We have had numerous opportunities of satisfying ourselves of the general accuracy of these observations of Mr. Gulliver ; but we cannot accede to the notion that the yellovvish green, soft, sometiines almost diffiuent co agula, frequently seen in veins (coagula which, according to the spirit, if not the absolute letter, of Mr. Gulliver's doctrine, should con sist merely of softened fibrin and accidentally imprisoned blood disks), never contain, and hence never consist, in part, of pus. We have more than once discovered fully-formed and well-conditioned pus-corpuscles in such co agula, which, upon mere naked-eye evidence, we had regarded as wholly composed of softened fibrin. We refer here to cases where no signs of inflammatory (or other) alteration exist in the coats of the vein, and where those coats appear to have nothing to do with the appearances referred to ; for the corpuscles appear chiefly, or it may be alto gether, in the centre of the coagula. Now such cases seem to prove one or other of the following three propositions : That corpuscles exist, having all the micro-chemical characters of those of pus, yet in reality of a different nature ; that stagnating liquor sanguinis is capable of undergoing, in its own proper sub stance, inflammatory- changes ; or that the pus-corpuscle is capable of forming, in stag nating liquor sanguinis through some peculiar influence of non-inflammatory nature. Reason, collateral experience, and the general laws of pathology, point to the second of these pro positions as the most probable of the three; but it is wisest for the present, perhaps, to refrain from adopting any one of them.
(c.) Epithelial fluid. —Broken or perfect epithelial scales sometimes accumulate in very considerable quantities in certain serous fluids ; and the resulting mixture cannot with the naked eye be positively distinguished, either by colour, consistence, or odour, from pus. In the Fallopian tube (somewhat di lated) of an anasarcous woman, who died under our care at University College Hos pital some time since, we found fluid of this kind, containing (as shown by the microscope, the only test in such cases,) not a single pus corpuscle, but abundance of epithelium. We have seen tbe same kind of fluid in the pelvis of the kidney.
The microscopical distinctions of the un altered red-corpuscle of the blood, and the pus-corpuscle, are so numerous and obvious that they need not be enumerated ; it is nn possible to confound the two objects. The red blood-corpuscles, however, when acted upon by various re-agents (serum, urine, pus, artificially added saline solutions, &c.) acquire a more or less accurate resemblance to those of pus ; they in truth increase somewhat in bulk, lose their regularity of outline, which becomes ragged, and alternately notched and studded with minute prominences, — appear ances which have led to very remarkable errors. Nevertheless, the resemblance is far, even, from seemingly perfect ; the altered red corpuscle is smaller than the other, and is not minutely granular on the surface : if there be doubt, however, in the case, acetic acid, by dissolving the body (if it be a red-corpuscle), or producing the changes already described (if it be one of pus), will settle the question.
The colourless corpuscle of the blood in its unaltered state is with difficulty distinguishable from the pus-corpuscle ; the two bodies have, by practised observers even, been confounded. It has the same minutely granulated aspect ; and acetic acid discloses, as in the pus-cor puscle, a nucleus in its interior. The colour less corpuscle is smaller than the other, how ever (the mean ratio of their sizes being as 22 to 27, nearly). The nucleus is either single, bipartite, or tripartite.
The process by which pus is formed —in other words, pyogenesis or suppuration — was long supposed to be one of disintegration and solution of the natural tissues. We need
not devote space to the elaborate refutation of this rude conception : suffice it to say, that pus may be produced for years froth mucous membranes, without even abrasion of their surfaces having occurred, and that the ele mentary textures (e. g. the cellular) may, at the outset of the suppurative process, be shown to have retained all their natural pro perties.
We might, on the score of its obvious fal lacy, similarly pass by the notion that the corpuscles of pus are simple modifications of the red-corpuscles of the blood ; but as, even recently, symptoms of a return to this pre viously-exploded idea have appeared on the Continent, a few words on the subject seem called for. M. Gendrin (Hist. Anat. de l' In flainination,4-e.) taught that in consequence of the stagnation of the red-corpuscles in duced by inflamrnation, those bodies are first converted into pus-corpuscles in the interior of the capillary vessels, and, secondly, exude thence into the intercapiliary texture. The experiment upon which the first portion of this doctrine was based has been repeated by Dr. Wood*, Mr. Gulliver, and others ; and either no appearance at all of the alleged puriform matter discovered, or its characters proved to be those of softened fibrin. As respects the exudation of ready-formed pus corpuscles, the theory manifestly involves an impossibility, as the structure of the walls of the capillary vessels is too close to permit the passage of bodies of such dimensions.
Besides, M. Gendrin has forgotten to explain why, if the pus-corpuscles escape from the vessels, the blood-corpuscles, of much smaller size, as they are, do not follow abundantly in their track. M. Donne* some time since re vived the idea of conversion, believing that he had seen red-corpuscles changed into puru lent in a mixture of pus and blood out of the body : he was deceived by the physico chemical changes already referred to, which pus, like various other fluids, effects in the blood-corpuscles.
The true doctrine of pyogenesis is a modi fication of that of " secretion " taught by Simpson (1722), de Haen (1756), Morgan (1763), Brugmans (1785), and John Hunter. The direct microscopical evidence, upon which it has been finally established, was ori ginally and mainly supplied by Wood, Gueter bock, and Henle. This evidence is to the effect that, as a general fact, the generation of the solid materials of pus takes place wholly outside the vessels in a hyaline blastema. In that blasterna granules first appear ; subse quently, bodies of larger sife form, either independently of the granules or around them, and, collecting in variable numbers, or remaining single, present the characters of, and actually constitute, the nucleus of the pus-corpuscle. The involucrum, or cell-wall, next forms ; and, at first clear and trans parent, subsequently grows granular. One of the readiest plans of observing this series of changes, is by using the exudation-fluid from a blistered surface,—but the same phenomena may be traced on wounded stftfaces.
The elementary tissues of the body are not at first altered in any appreciable manner by the occurrence of suppuration among them-1'; solution of their substance may at length be, and frequently is, more or less completely effected. This solution-process is of triple nature : it is physical, in that mere maceration aids in its production ; chenzical, in that in certain unhealthy states of the system, solvent agents, .Stc.$ are generated in suppuration ; vital, in that the tissues themselves, in certain constitutional conditions, lose partially or completely their force of cohesion.