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in immediate contact with the cells of the rete mucosum (Fig. 83). The case is especially favourable when, in consequence of any disease, as for example small-pox, a slight tumefaction of the whole thickness of the skin in the parts affected has taken place, and the corpuscles are a little larger than they normally are. In ordinary papillae it is somewhat more difficult to discover these elements, still upon closer examination they may be seen everywhere, even by the side of the tactile bodies.

Thus, even in the finest of these prolongations of the cutis, it is not an amorphous mass which is found, bearing a constant relation to the vessels and nerves; on the contrary this mass of connective tissue always manifests itself as the one thing invariably present in the structure, as the real fundamental constituent of the different (vascular and nervous) papillae, and the individual papillae do not acquire a different character until in the one case vessels, in the other nerves, are added to this fundamental substance.

We certainly know little concerning the special relations which the vascular papillae bear to the functions of the skin, still it can scarcely be doubted that an important relation must exist, and that as soon as we are better able to separate the different offices of the skin, greater importance will be attached to the vascular papillae also. This much however we can even now say, that it is incorrect to imagine that a special nervous branch exists in every anatomical division of the skin; just as physiological experiments 1 shew that considerable sensitive districts exist in the skin, so also more minute histological investigation teaches us that there is a relatively scanty termination of nerves upon the surface. If therefore we think fit to divide the skin into definite territories, those appertaining to the nerves will, as a matter of course, be larger than •those belonging to the vessels. But every vessel-territorv

1 The allusion is to Weber's experiments with Compasses-- Trans.

VESSEL-, NERVE- CELL-TERRITORIES IN THE SKIN. 245

(papilla) also which is marked out by a single capillary loop is divided into a series of smaller (cell-) territories, all of which certainly lie along the banks of the same vessel, but still have an independent existence, each of them being provided with a special cellular element.

In this manner it is very easy to explain how within a papilla a single (cell-) territory may become diseased. Suppose, for example, that such a territory swells up, increases in size, and continually keeps shooting farther and farther upwards, then arborescent ramifications may arise (acuminate (spitzes) condylomax) without the whole papilla's being affected in a like manner. The vessel does not shoot

Fig. 84.

[graphic]

up until later and forces its way into the branches when they have already attained a certain size. It is not the vessel which pushes out the parts by its development, but the first signs of development always show themselves in the connective tissue of the papilla. The study of the conditions of the skin therefore affords special interest to those who wish to devote themselves to the critical examination of the doctrines held concerning general pathology. And first with regard to the neuro-pathological views, it is quite inconceivable how a>nerve which lies in the middle of a whole group of nerveless parts, can contrive to force a single papilla from among this group, with which it has not the slightest connection, into a state of pathological activity, in which the remaining papillae of the same nerve-territory take no share. Just as difficult is it, in the diseases of non-vascular papillae, to find an explanation which shall accord with the views of a humoro-pathologist. Even when in a vascular papilla the different cell-territories attain different states, these would not admit of a ready explanation, if we were to regard the whole process of nutrition in a papilla as directly dependent upon the general condition of the vessel which supplies it.

Fig. 81. The fundamental substance (connective tissue) of an acuminate condyloma of the penis with freely budding and branching papillae, after the epidermis and the rete mucosum have been completely detached. 11 diameters.

1 The Germans speak of condylomata lata and acuminata. The condyloma latum is invariably of syphilitic origin, and is identical with the plaque muquense of the French, who never use the term condylome in this sense. Condyloma acuminatum, on the contrary (by the French termed simply condylome), is not syphilitic in its nature, but frequently occurs in Gonorrhoea, though it is also met with independently of this disease.—From a MS. note by the Author.

Similar considerations might be entered upon with regard to all points of the body. Still we have in the skin a particularly favourable example for demonstrating how very incorrect it is to regard all vessels as subject to a particular nervous influence. There are a number of vessels which are entirely removed from the influence of all nerves, and, if we still confine our attention to the skin, the influence which a nerve is in a condition to exercise, is limited to this, that the afferent artery, which supplies a whole series of papillae in common (Fig. 44) may by its means be brought into an altered condition, so that a contraction or dilatation, and in correspondence with these states a diminished or increased supply of blood to a considerable district, takes place.

If now we return from this digression to our real subject, you will recollect that I had described to you my ignorance

OLFACTORY MUCOUS MEMBRANE. 247

concerning the real mode of termination which the nerves have in the tactile bodies. Whether the nerve ultimately forms a loop, or in any manner directly terminates in the internal substance of the body, is not, I think, as yet absolutely decided.

If now we consider other instances of the terminations of nerves, nowhere does any probability manifest itself that they really do form loops. In every case in which more certain knowledge has been acquired, the probability has on the contrary always become greater, that the nerves either terminate in a large plexus or reticxdar expansion; or that they end in special apparatuses, concerning which it is still doubtful whether they are peculiar processes of a particular shape, into which the nerves shoot out at their extremities, or whether they constitute peculiar parts, non-nervous in their nature, to which the nerves attach themselves. This latter mode of termination is, it would appear, characteristic of most of the higher organs of sense, but in no single instance, in consequence of the extreme difficulty which the investigation of these parts presents, have any views been proposed which have met with universal assent. Notwithstanding the numerous investigations into the structure of the retina and cochlea, the mucous membrane of the nose and mouth, that have been made in the course of the last few years, it must be confessed that the ultimate points of histological detail have not as yet been altogether satisfactorily settled. In nearly all cases there remain two possible ways in which the nerves may terminate. According to some their terminations are connected with special structures which, according to the language hitherto employed, cannot be regarded as being of a nervous nature, but are peculiar appendages of the nerves, though they are certainly stated by other observers to be directly connected with nerve-fibres, as for example in the nasal mucous membrane. This namely is regularly clothed with cylindrical epithelium, which isplen

tifully provided with cilia and forms several layers, lying one above the other, so that there are several rows of cells covering one another. In these, according to several recent observers, cells are met with, which terminate in a somewhat long filament, and do not, like other epithelial cells, end upon the surface, but run in an inward direction, so as to become directly continuous with the ends of the nerves. According to others, particularly Max. Schultze, on the contrary, and this view seems to be the more correct one, peculiar filiform ends of nerve force their way out between the epithelium. The objects of smell would therefore according to both views really come directly in contact with the structures forming the terminations of the nerves. Similar epithelium-like structures have recently been described as occurring also in the mucous membrane of the tongue, seated upon peculiar papillae, which appear to possess a pre-eminently nervous character.

These structures moreover might lay claim to a certain resemblance with the ultimate terminations which we find in the case of the optic nerve in the retina, and in that of the auditory nerve especially in the cochlea—terminations, which may in the latter case, as far as their external shape is concerned, be compared to long-tailed epithelial cells, whilst those in the retina constitute structures of peculiar delicacy. In the retina namely the optic nerve, after its entrance into the interior of the globe of the eye, spreads out in such a way, that its fibrous elements run along on the anterior side of the retina, that side, namely, which is turned towards the vitreous body (Fig. 85,/); posteriorly, there follows a stratum of varying thickness, which belongs to the retina indeed, but in no wise proceeds from the direct expansion of the optic nerve. In this layer we see, where it borders upon the layer of pigment-cells of the choroid coat, and in immediate contact with these cells, a peculiar stratum which has been subjected to a strange destiny, inasmuch as it was for a considerable time transplanted to the ante

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