presence of urea has a marked accelerating effect, greater as the amount increases up to about 10 per cent., upon the digestion of fibrin by pepsin, HC (0.3 per cent. HCI), or by trypsin. In much larger quantities it has a retarding influence. A saturated solution of urea is a valuable histological reagent. By its reaction on the connective tissues it greatly facilitates the separation of a tissue into its individual elements-that is, cardiac and skeletal muscle, lens-fibers, fat cells and except in the case of the connective tissue and possibly of the nerve-fiber, there is no danger of its action being too energetic or going too far. The properties of urea combined with palmitic acid are considered in the paper. The basic character of urea shown by its combinations with various acids suggests that it is acting as a base; but the fact that even in markedly acid proteid solution urea exerts a specific effect upon proteids makes this explanation improbable. The numerous definite crystalline compounds formed by the union of urea and mineral salts suggest that it may act by combining with the natural salts of a proteid and so give us an ash-free proteid. Electrolytes exert an influence antagonistic to some of the effects of urea upon proteids. The effects of urea upon proteid may be described as: 1. Those of a substance sensibilisatrice, rendering the proteid more prone to zymolysis, conversion into acid or alkali albumin. 2. Protective, since coagulable proteids are not heatcoagulable in its presence, but reacquire their coagulability when the urea is removed by dialy

sis. 3. Solvent.

Continuing the account of his investigations at the meeting of the British Medical Association, Dr. Ramsden said that a dead frog placed in saturated urea solution soon became transparent and shortly fell to pieces. The myeline sheath of nerve was rapidly altered and presented similar appearances to that of degeneration. Urea converted native egg-white into a jelly. The author at first supposed that urea in these reactions was active as a base, but further experiments negatived this view-for example, urea was equally active on proteid in acid solution. Dr. Ramsden considered that it might act by rendering the proteid more sensitive to the action of any acid or alkali present. He had prepared crystalline compounds of urea with proteids and palmitic acid.

An inquiry by Messrs. Atwater and Benedict into the nutritive value of alcohol, reported in the proceedings of the National Academy of Sciences, concerned the value of alcohol as a fuel in the human body, and a comparison of it as to this point with sugar, starch, fats, and other nutritive matters in ordinary foods; and also the effect of alcohol upon the proportion of nutritive substance digested from food with which it was taken. More than 98 per cent. of the alcohol taken by the subjects was found to be oxidized in the body, and its potential energy to be converted into kinetic energy as completely as that of ordinary nutritive matters. Alcohol seemed to be effective in protecting the body fat from consumption, but less so in the protection of body protein. A slight advantage was found by the authors in favor of the non-alcoholic diet as regards the utilization of the total energy of the food, especially in cases involving hard muscular exertion, but the difference was very small, and did not exceed the possible limits of experimental

error.

Dr. Arthur Clopatt, of Helsingfors, has reported to the Congress of Finland Physicians concerning a series of experiments he has made on the

effects of alcohol upon the weight of the body. His conclusions were: 1, That alcohol, when the system has become accustomed to it, supplies the place of both nitrogenous and non-nitrogenous food by rendering a smaller amount necessary; and 2, that it has no demonstrable action in promoting the absorption of food from the intestine. The author in his paper cites the older authorities on the subject, such as Tiedemann, Gmelin, and Lallemand, as having believed that alcohol was excreted unburned from the economy; and the later experiments, including those of Anstie, Binz, and Strassmann, as having shown that it is to a certain extent destroyed in the body by oxidation.

From the researches of Drs. Osborn and Zobel, as communicated to the British Association, it appears that glycogen when hydrolyzed by a diastase ferment gives rise to bodies very similar to those derived from starch. Among these is the body called isomaltose, which was shown by Brown and Morris to be a mixture of maltose and a dextrin-like body. When acted upon by saliva glycogen gave dextrin, dextrose, and maltose.

The experiments of E. Weymouth Reid on the intestinal absorption of solutions go to show that a physical explanation of absorption is not admissible.

Glands and Secretions.-A crystalline body of constant composition has been obtained from the suprarenal gland by Jokishi Takamine, who, on account of its extremely potent action as a vasomotor constrictor, was led to believe it the active principle of the gland, and named it adrenalin. It is a white, light, microcrystallized body; assumes fine forms; has a slightly bitter taste; is sparingly soluble in its dry form; has a faintly alkaline reaction; and combines with various acids to form salts. It is a powerful reducing agent in alkaline and neutral solutions, and absorbs oxygen from the air. It may be used as a photographic developer. The author observes that the isolation of the active principle of the gland seems to point toward the fact that the wonderful physiological actions of the various glands may depend upon the effects of apparently simple chemical substances. Such isolation would naturally give an impetus to the search for active principles of the various organs concerning which we know but little.

Experiments illustrating the importance of the adrenal glands to life are described by Dr. Hans Stehl and Dr. Otto Weiss in Pflüger's Archiv. The investigations of Tolstoi and Nothnagel, who thought these glands were not essential, were regarded as liable to criticism, because the authors had not made sure of the absence of accessory adrenals. The authors found structures of this kind in rabbits. Operations of total extermination were performed on dogs, cats, mice, a hedgehog, a weasel, and frogs. Experiments made on animals from which only one adrenal was removed were uniformly fatal in guinea-pigs, but other animals did not seem to suffer much inconvenience. In animals that died after both glands had been removed, the symptoms were great mus cular weakness and apathy; the gait was vacillating, the legs were strangled, and the head was depressed, the temperature fell slowly, the bloodpressure was diminished, and where both adre nals were removed, it fell till the death of the animal. Transplantation of the adrenals, even into parts that were highly vascular, was never successful. It was difficult to determine certainly the cause of death. Some attributed it to loss of nervous power; others to the failure of supply of a substance secreted or produced by the adrenals which, entering the blood, keeps up the blood

pressure; and others to the accumulation in the blood of some deleterious substance, and weakening of the blood-pressure, which is ordinarily destroyed by the adrenals.

Prof. Schäfer and Dr. Magnus, of Heidelberg, have found as to the effects of intravenous injection of extract of pituitary body upon the activity of the kidneys, that the epithelial part of the pituitary body causes a marked increase in urinary secretion. That part of the gland had always previously been supposed inert. It is urged that the diuretic action now proved to be excited by the gland has a direct bearing upon the disease called acromegaly, in which the pituitary body is enlarged and diuresis is present.

In an investigation of the histological and chemical position of iron in the spleen, Dr. W. Brodie, of Edinburgh, by the use of microchemical methods, found the metal contained in the cells and also in bodies not of a cellular nature. Three varieties of iron-containing elements are described in the author's paper as belonging to the latter class; and besides these, three proteid bodies containing iron which had been obtained by means of purely chemical methods.

The conclusions drawn by Prof. Ludwig Aschoff, of Göttingen, from experiments concerning the origin of urine albumin tend to confirm Merten's researches and to support the view that the albumin present in nephritic urine is derived from the blood, and is different from the specific kidney albumin. According to the results hitherto obtained a difference appears to exist between the blood serum albumin and the kidney epithelium albumin. On the other hand, the investigations of von Dungern, Moxtet, Metchnikoff, Schützen, and others, point to the existence of a relationship between the proteid constituents of the different epithelial cells as well as of the blood-cells, inasmuch as the injection of one kind of cell may yield a serum that acts on several species of cells. In a paper read at the annual meeting of the British Medical Association, July 30, after pointing out that the formation of lymph might be considered in its relation either to the blood or to the tissues, Mr. F. A. Bainbridge passed on to deal with the relation existing between the tissue activity and lymph formation. He said that in the case of the submaxillary gland, the liver and the pancreas increased accretion-that is, increased metabolism invariably led to increased lymph formation. The possibility of the formation of lymph being due to altered capillary pressure and permeability was excluded, and it seemed probable that the lymph was formed as a direct result of the metabolism. The author supposed that during metabolism crystalloid bodies were formed in the tissues; these passed by diffusion into the lymph, raised its osmotic pressure, and therefore attracted water from the blood, the result being an increased flow of dilute lymph.

Among the results obtained in other experiments by Bainbridge respecting the formation of lymph in the liver was the fact that the intravenous injection of moderate quantities of sodium taurocholate or of pure hemoglobin leads to an increased flow of lymph from that organ, and to increased metabolic activity of the liver cells.

Representations having been made by some authors that sugar in recognizable quantities had been found in liver after it had been boiled free of that substance, and the conclusion seeming a difficult one to understand, experiments were made by F. W. Pavy and R. L. Siau with the liver of the cat and of the rabbit. The results in both cases were the same, and induced the conclusion that in a sterilized state no sugar is formed in VOL. XLII.-36 A

liver substance when it has been subjected to thorough boiling.

The Muscular System.-Two kinds of muscular soreness have been determined in the ergographic experiments of Mr. Theodore Hough. One kind is very marked during work, and may be noticeable for two or three hours afterward. It then passes entirely away. The other kind is not noticed at all at the time of the tracing and for some time afterward. It usually begins about eight hours after the work, increases to a maximum which may occur from ten to twenty-four or even more hours later. Indeed this soreness may not make its appearance till the second day after the tracing. It gradually passes away, but may be noticeable for four or more days. The first kind of soreness would seem to be due to the same causes as those which produce fatigue, namely, the presence of the diffusible waste products of exertion. There are reasons for supposing that the second kind of soreness is fundamentally the result of ruptures within the muscle.

Presenting the results of a series of experiments relating to the mechanism connecting the muscular apparatus with the centers for willed movement having their seat within the brain, Prof. Schäfer compared the relative effects of transection of the pyramidal tracts and of the vertical columns of the spinal cord. His observations had been made upon monkeys. Section of the vertical column of the spinal cord had been found to produce paralysis of voluntary movement in the parts of the body lying behind the segmental level of the lesion. The descending fibers of the vertical column of the cord were in the main derived from the cells of the nucleus of Deiters in the bulb, a group of fibers that were, on the other hand, related to the impulses entering the brain from the labyrinth organ, namely, the semicircular canals and the ololith organ. It had been proved by Ewald and others that the destruction of the labyrinth organ entailed diminution and impairment of the tonus of the voluntary muscles of the body.

The Nervous System.-In his presidential address before the American Neurological Association, Prof. Joseph Collins reviewed the most important work done in neurology during the year. The neuron theory, he said, which to-day stood as the basis of all neurology and neuropathology, in spite of criticisms and of the most elaborate histological investigations, had become more firmly established than ever. Recent researches, notably those of Apathy and Bethe, were explained as not really antagonistic to it. All investigations tended to show that ontologically the neurous (or nerve elements) became more intimately united in series, and that such intimacy was structurally heightened by use. There were, however, many obscurities still surrounding the question of the growth of axis-cylinders in relation to the cell bodies or trophic centers, which required to be cleared up. There also remained for solution the question whether in the human cerebral cortex the presence of the dendritic cell-processes and the neuroglia sufficed to account for the relatively large separation of the active cell-bodies, or whether a certain amount of intercellular substance remained which accounted for the appearance in question.

In the field of central localization, the results obtained by Horsley and Beevor through the methods of local electric stimulation of the cortex in the higher anthropoid apes had been corroborated and extended by Sherrington and Grünbaum. Flechsig, in the latest of his wonderful researches on the association centers of the human brain,

was able to show that from thirty to forty "areas "" or centers could be mapped out in accordance with their times and rates of development. Important confirmation of the same had come from the researches of Schäffer, of Budapest, and Storch, of Breslau, on general paralysis. Much attention had been devoted to the study of tendon reflexes, the most important and valuable discovery in this direction being the so-called Babinski reflex, which is now accepted as a definite indication of degeneration of the pyramidal tract. The subjects of toxemia and of internal secretion were receiving more attention, and further investigations in these directions were needed to elucidate the pathology of exophthalmic goître, acromegaly, and allied disorders. Quite recently, Prof. Mills, of Philadelphia, had shown that the Röntgen rays were of use in determining the site and occurrence of certain cerebral tumors. Dr. Henry Head had published a suggestive report upon visceral diseases and the mental changes accompanying them, and there was still great room for the further elucidation of such neuroses as hysteria, neurasthenia, and hypochondriasis, in which mental diseases coexist. On the whole there had been more than usual activity in the realm of neurology; and questions of vastest importance were still awaiting solution.

An important research has been published by Prof. Karl Schäffer, of Budapest, on the Topography of the Cortical Degeneration in General Paralysis of the Insane. The author regards his observations as tending to support Flechsig's Association Centers of the Brain, and concludes that the morbid process (degeneration of medullated nerve-fibers) affects chiefly those centers, viz.: those in the prefrontal, parietal, insular, and supracallosal regions of the hemisphere. "The cortical degeneration in general paralysis is not an irregular, diffuse process, but, on the contrary, a regular, localized, selective, morbid affection of the cortex."

At the suggestion of Prof. Halliburton, a research was undertaken by R. H. C. Gumpertz into the specific gravity of the brain. It had especially in view the statement made by Sir James Crichton Browne "that he had found the specific gravity of the female brain less than that of the male brain, the difference being in the gray matter. The most complete previous research on the subject appeared to be that of Danilewsky, who found the specific gravity of the brain to be 1.038; that of the gray matter, 1.033; and that of the white matter, 1.041; and the average thickness of the gray matter, 2.5 millimeters. The author, experimenting upon a larger number of cases of healthy men and women who had suffered from no brain disorder, found as the average specific gravities in the respective parts of the brains of seven men-frontal, 1.0352; Rolandic, 1.0365; occipital, 1.0356; the whole brain, 1.0361; and in six women-frontal, 1.0360; Rolandic, 1.0368; occipital, 1.0365; the whole brain, 1.0364. These results are somewhat lower than those given by Danilewsky; they show considerable variations between the specific gravities of different parts of the same brain and of different brains in both sexes; and indicate that the average specific gravity is practically identical in both sexes. A low specific gravity of brain does not imply poor quality, for the part which is most important and most active-the gray matter-has a lower specific gravity than the white matter.

Specimens exhibited to the British Association by Dr. John Turner in illustration of a paper on some new features in the intimate structure of the human cerebral cortex showed: 1, A beaded

network enveloping the pyramidal cells of the cortex and the dendrites; and 2, an intercellular plexus of the nerve-fibers not previously demonstrated to exist. The preparations demonstrating these points had been made by placing pieces of the brain tissue directly on removal from the body, and without previous hardening or fixing, into a strong solution containing methylene blue and hydrogen peroxid. From this mixture, after a sufficient time had elapsed, the tissue was transferred to a solution of molybdate of ammonia. The tissue was then, after this fixation, dehydrated, embedded in paraffin, and cut into sections. The beaded network was a network, not of neurological fibers, but of processes of true nervecells. It loosely invested the pyramidal cells and their dendrites. It was made up of the fiber ramifications of stouter fibers which could be traced from certain pyriform dark cells in the cerebral cortex. The cells were generally small, and exhibited no signs of any network around them. There seemed, in fact, to be in the cortex of the cerebrum at least two systems of nerve-cells-the pyramidal variety, which were pale under the method of examination employed in the experiments, and the smaller darkly stained pyriform nerve-cells. The latter possessed branches which ramified and produced by a fusion a true network formed by actual anastomosis. The system of dark cells constituted a continuum.

The hypophysis cerebri is described by E. von Cyon in Pflüger's Archiv as having a double function; it controls intracranial blood-pressure and regulates metabolism. The former function is affected mechanically by the circumstance that every increase of blood pressure in the brain constitutes a stimulus to the hypophysis and is followed by an increase in the strength and a slowing of the cardiac beats with a slight rise of extracranial pressure. Those rarer and stronger beats of the heart which Cyon names "action pulse," augment the rapidity of the venous blood current, especially in the veins of the thyroid body, and thus remove from the brain the abnormal quantity of blood. There is reason to believe that the same effect is in part due chemically to the production of substances which are probably two in number, one of which excites vagal centers, while the second excites the accelerators. The action-beats caused by these coincident and harmoniously acting antagonistic agents are highly favorable to the rapidity of the venous blood-current. The influence exerted by the hypophysis and its secretions on metabolism is also probably effected by their action on the vagi and the sympathetic nerves, and is indicated by increased circulation and a diminution of the body weight. Persistent stimulation of the hypophysis, especially by electric currents, is followed, as a secondary effect, by violent epileptiform convulsions, which are most easily explained by regarding them as disturbances of the circulation in certain parts of the brain. A great increase in the

secretion of urine is observed in all cases of stimulation of the hypophysis.

Prof. W. C. Halliburton and Dr. T. W. Mott introduce a paper on the regeneration of nerves by referring to two opinions prevailing on the subject: one that the new nerve-fibers sprout out from the central stump of the divided nerve: the other that they are of peripheral origin. Those who held the latter view relied on histological evidence. But a strand of cells that looks like nerve-fiber might not be physiologically nervefiber, inasmuch as it might not be capable of being excited as true nerve-fiber is, or of conducting nerve-impulses as a nerve-fiber can do. These

functional performances were the true criteria for nerve-fibers. Among recent observers, Howell and Huber, who had used both histological and experimental methods, had arrived at the conclusion that the axis-cylinder, the essential portion of a nervefiber, had an exclusive central origin; they admitted that the peripheral tissues in which it was embedded were active in preparing and generating a nutritive scaffolding for it. The authors had obtained experimental results which, so far as they at present went, confirmed these views.

The truth of the view, which has long been generally held, that repeated or excessive activity caused fatigue of nerve-endings, but had no effect upon the fibers that conduct the nervous impulses, has been questioned by Herzen, who asserted that after a nerve-trunk had been subjected to repeated stimuli the subsequent response of the nerve showed signs of impairment when examined by electric tests. Observations of this impairment made by Prof. Gotch have shown that it was a change confined in its situation to the neighborhood of the place of the electrodes by which the electric currents used for fatiguing the nerve were applied to it. Were the effect a true fatigue effect, its locus should not be confined to the electrode region, but should be distributed throughout the nerve; because the process of conduction of nerve-impulses occupying the whole length of the nerve, the true fatigue which arose as their aftereffects must have a similar distribution. The changes which were confined to the immediate neighborhood of the electrodes by which the long series of fatigue-producing currents were introduced, were those to which much attention has long been devoted as electrotome. Probably the process involved was one of electrolysis, and certainly its relation to fatigue in the true sense was at most extremely remote.

T. Grigor Brodie and W. D. Halliburton, having observed that the assertion that the nerve fibers are incapable of fatigue rests on the excitation for long periods of time of medullated fibers, determined to repeat the experiments, with some modification, on non-medullated fibers. Selecting the nerves leading to the spleen, they found that even after many hours of stimulation no evidence of fatigue could be demonstrated. Nevertheless, they obtained proof that certain non-medullated as well as medullated fibers are injuriously affected by prolonged faradic stimulation, and that the spot which has been excited is no longer excitable until a considerable period of rest has elapsed.

Prof. C. S. Sherrington and Dr. A. S. Grünbaum, describing before the British Medical Association the experiments they had made upon the motor cortex in anthropoid apes (13 chimpanzees, 2 orangs, and 1 gorilla), mentioned as a most important point brought to light in their researches that the excitable motor region, though extending deeply into the Rolandic or central sulcus, did not extend on to the free surface of the post-central convolution-an observation that was in opposition to the results of previous observers. The authors gave the movements obtained from their different areas broadly as follow: In the face area-eye, eyelid, nose, jaw, vocal cords, mastication, and also movements of the mouth and tongue; in the arm area- -shoulders, elbow, wrist, fingers, and thumb; in the leg areatoes, ankles, knee, hip; in each case from above downward. Movement of the arms was obtained by stimulation just at the border between the external and mesial surfaces of the hemisphere. A further difference from the result of other observers on the anthropoids was the case with

which epileptiform convulsions were obtained from the cortex. The authors had first studied the results of ablation of parts of the cortex and found that marked paralysis occurred from even a small lesion, but that this was recovered from; and they had also observed almost complete recovery after double extirpation of the arm area. Prof. Sherrington had also investigated the direct pyramidal tract in the anthropoids, and found that in the chimpanzee a vertical pyramidal tract occurred as in man, and was also, as in man, of a very variable individual character.

The paper of Prof. Sherrington and Dr. Grünbaum was followed by an account by Dr. Campbell of his studies of the histological features of the cortex of anthropoid apes. The author enumerated as special characters which he had found in the motor region: 1. The possession of a wellmarked zone or tangential field. 2. A supraradiating field. 3. A radiary zone of great depth and richness in nerve-fibers, or of great "fiber wealth"; further, there were large ganglion-cells or cells of Betz in this region. These histological results were in complete accord with the experimental results of Sherrington and Grünbaum, as the motor type of structure was bounded posteriorly by the fissure of Rolando and did not extend into the post-central convolution.

The importance of cholin in blood in cases of nerve degeneration, not only in such diseases as general paralysis, but in various diseases of the central and peripheral nervous system, is shown by Dr. T. W. Mott and Dr. W. D. Halliburton in an article on The Chemistry of Nerve Degeneration. The detection of cholin, which is a product of the decomposition of lecithin, is effected by a chemical test-the obtaining of the yellow octahedral crystals from the blood; and also by a physiological test, viz., a temporary fall of pressure when it is injected intravenously in animals. Degenerate nerves of animals were examined by the Marche reaction, which consists of a mixture of osmic acid and Miller's fluid, by which degenerate nerve-tissues are stained an intense black, while healthy fibers are not stained.

Almost all the experimental evidence with regard to the localization of cortical centers has been obtained from observations on monkeys and lower animals; and except for the work of Beevor and Horsley upon the orang-utan no observations have been made on anthropoids. Sherrington and Grünbaum, however, as a result of some more extensive work on the same subject, have recently in part confirmed and in part modified our previous knowledge.

The presence of a facial reflex, sometimes known as the extraorbital reflex, has of late attracted considerable attention. The manifestation is produced by striking some part of the forehead, and is followed by contraction of the orbicularis, with more or less movement of the eyelids. It is generally found that on tapping the frontal region contraction of the orbicularis takes place on both sides. The path for the reflex passes centripetally through the fibers of the supraorbital nerve to the sensory nucleus of the fifth nerve, and thence to the nucleus of the upper branches of the seventh nerve on both sides. Macarthy, in the Neurologisches Centralblatt, says that he found the reflex present in 100 normal persons investigated. Further observation is required to decide whether this is a true reflex or not, and also to show what significance may be drawn from its presence or absence. Dr. Walker Overend has called attention to the fact that he had previously described this reflex in the Lancet of March 7, 1896.

The idea has often been put forward that where an organ has a nerve-supply from two sources, the two sets of nerves must have actions which are physiologically antagonistic. The results made known in a paper by C. H. Fagge detailing researches on the innervation of urinary passages in the dog, taken in conjunction with previous work by other observers on the same subject, show that, in the case of those organs, the difference between the two sets of nerves (sympathetic and sacral) is morphological rather than physiological.

Narcotic effects have been found by Dr. Hermann Beyer to be exerted by odorous substances on the sensory and motor nerves of the frog. When the animal was made to breathe air charged with odors, the succession of events resembled that of chloroform narcosis in there occurring a preliminary state of excitation followed by motor and sensor paralysis. A considerable number of the substances experimented with, which are named in the author's paper, acted quickly and strongly, while others were less active. The frogs were placed near a sponge or wad wet with the odorous substance, but not in contact with it. Heat, respiration, and muscular power were affected. Special experiments indicated that the absorption of vapor is effected to a larger extent by the skin than by the lungs, and that the impaired excitability and coordinating power resulting have a central origin. Experiments on the direct action of odorous substances showed a loss of excitability on the part of the nerve exposed, extending gradually upward and more slowly down

ward.

Special Senses.-A communication has been published in the New York Medical Record by Prof. G. E. de Schweinitz on Deleterious Results of Certain Common Drugs and Narcotics on the Organs of Sight, in which the results of observations of the author's practise during recent years in the ophthalmological department of the Philadelphia Hospital are recorded. The most important form of functional visual defect or amblyopia noticed was produced by quinin. It was manifested in different ways and degrees varying with the doses and with the idiosyncrasies of the patient. With moderate doses, temporary dimness of sight occurred. When the doses were large (60 to 80 grains a day), the affection assumed a second and more serious form. Blindness of sudden onset and almost complete in degree resulted, and lasted several days. Ophthalmoscopic examination showed great pallor of the optic disks and blanching of the retina. Quinin in large doses also had toxic effects on the ganglion cells of the retina. This quinin blindness is described as similar to that caused by salicylates or by antifebrin, and the actual changes are very similar. Iodoform when absorbed from dressings of wounds and burns, or after administration by the mouth, occasionally produced amblyopia. Alcoholic amblyopia was produced by ordinary alcohol, and in a more intense degree by methyl alcohol; and substances in which methyl alcohol was an ingredient had a similar effect. Certain strong forms of tobacco, particularly if smoked in a pipe or on an empty stomach, were specially liable to give rise to amblyopia. Usually, how ever, several years passed before the vision was thus affected; while an indescribable haze or fog seemed to obscure the view. Pallor of the optic disk and central scotoma for red and green in the field of vision were observed. If the patient was intemperate, the disease progressed more rapidly. The histological investigation showed that the retinal ganglion-cells in the macula lutea

underwent degeneration; and some change could be detected in the macular fibers of the optic nerve. Which of the active principles in tobacco was the actual agent was not determined. Among the forms of amblyopia due to occupation were those occurring among lead-workers and india-rubber workers (in whom the effect was produced by the carbon disulfid used as a solvent for the rubber). Amblyopia was also met with as a result of being exposed to or inhaling fumes of nitrobenzene or dinitrobenzene, a substance which is produced in chemical factories, and is commonly known as essence of almonds. The photosensitive pigment, or visual purple, which is supposed to belong to the rods only, and not to be present in the cones, has been found by Dr. F. W. Eldridge Green present in the central region of the retina, in which there are cones only and no rods. On examining the retina of the monkey when the animal had been kept in the dark for twenty-four hours in order to increase the amount of visual purple, the central region of vision, the yellow spot, instead of being free from the pigment, was the most purple spot of the whole retina. The purple was, however, seen by microscopical examination to be around and not actually within the cone. The author advanced the theory that the cones were sensitive only to changes in the visual purple, not to light itself.

At the annual meeting of the British Medical Association Dr. F. W. Eldridge Green described his view of the origin of a visual impulse as being that light falling upon the retina liberated visual purple from the rods, and this, being acted on by light, stimulated chemically the cones and an impulse was transmitted along the visual path to the brain and received by a light perceptive center which did not appreciate color but simply light and shade. Color perception was due to a special center separate from the visual center, but closely connected with it, a color being simply a point of difference capable of being seen by this center.

Observations are described by Dr. C. S. Myers as having been made by means of tuning-forks concerning the smallest musical tone-difference perceptible to the people of Scotland and those of Torres Straits. But little difference in the original capacity to distinguish tones was found between the children of Murray island and those of Aberdeenshire; but with practise the Scottish children improved very rapidly and uniformly. The adult Murray Islanders for the most part failed to detect intervals of a semitone. The average difference of frequency of vibration just distinguishable by them was 15 vibrations per second; while for the adult Scotch examined it was 9 vibrations.

In the third volume of the Journal of Physiol ogy, p. 22, Sir W. R. Gowans described a case of disease which suggested strongly that the path for taste reaches the brain by the roots of the fifth nerve, both as regards the front and the back of the tongue. Since the article was published the author has met with strong confirmatory evidence from cases of disease. But he regards such evidence as unimportant when compared with the proof of the fact supplied by the modern surgical procedure of the removal of the Gasserian ganglion and the adjacent part of the fifth nerve, known as Krause's operation for neuralgia. Five cases of operations are adduced in the author's paper in the Journal of Physiology (vol. xxviii, No. 4), 4 cases by Mr. Horsley and 1 by Mr. Ballance, these being the last consecutive cases in which the operation was