bolus is formed, which remains long in the oesophagus, and the transformation of the amylaceous matter of its food may be ascertained if we tie this canal. But if, by an opening into the parotid duct, we remove the fluid of the parotid gland, before it reaches the mouth, and place it in contact with starch, no such conversion into sugar occurs. It is the same, also, with the saliva drawn from the maxillary ducts in the dog. There is, then, in the buccal saliva something peculiar, dependent upon all its constituent principles. In fact, we have the fluid of the three glands united, mucus, atmospheric air, the absorption of oxygen, and a tendency to produce carbonic acid. The pancreatic fluid of itself effects the transformation.

Can the gastric juice convert alimentary bodies into sugar? It is a singular circumstance, that sometimes starch is promptly thus transformed, and sometimes not at all. The transformation takes place if the juice is alkaline, like the saliva, but not if it is acid. If the acid gastric juice does not transform starch into sugar, it possesses the power of dissolving azotised aliments, such as meat. This difference in the juice, according as it has to act upon amylaceous or azotised substances, is one of M. Bernard's important discoveries, whence therapeutical applications may flow. As the acid of the stomach is the lactic, it is this we should prescribe for individuals whose digestion of animal food is difficult; while alkaline drinks are proper for those who digest vegetable aliment with difficulty.

Starch is also transformed into sugar in the intestinal canal, as shown experimentally by M. Magendie. The same change takes place when it is placed in contact with a solution, an infusion, or a decoction of the brain, spleen, pancreas, &c. The urine itself can effect this transformation. So, too, if starch be introduced by injection into the blood, it is converted into sugar. Thus, almost all parts of the body may contribute to transform alimentary starch into sugar; but the liver alone has the property of producing sugar without starch, as shown by M. Bernard's investigations. This same distinguished chemist has more recently shown that this production of sugar by the liver is under the influence of the nervous system. M. Bernard, after several experiments, discovered that, if the floor of the fourth ventricle is pierced within a very circumscribed space, in less than half an hour a very considerable quantity of sugar was found in the blood and urine, without the regimen of the animal having undergone any change whatever. This curious fact has naturally directed attention to the condition of the floor of the fourth ventricle in diabetic patients; and, in a recent autopsy, two dark spots, at the place where the part must be penetrated in order to produce the sugar, were observed. M. Bernard has been enabled to produce the same phenomenon in another manner, viz. by pricking or gently galvanising the eighth pair in the neck; but the increased secretion so produced is of short duration. Another experiment, by its negative results, affords additional proof that this secretion of sugar is under the influence of the nervous system. The two nerves of the eighth pair are divided in the neck of a rabbit; and, if the animal survives the operation for some hours (which is necessary, in order that the sugar already formed in the liver may pass away into the circulation), the liver no longer, however treated, offers any traces of

sugar.

The transformation of amidon into sugar, as also the natural production of sugar in the liver, appears, then, to be one of the great functions of the economy,—one of the true conditions of existence. In late times, animals have been denied the property of producing sugar or fat, these bodies existing ready formed in the aliment. All now stated demonstrates, however, that the animal machine is not only a true sugar-manufactory, but that it may even produce it without requiring even the alimentary starch for the purpose of conversion.

Disappearance of sugar from the economy. In proportion as sugar is formed in the liver, it is carried away by the venous and arterial currents which traverse that organ, and it should therefore be found in the vessels proceeding from it; and M. Bernard has found it in the supra-hepatic veins, in the vena cava superior, and in the right cavities of the heart. But in other parts of the body the blood con

tains no sugar, or only very feeble traces of it. It is found neither in the veins constituting the vena cava inferior, in this trunk itself, nor in the splenic veins, and scarcely any traces are found in the blood of the veins returning from the head. Nevertheless, for about five hours after the digestion of amylaceous substances a notable quantity of sugar may be found in all the veins. This lapse of time shows that the sugar is destroyed only gradually, and that it is necessary for it to pass a great number of times through the lungs before it disappears entirely. Since we do not find the sugar produced by the liver after it has traversed the lungs, it must become destroyed in these organs. Here, then, is an entirely new fact. Something takes place in the respiratory process which was entirely unknown. May not this be the cause of animal heat? In spite of all the ingenuity of the illustrious Lavoisier's theory, he supported it by no direct proofs; for it is not only oxygen, but also nitrogen and hydrogen, which, passing into the blood, produce carbonic acid. There is nothing impossible, then, that from the destruction of sugar in the lungs the carbonic acid of respiration may result. [This doctrine has long been taught in this country, especially since the researches of Dr. Buchanan of Glasgow demonstrated the existence of sugar in the blood, for a short time after the use of amylaceous articles of food.]

Respiration does not act in the same manner in the destruction of all species of sugar. If we inject a solution of cane-sugar, mannite, or the sugar of milk, the whole of this sugar is found in the urine; but if we inject glucose or grape-sugar, unless a large quantity has been thus introduced, we do not find any in the urine. But if the first-mentioned descriptions of sugar are not destroyed in the lungs, this is no longer the case when animals are fed by them. In this case we no longer find cane-sugar in the urine, because, by digestion, it has been transformed into glucose, and decomposed by the lungs. Under these different circumstances, sugar is always tending to disappear from the economy. The first-named species, escaping the respiratory act, are eliminated by the urine; while glucose, which is the sugar of diabetes, is destroyed in the lungs.

The following table exhibits the quantity of the different kinds of sugar it is necessary to inject into the jugular, in order that they may be detected in the urine. Thus, there are physiological differences nowise indicated by chemistry; and it will be especially remarked that the sugar of the liver, i. e. the natural sugar of the economy, is destroyed in the act of respiration with far greater facility than the sugar proceeding from alimentary substances:

Applications. There are only two diseases known, in which the quantity of sugar in the economy has been proved to be increased, phthisis and glucosuria. It had been long observed that the urine, as well as the expectoration, of phthisical patients is sometimes saccharine; but a distinction must be made between such cases and those which only become phthisical as a result of diabetes. M. Bernard declares that the urine in true phthisis is not saccharine; but that the quantity found in the blood is much increased. Having observed such increase in the blood of a young girl, who had been bled, and whose urine exhibited no sugar, he predicted, although no other sign of phthisis was present, that she would fall a victim to this disease, which she did. But researches into this subject require to be multiplied. It is certain that diabetes induces as one of its consequences the most serious pulmonary affections; and now that we are aware that one of the functions of the lungs is to destroy the sugar as it is formed, we cannot be surprised at their becoming fatigued in the effort to decompose all that is formed. For this they do not suffice, and an immense quantity escapes by the urine. It is also found in the expectoration, in the matters vomited and passed by stool (M. Magendie

has found large quantities in the cholera evacuations), and in the sweat. In this disease, which is characterised by emaciation, we find weakness of sight, loss of the generative faculties, sleeplessness, an excessive thirst, a voracious appetite, and active digestion, as if to furnish material for this incredible activity of fabrication; but under this terrible influence, consumption arrives, and the patient is sometimes carried off with great rapidity.

Two distinguished chemists, MM. Bouchardat and Mialhe, have recently offered their explanations of the mode of production of this affection, and suggestions as to the best means of coping with it. According to M. Bouchardat, the diabetic urine proceeds from the transformation of fecula into sugar, and the quantity of this will be found to be great in proportion to the quantity of bread and feculent aliment consumed; and he advises a modification of the animalized regimen which had already been employed by Rollo, Thenard, Dupuytren, &c. He gives also a glutinous bread, containing only one fifth of flour, and endeavours to regulate the functions of the skin by warm clothing, exercise, and the use of baths. In obstinate cases, he thinks well of the carbonate of ammonia as a medicine, only using the bicarbonate of soda when the glucose is in moderate quantity, and the urine simultaneously contains uric acid. Lime-water and magnesia, by retarding the solution of feculent matters, become useful adjuvants, being, however, of only temporary avail. According to M. Mialhe, the defective decomposition of sugar and its passage into the urine, depends upon the insufficient alkalescence of the humours; it being, in his opinion, by the instrumentality of the alkalies of the blood and of the animal fluids, that digestion of amyloid and saccharine substances is effected. His treatment consists in the administration of the alkaline waters of Vichy, and the re-establishment of the functions of the skin, the alimentation becoming then a secondary consideration. To both these views of the nature of the disease, the natural production of sugar in the liver and the saturation of the blood by it when the eighth pair are excited at their origin, or in their course, present serious objections. To M. Mialhe's view may also be opposed the facts, that the blood, only slightly alkaline in its normal state, does not become acid in diabetes, and that a more alkaline fluid than it has been found, by M. Magendie's experiments, not to decompose the glucose. The serum of the blood of the horse is less alkaline than is that of man, and yet the sugar is just as easily destroyed in the one as the other. In fact, it is not by the alkali of the blood that such destruction is effected, but, as shown by M. Magendie, by the respiratory action. M. Bernard believes the disease to be an affection of the pneumogastric nerves; but we may also ask whether, in some cases, it may not arise from some peculiar alteration in the liver.-From a Report of M. Magendie's Lectures at the College de France; by M. Fauconneau-Dufresne. L'Union Médicale, Nos. 72, 75, and 79.

On the Medullary Substance of Bones. By MM. GOSSELIN and REGNAULD. MOST anatomists have in general terms described the existence of a medullary membrane supporting and surrounding the medullary substance; but when they enter into particulars concerning it, they declare its tenuity to be such that its existence is demonstrated with difficulty. In the present paper the authors declare that careful examination conducted by the naked eye, the microscope, and chemical tests, in a great variety of cases, have convinced them that in point of fact no such membrane does exist, the doubts already expressed by Ruysch in respect to it becoming thus fully confirmed.

The medullary substance presents very different appearances, not only in different species of animals, but even in different individuals. The modifications may be classed under two principal heads, which for distinction's sake we may term the fatty medulla and the gelatiniform medulla. In the first of these it almost entirely consists of semi-fluid, fatty substance, and of extremely delicate vessels forming a network on its surface and in its substance. In the other there is but a small proportion of fatty matter, the substance then having the appearance and consistence

of a red jelly, the vascular network being here still more abundant. Both these varieties are compatible with health, the substance containing more or less fat, according to peculiar predisposition. Disease, however, exerts its influence, and under the operation of inflammation fat is absorbed, that part of the skeleton then presenting the gelatiniform type, even while the other parts present the fatty. Longcontinued general disease may similarly affect all the bones; but the differences which result are so great, that no general rule can be laid down. Age, however, has a more marked and constant influence. In early life the substance is very vascular and gelatiniform, and does not present the colour of fat; but as development advances, the fatty type is gradually assumed, though not completely until after the consolidation of the epiphyses. The same appearances present themselves, whether the substance is examined in the medullary canal of a long bone, or in the cellules of the spongy tissue.

Originally the medullary canal is but a canalicule, containing a much larger artery than the other canalicules, which freely ramifies into the substance of the bone. These and the accompanying venous ramifications afterwards become mingled with some adipose cells, and with a matter, which, though not gelatine, much resembles it. As ossification goes on, this canal becomes enlarged by the absorption of its inner layers, for the purpose, as shown by M. Flourens, of affording the long bones a greater power of resistance without increasing the quantity and weight of osseous matter. In proportion as this absorption of the innermost layers of the canal takes place, the adipose or gelatiniform matter is deposited, filling up the empty spaces, supporting the vessels, and keeping an abundant vascular network applied against the internal surface of the canal; its office, though important, being purely mechanical, The fat of the bones, then, differs from that of other parts of the body, in not being divided into lobes or lobules by prolongations of the membranous areolar tissue. The cells are separated only by delicate capillaries, and are mingled with more or less gelatiniform matter. Just as the vascularity is great, the proportion of fatty matter is smaller. It would seem that the deposition of the fat compresses and causes the disappearance of a portion of the vessels. In this way, when active nutrition is required, as in the child, there are abundance of vessels and little fat, while, in the aged, there is a larger proportion of fat and fewer vessels. This conThus in osteitis, the portion of the bone which nexion is observed also in disease. is red with vessels has a less proportion of fat than the other parts, which may possess even a larger proportion than usual. So in that singular change in bones termed their fatty condition, the naked eye can detect no vessels in the medullary substance, sufficient of them only remaining to maintain the slow and incomplete nutrition of the part.

Denying the existence of a medullary membrane, the physiological and pathological actions attributed to it must be otherwise explained. We cannot say, with M. Flourens, that it effects the absorption of the inner layers of the canal, this being in reality accomplished by the capillary vessels supported by the medulla. So, too, a membrane takes no part in the formation of callus, and in accomplishing the various changes supervening upon osteitis; but the material for all these may be amply supplied by the vascular network.-Archives Générales, t. xx, pp. 257-74. [We should be disposed to regard the "gelatiniform matter" of these authors as an organizable blastema, the incipient condition of fibrous or fibro-membranous tissue.]

On the Ganglia and Nerves of the Heart. By ROBERT LEE, M.D., F.R.S., &c. WITH a view of confirming by analogical evidence the statements which he has made with regard to the uterine nerves, Dr. R. Lee has made several minute dissections of the nerves of the heart, the results of which are presented in this paper, or rather in the delineations which accompany it. These results confirm the statements of Scarpa, as to the existence of a large number of nervous filaments passing over and into the muscular substance of the heart, quite independently of the coronary arteries, which have their own plexuses; and also as to the

1

existence of numerous fusiform enlargements upon these nerves. "The series of my dissections," says Dr. Lee, "shows that the nerves of the heart, which are distributed over its surface and throughout its walls to the lining membrane and columnæ carneæ, enlarge with the natural growth of the heart before birth and during childhood and youth, until the heart has attained its full size in the adult; that the nervous supply of the left ventricle is greater than that of the right, and that when the walls of the auricles and ventricles are affected with hypertrophy, the ganglia and nerves of the heart are enlarged like those of the gravid uterus.” In his last dissection of the nervous system of a young heifer's heart, he states that he has made distinctly visible to the naked eye no fewer than ninety ganglia or ganglionic enlargements on the nerves of the anterior surface only, which pass obliquely across the arteries and the muscular fibres of the ventricles, from their base to the apex. The ganglia of the posterior surface also are very numerous, but of smaller size than those of the anterior. And besides these, there are very great numbers of ganglia in the walls of the heart itself; so that, according to Dr. Lee, "it can be clearly demonstrated that every artery distributed throughout the walls of the uterus and heart, and every muscular fasciculus of these organs, is supplied with nerves upon which ganglia are formed.”—Philosophical Transactions, 1849, Part i.

[We must repeat, in regard to the nerves and ganglia affirmed by Dr. Lee to exist in the heart, that which we formerly remarked as to his statements in regard to the uterine nerves and ganglia (p. 9),—that he must not expect histologists to admit their existence, until he shall have given that proof of their nature which microscopic examination alone can yield.]

On the Size of the Eye at different Ages. By M. QUETELET.

The size is taken from one palpebral angle to the other; and it would seem that, towards the age of 5, the eye has nearly acquired its entire development.—Annales d'Oculistique, tom. xxi, p. 170.

On Luminosity of the Human Body. By Dr. SCHNEIDER.

DR. SCHNEIDER is acquainted with a strong, healthy, dark-haired Capuchin monk, who, on removing his head-dress, always induces a number of shining, crackling sparks from the hairy scalp. Fearing that the large quantity of the good beer he was in the habit of taking had something to do with this, he diminished his potations, and the appearance also diminished somewhat, though it did not cease entirely, continuing still perceptible during an illness which prevented his taking beer for three weeks. In another case, luminous sparks were given out whenever the patient passed his urine. Nasse has collected various examples of this preternatural illumination. Marsh relates two cases, in which the heads of phthisical patients were surrounded by phosphoric light. Kaster relates one, in which light was seen in the perspiration and body-linen after violent exertion. Jurine, Guyton, and Driessen observed luminous urine after prior exertion in healthy persons; and Nasse met with it in a phthisical patient. Percy and Stokes saw a bright light emitted from a cancerous ulcer; and the breath of spirit-drinkers, it is well-known,

emits it.

In the opinion of Nasse, this appearance chiefly depends upon impeded respira