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But at a time when the more minute elements of tissues were at most only known as globules, and when very different virtues were attributed to these globules, it was quite excusable that everything should be referred to the vessels, particularly after the comparison John Hunter made between pathological new formations and the development of the chick in the egg, when he endeavoured to shew that, just as the punctum saliens in the hen's egg constitutes the first phenomenon of life, the vessels also were the first things to show themselves in pathological formations. You no doubt still remember how several " parasitical" new formations were described by Rust and Kluge as provided with an independent vascular system, which, without having any connection with the old vessels, developed itself quite independently, as is the case in the chick. Many attempts had indeed been made even before this to refer the apparently so irregular forms of new formations to physiological paradigms, and herein essential service has been rendered by natural philosophers. At the time when theromorphism played a conspicuous part, and many analogies were discovered between pathological processes and the normal states of inferior animals, comparisons also began to be instituted between new formations and familiar parts of the body. Thus, Johann Friedr. Meckel, the younger, spoke of mammary and pancreatic sarcoma. What has very recently been described in Paris as heteradenia (Heteradenie), or a heterologous formation of glandular substance, was in the school of the natural philosophers a pretty generally accepted fact.

Since the study of embryology has been prosecuted in a more histological manner, the conviction has gradually more and more been acquired, that most new formations contain parts which correspond to some physiological tissue, and in the micrographical schools of the west a certain number of observers have come to the conclusion, that in the whole

series of new formations there is only one particular structure which is specifically different from natural formations, namely cancer. With regard to this, the most important points urged are, that it differs altogether from every other tissue, and that it contains elements sui generis, whilst, singularly enough, a second formation, between which and cancerous tissue the older writers were wont to draw parallels, namely tubercle, has-although to it too nothing strictly analogous could be discovered-been much neglected, owing to its having been regarded as an incomplete and somewhat crude product, and as a structure which had never become properly organized. organized. Yet, upon a more careful examination of cancer or tubercle, we shall find that everything depends upon our searching for that stage in their development, in which they are exhibited in their perfect form. We must not examine at too early a period, when their development is incomplete, nor yet at too late an one, when it has proceeded beyond its highest point. If we restrict our observations to the time when development is really at its height, a physiological type may be found for every pathological formation, and it is just as possible to discover such types for the elements of cancer as to find them, for example, for pus, which, if it be sought to maintain the specific nature of certain formations, is just as much entitled to be regarded as something peculiar as cancer. Both of them stand upon precisely the same footing in this respect, and when the older writers spoke of cancer-pus they were in a certain measure right, inasmuch as cancer-juice is only distinguished from pus by the higher degree of development to which its individual elements have attained.

A classification of pathological structures also may be made upon exactly the same plan as that which we have already ventured upon in the case of the physiological tissues. In the first place, there are also among these structures some

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which, like the epithelial ones, are essentially composed of cellular elements, without the addition of anything else of consequence. In the second place, we meet with tissues which are allied to those called connective, inasmuch as in addition to the cells a certain quantity of intercellular substance is present. In the third and last place come those formations which are akin to the more highly organized structures, blood, muscles, nerves, &c. Now, a point to which I must at once direct your attention is, that in pathological formations those elements the more frequently exist, and the more decidedly prevail, which do not represent the higher grades of really animal development, and that, therefore, on the whole, those elements are most rarely imitated which belong to the more highly organized, and especially, to the muscular and nervous, systems. Still, these formations are by no means excluded; we find pathological new formations of every description, no matter to what tissue they may be analogous, provided it possess distinctive features. It is only with regard to their frequency and importance that a difference prevails, and this is of such a nature that the great majority of pathological productions contain cells analogous to epithelial cells, or to the corpuscles of the connective tissues, and that of those structures which we have included in the last class of normal tissues, the vessels and parts which may be compared with lymph and lymphatic glands are the most frequently met with as new formations, whilst real blood, muscles, and nerves, are the most seldom found as such.

But, if we ultimately arrive at such a simple view of the matter, the question of course arises, what becomes of the doctrine of the heterology of morbid products, to the upholding of which we have long been accustomed, and to which the most simple reflection almost inevitably conducts Hereunto I can return no other answer than that there is no other kind of heterology in morbid structures

us.

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 (homœoplastic 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 (Bindegewebs-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

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

Fig. 27. Diagrams of hepatic cells. 4. 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. b. Divided nuclei. c, c. Divided cells.