Humoral pathology is simply a requirement of common practical sense; and it has always held a place in medical science, although the limits of its domain have, no doubt, been variously circumscribed or interpreted at different times. Of late years it has met with a new basis and support in morbid anatomy, which, in the inadequacy of its discoveries in the solids to account for disease and death, has been compelled to seek for an extension of its boundary through a direct examination of the blood itself.

Not alone has pathological anatomy demonstrated the existence of blood diseases in unlooked for detail; it has at the same time solved a problem of the weightiest import. It has, we think, decided in favor of a humoral pathology, by demonstrating a primitive anomaly of blaste-mata; by demonstrating the endogenous impairment of the blood within the vascular system, in the inflammatory process, as the basis of the variations in exudates [blastemata]; lastly, by demonstrating the dependence of local morbid action upon pre-existent impairment of the general circulation. Our attention will be here directed to diseases of the blood in its totality, and to local dyscrasial processes, with inflammation at their head, only in so far as these offer the basis and starting-point for consecutive disease of the entire blood-mass. It is remarkable, however, and no less important for practice than for science, that the essential forms of these local dyscrasial processes, - perhaps of all local dyscrasial disease, - occur, likewise, as primitive affections of the entire blood-mass. This is proved by the varied character of the products of the inflammatory dyscrasial process, and a comparison in detail of these products with anomalies of the general blood-crasis. Thus, primitive pyaemia, fibrin-crasis, sepsis of the blood, severally occur independently of all local beginning, and of all infection.

There are, indeed, two ways of investigating and recognizing blood-diseases: first, the anatomical examination of the blood in the dead subject, or of blood obtained during life through spontaneous or artificial hemorrhage; and secondly, chemical analysis. Both kinds of investigation should be supported, and the results controlled, by a concurrent examination of the secretions and excretions, of the general condition of the solids, and of new-formations, especially of such exudates as are the offspring of inflammation.

In fine, both kinds of research should go hand in hand. For, although a deeper insight into the changes suffered by the blood may be reserved for chemistry, it must needs be based upon sound anatomico-humoral premises. Up to the present day chemistry has not taken this duly into consideration, so that as yet this science cannot be said to have far excelled the achievements of a circumspect anatomical survey, notwithstanding the limited resources at the disposal of the latter.

Upon the chemical pathologist we would strongly urge an unremitting prosecution of his researches. We would recommend him to direct his labors more particularly towards ascertaining the precise character of the impairment suffered by the proximate ingredients of the blood, and of the anomalies impressed upon its elementary composition. The interests of haemato-pathology would after all, perhaps, be best served by the examination, in the above sense, of blood taken from the dead subject, the diagnosis of the case having previously received the light of a general post-mortem examination.

Our own task in these pages will be limited to establishing a purely anatomical pathology of the blood; we shall therefore restrict ourselves, as nearly as possible, to anatomical facts, although without neglecting to avail ourselves of the collateral support of such chemical data as may be relied upon at the present hour.

It is the business of pathological anatomy to determine both the physical properties of the blood in its totality, and also the relative quantity, and more especially the quality, of its more immediate components.

The two main components which come peculiarly within its province are, first, those essential form-elements, the blood-globules; and secondly, the spontaneously separating, coagulating, solidifying fibrin, - that component which, owing to its varying tendency to become organized, is, in an anatomical sense, the most important of all. We will here summarily refer to what has been said in the introduction to the doctrine of blaste-mata and to the section on exudates, and then proceed to treat of blood diseases in what would appear to be their most natural order. The subject is, however, so intimately allied to that treated of in the chapters referred to, that a certain amount of repetition will, perhaps, be unavoidable in the following pages.

Affections of the blood are, like those of the solids, either primitive or consecutive. And again, the former, equally with the latter, suggest an inquiry as to whether they result from an immediate influence of the morbific agent upon the blood, or are determined by the nervous system, as the actual percipient, alienated both in matter and in function. This question can, however, hardly affect us in this place, since the latter view mainly rests on speculative grounds, and upon the fact that obvious injury to, or sensible anatomical disturbance of, the nervous system sooner or later results in disease of the blood.

The latter are determined in very different ways by anomalies in the solids. Thus, the hindered eliminating activity of an organ occasions retention of effete matter in the blood; an abnormal plastic process influences the blood crasis, directly or indirectly, through the anomaly in the interchange of matter. Take for example, the infection of the blood within the range of an inflammation.

To diseases of the solids, as local morbid processes in the broadest sense, affections of the blood stand in a twofold relation:

1. The Anomalous Crasis

The Anomalous Crasis is a pre-existent one - the primitive affection; the local disease a localization thereof - the secondary affection. The point of localization, apart from the effect of concurrent external influences, is determined by a specific relation of the crasis to certain organs presided over by the nerves. The forms it assumes are chiefly those of hyperemia and stasis - inflammation, absolute stasis, - exudation, or, without the latter, a product-formation completed within the bloodvessels; for instance, spontaneous coagulation of diseased fibrin, pus-formation within a greater bloodvessel or within the capillaries of an organ.

The relation of the various erases to the organs and textures, nay, even to particular sections of organs, is manifold. Thus, the croupous fibrin-crases evince a very marked preference for the mucous membrane of the air-passages, and for the lungs themselves; the typhus-crasis, for the mucous membrane of the ileum; the exanthematous erases, for the common integument and for mucous membranes.

2. The Anomaly Of The General Crasis

The Anomaly Of The General Crasis is consecutive; that is, the consequence of a local disease, and especially of local dyscrasial processes, whereof the products are taken up into and affect the general blood-mass. This happens -

(a.) Through resorption of the effused products by means of the lymphatics, or immediately into the veins.

(B.) Through Reception Into Patent Bloodvessels

This process includes the reception of products thrown out into the cavity of larger bloodvessels, - pus, for example.

(c.) Most of all, through the off-flowing, and the return into the veins, of plasma degraded in the local process, in a manner corresponding with the quality of the exudate. [See "Relation of the Inflammatory Process to the Crasis."]

It is, however, to be understood that, neither does a dyscrasis necessarily always become localized, nor a local dyscrasial process invariably give rise to a consecutive dyscrasis of the entire circulation. In the former case, a certain degree of intensity of the dyscrasis is no doubt requisite; in the latter case, the reception of a sufficient quantity of plasma, degraded in the manner aforesaid by the local process, or else of a hete-rogeneously diseased, - for example, of an ichorous or septically constituted - plasma is indispensable.

Blood diseases are, moreover, either protopathic, whereby we mean developed out of the normal crasis, or deuteropathic, that is created out of another anomalous crasis. [Meta-schematism.] Deuteropathic erases occur in the simplest manner, as impoverishment of the blood in one or more ingredients, drained away by excessive deposition into textures or upon membranous expansions.

Blood diseases are both acute and chronic, and they are marked accordingly by the rapidity or by the slowness of their career. This is contingent upon the character of the dyscrasis, upon its grade, and upon the significance of the organ in which it becomes localized.

They issue:

(A.) In Transition To The Normal Blood-Crasis

This occurs under various conditions, for the most part obscure; for example, under the return of the free function of an organ, under exhausting localization of the dyscrasis in one of the aforesaid processes, or in some secretion. In this way tuberculosis and cancer may lose their general import and become local affections, which either go on vegetating under the normal condition of the blood, or enter into a retrograde metamorphosis.

(B.) In Transition To Another Anomalous Crasis [Meta-Schematism]

Such transitions are multiform, some of them appearing to be necessary conversions when the original crasis is at its acme, others to represent the final wearing out of some component of the blood. With respect to others, however, we are still in every way completely in the dark.

(c.) In death, not only through overwhelming localization in vital organs, often coupled with palsy of their function; not only through exhaustion of organic matter and of the powers of life, owing to redundant local production; but also, in many instances, through unfitness of the dyscrasial blood for the upholding of processes essential to life, for the maintenance of nutrition generally, but especially of respiration and of the energies of the entire nervous system, both central and peripheral.