nic centre, he divided the gustatory nerve, and the secretion from the gland was immediately stopped. He then pinched the centripetal end of the cut nerve which communicates with the brain, and a large quantity of saliva was secreted, whilst the ducts of the parotid and sublingual glands remained dry.* He subsequently varied the experiment by cutting the chorda tympani, leaving the gustatory nerve intact, and secretion immediately ceased, as in the first experiment. He then inserted a tube into the Whartonian duct, and communicated a weak current to the peripheric end of the divided nerve. Every time that this was done, a drop of saliva was seen to fall from the tube. Thus secretion was arrested by section of the tympano-lingual nerve, and reproduced by the stimulus of electricity communicated to its distal extremity. When applied to the centripetal end of the divided nerve, the electric current had no effect.

These experiments supply us with something like evidence, from which to infer that secretion may be, in some way or other, dependent on cerebro-spinal influence, modified, as I have before suggested; and as the nerve-current of a sensitive nerve, on which the first experiment was performed, is centripetal, the irritation of pinching the central portion of the cut nerve could only be conveyed to the gland by the reflex action of the returning motor nerve. Whereas when the chorda tympani was divided, secretion was re-established by communicating an electric current through the peripheric end of the nerve. But the electric current has no effect when Comptes Rendus, vol. xxxiv. p. 474.

*

applied to the peripheric portion of a divided sensory nerve; and we are therefore warranted in the assumption that it is through the influence of the motor nerve that secretion is re-established.

Something more, however, is suggested to the mind by the fact of the ducts of the parotid and sublingual glands remaining dry, whilst the Whartonian duct poured out saliva; and that is, that every gland stands in relation to a special act, and that its function is determined by a special and independent influence.

If the facial nerve be divided as it passes out of the stylo-mastoid foramen, the secretion of the parotid gland is but little affected. If, however, the facial be divided at its origin, inside the skull, secretion, both from the parotid and submaxillary glands, is abolished.* There is something, therefore, between the origin of the facial nerve and the stylo-mastoid foramen, to which such arrest of secretion is due. It cannot be the facial alone, for its ablation has but little effect, either on the parotid or submaxillary gland. Neither can it be the chorda tympani alone, for section of that nerve does not influence the parotid secretion, but stops that of the submaxillary. But the division of the facial nerve in the hiatus Fallopii involves the resection of the portio intermedia of Wrisberg, which expands, in the Fallopian canal, into the geniculate ganglion. Thus we have an indication that the secretion of the parotid is dependent on a ganglionic centre.

If the facial nerve be left uninjured, and the nerves

* Leçons sur la Physiologie et la Pathologie du Système Nervaux. M. C. Bernard. Tome ii. p. 154, 155.

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of Remak (which proceed from the superior cervical ganglion to be distributed to the ramifications of the internal maxillary artery) are cut, the secretion of saliva goes on more abundantly and continuously. It has also been observed that, when the floor of the fourth ventricle is slightly wounded in the immediate vicinity of the nuclei of the fifth pair of nerves, well-marked salivation from the parotid glands is set up. If the wound be in the mesial line, ptyalism is induced on both sides; but if the wound be on one side, then the increased secretion is occasioned in the parotid of the opposite side.*

The results of these experiments are strictly in accord with those on which I have already commented; arrested secretion by section of the motor fibres of the vaso-motor nerves, increased secretion by section of the fibres of Remak, and increased secretion by excitation of the sensory nerves.

M. Claude Bernard divided the sympathetic in the upper part of the dorsal region of a horse; a greatly increased vascularity was the immediate result, and the corresponding parts of the surface were bathed in sweat.†

He also found considerable distention of the pericardial vessels, and serous exudation from them, after injuring the cardiac ganglia of the sympathetic. This experiment was repeated and verified by Schiff, and Remak explained the phenomena by the assumption that when the blood vessels are deprived of the inhibitory influence of the sympathetic nerves proper, they dilate and allow blood-corpuscles to

* Medical Times and Gazette, 1860, p. 362.

Ibid. 1861, p. 544.

penetrate into those minute arterioles, through which blood-plasma only should be propelled.*

On injuring the solar plexus, or on dividing the main trunks of the sympathetic, Budge ascertained that the circulation of the blood in the liver is increased, and the secretion of bile augmented, and in two cases he found the liver itself enlarged. On extirpating the mesenteric plexuses in rabbits, the fæcal pellets became so soft that none of the ordinary rounded masses were found in the rectum. The fæces were pulpy, and covered over with a slimy mucus. M. Claude Bernard extirpated the semilunar ganglia in a large shepherd's dog, and observed the same results.‡

Jaschkowitz, by dividing the sympathetic nerves of the spleen in cats and dogs, caused an increased flow of blood to that organ, and a copious deposit of hæmatin pigment in its cells.§

In the experiments instituted by Bernstein on the pancreas, he discovered that, notwithstanding the absence of secretion in that organ during fasting, on dividing the sympathetic nerves going to it, a continuous flow of pancreatic fluid is produced.|| The originating power of the ganglionic centres is

* The ulterior stages of inflammation have been still further explained by Waller, Reicher, Cohnheim, and Stricker, by the proposition that pus-corpuscles are nothing but the colourless blood-corpuscles filtered from the blood through the walls of capillary vessels. In a very elaborate paper contained in Virchow's Archiv, for September, 1867, Cohnheim demonstrates the truth of this proposition by exciting inflammation in the peritoneum of frogs.

† Nova Acta, Acad. Cæs. Loop. Car. Nat. Cur. xix. p. 257, 1860. Leçons sur la Physiologie et la Pathologie du Système Nervaux. Tome ii. p. 522.

§ Jaschkowitz de Discisionis Plexus Lienalis efficitate in Lienem. || Sächs Akad. Sitzungberichte Math. Phys. Class, 1869.

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indicated by the fact, that when secretion is thus artificially produced, it is not arrested by placing the animal under the influence of woorara. The special relation, moreover, in which the action of the pancreas stands to the digestion of food, increasing immediately after a meal, attaining its maximum about three hours after, and then gradually diminishing, shows the local centralisation of nervous influence.

The structure of the kidneys is almost suggestive of the function of each component part.

The Malpighian tufts, and the special capillaries surrounding them, shut up within the Malpighian capsules, in which there is but little of epithelial cell structure, exhibit the most perfect contrivance for that simple and independent filtration of fluid which is known as exosmose-a simple outpouring of the watery part of the blood into the capsules, to flush, as it were, the tortuous tubuli uriniferi in front.

The cortorted tubuli, surrounded by their special capillaries, to which the ultimate fibres of the renal plexus have been traced, and constructed of basement membrane, lined with the rounded, glandular variety of epithelial cells, indicate a secretory structure; and here, undoubtedly, it is that the salts which characterise the urine are eliminated from the blood.

Section of the splanchnic nerves, as performed by Eckhardt, induces hyperæmia of these latter capillaries, albuminuria, and increased renal secretion ;

* Arbeiten aus der Physiologischen Anstaltzen. Leipzig, Vierter Jahrgang, 1869.