Page images



The water which drowns us as a ments are combined, nor in what state fluent stream, can be walked upon as the substance is. Even when he has ice. The bullet which, when fired ascertained the real composition and from a musket, carries death, will be properties of any substance, he has harmless if ground to dust before still to ask the physiologist what are being fired. The crystallised part of the conditions presented by the orthe oil of roses, so grateful in its fra- ganism in which this substance is to grance-a solid at ordinary tempera- undergo chemical transformation. We tures, though readily volatile--is a know that a change in the conditions compound substance containing ex- will cause a change in the manifestaactly the same elements, and in ex- tion of a force ; so that often what oractly the same proportions, as the dinarily takes place in the laboratory gas with which we light our streets. will not at all take place in the orThe tea which we daily drink, with ganism. Chlorine and hydrogen are benefit and pleasure, produces palpi- gases having a powerful affinity for tations, nervous tremblings, and even each other--that is to say, they will paralysis, if taken in excess; yet the unite when brought together in the peculiar organic agent-called theine daylight : but if we change the con-to which tea owes its qualities, may ditions—if we bring them together in be taken by itself (as theine, not as the dark-their affinity is never manitea) without any appreciable effect.* fested; and thus, while in the sunThe water which will allay our burn- light they rush together with exploing thirst, augments it when con- sive force, producing an intense acid, gealed into snow; so that Captain they will remain quiescent in the Ross declares the natives of the Arc- darkness, and for all eternity would tic regions“ prefer enduring the ut- form no combination. Again, this most extremity of thirst rather than same chlorine decomposes water in attempt to remove it by eating the sun's rays; but in darkness it has snow.”+ Yet if the snow be melted, no such power. If such are the effects it becomes drinkable water; and it of so simple a change in the condimust be melted in the mouth. Never- tions, it is easy to imagine how varitheless, although, if melted before en- ous must be the differences between tering the mouth, it assuages thirst the phenomena which occur in the like other water, when melted in the laboratory, and those which the same mouth it has the opposite effect. To substances present under the comrender this paradox more striking, we plex conditions of the organism. have only to remember that ice, which The chemist employs vessels of melts more slowly in the mouth, is glass, in which he isolates the very efficient in alsaying thirst. substances he examines, keeping

These facts point to an important them free from the interference of consideration, which has been little other substances, because he knows regarded by the majority of those that, unless such interference be who have written on Food : the con- avoided, his experiment is nullisideration of the profound differences fied. He knows, for example, that which may result from simple diffe- the water which, if poured into rences in the state of substances. The a red-hot crucible, flies up into his chemist, in his elementary analysis, face as steam, will rapidly, pass necessarily gives no clue to such dif- into ice if a little liquid sulphurferences. He tells us of what ele- ous acid happen to be present. He ments an article of Food is composed, knows, in short, that the stronger but be cannot tell us how those ele- affinity prevents the action of the

SCHLEIDEN : Die Pflanze, 1858, p. 205.
+ Ross: Narrative of Second Voyage, p. 366.

weaker affinity; and to be sure of acknowledge, then, that when certain his experiment he must isolate his combinations of carbon, oxygen, hy. substances. But in the vital labora- drogen, nitrogen, and salts, assume tory no such isolation is possible. The the form of a cell, the properties of organism has no glass vessels, no air- these substances become profoundly tight cylinders. Vital processes go modified. on in tissues which, so far from iso- . Such considerations need all our lating the substance introduced-s0 attention in dealing with so complex far from protecting it against inter- a question as that of Food. They ference, do inevitably interfere, and show us, what indeed we had last are themselves involved in the very month occasion to see in detail, the changes undergone by the substance. radical incompetence of Chemistry Thus, while it is true that an alkali to solve any of the questions of Phywill neutralise an acid out of the or- siology, and urge us to reject, as misganism, we must be cautious in ap- directed labour, all attempts at esplying such a chemical principle in tablishing anything more than chethe administration of drugs, because mical facts in the "Chemistry of

' the alkali stimulates a greater secre- Food.” It was undoubtedly a great tion of the gastric acid ; so that over discovery which Mulder made in and above the amount neutralised, 1838, that the albumen of plants was there will be a surplus of acid free, identical, or nearly so, with the alowing to the interference of the tis- bumen of animals, and consequently sues in which the process takes place. that, when the ox ate grass, and the

Besides the complications which lion ate the ox, both derived their occur from the inevitable interference nutriment from the same chemical of the organism itself, and from the substance. A great discovery ; but differences resulting from differences we cannot agree with Moleschott in in the state of bodies, there are other thinking this discovery first settled complications arising from causes pe- the basis of a science of Food. It culiarly vital. Chemistry must ever was a chemical triumph, fruitful in remain incompetent to solve the pro- results to Chemistry ; but its physioblems of life, if only from this, that logical bearing has been greatly exin Biology questions of Form are aggerated, and has given increased scarcely less important than questions impetus to that chemical investigaof Composition. Spread out a cell tion of Food, which, as we have said,

, into a layer, and you will find, that cannot, in the nature of things, be in ceasing to be a cell it has ceased other than misleading. And although to act as an organ—it has lost all the Mulder has shown the inaccuracy of properties which distinguished it as Liebig's notion, that vegetable albuà cell. Thus, the green cells of the men is identical with the fibrine of plant decompose carbonic aid. Even the blood, and vegetable caseine with the torn leaf will equally fix the car- the caseine of the bloodt—although bon and liberate the oxygen, provided he energetically repudiates as unphiits cells are preserved in their in- losophical the idea of a chemical apategrity of form. But if these cells lysis furnishing any true standard of are crushed, or otherwise injured, nutritive value, yet he does not this vital property ceases, because the seem to have clearly apprehended cell alone is capable of manifesting what the true method of investigait.* Under the influence of yeast, tion must be; and his criticism of sugar is decomposed into alcohol and Liebig is mainly negative. carbonic acid ; but if the yeast-cells To the chemist there may be little be crushed and disorganised, their or no difference between plant and action on the sugar is said to be quite flesh as food; to the physiologist the different : instead of converting it difference is profound : he sees the into alcohol and carbonic acid, they lion perishing miserably of inanition convert it into lactic acid. We must in presence of abundant herbage,

LEHMANN : Lehrbuch der

MULDER : Versuch einer Physiol. Chemie, i. 193. Physiol. Chemie, iii. 170.

+ MULDER: Physiol. Chemie, p. 917.


which to the elephant or buffalo fur- why, in spite of all this, the Blood nishes all that is needful. The ox can never furnish us with the desired eats the grass, and the tiger eats the standard. ox, but will not touch the grass. In the first place, while Blood is The flesh of the ox may contain little truly the vehicle of nutrition, it is at that is not wholly derived from the the same time the vehicle of many grass ; and the chemist analysing the products of decay and disintegration. Hesh of both may point out their It carries in its torrent the materials identity ; but the question of Food for the use of to-day and to-morrow, is not, What are the chemical consti- but it also carries the materials tuents of different substances ? but, which, vital yesterday, are effete toWhat are the substances which will day, unfit to be retained, and are nourish the organism? If the ani- hurrying to the various issues of exmal will not eat, or, having eaten, cretion.F Blood is thus at once purcannot assimilate, a certain sub- veyor-general and general sewer, carstance, that substance is no food for rying life and carrying death. We it, be its chemical composition what shall therefore always find in it subit may:* We thus see that digesti- stances which are not alimentary, bility is an important element in the mingled with those which are; and estimate of Food : unless the sub- we cannot separate these, so as to stance can be digested, it cannot be make our analysis of use. In the assimilated, cannot nourish; al- second place, among the substances though, perhaps, if assimilated, the normally current in the circulation we substance might have a high value. do not find several which are notoriA pound of beef-steak contains an ously serviceable as aliments. Some enormous superiority of tissue-mak- of these, as theine, caffeine, alcohol, ing substance over that contained in &c., are not present in the blood ; and a pound of cabbage ; yet to the rab- others, as fats and the carbohydrates, bit the cabbage is the superior food, are present in quantities obviously while to the dog the cabbage is no too small for the amounts consumed food at all.

as food. Finally, although substances When we consider the part played are nutritive, or blood-making, in by Food, as furnishing the materials proportion to their resemblance to out of which the organic fabric is blood, yet this resemblance must constructed, and its actions facili- exist after the process of digestion, tated, it seems natural to assume not before it; since no sooner is any that the Blood is the proper stand- substance taken into the stomach ard we should have in view, and than a series of changes occurs that we should designate those sub- changes indispensable for its admisstances as Aliments which, directly sion into the circulation, but which or indirectly, go towards the forma- impress on it a very different charaction of Blood. Yet, on a deeper scru

ter from the one it bore on its entiny, this is seen to lead us a very trance. A beef-steak is assuredly

An analysis of Blood more nearly allied in composition to will neither give us a complete list the blood of an ox than the dewy of alimentary substances, nor indi- grass of the meadow ; yet the grass cate the alimentary value of each becomes converted into blood in the special substance. True it is that course of the changes impressed on all the tissues are formed from the it during digestion, and what was Blood, and that all alimentary sub- thus unlike becomes like, or, as we stances, in their final state previous say, assimilated. The experiments to assimilation, make their way into of Claude Bernard are highly suggesit. But we will briefly point out tive on this point. He found that if

[ocr errors]

little way.

* It is curious that carnivora feed chiefly, sometimes exclusively, on herbivora, and not on carnivora, whose flesh most resembles their own.

+ See on this point John Simon, Lectures on Pathology, p. 23 :-"Mentally we can separate these three kinds of blood, but experimentally we cannot. They are mixed together-past, present, and future-the blood of yesterday, the blood of today, and the blood of to-morrow—and we have no method of separating them."

sugar or albumen were injected into idea is so plausible that its acceptthe veins, it was not assimilated, but ance was general. Nevertheless nowas eliminated unchanged by the thing is more certain than that milk kidneys; whereas, if either substance is not this model food, since, however were injected into the veins together it may suit the young lion or the with a little gastric juice, assimila- young child, we cannot feed the tion was complete. In another ex- adult lion or the adult man on milk periment he found that if sugar and alone : we can feed the lion on bones albumen were injected into the portal and water, and the man on bread and vein, which would carry them through water, but not on milk. A model the liver, where certain changes are food for the young, it ceases to be so always impressed on them, they for the adult ; that relation which would be assimilated; but if he inject- existed between the food and the ed them into thejugular vein, bywhich organism in the one case, no longer they would reach the lungs without exists in the other. passing through the liver, no assimi- If milk does not furnish us with sation would take place. We here an absolute standard (except for the once more see the necessity of taking young), it furnishes an approximative into account the organism and its standard of great value. Its comvital acts, whenever we would at- position points out the proportions tempt an explanation of Food. of inorganic and organic substances

The general considerations which necessary in the food of the juvenile a priori caused us to relinquish the organism, and of course approximaidea of finding a proper standard in tively in that of the adult." In 1000 the composition of the Blood, are parts milk containsfully confirmed by the results of


873 Payen's experiments, which show Caseine (nitrogenous matter), 48 that Blood' is not a good aliment. Sugar of milk,

44 He fed pigs on equal proportions of Butter,

30 flesh and blood, and found that they Phosphate of lime,

2.30 exhibited all the signs of starvation ;

Other salts,

2.70 whereas, when fed on flesh under

1000 similar conditions, except that blood was absent, they fattened and grew The reader may remark with some strong.*

surprise, that in an aliment so notoriThe Blood, then, must be given ously high in nutritive value as milk, up. Shall we try Milk? Others the proportion of nitrogenous matter have done so before us, making it is so very insignificant as to render the standard of Food, because it is the hypothesis of nitrogenous matitself an aliment which contains all ters being pre-eminently the nutritive the substances necessary for the matters somewhat perplexing. As

nourishment of an organism during we last month gave so much space to ' the most rapid period of growth. Out that hypothesis, we need not here re

of milk, and milk alone, the young consider it; but contenting ourselves elephant, the young lion, or the young with the indication furnished by the child, extracts the various substances analysis of milk, note how that analywhich furnish muscles, nerves, bones, sis further aids our investigation, by hair, claws, &c.; milk furnishes these proving the necessity of four distinct in such abundance, that the increase classes of principles in Food. These of growth is far greater during the four classes are, the inorganic, the period when the animal is fed ex- albuminous, the oily, and the sacchaclusively on it, than at any subse- rine. The proportions of these subquent period of its career. * In stances requisite will, of course, vary milk," says Prout, "we should ex- with the needs of the various organpect to find a model of what an isms, as modified by race,age, climate, alimentary substance ought to be-a activity, and so forth ; but nutrition kind of prototype, as it were, of will be imperfect unless all four are nutritious elements in general.” The present, either as such, or else under

* Payen: Des Substances Alimentaires, p. 45.

[ocr errors]



conditions of possible formation- rice, would, it is said, outrun, knock thus fats and sugars can, we know, down, or in any other way prove be formed in the organism with a superiority in strength over the proper allowance of materials ; and Gaucho of the Pampas, who lives on I am strongly disposed to think that flesh. And not only are some organalbuminous substances can also be isms ill adapted to a flesh diet, as we formed, though not unless some have seen, but, according to Andersalbumen be present to act as son, the strongest man he ever knew leaven.

scarcely ever touched animal food : We are thus, by the principle of this was a Dane, who could walk exclusion, reduced to the one method from spot to spot carrying a stone, of investigation which remains, and which was so heavy that it required that is to interrogate the organism, ten men to lift it on to his shoulders ; not the laboratory.

his chief diet was gallons of thick

sour milk, tea, and coffee ;* a diet * Experience, daily fixing our regards

which no ordinary man could supOn Nature's wants,"

port with success. must guide us in the search. Το Having discussed the chief topics ascertain what substances are nutri- of Food in general, we may now tious, we must ascertain those which ascertain what Science can tell us really nourish ; and the relative value respecting the various articles emof these can only be ascertained by ployed as nourishment by man. Our extensive and elaborate experiments inquiry falls naturally under two on the feeding of animals, conducted heads-first, the Alimentary Prinon rigorously scientific principles. In ciples, considered separately ; and other words, we must adopt that next, the Compound Aliments, or very method which common sense those articles of Food and Drink has from time immemorial pursued; which make up the wondrous variety with this important difference, that of human nourishment. instead of allowing it to be, as hither- Albumen.—This substance, famito, wholly empirical, we must subject liar to all as the white of egg, conit to the rigour, caution, and pre- stitutes an important element in cision, which characterise Science. Food. It exists as a liquid in the And even when Science shall have blood, as a solid in flesh. When established laws on this point, such raw, or lightly boiled, it is readily as may accurately express the gene- digested ; less so when boiled hard, ral value of each substance as food, or fried. Majendie has observed that there will always remain consider- the white of eggs combines many able difficulty in applying those laws, conditions favourable to digestion, owing to that peculiarity of the vi- for it is alkaline, contains saline tal organism, previously noticed matters, especially common salt, in namely, that the differences among large proportions, and it is very individuals are so numerous, and nearly allied to the albumen found often so profound, as to justify the in the chyle and blood. It is liquid,

one man's meat is another but is coagulated by the acids of man's poison.” Thus, while experi- the stomach, forming flocculi having ence plainly enough indicates that, slight cohesion, and rendered easily in Europe at least, meat is more soluble again by the intestinal juices. nutritious than vegetables, those who Many people imagine that white of eat largely of meat being stronger egg is injurious, or innutritious, and and more enduring than those who they only eat the yolk. To some eat little or none; we must be cau- this may be so, and when experitious in the application of such a

ence proves it to be so, white of egg principle. Difference of climate may, should not, of course, be eaten ; but, and difference of temperament cer- as a general rule, white of egg is agreetainly does, modify this question. able and nutritious. Nevertheless, The Hindoo sepoy, who lives on if given alone, neither white of egg


* ANDERSSON : Lake Ngami, p. 58.

« PreviousContinue »