Microscopic Analysis, therefore, from which important disclosures in relation to the diagnosis of benignant and of malignant growths, and tenable grounds for the establishment of a system were expected, has in reality thrown but an uncertain light upon the subject.

Certain new growths are especially intended for the more or less perfect restitution of loss of substance, howsoever occasioned. These regenerated textures are sometimes perfectly identical with the lost ones, in formal and chemical composition, as also in function; sometimes entirely dissimilar. The latter kind are represented in scar-texture, which, again, may have an evanescent existence, as in provisional cicatrix, out of which is developed, and which merges in, a texture identical with the lost one; as, for instance, the fibroid scar-texture that ensues upon loss of substance in the bones of the skull; the scar-callus occurring at the point of a lesion of continuity in a nerve. Or again, the cicatrix may be permanent, consisting throughout of a fibrous texture of various degrees of perfection, in which the elements of the lost texture are never reproduced; such is the muscular, the glandular cicatrix.

New growths once established either sustain themselves without alteration of bulk, or else wane and shrivel in various ways, or even disappear altogether. Products of inflammation, even such as have assumed a textural character, unquestionably become reabsorbed; so, in like manner, do new growths of embryonic structure.

Again, they liquefy under various transformations of their chemical components, or they become diseased in manifold ways.

Finally, new growths increase. This increment takes place through juxtaposition; that is, through the accession of blastema upon the periphery of the existing structure. Such is the growth of non-vascular formations, especially of those which do not rise above the lowest grade of development; as, for example, tubercle. Or the increase takes place through the intussusception of new blastema from those bloodvessels of the diseased organ which supply the new growth, or from an adventitious vascular apparatus newly developed for the supply of the new formation. Finally, an increase of volume may be based upon the variety of chemical conversions attending the development of textural elements out of blastema, and, in vascularized heterologous products, attending the growth of those elements themselves.

Growth and intrinsic development by no means keep pace with, but rather stand in an inverse ratio to, each other. Rapidly vegetating heterologous growths are mostly distinguished by an embryonic structure. Upon the rapidity of its growth depends, in a great measure, the degree of influence exercised by the heterologous product upon the affected organ, upon its vicinity, and upon the organism generally.

This influence, considered locally, consists in pressure and tension of textures and of entire organs; in displacement and extinction of textures; consequently, in the production of pain, and in embarrassment or complete hindrance of function.

The influence upon the entire organism is sometimes deducible from that which is local, shaping itself differently according to the different seat of the new formation. In the instance of heterologous products luxuriating by growth and multiplication, this influence consists in causing the wasting of organic matter and of power, or in the establishment of a consecutive dyscrasial state. This latter may be brought about in a twofold manner:

(a.) Either through the withdrawal from the fluid of nutrition of some particular substance employed as a material in the heterologous structure - as in defibrination of the blood and oedema in tubercle - in dropsy consequent upon albuminuria.

(b.) Or else in a positive manner, namely, through reception into the blood and lymph of substances generated in the interchange of matter that constitutes the nutritive process of the heterologous product, and still more through reception of the heterologous matter itself, in the shape of intercellular substance, or of elementary cells, and the like. This directly leads to contamination of the fluid of nutrition, and thereby to a dyscrasy reflecting the character of the heterologous growth. It is the more speedily brought about where circumstances are generally favorable to endosmosis or resorption, and particularly so in the locality of the heterologous growth, where this latter is bulky or highly vascular, or situate in organs rich in blood and lymph-vessels, where its mass (its intercellular substance) is more or less fluid. It occurs, however, in heterologous growths, both solid and poor in bloodvessels, when their texture has become disintegrated and liquefied by hyperemia and inflammation. To sum up, new growths possess sometimes a general, sometimes a local character. Nay, one and the same new formation may, at various, successive periods, acquire now the one, now the other character. A growth, originally of general import, may in particular assume a local one instead.

New growths vary considerably as to the organs and texture which they affect by preference; each possessing, in this respect, a scale of frequency of its own. Some organs are pre-eminently subject to one particular kind of new formation.

Certain new formations become developed and subsist unmistakably in concurrence; certain others never cohabit, the presence of the one serving to exclude the other, - the appearance of the one arresting the development of the other. Exclusiveness or repulsiveness of this kind is, as might be expected, mutually evinced by new growths based upon dyscrases of opposite characters. On the other hand, new formations rooted in kindred dyscrases, do exist confederately, and purely local new formations enter into every phase of combination.

Let us now turn from the consideration of confirmed new formations to that of their blastema and of its metamorphoses.