The most remarkable evidence, hovvever, of the connection between the generation of white corpuscles in the blood, and the production of fibrin, is derived from the phenomena of in flammation. A decided increase in the normal proportion of fibrin in the blood (from 2i to 3i parts in 1000) may probably be looked upon as the essential indication of the existence of the inflammatory condition. For it appears from the observations of Andra! and Gavarret (which have been confirmed by many other pathologists) that such an increase uniformly manifests itself, when a local inflammation com mences,—even when the proportion of fibrin has previously been abnormally low, as in febrile diseases ; that it bears a constant rela tion with the extent and intensity of the diseased action ; and that it diminishes with the abate ment of the morbid condition of the part affected. In some instances, the proportion of fibrin was seen to rise as high as 9 or even 10 parts in 1000; but an increase to the amount of 6, 7, 8 parts, was more common. That this pro duction of fibrin is due to a local change can scarcely be doubted ; since it is frequently observed to commence before any consti tutional sy m ptoms man i fest themsel ves ; and it may be reg-arded, in fact, as one cause of these symptoms. Now the recent microscopic ob servations of Mr. Addison* and Dr. W i II ia which were made independently of each other, have established the important fact, that a great accumulation of white corpuscles takes place in the vessels of an inflamed part; and this seems to be caused at first by a deter mination of those already existing in the circu lating fluid, towards the affected spot ; but partly by an actual increase or generation of these bodies, which appear to have the power of very rapidly multiplying themselves. The accumulation of white corpuscles may be easily seen, by applying irritants to the web of a frog's foot. Mr. Addison has noticed it, in the human subject, in blood dmwn by the prick of a needle, from an intlamed pimple, the base of a boil, the skin in scarlatina, &c. And the writer, without any knowledge of these observations, had remarked a very obvious difference between the proportions of white corpuscles, in blood drawn from a wound in the skin of a frog immediately upon the incision being made, and in that drawn a few minutes after ; and had been led, like the observers just quoted, to refer this difference to a deter mination of white corpuscles to a part irritated. The absolute increase, sometimes to a very con siderable amount, in the quantity of whit corpuscles in the blood of an inflamed subje has been verified by Mr. Gulliver and seve other observers. These facts, therefore, affo strong ground for the belief, that the producti of fibrin in the blood is closely connected wi the developraent of the white corpuscles; ar when we consider them in connection with t facts previously urged, there scarcely appears be a reasonable doubt, that the elaboration fibrin is a consequence of this form of cell-li and is, in fact, its express object.
A recent observation of Mr. Addison's, mo over, would seem to indicate, that no mconsid able proportion of the fibrin of the circulati blood is contained within the white corpuscl " Provide six or eight slips of glass, such as usually employed for mounting microscopi objects ; and as many smaller pieces. Davi drawn blood from a person with rheum fever, or any other inflammatory disease, pl a drop of the colourless liquor sanguiuis, it fibrillates, on each of the large slips of cover one immediately with one of the sma slips, and the others one after another at int vats of thirty or forty seconds : then, examining them by the microscope, the will exhibit colourless blood corpuscles various conditions, and numerous white mo cules distributed through a more or less copi fibrous network ; and the last will be a tong coherent, and very elastic membrane, which cannot be broken to pieces nor resolved into smaller fragments, however roughly or strongly the two pieces of glass be made to rub against each other. This is a glaring instance ' of a
compact, tough, elastic, colourless, and fibrous tissue, forming from the colourless elements of the blood ; and the several stages of its formation may be actually seen and determined. Nu merous corpuscles may be observed, in all these preparations, to have resolved themselves, or to have fallen down into a number of minute molecules, which are spread out over a some what larger area than that occupied by the entire corpuscles; and although still retaining a more or less perfectly circular outline, yet refracting the light at their edges, in a manner very different from that in which the corpuscles themselves are seen to do. It is from these and various other larger and more irregular masses of molecules on disintegrated corpuscles, that the fibrinous filaments shoot out on all sides, as from so many centres ; or frequently the filaments are more copious in two opposite directions." A different view of the cause of the produc tion of fibrin, however, has been entertained by some eminent physiologists ; and it does uot seem right to allow the opinions of Wagner, Ilenle, and Wharton Jones to pass without notice, even though they appear to the writer to be easily set aside. By these observers, the elaboration of fibrin has been attributed to the red corpuscles, and has been regarded as one, at least, of their special functions. Nearly all the arguments, however, which have led us to, assign this duty to the white corpuscles, tell equally against the doctrine now under con sideration. The presence of fibrin in the circu lating fluid may be regarded as a universal fact ; but the red corpuscles are restricted to verte brated animals : how, then, is the plastic element elaborated in the invertebrata ? The number of red corpuscles in the blood of different classes bears an obvious relation to their amount of respiratory power, and to thefunctional activity of the several organs, which is closely connected with the amount of oxygen introduced into the system ; but it does not bear the same relation with the activity of the fbrinative processes, which may be taking place energetically (as in the developement of the embryo, or in the re paration of parts in the adult) in a state of functional quiescence. That the proportion of red corpuscles in the blood had a special rela tion to the nervous and muscular energy of an animal, and to the amount of oxygen consumed by it, has long ranked as a physiological truth ; and the opinion has been gradually gaining ground, that although the liquor sanguinis is undoubtedly affected in a considerable degree by exposure to oxygen in the respiratory capil laries, the red corpuscles are the special agents by which oxygen is conveyed into the systemic capillaries, that it may furnish the conditions required for muscular contraction and other functional operations, which depend upon a due supply of arterial blood. In the inverte brated animals in general, the amount of respi ration is so low, that this special provision is not required. There is an apparent exception, hrlwever, in the case of Insects, which have no red corpuscles, and which yet can display a greater amount of animal energy;hnd—which consume (when in a state of activity) a larger quantity of oxygen in proportion to their size, than beings of any other class whatever. But here the exception proves the rule ; for the con veyance of oxygen through the tissues is not accomplished in Insects by the circulating fluid, which has a comparatively sluggish movement, but is effected more directly by the ramifying trachew, which introduce air into the minutest portions of the structure.