the tubercle are seen cells larger than the above, often containing many nuclei, and manifestly representing connectivetissue-cells in a state of active hyperplasia or tubercular development. In and among the cluster of cells which compose the tubercle is a faint stroma, the original connective tissue, together with, occasionally, blood-vessels, not newly formed, for tubercle is non-vascular, but belonging to the tissue in which the tubercle arises. Very much the same appearance is obtained from fine sections of liver or kidney, and from serous membranes affected with tubercle, the connective tissue in all cases serving as the matrix for development. In the lungs, wherever connective tissue is to be found there may tubercles be present but whether tubercle may also be developed out of the epithelium lining the alveoli and grow inside the air-cells, is a point on which we find our authors at issue. Virchow denies that the little deposits found inside the air-passages and aircells are tubercles. For him these are mere products of inflammation or catarrh which choke up the small bronchi and, on section, so closely resemble tubercle proper that they may be called "spurious tubercle." He professes himself able to distinguish between these spurious tubercles and the true tubercles of the connective tissue, a distinction which, if it be real, must require unusual skill and assurance to make. Villemin, on the contrary, maintains that there are positive intravesicular tubercles, which are no more the products of catarrh than the extravesicular. Careful microscopical observation enables him to assert, that the fine wall which partitions off the air-sacs from one another is not a homogeneous membrane, but encloses in its substance a cellular element peculiar to itself. Under a high magnifying power a beautiful network of capillaries is seen covering this wall, between the meshes of which network he can detect a cellular element occupying nearly the whole of each open space. There is, he asserts, no epithelial lining to the alveoli, but the tubercles are formed out of the above cells, and grow into the cavities of the air-sacs, filling them up. Lebert, again, believes that pulmonary tubercles or granules, as he calls them, take origin indifferently in the cells of the connective tissue or in the epithelium of the alveoli, being both intra- and extra-alveolar. If, he says, you call the little particles outside the alveoli tubercles, you must call those that are within likewise tubercles. They are all a part of the same disease, a result of the self-same irritant. Bizzozero likewise holds that the little intra-alveolar masses which accompany tubercle are really tubercles and spring out of the epithelium that lines the alveoli. In the case of the lymphatic and ductless glands, Virchow, though he alludes on more than one occasion to the closeness of the link which binds the connective tissue with the lymphatic system, yet insists that it is in the connective-tissue-framework of these glands, not in the gland-cells, that the tubercles originate. But Villemin, looking at the connective tissue and lymphatics as parts of one great system, which he designates the lymphatico-connective system," believes that tubercle may originate both in the cells and in the connective tissue of the lymphatic and ductless glands. Hence, in tubercular disease of these organs, the microscope cannot of itself distinguish tubercle from simple hyperplasia, inasmuch as elements identical with those already existing in health are simply reproduced in excess. It is, consequently, a matter of extreme difficulty, nay, in some cases impossible, to say whether a given change in one of these glands is simple hyperplasia or tubercle. This question, then, must remain for the present an open one. That tubercle originates mainly in the connective tissue is the expressed opinion of all these modern authors. That it may also find a nidus of development in epithelium and gland-cells is probable, but not yet clearly determined. Tubercle has the shortest life of any pathological product; it is born but to die. Hence its power of growth is exceedingly limited, and its hurtfulness, when solitary, but small. Herein, however, consists its deadliness-that it is the expression of a general disease; that the same cause which produces it is circulating through the body, and may produce thousands similar to it wherever connective tissue is present; and that it has, as Virchow was the first to point out, manifestly malignant properties, spreading to the tissues in its neighbourhood and infecting distant organs by dissemination of its germs or juices. Thus, though there is a marked limit to the size of the individual tubercle, there is no limit to the size of the masses that are formed by agglomeration of tubercles, or to the number of tubercles which may be scattered through the body. Do we not see in these properties something that reminds us of the outbreak of an eruptive fever, and something, too, that recalls the behaviour of cancer? An early tendency to die is, then, the most characteristic and distinguishing mark of tubercle. Fatty degeneration, beginning first at the centre of the knot, gradually spreads to the circumference, and gives it the well-known yellow colour from whence the name of "yellow tubercle" is derived; till, little by little, the whole particle softens and breaks down into a cheesy granular débris. We have, therefore, but to picture to ourselves a large cluster of tubercles passing through this change in the midst of some organ, as the lung or the kidney, in order to understand what wholesale devastation may be thus wrought, and how a cavity or "vomica" may be formed, in which are contained the remains of the softened tubercles, and of the broken-down tissue involved by the tubercles in destruction. On the other hand, if the part diseased be a free surface (as a mucous membrane), the disintegration and softening of the tubercular mass will give rise to the formation of an ulcer which differs from the ordinary process of ulceration by the fact that the base and sides of the ulcer are walled in by the remaining tubercular matter. |