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LECTURE VII.

MARCH 6, 1858.

THE BLOOD.

JFibrine.—Its fibrillre.—Compared with mucus, aud connective tissue.— Homogeneous condition.

Red blood-corpuscles. — Their nucleus and contents.—Changes of form.— Blood-crystals (Haematoidine, Hfemine, Haematocrystalline).

Colourless blood-corpuscles — Numerical proportion.—Structure.—Compared with pus-corpuscles.—Their viscosity and agglutination.—Specific gravity. — Crusta granulosa. — Diagnosis between pus-, and colourless bloodcorpuscles.

I Intend to lay before you to-day, gentlemen, some further particulars with regard to the history of the blood.

I concluded my last lecture by impressing upon you the necessity of localizing the different dyscrasiae; employing the term localize, not in its ordinary sense, as the dyscrasiae have heretofore been considered as localized, but rather in a genctical meaning, in accordance with which we constantly refer the dyscrasiae to a pre-existing local affection, and regard some one tissue as the source of the persistent changes in the blood.

If now we consider the different dyscrasiae with regard to their importance and their source, two great categories of dyscrasic conditions may at the very outset be distinguished, according namely as the morphological elements of the blood become changed, or the deviation is more of a chemical one, and seated in the fluid constituents.

FIBRINE. 135

Among these latter, it is the fibrinc, which, in consequence of its coagulability, first, and that very soon after the blood has been removed from the living body, assumes a visible form, and which for this reason has frequently passed for a morphological constituent of the blood. This notion concerning it has of late been maintained in many quarters, and has indeed always had a traditional existence in medicine, inasmuch as from ancient times fibrine was constantly brought forward in addition to the red constituents of the blood as a special element, and it was the custom to estimate the quality of the blood not only from the number of the blood-corpuscles, but frequently in a much more positive manner from the amount of fibrine.

This dissociation of fibrine from the other fluid constituents of the blood is to a certain extent of real value, because fibrine, like the blood-corpuscles, is quite a peculiar substance, and so exclusively confined to the blood and the most closely allied juices, that it really may be viewed as connected rather with the blood-corpuscles than with the mere fluids which circulate as serum. If we consider the blood in its really specific constituents, in those, by means of which it becomes blood, and is distinguished from other fluids, it cannot be denied that, on the one hand, the corpuscles with their haematine and, on the other, the fibrine of the liquor sanguinis are the elements, in which the specific differences must be sought for.

If now we next proceed to consider these constituents a little more closely, the morphological description of fibrine is comparatively rapidly made. On examining it, as it appears in blood-coagula, it is nearly always found in the form described by Malpighi, the fibrillar. Its fibres generally form extremely fine interlacements, delicate networks, in which they usually cross and join one another in a somewhat tortuous form. The greatest variations exhibited by these fibres when forming out of the blood, have reference to their size and breadth; these are peculiarities concerning

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which it has not hitherto been possible to form any certain judgment. I meet with these variations pretty frequently, but without being in a position to assign the causes which determine them. The extremely fine and delicate fibres are those usually met with; but sometimes we find far broader, and almost ribbon-like fibres, which are much smoother, but in other respects cross and interlace in pretty nearly the same manner. Essentially, therefore, there is always present in a clot a network composed of fibres, in the meshes of which the blood-corpuscles are enclosed. If a drop of blood be allowed to coagulate, fine filaments of fibrine can be seen everywhere shooting up between the blood-corpuscles.

With regard to the nature of these fibres, we may observe, that there are only two other kinds which, histologically speaking, bear at all a near resemblance to them. The one kind occurs in a substance which, singularly enough, effects an approximation between the most ancient, perfectly antique, craseological ideas and the modern one, namely in mucus. In theoldllippocratical system of medicine the whole mass of fibrine is, as is well known, included under the terms pldegma, mucus, and when we compare mucus with fibrine we are obliged to confess that there does indeed exist a great similarity between them in the form they assume upon coagulation. In a similar manner to fibrine, mucus also forms into fibres which frequently become isolated and then coalesce so as to give rise to certain

Fig. 50. Coagulated fibrine from human blood, a, Fine, b, coarser and broader, fibrils. e, Red and colourless blood-corpu3cles inclosed iu the ooagulum. 2S0 diameters.

PIBELLS OF FTBRINE.MUCUSAND CONNECTIVE TISSUE. 137

figures.—The other substance which belongs here is the intercellular, or, if you will, the gelatine-yielding substance of connective tissue, the collagen (gluten of earlier writers). The fibrils of connective tissue only differ in that they are not usually reticulated, but run a parallel course, whilst in other respects they resemble those of fibrine in a high degree. The intercellular substance of connective tissue presents another point of resemblance with fibrine in the great analogy of its behaviour with reagents. When we expose it to the action of diluted acids, especially the ordinary vegetable acids, or also weak mineral acids, the fibres swell up and disappear before our eyes, so that we are no longer able to say where they are. The mass swells up, every interspace disappears, and it looks as if the whole were composed of a perfectly homogeneous substance. If we slowly wash it and again remove the acid, a fibrous tissue may, if the action have not been too violent, once more be obtained, after which the previous condition can be produced afresh, and changed again at pleasure. This behaviour has hitherto remained unexplained, and for this very reason Reichert's view, which I have already mentioned, that the substance of connective tissue is really homogeneous and the fibres are only an artificial product, or an optical delusion, has something alluring in it. In fibrine, however, the individual fibres can, much more distinctly than is the case with connective tissue, be so completely isolated, that I cannot help saying that I regard the separation into single fibres as really taking place, and not merely as an artificial one, or as a delusion on the part of the observer.

But it is very interesting to observe that this fibrillar stage of fibrine is invariably preceded by a homogeneous one, just a3 connective tissue originally wears the form of a homogeneous intercellular substance (mucus) from which fibres are only by degrees, if I may so express myself, excreted, or, to employ the usual term, differentiated. So fibrine, too, which is first of all gelatinous, becomes differentiated into a fibrillar mass. And indeed in the case of inorganic substances also we find certain analogous appearances. From deposits of calcareous salts or silicic acid, which were originally perfectly gelatinous and amorphous, solid granules and crystals are gradually separated.

The name fibrils may therefore still be retained to designate the usual form in which fibrine presents itself, but at the same time it must be borne in mind, that this substance originally existed in a homogeneous, amorphous, gelatinous condition, and can again be reduced to it. This reduction can not only be effected artificially, but takes place also naturally in the body itself, so that where we have previously found fibrils, we may afterwards meet with the fibrine in a homogeneous condition, as for example, in the vessels, where aneurysmal coagula, and others, are gradually converted into a homogeneous mass of cartilaginous density.

Now with reference to the second portion of the blood, the blood-corpuscles, I may express myself briefly, as they are well-known elements. I have already remarked that nearly all the histologists of the present time are agreed that the coloured corpuscles of the blood of man and the higher mammalia contain no nuclei, but that they are simple vesicles, concerning the cellular nature of which doubts might be permitted, if we did not happen to know that,

at certain periods of the de

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Fig. 51. Nucleated blood-corpuscles from a human foetus, six weeks old. a. Homogeneous cells varying in size, with simple, relatively large, nuclei,

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