The exudation of white corpuscles from the inflamed capillaries in inflammation was discovered by Beale in 1863, together with their transformation into pus-corpuscles, but it was then shown by him that this was only one of the sources of pus. The transformation of the to be detached mucus-corpuscles into a degraded but more viable and rapidly growing form of protoplasm, viz., pus, is the first step; and the degradation of the protoplasm of the fixed tissues and of the blood into the same, is the second step in our comprehension of the contagia or germinally degraded bioplasts. It has been long known that pus was liable to be of an acrid and irritating nature, and it appears now that this depends on its containing actually living bioplasts, and on the character and degree of germinal degradation of their vital powers. For the pus-corpuscles, as usually figured in books, are dead, as are also the majority of those contained in abscesses in the living body. But many can be found living, especially those formed by the degradation of the protoplasm of mucus and epithelium cells, and these form the first links in the chain of degrees of viability, and differentiation of the disease-germs. The living pus-corpuscle has no cell-wall, but is a formless mass, in continual movement, pushing out protrusions, which become detached, and form new corpuscles. In inflammation of the mucous membrane of the bladder, Dr. Beale has seen them living and moving forty-eight hours after separation from the body, and I can confirm the fact from my own observation. Dr. Beale also states that these same corpuscles can be kept alive in water to which a little serum or albumen has been added. From what we thus know of the viability of pus, which is comparatively so little removed from health, we can easily imagine how the further degraded and differentiated bioplasts of the specific fevers may have sufficient viability to allow the preservation in moist or liquid media, and even the partial

desiccation and transportation through air characteristic of miasms and viruses. It may be said that these last differ so much from pus in appearance, that we cannot reason from any analogy between them. But it is not so; the difference between the appearance of common pus and the clear vaccine virus, for example, is no doubt great, but that depends on the accidental ingredients in which the active part common to both is suspended. (§ 2.) "It is impossible to distinguish many pus-corpuscles from lymph-corpuscles, white blood corpuscles, and many other masses of germinal matter; indeed, if we examine the developing brain of an embryo at an early period, it will be found that this important structure consists of nothing more than a number of spherical cells, which could not, by any means we are yet acquainted with, be distinguished from many forms of pus-corpuscles."* In fact, the bioplasts constituting disease-germs simply share in the common characteristics of all protoplasm, viz., that all kinds are, to outward appearance, exactly alike, from that of the simplest vegetable up to that of the brain of man, although in vital properties they differ so enormously. This is no hypothesis, but a simple fact, and is therefore in favour of the graft-germ theory against the parasitic theory, for the impossibility of finding morphologically specific organisms in the specific fevers, drives its advocates to the hypothesis of physiological specificity of common microccoci. In the graft theory no specific outward distinction is expected or required for the abundant bioplast formations which are met with in the specific fevers, and many of which have been erroneously described as micrococci.

§ 18. Together with the mucous and epithelial cells of the mucous membrane and glands, the bioplasm of the blood itself forms the chief source of the degraded bioplasts which constitute disease-germs. Not only does the blood contain Beale, Disease Germs, p. 130.

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the visible white corpuscles, but an infinity of smaller particles of living matter, and these, as well as the more palpable white corpuscles, become degraded, and thus the source of the disease-germs of contagious and specific fevers.

In all fevers, even when arising from simple non-specific causes, such as catarrhal and inflammatory fevers, this bioplasm of the blood is increased in quantity, and to a certain extent, no doubt, altered in quality, so we can easily imagine it to degenerate, as mucus-bioplasm does, into pus, and thus become the contagious matter of the specific fevers, or, at least, of those in which the blood is specially involved. Now, we are reminded by Dr. Beale that the living matter of the epithelial cells and of the blood possesses remarkable formative powers, which survive even in the adult, and, in particular, the blood bioplasts, when exuded, may develop into analogues of some of the lower tissue-cells, and thus take part in regeneration of tissue and healing of wounds. This is attributed to their being descended from the protoplasm of the germinal area at a period of development before that of most of the fixed tissues, and they therefore inherit some of that more general formative power which enables some animals lower in the scale to regenerate lost complete parts. It is to be noted also that it is just this class of living matter which furnishes the basis for all infective diseases.

It is therefore hardly necessary to go beyond blood and epithelial bioplasts in considering degeneration or degradation of living matter as the cause of infective matter. And with protoplasm of such formative powers, we can easily imagine that degradation may take place from mere alteration in the external essentials of life, viz., pabulum, conditions, and stimuli; also when protoplasm, so degraded, has become more viable, it may be mutually transplanted, not only between one individual and another of the same species, but also between others widely different in the

biological scale, even to those of the vegetable kingdom. On this point, as on many others, Dr. Beale has been anticipated by Fletcher, in whose General Pathology (1842) we read:-"Vegetables secrete like animals, and are liable by disease to have their secretions vitiated. Now, diseased animal secretions produce contagious diseases; analogy would therefore lead us to suppose that those miasms from which infectious diseases arise, such as those of marshes, are in like manner secretions from diseased vegetables." This position. was supported by the facts known at the time, and now Dr. Beale adds from the facts now known, including his own discoveries, "it is not improbable that the germinal matter of some of the lower, simpler plants and animals, when exposed to altered conditions, may give rise to morbid forms, bearing a relation to their normal healthy, living, germinal matter, similar to that which pus bears to the germinal matter of healthy tissues. It may be that the matter of the malarial poison may thus result, in which case it must be regarded as a morbid bioplasm of some low organism—not as a species of any kind whatever--but as a deteriorated form of living matter, freely multiplying, but incapable of returning to its primitive healthy state. (p. 117.)

It is unnecessary to adduce, in support of this, the now admitted fundamental identity of life in plants and animals, and, in particular, the facts more recently made known by Charles and Francis Darwin, but I may quote a striking illustration, given by Dr. Beale himself, of the analogy of the living juices in the two kingdoms:-"If the clear transparent material which moves round the cells of the Vallisneria and other plants be carefully examined under very high powers, magnifying upwards of 2,000 diameters, it will be discovered that this is not a simple fluid, like water, containing the nucleus and chlorophyl. But the apparent fluid has suspended in it an infinite number of particles of

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living matter, like those of which the amoeba, white bloodcorpuscles, and other forms of living matter consist." He then goes on to state that it is to the vital movements of these particles that the circulation in the cell is due, and that these particles in the vegetable cell bear the same relation to the nucleus as the similar fine protoplasmic particles do to the white corpuscles of the animal blood, while the red corpuscles correspond to the chlorophyl particles. Having thus, as a basis, the existence of certain kinds of protoplasm of a lower order of individuality forming an essential part of higher organisms in which degradation and the capacity for a certain amount of independent viability and growth, we next enquire for experimental proofs that such really happens. It is impossible here to go into details, but it may be simply said that abundant proof has been furnished by the experiments of B. Sanderson, Lewis and Cunningham, Onimus, Vulpian, Clementi and Thin, and others, of the following points :

If you introduce into the peritoneum any common irritant, such as solution of ammonia, boiled so as to sterilise it from bacterial germs, an inflammation of moderate intensity is set up. If now a very small portion of the exudation fluid of this first generation, as it were, be injected into a second animal, we have a much more intense inflammation set up. From this second generation a third and fourth, and further, may be derived, each increasing in virulence and intensity, till death is produced in a few hours by the introduction of a fraction of a drop. If, however, the matter of the first inflammation be boiled, it has no such poisonous effects; the poison also is non-dialysable—in these two points agreeing with the theory of degraded living matter. It is true that, although no bacteria are introduced at first, they are found in the subsequent increasingly poisonous