These are, first, affections of the nervous system, as traumatic lesions of the brain and nerves; certain cerebral affections, moral effects, strong emotions, profound sorrow, hard and prolonged study, nervous excitement: also too frequent coitus - venus im-modica - and onanism, have been reckoned as causes of Diabetes; in two or three severe cases this last habit has been admitted. Sugar is also found in the urine in certain nervous maladies, as hysteria, epilepsy; even after fits of coughing in hooping-cough Glycosuria has existed; but in these cases the usual symptoms of Diabetes do not occur.

Traumatic lesions and diseases of the brain. Irritation of the pneumogastric nerves or pricking the floor of the fourth ventricle or the olivary bodies, from which the pneumogastric nerves arise, has given origin to sugar in the urine. Cerebral disturbances may also determine Glycosuria, such as arise from falls on the head or neck, but the sugar disappears as the effects of the injury pass away: if, however, disease is set up, as the result of these injuries, in the fourth ventricle or its neighbourhood, then the sugar in the urine may become permanent, and the kidneys, not being able to get rid of the quantity formed, its retention gives rise to the constitutional symptoms, and we have Diabetes.

Professor Grisolle mentions a case of Diabetes following upon disease in the nervous centres. A woman aged fifty-two became hemiplegic and, in less than a year after, Diabetes manifested itself with great intensity. The post-mortem examination in a case of Diabetes which had lasted seven years showed small spots of blood between the layers of the optic thalamus and corpora quadragemina. M. Levrat, in his thesis, mentions a case where, on post-mortem examination, a colloid tumour was found in the fourth ventricle.

Dr. Luys, in a post-mortem of a case of Diabetes, found the anterior wall of the fourth ventricle was more vascular than in the normal state; the large venous trunks were delineated on its surface. On looking more closely, tawny spots were observed disseminated in the upper parts below the superior processes of the cerebellum, also similar spots below the origin of the auditory nerves: these tawny spots were due to fatty degeneration of the nerve cells; in place of presenting regular shapes, fringed prolongations, and circumscribed nuclei, the cells were transformed into an irregular granular mass exclusively constituted by aggregated yellowish granulations more or less closely attached to each other: so complete was the alteration of tissue, that it might be said that the histological elements had reached the last stage of retrograde evolution and had ceased to exist as anatomical individualities. Dr. Luys describes another case in which there was found great vascularity with brownish discoloration of the anterior wall of the fourth ventricle, which was also notably attenuated. Histological examination disclosed a remarkable turgescence of the minute capillaries, and showed that the presence of the yellow patches, in some places tawny and brownish, was solely due to a peculiar degeneration of all the cells of the nervous tissue. The cells in progress of retrograde evolution were filled with yellowish granulations, having jagged, half-destroyed edges and presenting only some scarcely recognisable fragments.*

Dr. Dickinson, also, in the last volume of the Royal Medical and Chirurgical Society's Transactions, has described five cases of postmortem in Diabetes, in which peculiar morbid changes were constantly found in the cerebrospinal system; in all the alterations were of the same nature, and for the most part in the same situation. The earliest change recognised was a dilatation of the arteries, followed by a degeneration of the nervous matter at certain points external to them. The extension of the degenerative process produced cavities seen without the microscope; these cavities contained blood vessels, extravasated blood, grains of pigment, and the product of nerve decay. These contents were absorbed, simple vacuities being left. These were found in every part of the spinal cord and encephalon, attaining their greatest development in the medulla oblongata and pons varolii.

Sugar has also been met with in affections of the spinal cord. M. Becquerel mentions a case of acute myelitis in which it was found; also a case of spinal meningitis with inflammatory swelling of the pia mater, softening of cord substance, and a cyst in the cerebellum. Lebert has seen a haemorrhage into the upper part of the spinal column accompanied with intense Diabetes. In the works of Scarlau two cases are mentioned, in which there were all the constitutional symptoms of Diabetes and the autopsy showed softening of the cord, hypertrophy of the meninges and gelatinous exudation into them.

* Trousseau's Clinical Medicine, Vol. 3, p. 495, etc.

Irritation of the pneumo-gastric nerve is a cause. Mr. Nyman,* at the autopsy of a gentleman who had long suffered from Diabetes, found, on examining the thorax, a calculous mass the size of a hazel nut beneath the bifurcation of the trachea which appeared to exercise pressure upon the nerve: he met with the same state three times when making the post-mortem examination on cases of Diabetes: in fact, irritation of any part of the pneumo-gastric may cause the disease, it being the afferent nerve to the fourth ventricle, from whence the impression is reflected, through the sympathetic, to the liver and so producing Diabetes.

* G. Nyman 1857. Dublin Hospital Gazette, Vol. no. 14.