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than the abnormal manner in which they arise, and that this abnormity consists either in the production of a structure at a point where it has no business, or at a time when it ought not to be produced, or to an extent which is at variance with the typical formation of the body. So then, to speak with greater precision, there is either a Heterotopia, an aberratio loci, or an aberratio temporis, a Heterochronia, or lastly, a mere variation in quantity, Heterometria. But we must be very careful not to connect this kind of heterology in the more extended sense of the word with the notion of malignity. Heterology is a term that, in its histological meaning, may be applied to a large proportion of pathological new formations, which, as far as the prognosis is concerned, may unquestionably be called benignant; it is not rare for a new formation to occur at a point where it is certainly entirely misplaced, but at the same time does not occasion any considerable mischief. A lump of fat may very likely arise in a place where we should expect no fat, as, for example, in the submucous tissue of the small intestines, but, let the worst come to the worst, the result is only a polypus, which protrudes on the inner surface of the bowel, and may become tolerably large without giving rise to any symptoms of disease.

If we consider the structures which are called heterologous in the more restricted sense of the word, with reference, namely, to the points at which they arise, they may be easily separated from the homologous ones (homceoplastic ones of Lobstein), by their deviating from the type of the part in which they arise. When a fatty tumour arises in fatty tissue, or a connective-tissue (fibrous) tumour (Binder. gewebs-Geschwulst) in connective tissue, the type followed in the formation of the new structure is homologous to the type followed in the formation of the old one. All such formations are, as usually designated, included under the term hypertrophy, or under that of hyperplasia, if we

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adopt the name I have proposed for the sake of more accurate distinction. Hypertrophy, according to the meaning which I attach to the word, designates those cases in which the individual elements of a structure take up a considerable amount of matter, and thereby become larger; and in which, in consequence of the simultaneous enlargement of a number of elements, at last the whole of an organ may become swollen. When a muscle becomes thicker, all its primitive fasciculi become thicker. A liver may become hypertrophied simply in consequence of a considerable enlargement of its individual cells. In this case

Fig. 27.

[graphic]

there is real hypertrophy without, properly speaking, any new formation. Essentially different from this process are the cases in which an enlargement takes place in consequence of an increase in the number of the elements. A liver, namely, may also become enlarged by a very abundant development of a series of small cells in the place of the ordinary ones. Thus, when simply hypertrophied, we see the panniculus adiposus of the skin swell up in consequence of every single fat-cell's absorbing a larger quantity of fat than usual, and when this takes place in thousands upon thousands, nay, we may say, in hundreds of thousands and millions of cells, the result is very obvious and strikes the eye (polysarcia). But it is just as possible for new cells to form in addition to the old ones, and for an increase of size to take place without any enlargement of the individual cells. These are essentially different processes, and may be styled simple and numerical hypertrophy.

Fig. 27. Diagrams of hepatic cells. A. Their simple physiological appearance. B. Hypertrophy: a, simple; b, with accumulation of fat (fatty degeneration, fatty liver). C. Hyperplasy (numerical or adjunctive hypertrophy). a. Cell with nucleus and divided nucleolus. 4. Divided nuclei, c, c. Divided

cells.

Hyperplastic processes (numerical hypertrophy) in all cases produce a tissue similar to that of the original part; hyperplasia of the liver gives rise to new hepatic cells; that of a nerve to new nerve-substance; that of the skin to a fresh production of the elements of the skin. A heteroplastic process, on the contrary, engenders histological elements which correspond, indeed, to natural forms, elements, for example, resembling in structure those peculiar to glands, nerve-substance, the connective and epithelial tissues, but these elements do not arise in consequence of a simple increase in the number of such as previously existed,but in consequence of a change in the original type of the parent tissue. When cerebral matter forms in the ovary, it does not arise out of preexisting cerebral matter, nor through any act of simple cellproliferation; when epidermis springs up in the muscular substance of the heart, however much it may correspond to that on the external surface of the skin, it is, notwithstanding, a heteroplastic structure. When we find hairs quite natural in structure in the substance of the brain, however great the correspondence they exhibit with the hairs of the external surface, they will nevertheless be heteroplastic hairs. In like manner we see cartilaginous tissue arise, without the existence of any essential difference between it and ordinary, familiar cartilage, as, for example, in enchondromata. Still, an enchondroma is a heteroplastic tumour,

DEGENERATIVE NEW TOEMATIONS. 67

even when occurring in bone, for perfect bone has no longer any cartilage in the parts where the enchondroma forms, and the term cartilage of bone (Knochenknorpel), as a designation for the organic basis of bone, is nothing but a term. It is either from osseous or medullary tissue that the enchondroma springs, and at the very point where real cartilage exists, for example, at the articular ends of the bone, no cartilaginous tumours, in the ordinary sense of the word, arise. It is not, therefore, with an hypertrophy of preexisting cartilage that we have here to deal, but with a genuine new formation, which begins with a change in the local histological type. According to this manner of viewing the subject which is essentially different from that previously current, no attention is therefore paid, in considering the question of the heterologous or homologous nature of a new formation, to the composition of the structure as such, but only to the relations which subsist between it and the parent soil from which it springs. Heterology, in this sense, designates the difference of development in the new, as contrasted with the old, tissue, or, as we are wont to say, a degeneration, a deviation from the typical conformation.

This is, as you will see, also really the most important point upon which we can ground our prognosis. We find tumours, which present the most striking resemblance to the most familiar physiological tissues. An epidermic [epithelial] tumour (Epidermis-Geschwulst) may, as I have already pointed out, in its elementary structure entirely correspond to ordinary epidermis, but in spite of this it is not always a benignant tumour of merely local import, which may be traced to a merely hyperplastic increase in preexisting tissues, for it sometimes arises in the midst of parts which are far from containing epidermis or epithelium, as, for example, in the interior of lymphatic glands, or in that of thick layers of connective tissue, which are at a distance from any surface, and even in bone. In these cases the formation of epidermis is certainly quite as heterologous as it is possible to conceive anything to be. But practical experience has shown us that it was altogether incorrect to conclude from the mere correspondence of the pathological tissue with a physiological one, that the case would continue to follow a benignant course.

It has been, as I must remark with particular emphasis, one of the greatest and, at the same time, best-founded reproaches which have been levelled against the most recent micrographical doctrines,that, regarding the subject from the certainly excusable point of view, namely, the correspondence between manynormal and abnormal structures, theyhave declared everypathological new formation to be innocuous which exhibits a reproduction of pre-existing and familiar tissues of the body. If what I have communicated to you as my view be correct, namely, that throughout the whole range of pathological growths no structure of an absolutely new form is to be found, but that we everywhere meet with structures which may in one way or another be regarded as the reproduction of physiological tissues, then this point of view falls to the ground. In support of my view, I can at least adduce the fact that I have, in all disputes concerning the innocent or malignant nature of definite forms of tumours, up to the present time always proved to be in the right.

Before we quit the consideration of General Histology, I would invite your attention for a few moments to a few points of primary importance which obtrude themselves upon us on nearly every occasion. Whilst, namely, the animal tissues were being studied in their affinities to one another, questions relating to these affinities were at different times stumbled upon, which gave rise to generalizations that were more of a physiological character.

When Reichert undertook to collect the connective tissues into one, larger group, he set out with this position chiefly,

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