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used in respiration. It is from this source mal products is gelatine. It constitutes the that fat is derived.
mass of the skin, of most membranes, and We do not remember to have met with of the organic part of the bones. But it a more beautiful instance of adaptation to differs from fibrine, albumen, and caseine in circumstances than this of the production this, that, although formed from proteine, it of fat in stall-fed animals, considered in re- cannot, like these substances, be made again lation both to its cause and its effect; and to yield proteine. Once formed, gelatine no for the development of this curious sub- longer belongs to the series of compounds ject we are indebted to the sagacity of Pro- of proteine. The consequence of this is, fessor Liebig.
that it is altogether incapable of yielding He first directs atttention to the compo- blood, or consequently of contributing to sition of starch and sugar, in which carbon the growth or nutrition of the fibrous or is to hydrogen as 43 to 6 nearly in 100 other tissues which contain proteine. Aniparts, the rest being oxygen ; while the mals fed exclusively on gelatine soon die proportion of these elements in fat is 79 to with all the appearances of starvation. Yet 11 nearly—in other words, the same. From there is no doubt that, when mixed with this he concludes that the only way in other animal food, it serves some purpose which starch can pass into fat is by a loss in the economy; for dogs eat bones, and of oxygen; and, in fact, if we subtract the gelatine is not to be found in their exfrom the composition of starch a certain cretions. Besides, the uniform experience amount of oxygen, the remainder will ex- of medical men proves that food composed press exactly the proportion of the elements principally of gelatine, such as strong soup in fat. Now the direct cause of the pro- or jelly, is most advantageous as an article duction of fat is a deficiency of oxygen, so of diet for convalescents. that the separation of fat tends directly to There has lately occurred in Paris a make up for the deficiency which caused it; controversy on the use of the gelatine of and the growth of fat in a sedentary man, bones for hospital soup, as recommended or in a stall-fed animal, is a beautiful pro- by. D’Arcet, and the most contradictory vision of nature to furnish from another opinions as to its qualities are daily pubsource the oxygen which respiration ought lished. Professor Liebig has, we think, to have supplied, and which is required to decided this question. He has shown that keep up the animal heat. The author has, gelatine cannot yield blood, and that by we think, succeeded in proving the exist- itself
, therefore, it cannot support life. But ence of a very close connection between he supposes that it is dissolved in the stothe formation of fat and the respiratory mach, and, being conveyed in the blood to process, and he gives a very interesting ex- every part of the body, acts as nutriment planation of the various means resorted to to the gelatinous membranes and bones for fattening animals; all of which, although alone. This ingenious idea explains both hitherto empirical, admit of the most satis- how gelatine mixed with other animal matfactory elucidation on the principles here ter forms a good diet; and how it is pecuindicated. Thus,
liarly adapted for the sick and convalescent, * Experience teaches us that, in poultry, the in whom it acts by giving nutrition to the maximum of fat is obtained by tying the feet and gelatinous tissues, and so sparing much of by a medium temperature. These animals, in the energy of the enfeebled digestive syssuch circumstances, may be compared to a plant, tem, which is thus not consumed in produpossessing in the highest degree the power of cing gelatine for these tissues, but is exconverting all food into parts of its own struc pended in the digestion of sanguiferous ture. The excess of the constituents of blood forms flesh and other organized tissues, while nourishment. We can now readily credit that of starch, sugar, &c., is converted into fat. the statements of D'Arcet, who has shown When animals are fattened on food destitute of that in all the hospitals where the gelatine pitrogen, only certain parts of their structure of bones has been used as a principal, but increase in size. Thus, in a goose fattened in this not the only, article of animal food, the method, the liver becomes three or four times lar, patients relish it, the success of the treatger than in the same animal when well fed ment has been much increased, and the with free motion; while we cannot say that the
period of convalescence on the average organized structure of the liver is thereby in
much diminished. Now that we possess creased. The liver of a goose sed in the ordinary way is firm and elastic; that of the imprisoned what appears to be the true theory of the animal is soft and spongy. The difference con
action of gelatine, it is to be hoped that sists in a greater or less expansion of its cells, the prejudice, previously very natural, which are filled with fat.'--p 94.
which exists in this country against its use, One of the most remarkable of the ani- may be overcome, and that our hospitals
may participate in the benefits of D'Arcet's | severe muscular exertion. Thus the chief benevolent system, which, when success- objects of our agriculture are found to be fully conducted, has likewise the advantage those substances which are most effectual, of superior economy.
even when taken alone, in supporting aniThe food best adapted for man is that mal life. The potato is not to be forgotten. which contains a due mixture of azotised It is not so rich in fibrine as wheat-flour, matter (fibrine, albumen, &c.), and non- but it has enough, with the starch or respiazotised matter (sugar, starch, &c.). Hear ratory matter it contains, to be a most valour author :
uable article of diet. "A nation of hunters, on a limited space, is We must briefly notice another very inutterly incapable of increasing its numbers be- teresting section of this work. It is that yond a certain point, which is soon attained. which treats of the action of medicines and The whole of the carbon necessary for respiration poisons on the system. must be obtained from the flesh of animals, of
The first class of such agents is that of which only a limited number can find food on the space supposed.
substances which produce a very marked • But 15 lbs. of flesh contain not more carbon effect, without their elements taking a dithan 4 lbs. of starch; and while the savage, with rect share in the changes which ensue. one animal and an equal weight of starch, could These bodies originate as it were an acsupport life and health for a certain number of tion, wbich is subsequently propagated from days, he would be compelled, if confined to flesh particle to particle. They are uniformly alone, in order to procure the carbon necessary substances in a state of change or transfor respiration and for the animal heat, to consume five such animals in the same period.
formation, and appear to act on the blood • It is easy to see, from these considerations, as yest does on a solution of sugar. In this how close the connection is between agriculture class appear miasms, contagions, and the and the multiplication of the human species. singular sausage poison of Wurtemberg. The cultivation of our crops has ultimately no The latter is an excellent sample. Sausaother object than the production of a maximum ges, made in a peculiar way, are much milation and respiration in the smallest possible used in that country. When ill-prepared, space. Grain and other nutritious vegetables yield us, not only in the form of starch, &c., the are invariably fatal. The patient graducarbon which protects our organs from the action ally dries up into a sort of mummy, and, of oxygen, and serves to produce also the heat after weeks or months of misery, death essential to life, but also, in the form of vegetable closes the scene. But there is no poisonfibrine, albumen, and caseine, our blood, from ous substance to be detected in the sausage. which all the other parts ofthe body are developed. It is, according to our anthor, in a peculiar
• Man, when confined to animal food, respires, like the carnivora, at the expense of the matters state of fermentation, which is not checkproduced by the metamorphosis of organised ed by the action of the stomach, and which tissues: and, just as the lion, tiger, and hyena, unfortunately is communicated to the in the cages of a menagerie, are compelled to blood. It never ceases till every part ca. accelerate the waste of the organised tissues by pable of solution has been destroyed, and incessant motion, in order to furnish the matters death, of course, must follow.
But, as it necessary for respiration and for animal heat, so the savage, for the same object, is forced to make appears that the poisonous sausage may be the most laborious exertions, and to go through rendered quite safe by boiling, and by a vast amount of muscular exercise. He is other simple means of arresting fermentacompelled to consume force, merely in order to tion, we may hope that the true theory of supply matter for respiration.
the poison will lead to a successful treat* Cultivation is the economy of force. ment of this frightful accident, which unThe unprofitable exertion of power, the waste happily is very frequent. Miasms and conof force in agriculture, in other branches of in- tagions act on the very same principle; acteristic of the savage state, or of the absence and the reason that all are not affected by of cultivation.'—pp. 76—78.
them seems to be, that they require the Nature furnishes one substance in the presence of a peculiar compound in the animal kingdom which is perfectly fitted to blood, which enters into decomposition, sustain life. It is milk, a mixture of case- and when the whole of this peculiar matine, sugar, fat, and salts, with water. It is ter is destroyed, the disease disappears. If curious that the nearest approach to this in there be much, the case is severe—if little, artificial food is bread, which is a mixture the case is mild ; and apparently, in many of vegetable fibrine (gluten) and starch, contagious diseases, the peculiar decomalong with salts. Bread and water, it is posible matter, once destroyed, can never well known, will support life permanently. be renewed; so that these diseases occur Flesh will do so likewise—with the aid of
of those echose clatements scalents sharsisin peculiain principles of easparaguse and se ale takes the changes produced. This class is sub asparagine; which also, by the addition of oxy! divided into orders, of which the first in- gen and the elements of 'water, yields the ele
ments of taurine. * cludes the metallic poisons. These enter • The addition of the elements of water and directly into combination with the tissues, of a certain quantity of oxygen to the elements and if the vital force cannot destroy the of theobromine, the characieristic principle of compounds thus formed, death ensues. The the cacao-bean (theobroma cacao,) yields the second order contains empyreumatic and elements of taurine and urea, of taurine, carantiseptic substances, which act by check- bonic acid, and ammonia, or of taurine and uric
acid. ing the vital transformations; just as, out
• To see how the action of caffeine, asparaof the body, they check fermentation or gine, theobromine, &c., may be explained, we putrefaction.
must call to mind that the chief constituent of The third order consists of substances the bile contains only 3.8 per cent. of nitrogen, whose elements take a share in certain of which only the half, or 1.9 per cent., belongs vital processes of secretion or excretion, to the taurine. and thus excite abnormal appearances, ei
• Bile contains, in its natural state, water and ther accelerating, disturbing, or retarding weight of the former to 10 of the latter. it
solid matter, in the proportion of 80 parts by. the functions. These may be divided into
we suppose these 10 parts by weight of solid azotised and non-azotised.
matter to be choleic acid, with 3:87 per cent. of It is very remarkable that no medical nitrogen, then 100 parts of fresh bile will conagent devoid of nitrogen is poisonous in tain 0:171 parts of nitrogen in the shape of taumoderate quantity; while those containing rine. Now this quantity is contained in 0.6 nitrogen, all except three, are poisonous parts of caffeine ; or 2 8-10 grains of caffeine can in a very small dose.
give to an ounce of bile the nitrogen it contains This last division
in the form of taurine. If an infusion of tea includes the vegetable alkalis, morphia, contain no more than 1-10th of a grain of cafquinine, strychnia, &c.
feine, still, if it contribute in point of fact to the Professor Liebig remarks that
formation of bile, the action, even of such a quantity, cannot be looked upon as a nullity.
Neither can it be denied that, in the case of an · We shall never be able to discover how men excess of non-azotised food and a deficiency of were led to use the infusion of a certain leaf motion, which is required to cause the change (tea), or the decoction of a certain seed (coffee). of matter in the tissues, and thus to yield the But some cause there must be, which has in- nitrogenised product which enters into the comduced whole nations to make the practice a ne position of the bile—that in such a condition, cessary of life. And it is surely still more re- ihe health may be benefited by the use of commarkable, that the peculiar effects of both plants pounds which are capable of supplying the on the health must be ascribed to one and the place of the nitrogenised product formed in the same substance; the presence of which in two healthy state of the body, and essential to the vegetables belonging to different natural fami- production of an important element of respiralies, and the produce of different quarters of the tion. In a chemical sense-and it is this alone globe, could hardly have presented itself to the which the preceding remarks are intended 10 boldest imagination. Yet recent researches show-caffeine or theine, asparagine, and theohave demonstrated that caffeine, the active prin- bromine, are, in virtue of their composition, ciple of coffee, and théine, that of tea, are, in all better adapted to this purpose than all other nirespects, perfectly identical.
trogenised vegetable principles. The action of It is not less worthy of notice, that the Ame- these substances, in ordinary circumstances, is rican Indian, living entirely on flesh, discovered not obvious, but it unquestionably exists. for himself, in tobacco smoke, a means of re * With respect to the action of the other ni. tarding the change of matter in the tissues of his trogenised vegetable principles, such as quinine, body, and thereby of making hunger more en or the alkaloids of opium, &c., which manifests durable; and that he cannot withstand the ac- itself, not in the processes of secretion, but in tion of brandy, which, acting as an element of different phenomena, physiologists and patholorespiration, puts a stop to the change of matter gists entertain no doubt ihat it is exerted chiefly by performing the function which properly be on the brain and nerves. This action is comlongs to the products of the metamorphosed monly said to be dynamic-that is, it accelerates, tissues, when ihe diet is entirely animal. Tea or retards, or alters in some way, the phenomena and coffee were originally met with among na- of motion in animal life. If we reflect that tions whose diet is chiefly vegetable.
this action is exerted by substances which are • Without entering minutely into the medi- material, tangible, and ponderable; that they cinal action of caffeine (theine), it will surely appear a most striking fact, even if we chose to deny its influence on the process of secretion,
* We omit the elaborate tables of equations apthat this substance, with the addition of oxygen pended to these statements. They would only be in. and the elements of water, can yield taurine, the telligible to readers who are sure to study the orinitrogenised compound peculiar to bile.
disappear in the organism ; that a double dose | product, before a certain number of its elements acts more powerfully than a single one ; that, can become constituents of the nervous matter; after a time, a fresh dose must be given, if we and it must be considered as quite certain, that wish to produce the action a second time,-all a product of the vital process in a plant, introthese considerations, viewed chemically, permit duced into blood, will, ifiisconsposition be adapted only one form of explanation : the supposition, to this purpose, supply the place of the first, senamely, that these compounds, by means of cond, or third product of the alteration of the their elements, take a share in the formation of compound of proteine. Indeed it cannot be new, or the transformation of existing, brain considered merely accidental, that the composiand nervous matter.
tion of the most active remedies, namely, the · However strange the idea may, at first sight, vegetable alkaloids, cannot be shown to be reappear, that the alkaloids of opium or of cin- lated to that of any constituents of the body, chona bark, the elements of codeine, morphia, except only the substance of the nerves and quinine, &c., may be converted into constituents brain. All these remedies contain a certain of brain and nervous matter, into organs of vital quantity of nitrogen, and, in regard to their comenergy, from which the organic motions of the position, they are intermediate between the combody derive their origin; that these substances pounds of proteine and the fats. form a constituent of that matter, by the remo • In contradistinction to their chemical characval of which the seat of intellectual life, of sen ter, we find that the substance of the brain exsation, and of consciousness, is annihilated: it hibits the characters of an acid. It contains far is, nevertheless, certain, that all these forms of more oxygen than the organic bases or alkapower and activity are most closely dependent, loids. We observe, that quinine and cinchonine. not only on the existence, but also on a certain morphia and codeine, strychnia and brucia, quality of the substance, of the brain, spinal which are, respectively, so nearly alike in compomarrow, and nerves; insomuch, that all the mani- sition, if they do not produce absolutely the same festations of the life or vital energy of these mo- effect, yet resemble each other in their action difications of nervous matter, which are recog more than those which differ more widely in nized as the phenomena of motion, sensation, or composition. We find that their energy of acfeeling, assume another form as soon as their tion diminishes, as the amount of oxygen they composition is altered. The animal organism contain increases (as in the case of narcotine), has produced the brain and nerves out of com- and that, strictly speaking, no one of them can pounds furnished to it by vegetables: it is the be entirely replaced by another. There cannot constituents of the food of the animal, which, be a more decisive proof of the nature of their in consequence of a series of changes, have as. action than this last fact: it must stand in the sumed the properties and the structure which closest relation to their composition. If these we find in the brain and nerves.
compounds, in point of fact, are capable of taking • If it must be admitted as an undeniable truth, I a share in the formation or in the alteration of that the substance of the brain and nerves is the qualities of brain and nervous matter, their produced from the elements of vegetable albu- action on the healthy as well as the diseased men, fibrine, and caseine, either alone, or with organism admits of a surprisingly simple er. the aid of the elements of non-azotised food, or planation. If we are not tempted to deny, that of the fat formed from the latter, there is nothing the chief constituent of soup may be applied to absurd in the opinion that other constituents of a purpose corresponding to its composition in the vegetables, intermediate in composition between human body, or that the organic constituent of the fats and the compounds of proteine, may be bones may be so employed in the body of the applied in the organism to the same purpose. dog, although that substance (gelatine in both
Brain and nervous matter is, at all events, cases) is absolutely incapable of yielding blood; formed in a manner similar to that in which if, therefore, nitrogenised compounds, totally bile is produced; either by the separation of a different from the compounds of proteine, may highly nitrogenised compound from the elements be employed for purposes corresponding to of blood, or by the combination of a nitrogenised their composition; we may thence conclude product of the vital process with a non-azotised that a product of vegetable life, also different compound (probably, a fatty body.) All that from proteine, but similar to a constituent of the has been said in che preceding pages on the va- animal body, may be employed by the organism rious possible ways by which the bile might be in the same way and for the same purpose as supposed to be formed, all the conclusions which the natural product, originally formed by the we attained in regard to the co-operation of azo- vital energy of the animal organs, and that, tised and non-azotised elements of food, may be indeed, from a vegetable substance. applied with equal justice and equal probability The time is not long gone by when we had to the formation and production of the nervous not the very slightest conception of the cause of substance.
the various effects of opium, and when the action • We must not forget that, in whatever light of cinchona bark was shrouded in incomprehensiwe may view the vital operations, the produc ble obscurity. Now that we know that these tion of nervous matter from blood presupposes a effects are caused by chrystalizable compounds, change in the composition and qualities of the which differ as much in composition as in their constituents of blood. That such a change oc- action on the system; now that we know the curs is as certain as that the existence of the substances to which the medicinal or poisonous nervous matter cannot be denied. In this sense, energy must be ascribed, it would argue only we must assume, that from a compound of pro- want of sense to consider the action of these teine may be formed a first, second, third, &c., I substances inexplicable; and to do so, as many
have done, because they act in very minute, he proceeds to investigate; and in a most doses, is as unreasonable as it would be to judge ingenious dissertation he traces many anaof the sharpness of a razor by its weight.
logies between the vital force and the • Thus, as we may say, in a certain sense, of
forces of gravitation, cohesion, chemical caffeine or theine and asparagine, &c., as well as of the non-azotised elements of food, that they attraction, and electricity. He arrives ultiare food for the liver, since they contain the ele- mately at the conclusion, that the vital ments by the presence of which that organ is force is a force sui generis, in some respects enabled io perform its functions, so we may con- analogous to, yet distinct from all the sider these nitrogenised compounds, so remark- forces just enumerated. We endeavour able for their action on the brain and on the sub- in vain to penetrate the veil that conceals stance of the organs of motion, as elements of the mystery of life from our sight; but in food for the organs as yet unknown, which are destined for the metamorphosis of the constitu- tracing, as far as we are permitted to do so, ents of the blood into nervous substance and the causes of motion in the animal body, brain. Such organs there must be in the animal we come ultimately to chemical attraction, body, and if, in the diseased state, an abnormal modified in a very remarkable manner by process of production or transformation of the the unknown force. We have seen that constituents of cerebral and nervous matter has chemical attraction explains the change or been established; if in the organs intended for waste of matter, and the animal heat ; this purpose the power of forming that matter out of the constituents of blood, or the power of and we may add here, that the nervous resisting an abnormal degree of activity in its influence appears to depend, in some way, decomposition or transformation, has been di- on chemical changes in the substance of minished; then, in a chemical sense, there is no the brain. It is certain, at least, that the objection to the opinion, that substances of a exercise of the functions of the brain is atcomposition analogous to that of nervous and tended by waste of its substance, just as cerebral matter, and, consequently, adapted to the use of the muscles is attended by waste form that matter, may be employed, instead of the substances produced from the blood, either of their substance. Mr. Liebig regards the to furnish the necessary resistance, or to restore
nerves as conductors of the vital force, by the normal condition.
means of which an equilibrium of force "An accurate investigation would probably may be established; or available vital force discover differences in the composition of the may be conveyed from one part where it is brain, spinal marrow, and nerves. According not wanted, to another where it is rapidly to the observations of Valentin, the quality of consumed in producing motion. As the the cerebral and nervous substance is very rapidly altered from the period of death, and very
involuntary muscles never cease their mouncommon precautions would be required for the tions, sleep is necessary that the waste in separation of foreign matters, not properly be the voluntary as well as involuntary muslonging to the substance of the spinal marrow cles may be supplied. In the waking or brain. But, however difficult it may appear, state, one voluntary muscle may be acquirthe investigation seems yet to be practicable.'-ing new matter, while another which is pp. 178–190.
exercised is undergoing waste. In pursu
ing this investigation, we find that the We consider these hints of the author's, waste of matter, the supply, of oxygen, for they are no more, on a most obscure and the amount of force, mechanical or subject, as worthy of careful investigation. Otherwise, exerted in the body, are most We know, as he justly observes, that ner- closely connected together. In plants vous matter is formed from our food, which for want of nerves, the vital force cannot does not contain a trace of it; and there is be conducted away from the point where no absurdity in supposing that an organic it is produced ; it therefore manifests itself compound of appropriate composition, may in an unlimited growth or increase of mass. exert an influence of one kind or other on in animals the presence of nerves permits its formation.
the vital force to assume at one time the Another very important section treats form of chemical attraction, at another that of the nature of the vital force, of that of mechanical force; and when the nerves power which regulates all the operations lose, wholly or partially, their conducting of the body, and which impresses on them power, we have paralysis, syncope, or their peculiar character. The Professor spasm. But we feel the impossibility of first points out those particulars in which giving anything like an accurate notion of the vital force, in its manifestations, agrees this most interesting section, unless with other causes of motion or change. He were to quote the whole of it. Recomshows that although we cannot hope ever mending it, therefore, to the physiologist, to know what vitality is in its essence, yet we shall merely transcribe the concluding it is in our power to trace the laws by paragraph. which its action is regulated. These laws In what form, or in what way, the vital