vidual had previously laboured under an affection produced by the use of lead, which had left him in a state of much nervous debility. Notwithstanding this circumstance, this case clearly proves, that the affection is liable to be increased and brought on by local influences.

A lady of advanced age, lodged on the eastern coast of Kent, in a house that looked immediately upon the sea, and exposed to the glare of the morning sun. The curtains of her room were white, a circumstance which added to the intensity of the light. When she had been there about ten days, she observed one evening, at the time of sunset, that first the fringes of the clouds appeared red, and soon after the same colour was dif fused over all the objects around her, especially if they were white. This lasted the whole night, but in the morning her sight was again perfect. This alternation of morbid with sound sight prevailed the whole of the time the lady resided on the coast, which was three weeks; and for nearly as long after she left it, at which time it ceased suddenly of its own accord.

Some remarkable instances are recorded of want of power in distinguishing colours. These facts are important to bear in mind when testing the healthy condition of the organs of vision. In some cases a morbid condition of this sense (symptomatic of centric disease of the brain) consists in the patient not being able to distinguish one colour from another, as well as in their observing certain objects surrounded by a halo, variously coloured and tinted.

Dr. Priestly has published a curious case of error of colour in five brothers and two sisters, all adults. One of the brothers could form no idea whatever of colours, though he judged very accurately of the form and other qualities of objects; hence he thought stockings were

sufficiently distinguished by the name of stockings, and could not conceive the necessity of calling them white or black. He could perceive cherries on a tree; but only distinguished them, even when red-ripe, from the surrounding leaves by their size and shape. One of the brothers appeared to have a faint sense of a few colours, but still a very imperfect notion; and upon the whole, they did not seem to possess any other distinguishing power than that of light and shade, into which they resolved all the colours presented to them-so that dove, or straw colour, was regarded as white; and green, crimson, and purple, as black or dark. On looking at a rainbow, one of them could distinguish that it consisted of stripes, but nothing more. Dr. Nicholl relates the case of a boy who con founded green with red; and called light red and pink, blue. His maternal grandfather and one uncle had the same imperfection.

CHAPTER XXII.

Morbid Phenomena of Vision.

In diseases of the brain the visual power may be,

IMPAIRMENT AND LOSS OF VISION.-These are common and important symptoms of organic disease of the brain. The impairment of vision may come on gradually or occur suddenly. The sight is occasionally lost in one eye before the defect is observed, but, as a general rule, the disordered function of the eye is of slow and progressive growth, proceeding, pari passu, with the development of subtle structural changes in the delicate tissue of the brain, its membranes and vessels, more immediately connected with the origin, course, and distribution of the optic nerves.

Impairment of vision is often symptomatic of gastric, hepatic, and intestinal derangement. It is of importance not to overlook this fact, when diagnosing a suspected condition of brain disease, associated with what may be considered, symptoms of cerebral amaurosis.

This affection of sight arises, occasionally, from general debility, hemorrhage, morbid states of the blood, and exhausting and debilitating discharges. Sudden loss of vision has been known to succeed a severe mental shock.

It is observed as one of the consequences of typhus fever, and frequently succeeds blows upon the head, after the acute cerebral symptoms so induced have subsided. This condition of vision may also be the effect of lead poison, syphilis, the effect of tabes dorsalis, arthritis, or be consequent upon great and long-continued anxiety and distress of mind, interfering with the nutrition, and causing atrophy of those portions of the brain more immediately connected with the optic nerve.

Dr. F. Hawkins, when speaking of the inflammatory affections of the brain, says: "It is well known that sympathy with the nerves of the digestive organs will give rise to various affections of vision, from the slightest dimness up to temporary amaurosis, from the occasional appearance of a luminous spot, up to that of forms and spectra which are shaped by the imagination into distinct apparitions. It is difficult, therefore, to arrive at any certain conclusion with respect to the existence of cerebral disease from the indications afforded by the organ of vision; and numerous cases of affection of the optic nerves have been considered as only sympathetic, which, in fact, were symptoms of disease acting at once on the origin of those nerves of the brain. A gentleman came to town about two years ago on discovering suddenly, with surprise and alarm, that the sight of one eye had utterly failed him. He consulted all the oculists and surgeons chiefly celebrated for the treatment of such cases, and most of them were of opinion that this partial defect of vision was purely sympathetic, and would be removed by the use of senna and blue pill, and in fact it was, to a certain extent, so removed: but as he died soon afterwards in Ireland, with the symptoms, as I have been informed, of disease of the brain, and as he inherited, and himself evinced, a tendency to cerebral disorder, which appeared to be

hereditary (his mother being at this moment afflicted with hemiplegia), I think there can be little doubt that his temporary loss of sight was a symptom, not merely, as it was supposed, of dyspepsia, but of a morbid state then existing in the brain. In a recent case of paralysis the occurrence and fatal termination of which the friends of science everywhere deplore, it appeared from the result that a singular affection of the optic nerves which had previously been attributed to derangement of the stomach, indicated with too much truth the existence of irritation or pressure, affecting the organ of one of those nerves.'

In the early stages of cerebral amaurosis, termed amblyopia, or incomplete amaurosis, the patient complains of his vision becoming gradually indistinct, objects appearing either lighted up by a bright flame, or surrounded by a fog or mist. These symptoms are somewhat analogous to those described by Romberg as symptomatic of gutta serena.

"The outlines of objects," says Romberg, "appear not only indistinct, but also broken, and thus disfigured. The light of the candle appears rent; while reading, the patient misses single syllables, words, and lines, and he is forced to follow them by moving his eye, head, or entire body. At times, the upper or lower, the right or left half, the circumference or centre of the object only is seen; at others the loss of vision is still more partial, and is confined to different spots of small extent, and with differently shaped outlines. Instances also occur in which the object is only seen when it bears a definite relation to the eye, and it vanishes on the slightest movement of the eye or head."

Let me consider briefly some of the more characteristic symptoms of centric cerebral amaurosis connected with

"Croomian Lectures on the Inflammatory Affections of the Brain," by F. Hawkins, M.D.