called putrefaction: but these distinctions | carbonic acid gas. The carbon and hydroare not essential; for putrefying animal gen are derived, ultimately, from the food. matters will cause sugar to ferment, as well By comparing the amount of oxygen abas common yest. The fetid smell of putre- sorbed with that of carbonic acid given out, faction is chiefly owing to ammonia; and and with that of the food consumed, the hence it is observed not only in the fermen- author demonstrates that— tation of animal matter, but also of such vegetable bodies as contain nitrogen, and therefore yield ammonia.

Now the explanation given by our author of these and similar changes is this: that the ferment, or exciting body, is invariably a substance in an active state of decomposition. Its particles are therefore in a state of motion; and this motion, being communicated to those of the body to be metamorphosed, is sufficient to overturn their very unstable equilibrium, and to cause the formation of new and more stable compounds. The more complex the original compound, the more easily does it undergo metamorphosis. The Professor has produced, in support of this doctrine, an extraordinary number of facts, and has, by strict induction from these, demonstrated it almost mathematically. It appears to us that he has for ever banished the notion of the catalytic force-an unknown and mysterious power which some writers had invoked to explain the phenomena of chemical transformations.

The amount of nourishment required for its support by the animal body must be in a direct ratio to the quantity of oxygen taken into the system.'

But the amount of oxygen inspired varies very much. It is increased by motion or exercise, which increases the number of respirations: it is increased by cold, which renders the air more dense; and it is also increased in proportion as the barometer rises, for the same reason.

'The consumption of oxygen in equal times may be expressed by the number of respirations: tity of nourishment required must vary with the it is clear that, in the same individual, the quanforce and number of the respirations. A child, in whom the organs of respiration are naturally in a state of greater activity, requires food oftener, and in greater proportion to its bulk, than an adult, and bears hunger less easily. A bird, deprived of food, dies on the third day; while a serpent, which, if kept under a bell-jar, hardly consumes in an hour so much oxygen as that we can detect the carbonic acid produced, can live without food three months and longer.

pour in warm air is filled up by air itself in winter: that is, an equal volume of air contains more oxygen in winter than in summer.

'In summer and winter, at the pole and at the When we turn our attention to the living equator, we respire an equal volume of air. In animal body, there are certain processes or summer, the air contains aqueous vapour, while operations which at once present them-in winter it is dry. The space occupied by vaselves as the most interesting. Among these may be mentioned respiration, nutrition, the waste and supply of matter, digestion, secretion, and excretion, with the bearings of all on health and disease. On all of these subjects the views of the author are equally original and interesting.

'Wonders,' he remarks, surround us on every side. The formation of a crystal, of an octahedron, is not less incomprehensible than the production of a leaf or of a muscular fibre; and the production of vermilion from mercury and sulphur is as much an enigma as the formation of an eye from the substance of the blood.'-p. 12.

There are two essential conditions of animal life. First, the assimilation or appropriation of nourishment; secondly, the continual absorption of oxygen from the atmosphere. Now the quantity both of food and of oxygen introduced into the system of an adult is very considerable, and yet the weight of his body does not increase: it is clear, therefore, that as much must be given out as is taken in. But in what form is the oxygen, for example, given out? It is invariably in combination with carbon or hydrogen, or both, as water and

The cold air is warmed in the air-passages and in the cells of the lungs, and acquires the temperature of the body. To introduce the same volume of oxygen into the lungs, a smaller expenditure of force is necessary in winter than in summer; and for the same expenditure of force, more oxygen is inspired in winter than in summer.

"The oxygen taken into the system is given out again in the same forms, whether in summer or in winter: hence we expire more carbon in cold weather, and when the barometer is high, than we do in warm weather; and we must consume more or less carbon in our food in the same proportion: in Sweden more than in Sicily; and in our more temperate climate a full eighth more in winter than in summer. Even when we consume equal weights of food in cold and warm countries, infinite wisdom has so arranged, that the articles of food in different climates are most unequal in the proportion of carbon they contain. The fruits on which the natives of the south prefer to feed do not in the fresh state contain more than 12 per cent. of carbon, while the bacon and train oil used by from 66 to 80 per cent. of carbon. It is no difthe inhabitants of the Arctic regions contain ficult matter, in warm climates, to study mode'ration in eating, and men can bear hunger for

a long time under the equator; but cold and hunger united very soon exhaust the body.

The mutual action between the elements of the food and the oxygen conveyed by the circulation of the blood to every part of the body is THE SOURCE OF ANIMAL HEAT.'-p. 17.

We are tempted to continue our extracts from this part of the work. Speaking of the uniform temperature of the animal body, and of the effects of cooling, he says:

lers have related with astonishment of these people. We should then, also, be able to take the same quantity of brandy or train oil without bad effects, because the carbon and hydrogen of these substances would only suffice to keep up the equilibrium between the external temperature and that of our bodies.

'The Englishman in Jamaica sees with regret the disappearance of his appetite, previously a source of frequently recurring enjoyment; and he succeeds, by the use of Cayenne pepper and the most powerful stimulants, in enabling himself to swallow as much food as he was accusThe most trustworthy observations prove tomed to take at home. But the whole of the that in all climates, in the temperate zones as carbon thus introduced into the system is not well as at the equator or the poles, the tempera- consumed: the temperature of the air is too ture of the body in man, and in what are com- high, and the oppressive heat does not allow monly called warm-blooded animals, is invaria-him to increase the number of respirations by bly the same; yet how different are the circum-active exercise, and thus to proportion the waste stances under which they live? to the amount of food taken. Disease of some

kind therefore ensues.

'On the other hand, England sends her sick, whose diseased digestive organs have in a greater or less degree lost the power of bringing the food into that state in which it is best less resistance to the oxidising agency of the adapted for oxidation-and therefore furnish atmosphere than is required in their native climate-to southern regions, where the amount of inspired oxygen is diminished in so great a proportion: and the result, an improvement in the health, is obvious. The diseased organs of digestion have sufficient power to place the di

The animal body is a heated mass, which bears the same relation to surrounding objects as any other heated mass. It receives heat when the surrounding objects are hotter, it loses heat when they are colder, than itself. We know that the rapidity of cooling increases with the difference between the temperature of the heated body and that of the surrounding medium; that is, the colder the surrounding medium the shorter the time required for the cooling of the heated body. How unequal, then, must be the loss of heat in a man at Palermo, where the external temperature is nearly equal to that of the body, and in the polar regions, where the exter-minished amount of food in equilibrium with the nal temperature is from 70° to 90° lower. Yet, notwithstanding this extremely unequal loss of heat, experience has shown that the blood of the inhabitant of the Arctic circle has a temperature as high as that of the native of the south, who lives in so different a medium. This fact, when its true significance is perceived, proves that the heat given off to the surrounding medium is restored within the body with great rapidity. This compensation takes place more rapidly in winter than in summer, at the pole than at the equator.

In the animal body the food is the fuel; with a proper supply of oxygen we obtain the heat given out during its oxidation or combustion. In winter, when we take exercise in a cold atmosphere, and when, consequently, the amount of inspired oxygen increases, the necessity for food containing carbon and hydrogen increases in the same ratio; and by gratifying the appetite thus excited, we obtain the most efficient protection against the most piercing cold. A starving man is soon frozen to death; and every one knows that the animals of prey in the Arctic regions far exceed in voracity those of the torrid zone. Our clothing is merely an equivalent for a certain amount of food. The more warmly we are clothed the less urgent becomes the appetite for food, because the loss of heat by cooling, and consequently the amount of heat to be supplied by food, is diminished. If we were to go naked, like certain savage tribes, or if in hunting and fishing we were exposed to the same degree of cold as the Samoyedes, we should be able with ease to consume 10 lbs. of flesh, and perhaps a dozen of tallow candles into the bargain, daily, as warmly-clad travel

inspired oxygen: in the colder climate, the or gans of respiration themselves would have been to the action of the atmospheric oxygen. consumed in furnishing the necessary resistance

arising from excess of carbon, prevail in sum-
'In our climate, hepatic diseases, or those
mer: in winter, pulmonic diseases, or those
arising from excess of oxygen, are more fre-
quent.

it may be produced, increases the amount of
"The cooling of the body, by whatever cause
air, in a carriage or on the deck of a ship, by
food necessary. The mere exposure to the open
increasing radiation and vaporization, increases
the loss of heat, and compels us to eat more
than usual. The same is true of those who are
accustomed to drink large quantities of cold
the body, 98.5°.
water, which is given off at the temperature of
It increases the appetite,
and persons of weak constitution find it necessa-
tem the oxygen required to restore the heat ab-
ry, by continued excrcise, to supply to the sys-
stracted by the cold water. Loud and long-con-
tinued speaking, the crying of infants, moist air,
all exert a decided and appreciable influence on
the amount of food which is taken.'-pp. 23,

24.

When we read, as we lately did, of five substantial meals a day in Calcutta as very common, while four are universal there, liver complaint? or can we doubt that a can we be surprised at the prevalence of much nearer approach to the native diet would insure to our countrymen in India a condition of health much nearer what they

enjoyed at home? The attempt to trans-
port an English appetite to a tropical cli-
mate is utterly hopeless, and has cost
thousands of valuable lives.
Let us hope
that our author's lucid explanation of the
cause of liver disease may have some effect
in reforming our habits both in the East
and West Indies.

away.

'In all chronic diseases death is produced by the same cause, namely, the chemical action of the atmosphere. When those substances are wanting, whose function in the organism is to eased organs are incapable of performing their the support process of respiration; when the disproper function of producing these substances: when they have lost the power of transforming the food into that shape in which it may, by enThe accuracy of Professor Liebig's tering into combination with the oxygen of the views of the action of oxygen on the sys-the substance of the organs themselves, the fat air, protect the system from its influence-then, tem is shown by the phenomena of starva- of the body, the substance of the muscles, the tion, where the body so rapidly wastes nerves, and the brain, are unavoidably consumed. The true cause of death in these cases is the In the case of a starving man, 32 oz. of respiratory process, that is, the action of the atoxygen enter the system daily, and are given mosphere. Respiration is the falling weight, the out again in combination with a part of his body. bent spring, which keeps the watch in motion: Currie mentions the case of an individual who the inspirations and expirations are the stroke was unable to swallow and whose body lost of the pendulum which regulate it. In our or 100lbs. in weight during a month; and, accord-dinary time-pieces, we know with mathematical ing to Martell, a fat pig, overwhelmed in a slip accuracy the effect produced on their rate of of earth, lived 160 days without food, and was found to have diminished in weight, in that time, more than 120 lbs. The whole history of hybernating animals, and the well-establishled facts of the periodical accumulation, in various animals, of fat, which, at other periods, entirely disappears, prove that the oxygen, in the respiratory process, consumes, without exception, all such substances as are capable of entering into combination with it. It combines with whatever is presented to it; and the deficiency of hydrogen is the only reason why carbonic acid is the chief product: for, at the temperature of the body, the affinity of hydrogen for oxygen far surpasses that of carbon for the same element.

In the progress of starvation, however, it is not only the fat which disappears, but also, by degrees, all such of the solids as are capable of being dissolved. In the wasted bodies of those who have suffered starvation, the muscles are shrunk and unnaturally soft, and have lost their contractility: all those parts of the body which were capable of entering into the state of motion have served to protect the remainder of the frame from the destructive influence of the at

going, by changes in the length of the pendulum, or in the external temperature. Few, however, have a clear conception of the influence of air and temperature on the health of the human body; and yet the research into the conditions necessary to keep it in the normal state is not more difficult than in the cas eof a watch.'—p. 29.

trines which would attribute animal heat After effectually disposing of the docto some mysterious power in the nerves, or to the mechanical contraction of the muscles, the author proceeds to show that the quantity of carbon daily converted into carbonic acid in an adult, which is 13.9 oz., gives out, in combining with oxygen in the body, just as much heat as if burned in a furnace, and more than enough to account for the heat of the body being kept up, for the evaporation of moisture, and for the heat lost by external cooling. The only difference is, that the combustion is very slow, and the heat is extended over a much mosphere. Towards the end, the particles of longer period. Its amount is the same; the brain begin to undergo the process of oxid-its intensity is smaller. He comes to the ation, and delirium, mania, and death close the conclusion that there is nothing yet known scene; that is to say, all resistance to the oxid- to justify the opinion that there exists in ising power of the atmospheric oxygen ceases, and the chemical process of eremacausis, or decay, commences, in which every part of the body, the bones excepted, enters into combination with oxygen.

the body any other unknown source of heat besides the chemical action between the oxygen of the air and the elements of the food. The existence of this cause cannot be denied or doubted, and it is amply sufficient to explain all the phenomena.

When we turn to the important subject of growth or nutrition, the first point that arrests attention is the function of the blood, that wonderful fluid out of which all the tissues of the body are formed.

The time which is required to cause death by starvation depends on the amount of fat in the body, on the degree of exercise, as in labour or exertion of any kind, on the temperature of the air, and, finally, on the presence or absence of water. Through the skin and lungs there escapes a certain quantity of water, and as the presence of water is essential to the continuance of the vital motions, its dissipation hastens death. Cases have occurred in which, a full supply of All the parts of the animal body are produwater being accessible to the sufferer, death has ced from a peculiar fluid, circulating in its ornot occurred till after the lapse of twenty days.ganism, by virtue of an influence residing in In one case life was sustained in this way for the period of sixty days.

VOL. LXX.

8

every cell, in every organ, or part of an organ. Physiology teaches that all parts of the body

is proteine + P+S+ salts.
is proteine+P + 2S+ salts.
is proteine + S+ salts.

is proteine water.

is proteine+water+oxygen.

are proteine + ammonia + oxygen.

is proteine+ammonia + water + oxygen.

Now it is obvious, that if proteine be, product of the decomposition of animal present in the food, the other necessary matter. elements are all ready at hand. For animal food, of course, contains as much phosphorus, sulphur, and salts as the body to be nourished; while oxygen and water are always present, and ammonia is a constant

afterwards separated, exactly as fibrine does from blood.

nitrogen; an element indispensable to the existence of blood, as well as of every or"The second nitrogenised compound remains ganised animal solid. But in what form does nitrogen exist in these nutritious fibrine. It does not separate from the juice at dissolved in the juice after the separation of the vegetables? the ordinary temperature, but is instantly coagThere are found in the vegetable king-ulated when the liquid containing it is heated to dom three nitrogenised compounds, which the boiling point. When the clarified juice of alone are capable of supporting animal life, nutritious vegetables, such as cauliflower, and these have been called vegetable asparagus, mangel-wurzel, or turnips, is made fibrine, albumen, and caseine. The truly lutely impossible to distinguish from the subto boil, a coagulum is formed, which it is absointeresting result of recent investigations stance which separates as a coagulum, when the is, that these three compounds are, in serum of blood or the white of an egg, diluted composition and chemical properties, ab- with water, are heated to the boiling-point. solutely identical with the corresponding This is vegetable albumen. It is found in the animal principles. All are compounds of greatest abundance in certain seeds, in nuts, alproteine; and while the whole six are monds, and others, in which the starch of the identical in the proportion of organic ele- graminea is replaced by oil. ments, vegetable albumen is found to contain the same mineral elements as animal albumen, vegetable fibrine as animal fibrine, and vegetable caseine as animal table albumen, it is soluble in water, but differs caseine (milk, cheese).

"The third nitrogenised constituent of the vegetable food of animals is vegetable caseine. It is chiefly found in the seeds of peas, beans, lentils, and similar leguminous seeds. Like vege-.

'These three compounds are the true nitrogenised constituents of the food of graminivorous animals; all other nitrogenised compounds oc

from it in this, that its solution is not coagulated by heat. When the solution is heated or evaporated, a skin forms on its surface, and the ad All such parts of vegetables as can afford nu-dition of an acid causes a coagulum, just as in triment to animals contain certain constituents animal milk. which are rich in nitrogen; and the most ordinary experience proves that animals require for their support and nutrition less of these parts of plants in proportion as they abound in the curring in plants are either rejected by animals, nitrogenised constituents. Animals cannot be fed on matters destitute of these nitrogenised constituents. These important products of vegetation are especially abundant in the seeds of the different kinds of grain, and of peas, beans, and lentils; in the roots and the juices of what are commonly called vegetables. They exist, however, in all plants, without exception, and in every part of plants in larger or smaller quantity. These nitrogenised forms of nutriment in the vegetable kingdom may be reduced to three substances, which are easily distinguished by their external characters. Two of them are soluble in water, the third is insoluble.

as in the case of the characteristic principles of poisonous and medicinal plants, or else they occur in the food in such very small proportion, that they cannot possibly contribute to the increase of mass in the animal body.

we do not here imply mere similarity, but that even in regard to the presence and relative amount of sulphur, phosphorus, and phosphate of lime, no difference can be observed.

The chemical analysis of these three substances has led to the very interesting result that they contain the same organic elements, united in the same proportion by weight; and, what is still more remarkable, that they are identical in composition with the chief constituents of blood, animal fibrine and albumen. They all three dissolve in concentrated muriatic acid with the same deep purple colour; and even in their When the newly-expressed juices of vegeta-physical characters, animal fibrine and albumen bles are allowed to stand, a separation takes are in no respect different from vegetable fibrine place in a few minutes. A gelatinous precipi- and albumen. It is especially to be noticed, tate, commonly of a green tinge, is deposited, that by the phrase-identity of compositionand this, when acted on by liquids which remove the colouring-matter, leaves a greyish white substance, well known to druggists as the deposit from vegetable juices. This is one of the nitrogenised compounds which serves for the 'How beautifully and admirably simple, with nutrition of animals, and has been named vege- the aid of these discoveries, appears the process table fibrine. The juice of grapes is especially of nutrition in animals, the formation of their rich in this constituent, but it is most abundant organs, in which vitality chiefly resides! Those in the seeds of wheat, and of the cerealia ge- vegetable principles, which in animals are used nerally. It may be obtained from wheat flour to form blood, contain the chief constituents of by a mechanical operation, and in a state of blood, fibrine and albumen, ready formed, as far tolerable purity: it is then called gluten, but as regards their composition. All plants, be the glutinous property belongs not to vegetable sides, contain a certain quantity of iron, which fibrine, but to a foreign substance, present in re-appears in the colouring-matter of the blood. small quantity, which is not found in the other Vegetable fibrine and animal fibrine, vegetable cerealia. The method by which it is obtained albumen and animal albumen, hardly differ, sufficiently proves that it is insoluble in water; even in form: if these principles be wanting in although we cannot doubt that it was originally the food, the nutrition of the animal is arrested; dissolved in the vegetable juice, from which it and when they are present, the graminivorous