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as composed of a closed membrane containing a tolerably tough mass, which is the seat of the colour. Now in man the blood-corpuscles are, as is well known, flat, disc- or plate-shaped bodies, with a central depression on each surface, and, when « o C J J regular in form, constitute, as it were, a q m ao</q ring in the centre of which the colour m&®f

is fainter from the diminished thickness. The contents are generally somewhat summarily regarded as consisting of haematine, or the colouring matter of the blood. They are, however, unquestionably very complex, and what is called haematine forms merely a part of them; how great a part it has not been hitherto possible to determine. Whatever other matters are contained within the blood-corpuscle, belong entirely to its chemistry. Certain changes produced by the action of external media constitute all that can be seen of them. We observe that the blood-corpuscles, according as they imbibe oxygen, or contain carbonic acid, appear light or dark, whilst they alter their form a little. We know further that by the action of chemical fluids certain quantities of water are abstracted from the corpuscles, and that they then shrivel up and experience peculiar changes in form, which might very easily give rise to errors. These are not unimportant conditions, and I will therefore now add a few words concerning them.

of which a few are slightly granular, but the greater number more homogeneous; at * a colourless corpuscle, b. Cells with extremely small, but well defined, nuclei, and distinctly red contents. c. After the addition of acetic acid, the nuclei are seen in some instances shrivelled and jagged, in several, double; at * a granular corpuscle. 2S0 diameters.

Fig. 52. Human blood-corpuscles from an adult, a. An ordinary, discshaped, red blood-corpuscle; b, a colourless one; c, red corpuscles seen in profile, and standing upon their rims. d. Red corpuscles arranged in the form of rouleaux of money, e. Red corpuscles which have become irregular in outline, and shrivelled through loss of water (exosmosis). /. Shrivelled red corpuscles, with tuberculated margins, and a projection, like that produced by a nucleus, upon the flat surface of the disc. g. A still more shrivelled state. h. The highest degree of shrivelling (melanic corpuscles). Magnified 280 diameters.

When a blood-corpuscle is exposed to a loss of water by the action of a strongly concentrated liquid upon it, the first thing we observe is that, as fast as fluid exudes, little prominences arise on the surface of the corpuscle, at first very much scattered, sometimes at the border, sometimes more towards the middle, and in the latter case occasionally bearing a deceptive resemblance to a nucleus (Fig. 52, e,f). This has been the source of the erroneous assumption of nuclei, which have been so much described. If a blood-corpuscle be watched for a considerable time whilst under the action of concentrated media, more and more protuberances are seen to arise, and the surface of the corpuscle becomes less in diameter. At the same time little folds and knobs form with continually increasing distinctness on the surface, and the cell becomes jagged, stellate, and angular (Fig. 52, y). Jagged bodies of this sort are to be seen every moment on examining blood which has been for some time exposed to the air. Even mere evaporation will produce this change. We can effect it with great rapidity by altering the composition of the serum by the addition of salt or sugar. If the abstraction of water continue, the corpuscle grows smaller still, and ultimately becomes smooth again and at the same time globular (Fig. 52, h), or even perfectly spherical, whilst its colour appears much more intense, and the contained mass assumes quite a deep blackish-red hue. Hence we are able to draw the not uninteresting conclusion, that this exosmosis consists essentially in a withdrawal of water, during which perhaps one or more other matters pass out, as for example salt, but the essential constituents remain behind. The haematine does not follow the water; the membrane of the blood-corpuscle keeps it back, so that when a large quantity of fluid is lost, the haematine in the interior must of course become proportionately increased in density.


The reverse is the case when we employ diluted fluids. The more diluted the fluid, the more does the blood-corpuscle enlarge; it swells up and becomes paler. On treating blood-corpuscles, which have become smaller from the action of concentrated fluids, with water, we see them pass back from the globular into the angular form, and from this into the discoidal one; after which they continually become more and more globular, often assume very peculiar shapes, and again grow paler. This process may, if the dilution of the blood be effected with great precaution, be continued until the blood-corpuscles scarcely seem to retain a trace of colour, though they still remain visible. In ordinary cases, when much liquid is added at once, such a violent revolution is produced in the economy of the blood-corpuscle, that an escape of the haematine immediately ensues. We then obtain a red solution, in which the colouring matter is free and dissolved in the fluid. I call your attention to this peculiarity, because it is continually occurring in the course of investigations, and because it explains one of the most important phenomena in the formation of pathological deposits of pigment, in which we meet with a precisely similar escape of haematine from the blood-corpuscles (Fig. 54, a). The expression generally made use of under such circumstances is, that the blood-corpuscles are dissolved, but it has long been a well-known fact, that, as was first shewn by Carl Heinrich Schultz, although there apparently no longer exist any cells, yet their membranes may, by means of an aqueous solution of iodine, again be rendered visible, whence it is evident that it was only the high degree of distension and the extraordinary thinness of the membranes which prevented the corpuscles from being seen. Indeed, very violent action on the part of substances chemically different is required, in order to effect a real destruction of the blood-corpuscles. If, immediately after they have been treated with a very concentrated solution of salt, water be added in large quantity, we may succeed in bringing things to such a pass that the contents of the corpuscles are abstracted without their swelling up, and their membranes remain behind visible. This was the reason why Denis and Lecanu asserted that the blood-corpuscles contained fi brine; for they believed that, by treating them first with salt and then with water, they were able to demonstrate its presence in them. This so-called fibrine is, however, as I have shewn, nothing more than the membranes of the bloodcorpuscles; real fibrine is not contained in them, although their walls are certainly composed of a substance which has more or less affinity to albuminous matters, and may, when obtained in large masses, present appearances reminding one of fibrine.

Now with regard to the substances contained in the blood-corpuscles, they happen quite recently to have become invested with great interest in consequence of the more morphological products which have been observed to arise oat of them, and which have produced a kind of revolution in the whole theory of the nature of organic matters. I refer here to the peculiar forms of coloured crystals, which can, under certain circumstances, be obtained from the colouring matter of the blood, and which have acquirednot only on their own account great chemical, but also very considerable practical, interest. We have already become acquainted with three different kinds of crystals, of which haematine seems to be the common origin.

To the first form, with which I at one time busied myself much, I have given the name of Hamatoidine. This is one of the most frequent of metamorphic products, and is spontaneously formed in the body out of haematine, and that indeed often in such large quantities that its excretion can be perceived with the naked eye. This substance in its perfect form presents itself in the shape of oblique

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rhombic columns, and is of a beautiful yellowish-red, or frequently, when in thicker pieces, deep ruby-red, colour, and forms one of the most beautiful crystals Fl°- 53, we are acquainted with. In little plates too it is not uncommonly met with, and fre- |£3j

quently bears a considerable resemblance to fc|^A the crystalline forms of uric acid. In the ^«^ majority of cases the crystals are very small, W C, not merely microscopical, but even somewhat difficult of observation with the microscope. A man must either be a very keen observer, or provided with special preparatory knowledge, else he will frequently discover in the spots where the haematoidine is lying nothing more than little streaks, or an apparently shapeless mass. But, upon more accurate inspection, the streaks resolve themselves into minute rhombic columns, the mass into an aggregation of crystals. This substance may be considered as the regular, typical, ultimate form into which haunts tine is converted in any part of the body where large masses of blood continue to lie for any length of time. An apoplectic effusion in the brain, for example, cannot be repaired by any other process than by a large portion of the blood undergoing this form of crystallization, and if we afterwards find a coloured cicatrix at the spot, we may feel perfectly assured that the colour is dependent upon the presence of haematoidine. When a young woman menstruates, and the cavity of the Graafian vesicle, from which the ovum has been extruded, becomes filled with coagulated blood, the haematine is gradually converted into haematoidine, and we afterwards find at the spot where the ovum had lain, the beautiful deep-red colour of the haematoidine crystals, which remain as the last memorials of this episode. In this manner we

Fig. 53. Crystals of Hsematoidine in different forms (Comp. 'Arcliiv f. path. Anat.,' vol. i, p. 391, plate iii, fig. 11). Magnified 300 diameters.

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