the copaiba, might not be substituted for the cod-oil-either when this cannot be procured, or when the patient's stomach will not retain it-deserves a trial. We know that all the medicines of this class (the balsamic) have a marked influence on the respiration; they appear to be very rapidly absorbed, and conveyed out of the system, partly by the lungs and partly by the kidneys. In many cases of chronic bronchitis, senile catarrh, peripneumonia notha, &c., no remedy is better than the Copaiba or Peruvian balsam. Is it not possible that, when iodine is administered in combination with such substances, it may be directed in an especial manner to those organs which they more immediately affect?

The practice, adopted and recommended by Dr. Pereyra, of establishing an artificial drain in the immediate neighbourhood of the chest, (as in the flesh of the shoulder,) whenever one of the upper lobes of the lungs is diseased, is unquestionably very judicious, and should be followed more generally than it is. We have often witnessed decidedly good effects from this plan, in retarding the progress of the pulmonary lesion, and can therefore bear witness to the wisdom of the advice. The use too of a nourishing, but not a stimulating, diet, so as to support without over-exciting the powers of the system, should never be neglected, whenever the patient's stomach will bear it. On the whole, we report favourably of this pamphlet of Dr. Pereyra: it is a candid and faithful statement of an enlightened physician.-Rev.

PHYSIOLOGICAl Memoranda on the RELATIONS BETWEEN
DIGESTION AND RESPIRATION, &c.

The following observations appear to be based on those interesting researches, which of late years have been so assiduously carried out by MM. Dumas and Boussingault in France, and by M. Liebig and others in Germany. The great interest and importance of the subject will always command for it the attention of those who take a pleasure in making themselves acquainted with the marvellous workings of the living system-as they are revealed in the unmarred book of Nature herself, and not in the disgusting exhibitions of a vivisection

room.

"The activity of the Digestion appears to be, in a great measure, influenced by, and proportionate to, that of the Respiration. Whenever the latter function is very highly developed, or more than usually vigorous, we find that the animal will require food more frequently and in larger quantities than under the opposite conditions. A bird will die from starvation in the course of two or three days; while a serpent will live for months without any supply of nourishment. For the same reason, an infant, whose respiration is well-known to be much more rapid than that of an adult, requires to be fed more frequently for the first year than in after-life. How is it that hybernating animals can survive a whole Winter in their state of almost asphyxiated inaction?-simply because the respiratory process is all but arrested. During ordinary sleep the breathing is much slower than when we are awake and taking exercise; and hence it is (in some degree at least) that no desire for food is experienced for so many hours.Every one must have found by his own experience that lively conversation after eating is one of the best digesters. May not this be owing in part to the active play of the respiration, as well as to the general pleasing excitement of the whole nervous system?"

"In estimating the activity of the breathing, (and consequently the quantity of oxygen absorbed into, and of carbon eliminated from, the animal system), we

must attend not only to the number of respirations in a given space of time, but also to the temperature of the air that is respired. As the same, or nearly the same, volume of air is inhaled at each act of breathing in all seasons, it is quite obvious that, unless the respiration be considerably quicker in Summer than in Winter, the consumption of oxygen must be much less at one season than at another, and therefore (as explained in the preceding paragraph) that the necessity for food will become so much the less urgent. Now, although the breathing is somewhat quicker in warm than in cold weather, the increased frequency is by no means proportionate to the diminished density of the air. Hence it may justly be laid down as a general truth that an animal consumes less oxygen in Summer than in Winter, and therefore that it requires a smaller amount of nourishment. Does not the experience of every man prove the truth of this observation in his own case? and is it not the case that his appetite for strong animal food is much greater, when the weather is cold and bracing than when it is hot and relaxing? We must not, it is true, omit from our consideration the direct influence of various outward impressions on the Nervous system; the digestion, like every other function of a living body, is not a little affected by whatever either invigorates or enfeebles the general powers of the constitution. But, independently of this vital or animal agency, there is another of a chemical and organic kind, (such as we have been endeavouring to explain) which has never been rightly appreciated until of late years, when Animal and Vegetable Chemistry has been studied with such a philosophic spirit. By the act of Respiration, a certain quantity of oxygen is absorbed into, and a certain quantity of carbonic acid is eliminated from, a living animal body. As the basis of the latter gaseous substance must unquestionably be derived primarily from the food that is taken into the system, it may at once be presumed à priori that there is a direct relation and sympathy between these two most important functions."

"If then the consumption of oxygen during the process of respiration is so much more active in cold than in warm weather, it may naturally be asked how is it that the system relieves itself of the excess? or in what manner does it employ the large supply of this element in the first of these conditions? The answer to this is easy. For in proportion to the amount of oxygen absorbed by, so is that of carbonic acid evolved from, the lungs. Now the amount of the carbonic acid evolved depends entirely on the activity of the digestion, and on the quantity of carbon which is derived from the food that is eaten, and which becomes incorporated with the blood. When the digestion is vigorous, and the quantity of food consumed is great, a large supply of materials abounding in carbon and other elements is continually being added to the mass of the circulating fluid. These materials serve for different purposes. Besides contributing to the formation of new compounds to repair the constant waste that is going on in every part, a large proportion of the carbon combines with the oxygen that is always present in the blood, and passes out of the system at every act of respiration. The lungs are therefore the great emunctories for the discharge of carbon out of the body.

*

"Such being the case, we can at once understand the reason why the system requires a larger supply of strong nutritious food in Winter than in Summer, and why the inhabitants of the Arctic regions live almost exclusively upon articles of an animal nature, while those of the tropics may be sustained by a diet that consists almost entirely of vegetable matters. In the former, a much larger amount of oxygen is consumed during respiration, in consequence of the greater density of the air that is respired. The result of this is that the digestive function is exceedingly active, and it therefore requires a greater supply of strong food, in order to furnish a sufficient quantity of carbon, &c. for the formation of the large supply of carbonic acid, that is afterwards eliminated by the lungs.

"For the reasons now given, it may be readily understood why it is so much easier to fast for a length of time in warm than in cold weather, and why a lighter diet should be used in Summer than in Winter. Hence too we perceive the cause that an ill-fed animal will become emaciated much more rapidly in the latter than in the former season; for, if there be not a sufficient supply of carbon yielded by the food in order to combine with the oxygen absorbed during respiration, the system must derive it somehow, and this will be at the expence of the substance of its own body."

*

"The reciprocal action of the elements of the food on the one hand, and of the oxygen diffused through every part of the body, by means of the circulation, on the other, is the source of Animal Heat. This most important and curious function is now recognised to be owing (at least, in a very great measure) to the direct union of the oxygen in the blood with some combustible substance of a carbonaceous nature. It is obvious therefore that, just in proportion to the amount of carbonic acid that is formed within the system and evolved during respiration, so will be the degree of caloric generated in the animal system. Now we have already seen that this amount is influenced by the activity of the respiratory changes on the one hand, and by the quantity and quality of the food that is consumed on the other. Whenever the respiration is quick and active, the heat of the animal body is high; and vice versa. For this reason it is that the temperature of birds is higher than that of any other class of animals, and that the young creature is always so much warmer than the old. In common parlance we say that in age the blood is chilled: the remark is quite true, physically as well as poetically.

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Again, we have strong grounds for believing that more caloric is generated in the animal body during cold than during hot weather. Indeed, this must be so; for, as there is a larger absorption of oxygen and a larger formation of carbonic acid in the one condition than in the other, so there must necessarily be a greater development of caloric produced. It is thus that Nature so admirably compensates for the great abstraction of heat from an animal body during Winter, when the temperature of the air is so much below that of its surface. It is only on some principle like this, that we can account for the wonderful uniformity of the temperature of living animals of the same kind in different latitudes :—less heat being generated within the body in hot climates, because less is abstracted from it; and vice versa. As we have already explained, the cause of the lesser generation of animal heat in the one case than in the other is the lesser formation of carbonic acid within the body; and this again is in consequence, on the one hand, of the smaller consumption of oxygen during the process of respiration, and on the other, of the smaller amount of carbon received from the food that is eaten. The fruits, which serve as the chief means of nourishment to the inhabitants of tropical countries, do not contain above 12 per cent. of carbon; while the whale blubber and seal oil, on which the Laplander feeds, contain as much as from 65 to 80 per cent. of the same material. In Winter we all find the need of an animal diet; in Summer we require but little flesh food, and instinctively long for a lighter diet of vegetables and fruits. We thus perceive how beautifully Nature has accommodated all her arrangements to the varying conditions of season and climate; and we, at the same time, derive an important dietetic rule for the regulation of our living, according to the circumstances in which we are placed."

"From what has been said, in some of the preceding paragraphs, it will be obvious to every one that there is, and must necessarily be, an intimate relation between the activity of the Respiration and the consumption of oxygen during this process, on the one hand, and the activity of the Digestion and the introduction of carbonaceous and other matters into the blood, on the other. Unless this relation

be harmonious and equable, the state of the health will quickly proclaim that there is some disturbance in the balancing powers of the animal economy. If a sufficient supply of carbonaceous materials be not provided by the digestive process, while the consumption of oxygen in the lungs is large, there will be rapid emaciation of the body-in consequence of the absorption of every particle of fatty matter that it contains, to supply the demand for carbon that the absorbed oxygen is continually making for the formation of Carbonic Acid.

On the other hand, if the supply of carbon furnished by the digestive function to the blood exceeds the proportion that is required to satisfy the demands of the oxygen consumed, then it will either accumulate under some form or another within the body, or it must be discharged from the system by some other way than by that of respiration.

"In the one case, there will be a deposit of fat in the cellular tissue; and in the other, an extra duty, so to speak, will be thrown upon the liver, and this organ becomes stimulated to secrete a larger quantity of bile than is necessary in a state of perfect health.

"It has been long known that the Biliary secretion abounds in carbonaceous matter; indeed many physiologists have regarded the liver as the great eliminator of carbon from the system. The fact is true, although the theory may not be quite correct. Certain however it is that, whenever the carbon in the system is not duly eliminated by the lungs, there is usually forthwith an increased action of the liver set up; and vice versa. These two organs therefore, appear to act as balancing or compensation agents in the important process of discharging the carbonaceous matter out of the system; and thus it is that, when there is an undue amount of duty, so to speak, thrown upon one of these organs, the overacting viscus becomes more than usually subject to disease. In hot climates it is the liver, and in cold climates it is the lungs, that most frequently suffers. Are we not thus, by a very simple train of observation, led to perceive the importance of suiting the diet to the climate in which we reside? The practice of so many of the English, in the East and West Indies, of eating as much animal food under a tropical sun and in an attenuated atmosphere, as they were in the habit of doing in their own country, is well known to be a prolific cause of disease. A little attention to the simple suggestions of Nature herself-quite independently of the researches of the chemist and physiologist as to the why and the wherefore might annually save many valuable lives."

"The refrigeration of the body, from whatever cause this may proceed, is generally found to increase the desire for food. Mere exposure to the air in an open carriage or on the deck of a ship, although no active exercise be taken, whets and invigorates the appetite. With many people a large draught of cold water will produce a like effect, and with others the exercise of the lungs in singing, speaking aloud, &c. will do the same. In what manner does the impression of cold on the body produce an increase of appetite? Its action seems to be twofold in the first place, it tends to brace and stimulate the whole body, more especially the muscular and nervous systems; and, 2ndly, by carrying off the caloric of the body quickly, it no doubt promotes the combination of the oxygen absorbed by the lungs with the carbon existing in the blood. If then this combination take place more rapidly than usual, there will be a greater demand for a supply of fresh pabulum to compensate for the increased expenditure."

"No one can reasonably dispute the influence of the nervous system on the function of Respiration, as well as on the muscular powers that move the chest. Without the agency of the nerves, the stomach and intestines cannot prepare the elements, that are destined to combine with the oxygen absorbed during every act of breathing; and thus it is that this very act of absorption itself must also speedily cease. If the pons Varoli in a living animal be cut, or if it be stunned by

a blow on the top of the head, it will continue to breathe for some time-indeed the breathing may be more rapid than it was before;--but the heat of the body rapidly becomes less and less, until life is extinct. Now what is the cause of this? It seems to be that, as the absorbed oxygen no longer meets with a due proportion of the substances (carbon and hydrogen) with which it is destined to combine in the blood, the combustion, so to speak, is arrested; and thus there is no longer any fresh generation of animal heat.... ..... As the section of the pneumo-gastric nerves causes a cessation of the contractions of the stomach, and of the secretion of the gastric juice, and thus puts an immediate stop to the process of Digestion, in like manner any palsy or excessive weakness of the nerves of the bowels is invariably followed by some disturbance in the act of Respiration. Those two functions are united together by the closest ties of sympathy; and therefore we cannot be surprised that a lesion of one function should be almost invariably followed by a lesion of the other."

"Admitting that the existence of Magnetic and Electrical currents in the animal body may have some share in the development of the functions of its different organs, the ultimate cause or generating power of all these agencies is the transition of matter from one state of existence to another, during the process of transformation of the elements of the food into oxygenised compounds: viz. carbonic acid and water-those, which do not undergo this process of slow and gradual combustion, being rejected from the body under the form of excrementitious matters..... Now it is quite impossible that any given quantity of carbon or of hydrogen-whatever be the forms which they assume during this act of combination-can generate more caloric within an animal body, than is produced by the direct combustion of these elements in oxygen, or in atmospheric air. It is not indeed easy to determine with accuracy the amount of carbonic acid that is evolved from the lungs, or of the watery vapour that is exhaled not only from them, but also from the surface of the body. But perfect accuracy on this point could not assist us very materially in our physiological enquiries; nor does the want of it invalidate the general correctness of the conclusions which we have been endeavouring to establish.”—Annalen der Chemie, &c.

M. RACIBORSKI ON MENSTRUATION.

This very intelligent and active physician of the French metropolis has, within the last few months, read a very elaborate memoir on this much discussed subject before the Royal Academy of Medicine. Like most French medical writings, this memoir is far too lengthy and circumstantial; a vast number of particulars of little or no interest, or which are well known to every tyro in the profession, being most unnecessarily introduced. The following summary, however, of the author's views will well repay the trouble of a perusal.

According to M. Raciborski, the Menstrual discharge is (we use his own words) "an epiphenomenon (accessory phenomenon) of an important function devolved upon the ovaries, viz: the successive formation and separation of the ova and Graafian vesicles." It is not therefore, as many physiologists imagine, a mere issue or secretion intended to relieve the system of an over-supply of blood in the unimpregnated state; nor yet, as has been supposed by others, an important crisis which Nature often employs to abridge the duration of various diseases, and the least derangement of which is apt to be followed by a constitutional disturbance.

Formed in the very first year of life, or even sometimes before the birth of the infant, the Graafian follicles are found to go on gradually increasing in size and number, until they ultimately arrive at their complete development. The period