the modeling process. Liquor sanguinis, modified, is secreted; and, the serum or its watery portion being disposed of, the blastema remains pregnant with cells, which arrange themselves one upon another, presenting the appearance which has been undesirably called that of exudation corpuscles. Over all, an imperfect epithelium is formed, probably by means of transition cells. In this process, as in the more perfect one already described, a portion of the blastema is assimilated and more fully organized. New layers are developed, and the void is, at length, filled.

The effect of any external irritating influences and of any remaining inflammation having passed, the usual reparative process goes forward. In the ordinary nutrition of the system, effete matter is thrown off, as new matter is deposited; and so, in this case, the granulation deposit is separated and absorbed, as the new and more permanent tissue is formed. One peculiarity of appearance, however, remains, after a wound has been permanently healed. The granulation structure, which is removed by interstitial absorption, being less dense than the more permanent tissue, the portions. removed, in a given time, occupy more space than those which are deposited. The consequence is, that, after the work is completed, the parts are left contracted and a cicatrix shows itself.

Those fungous growths which are commonly called proud flesh, are the result of an excessive granulating process. That they occur in accordance with fixed law, and under modified nervous action, cannot be questioned, though we cannot trace all the workings of vitality in such exuberant formations.

In every case of lesion, in whatever way created, the healthy condition of the part must be restored by the reparative process, in some one of the modes now considered. If the lesion has

been produced by inflammation, and that under ordinary circumstances, as in the muscular and areolar tissues lying near the surface, and if, at the same time, there is no appreciable destruction of the tissues, the reparative process has comparatively little more to do than it has in serving the ordinary purposes of nutrition. When, however, the inflammation is upon a serous tissue, there is frequently a too luxuriant growth, ordinarily terined false or exudation membrane. In this case, the hyaline fluid is copiously deposited in much the same manner as in superficial fungous growths.

When fungous growths and exudation membranes give place to a normal condition of the parts, the process is evidently that of absorption, just as ordinary granulations are absorbed, when the more permanent structure is formed.

It is proper here to remark, that the plastic power of the blood, that is, its capability of being transformed into organized tissue, is in proportion to the quantity of fibrine which it contains. Though the chyle exhibits faint traces of fibrinization, immediately on passing the lacteals, and though the current of chyle and lymph united partakes more and more of this character, till it reaches the thoracic duct; yet, in the blood, the proportion of fibrine is greater than in any part of the lymphatic current, and that notwithstanding the constant withdrawal of it from the blood for the purposes of nutrition. From this fact it is sufficiently evident, that fibrine is elaborated, partly, by some agency in the blood vessels. As to what that agency is I have already given my opinion.

When blood is drawn from the body, and its fibrine is coagulated in a vessel, that coagulated fibrine has something like a rudimentary appearance of organization. It contains what appear

much like organic germs. This particular resemblance to the change effected by the conversion of the hyaline fluid into solid tissues, has probably been principally concerned in giving rise to confused notions and uses of terms, in speaking of the reparative process. These organic germs, or corpuscles, as they have been called, which appear in a clot of fibrine, seem to be formed by means of an electric influence derived from the atmosphere. But electricity is not nervo-vital fluid, and, therefore, cannot do the full work of that fluid. It, to some extent, imitates, but it cannot become vital action.

CHAPTER VI.

THE RED CORPUSCLES.

"The human blood corpuscles or red globules," says Dr. Morton, "are flattened circular discs, with a central concavity or depression on each surface, which, in some respects, gives them an

annular appearance. They vary between the 300th and the 400th of a line in diameter, and their thickness is about one fourth of that measure. Each corpuscle is a cell, of which the envelope is elastic, homogeneous, pellucid, and colorless; and the contents are of a more or less deeply red color. They are, however, destitute of distinct nuclei,-the dark spot which is seen in their centre being merely an effect of refraction, in consequence of the double concave form of the disc. But, since the corpuscles of the lower animals are distinctly nucleated, some physiologists insist, that the nucleus exists also in the blood of mammiferæ, although it has hitherto eluded positive demonstration."

"The vesicular envelopes of the blood discs have been supposed to be analogous in character to fibrine, being extremely delicate, transparent, and highly elastic membranes."

"The contents of the capsule consist of two different substances, called hæmatine" or hæmatocine, "and globuline."

"Hæmatine or hæmatocine is the compound that fills and forms," with globuline, "the substance of the corpuscle, and gives it its characteristic color. When the coloring matter is separated from the other constituents, it appears as a dark brown substance, insoluble in water, ether, acids, or alkalies, or in alcohol alone, but dissolves in alcohol with the addition of sulphuric acid or ammonia. This solution has also a dark color, and possesses all the properties of the coloring matter of venous blood. It contains a considerable proportion of peroxide of iron; but Scherer has proved, contrary to the received opinion, that the coloring matter is not derived altogether from the iron, because, when the latter is wholly separated from the hæmatine, a deep-red coloring matter still remains."

Kirkes and Paget, however, say of it, that, as ordinarily obtained, "it is soluble in water, by which it may, with the globuline, be washed out of the blood corpuscles; and from this solution it is precipitated, by most metallic salts and by concentrated acids. In the living or recent state of the blood corpuscles, the hæmatine is confined within their cell-walls, and appears to be insoluble in the serum; but, when the blood begins to decompose, and the cell-walls, losing their texture, permit the outward passage of their contents, both the hæmatine and the globuline are dis

solved in the serum which thus becomes blood-colored, and may impart its tinge to the surrounding parts. In the purest state in which it can be obtained, it is so far changed as to be insoluble in water, of a deep blackish-brown color, and not liable to change of color on exposure to gases. Boiling alcohol will dissolve small quantities of it, and it is freely soluble in alcohol acidulated with sulphuric, hydrochloric, or nitric acid, and in weak solutions of potash, soda, or ammonia."

"The presence of so large a proportion of iron, constitutes a peculiar feature in hæmatine. The mode in which the metal exists in it has been much discussed. By some it is supposed to be in the form of an acid, or a salt, or in the form of peroxide in arterial blood, and carbonate of the protoxide of iron in venous blood. The greater probability is, that the iron is combined, as an element, with the four essential elements, in the same manner as, it is held, sulphur is combined with them in albumen, fibrine, cystic oxide, &c."

"It is very doubtful, whether the rapid change of color, which is effected in respiration and on the contact of various gases, can be referred to any chemical changes whatever, in the hæmatine. Much more probably it is due to changes in the form of the blood corpuscles and their consequently different modes of reflecting and transmitting light. Saline solutions, if denser than the liquor sanguinis, contract and shrivel up the corpuscles, making them deeply bi-concave; and distilled water has the contrary effect, swelling out the corpuscles, and making them thickly bi-convex or spherical. Changes corresponding with these are produced, by the contact of oxygen and of carbonic acid with the corpuscles; -the former contracting them, and making their cell-membranes thick and granular,-the latter dilating them, and thinning and finally dissolving their cell-walls. Herein, then, is a sufficient explanation of the changes that the corpuscles undergo, without supposing any immediate chemical alteration in the hæmatine."

"Globuline," says Dr. Morton, "is obtained from the capsule of the red corpuscles and is their component element. It is regarded, by the chemists as a proteine compound, closely allied to albumen, -from which it differs, however, in being soluble in serum and in coagulating in a granular form, unlike the residue from albu

men. Henlé suggests, that globuline is albumen, modified by combination with the substance of the disc-envelopes. The globuline and hæmatine combined constitute the admitted contents of the globules, and are called the cruor."

Kirkes and Paget say, that "globuline appears to be a proteine compound. According to Simon, it bears some resemblance to caseine, on which account he nanied it caseine of blood; but Liebig and others regard it as more similar to albumen. It is soluble in water, and its solution, when heated, forms a granular coagulum."

What I have now quoted refers to the chemical character of the corpuscles. In regard to their origin, Dr. Morton says, "The human blood corpuscles are, by many physiologists, even by those who deny their nucleated character, regarded as cells, capable of reproduction in the manner of the cells of other tissues." In thus speaking of "other tissues," the doctor seems to regard the blood itself as a tissue. He continues,-"This process, according to the latest microscopists, is shown in the following manner. First, radiating lines are seen to pass from the centre to the periphery, dividing the disc into several segments, usually six in number; and these parts become gradually isolated from the parent corpuscle, and constitute as many new and independent cells. It is, in this manner, that the red corpuscles are rapidly generated by a power of self-production within themselves,-which is increased or retarded, however, by various circumstances."

Thus much, in regard to the nature of the red corpuscles, being understood, the grand but hitherto unsettled question arises, What is their function? Different conjectures have been formed. One is, that they convert the albumen of the blood into fibrine. But, to this view, there are serious objections. Fibrine is extensively found in the lymphatic vessels, and yet these vessels contain no red corpuscles. Again, invertebrate animals have no red globules in their blood; but albumen, with them, is changed into fibrine as readily as with animals having red blood.

Another conjecture is, that the red corpuscles are "carriers of oxygen to the various tissues, and of carbonic acid from these tissues to the lungs." To an extent this is, doubtless, the correct theory. Experiments, it is true, have shown very clearly, that a