It is well known that in animals and man lesions of the trigeminus nerve sufficient to produce anæsthesia (of its first branch more especially) are frequently, if not invariably, followed by ulceration and perforation of the cornea and phthisis bulbi. These were long held to be true dystropic changes, but about thirty and twenty years ago Snellen and von Gudden demonstrated independently and by different methods that these ocular lesions could be entirely prevented by absolute closure (perfect protection) of the eyelids prior to the experiment on the trigeminus. Not long afterward Brown-Séquard showed that the sloughing ulcers which occur about the foot of an animal whose sciatic nerve has been cut may be entirely prevented by care, cleanliness, and soft bedding. The conclusion to be drawn from these observations is that in almost all cases the ulcerations and sloughing observed in man during the course of a nervous disease sufficient to produce anæsthesia, such as traumatic neuritis, lepra anæsthetica, traumatic or simple myelitis transversa, disease of the trigeminal nerve, etc., are in reality produced by external agencies, injuries to the cuticle, action of filth, and, we think, the entrance of bacteria, which are well known to possess extraordinary powers of penetration into tissues whose protecting epithelial layer is removed. Clinical observation corroborates this view, for, with strict antiseptic treatment and under sealed dressings (collodion to ulcerated finger-tips), these ulcerations heal rapidly and completely, while the anæsthesia remains unchanged and the nervous lesions may even progress. At the same {59} time, while we believe the above to be the pathology of so-called trophic ulcers, we would admit the possibility of spontaneous neuritic ulceration and gangrene, as shown more especially in herpes. 3. ALTERED SECRETIONS.—Under the influence of disordered innervation secretions may be altered in quantity and in quality. Symptoms of this class may be caused by neural or by central lesions, and the mechanism of their action may be direct or reflex. (_a_) After section or lesion by disease of the cervical sympathetic nerve we observe increased activity of the entire skin in the affected area of the head and face: there is more perspiration, lachrymation, and more cerumen is found in the ear. In cases of lesions of a certain part of the oblongata we find one result to be polyuria. In many cases of nerve-injuries the sweat-glands and hair-follicles of the parts supplied by the affected nerve appear to be sometimes abnormally active, or in other cases inactive. In some rare cases of insanity profuse salivation and extraordinary growth of hair are striking symptoms. Lastly, in some functional nervous affections the various secretions and excretions may be altered to extraordinary extremes (_e.g._ the polyuria and anuria of hysteria).