the stomach,) but merely to the stimulus of the subacid cold fluid.

"How long the appearances were suspended I did not note, or have now forgotten. The fever continued with the same frequency of pulse, and pain in the side, attended with yawning and great increase of suffering while in the prone posture. Notwithstanding the saline antimonial medicine was continued, the figures returned; but they now consisted of books, or parchments, or papers containing printed matter. I do not know whether I read any of them, but am at present inclined to think they were either not distinctly legible, or did not remain a sufficient time before they vanished.

"It occurred to me, that all these delusions were of one sense only, namely, the sight; and, upon considering the recurrence of sounds, a few simple musical tones were afterwards heard, for one time only; soon after which, having dropped asleep, an animal seemed to jump upon my back, with the most shrill and piercing screams, which were too intolerable for the continuance of sleep. Diseased perceptions of the hearing did not again recur.”

CHAPTER VII.

SPECTRAL ILLUSIONS ARISING FROM INFLAMMATION OF THE BRAIN.

"And often where no real ills affright, Its visionary fiends, an endless train, Assail with equal or superior might,

And through the throbbing heart, and dizzy brain,

And shivering nerves, shoot stings of more than mortal pain."

BEATTIE.

OUR researches have hitherto been confined to the blood, which we have considered as giving rise, from its own independent chemical properties or bulk, to certain intense states of the mind. It is now of importance to inquire if similar effects may not be referred to nervous influence.

According to the very important physiological experiments of Dr Philip, it appears that the nervous system consists of parts endowed with the vital principle, yet capable of acting in concert with inanimate matter; and that in man, as well as in certain wellknown animals, electricity is the agent thus capable of being collected by nervous organs, and of being universally diffused, for purposes intimately connected with the animal economy, throughout every part of the human system. The agency, therefore, of the

nerves in contributing to produce numerous changes on the blood, and with them equally numerous states of the mind, must be very great; and it is for this reason, that throughout every part of the human body they accompany vessels in their course. One set of nerves takes a direction from the surface of the human body, or from its cavities; agreeably, also, to the impressions received from external matter, as well as to the differences of animal structure which occur in sensible organs, corresponding sensations and renovated feelings are excited. Hence, when we take into consideration the effect of certain gases on the blood in inducing definite qualities and degrees of vividness in our mental feelings, the conclusion is inevitable, that the nerves belonging to the sensitive organs of our frame cannot generate any mental affections without first producing those peculiar sanguineous effects which we have before described, and to which the immaterial principle of the mind seems, in some unknown manner, to be related. It may be also observed, that the mental feelings thus excited by the nervous influence on the circulation, bear a further relation to a set of nerves proceeding from small portions of the brain and spinal cord, which supply the muscles of voluntary motion; each distinct state of mind thus ultimately stimulating with a definite degree of force particular muscular fibres. But, besides the class of nerves concerned with voluntary motion, there is another and far more extensive description, which exercise, through the medium of the blood, an influence on the states of the mind. Nerves of this kind, consisting of a chain of ganglions, to which

communications from all parts of the brain, and spinal marrow are sent, form the cause of the processes of secretion. The healthy exercise of these functions is attended with a temperature considerably raised above that of the surrounding medium, and hence arise the different mental states which result from salutary and morbid assimilations, or from the moderate, intense, or languishing circulation of the blood. It is ther from these causes that various degrees of vividness may be imparted to our feelings.

This physiological view leads to the inference, that with respect to causes of irritation acting on the nervous system, they may either influence nerves connected with the transmission of sensations and ideas from external impressions, or they may influence those nerves which are concerned in the processes of secretion; in either case, however, the vividness of mental feelings cannot fail to be affected. On the other hand, by merely stimulating the nerves which are transmitted directly from the brain and spinal cord to the voluntary muscles, nothing more than irregular muscular actions can ensue. Causes of nervous irritation may also act in two ways; they may either directly influence the state of the blood, and with it the state of the mental feelings, or they may produce a similar effect, though far less in degree, by exerting a power over the elastic and involuntary muscular fibres of the heart, giving, by this means, either an increasing or diminishing resistance to the vital expansibility evinced in the volume of the circulating mass.

Dr Philip has mentioned, as a result of his experiments, that a chemical or mechanical agent very par

tially irritating the brain and nerves, is incapable of exciting the heart, but that it is influenced by all agents applied to any considerable portion of these organs, and that it feels the effect of such an influence as long as it is applied. Excitements of this kind are to be found in such inflammatory causes as sudden alternations of heat and cold, exposure to the rays of a vertical sun, the sudden suppression of accustomed evacuations, various kinds of poison, and inebriation. In certain forms of cerebral inflammation, the first symptoms evince an increasing intensity of all sensations. In the case of a lady, a patient of Dr Good, there was an intolerable acuteness of hearing and vision, insomuch that the slightest light and sound, even the humming of a fly, became insupportable. Ideas also were rendered more vivid. the inflammation increased, the acute sensibility to external impressions gradually diminished, while the recollected images of the mind assumed a most frightful reality. In an example which came under my own notice, ideas of vision were so intense, that although the patient closed his eyelids, he could not even then dispel the lively images of demons that haunted his bed. The sleep was moreover disturbed with the most horrible dreams.

But as

A very curious case of spectral illusions is related by Dr Alderson of Hull, in which the irritation of the brain or its membranes seems to have resulted from an extended inflammation under the scalp.

"A few months ago," says this writer, "I visited Mr R., who was seized, in his passage from America, with a most excruciating headach. He obtained some