Biology

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22102077088

Med

THE LIBRARY

Preface

The word Biology , which seems to have been employed for the first time by Treviranus, is far from bearing in the scientific vocabulary a completely settled import. It may not be unprofitable to determine the sense of the word. Etymologically it signifies literally “ science of life,” and embraces everything relating, intimately or remotely, to the study of organised beings ; that is to say, a whole group of sciences, among which is comprehended Anthropology, for instance. It is in this encyclopaedical sense that Auguste Comte took the word “Biology,” though as far as we ourselves are concerned we intend to give it a sense much more restricted. Under the designation “ Biology,” we merely place the exposition and the coordination of all the great facts and great laws of life, or nearly what is usually under* stood by “ General Physiology,” when this denomination is applied to the two organic kingdoms. In this volume we have simply attempted to state concisely what life is, and how organised beings are nourished, grow, are reproduced, move, feel and think.

VI

PREFACE.

Even while limiting ourselves to this comparatively restricted domain, we have had to consider, to group, to condense and to classify, an enormous mass of facts derived from all the natural sciences. Among these facts, numerous as the stars of the heaven and the sands of the ^ea, we have been compelled to make a choice, and to select as much as possible what was most important, most significative, most luminous.

We hope that the learned men who devote themselves to special subjects may find in our modest production some new combinations, perchance some of those general views which are sometimes lacking to certain men in other respects very distinguished, but who abide too closely in this or that district of knowledge, as happens often in this age when the division of scientific labour is carried to excess. Nevertheless, we do not write for scientific men. We wish especially to be read by the mass of enlightened people, whom our very incomplete system of public instruction has left almost unacquainted with Biology. In effect, our best establishments for secondary instruction limit their ambition to imparting sufficiently complete ideas of physics, and very incomplete ideas concerning chemistry; but they stop too timidly on the threshold of Biology, the mysteries of which are accessible only to a small number of special men. This is a defect exceedingly deplorable, exceedingly prejudicial to general progress. It is on account of this defect that so many false and even pernicious ideas continue to find acceptance and empire in public opinion ; hence it is, in a great measure, that true philosophy, or rather that philosophy which is alone solid and sound, that which flows directly and legitimately from

PREFACE.

vii observation and experiment, has such difficulty in diffusing itself.

The object of our little book is to remedy this serious educational deficiency in those who are otherwise enlightened. It is therefore a work of vulgarisation. Certain scientific men, too strictly confined within their own circle, and whose horizon is bounded by the walls of their laboratories, pronounce, with disdain, though unjustly, this term vulgarisation. To find the truth is surely a noble labour ; but what is the value of the discovered truth, if care is not taken to propagate it, to introduce it into the patrimony of general knowledge ?

On the other hand, it must be granted that the work of popularising has been brought somewhat into disrepute by a crowd of pseudo-scientific publications, the authors of which, trusting too little to the intelligence of the reader, either administer only an infinitesimal dose of science, or think themselves obliged to dilute the main idea with a deluge of light or pleasing words, sacrificing thus at once to the most amiable and most dangerous of our national peculiarities. Science only deserves its name upon condition of preserving a somewhat austere nobleness. For our part we have taken care not to rob science of that which constitutes its strength, and for this we trust the reader will give us credit. In our opinion there is not a person of moderate intelligence who will not be able, at the cost of a slight mental effort, to read and comprehend this book ; and we think also that by such a perusal of it, sufficiently clear and complete ideas of Biology will have been imparted.

This is not a polemical work, but rather an exposition viii

PREFACE.

of facts. Nevertheless, amongst these facts are some which are indisputable ; also, when we have met with them, we have not hesitated to formulate the conclusions or inductions which resulted from them. We have always done this temperately and with brevity, and without having any other motive than the love of truth.

We trust that this volume may he read, and that profitably, and that it may awaken, in a large number of its readers, love of and respect for science, namely, that which alone, in these sad times, is at once a refuge and a hope.

Ch. Letotjrneau.

CONTENTS,

Book I. Of Organised Matter In General

CHAP. FAGJS

I. — Constitution of Matter. — Unity of Substance in the Organic World and in the Inorganic World I

II. — Anorganic Substances and Organic Substances . ... 11

III. — Chemical Composition of Animals and Plants .... 19

IV. — Of Life 28

V. — Anatomical Constitution of Organised Bodies .... 35

Book II. Of The Primordial Phenomena Of Life

I. — Of Nutrition , . . . . . . 75

II. — Vegetal Nutrition 88

III. — Vegetal Assimilation and Dis-assimilation ..... 109

IV. — Of Animal Nutrition 121

V. — Of Assimilation amongst Animals . » . ; . . . . 125

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Contents

x

CHAP. PAGE

VI. — Of Dia-assimilation amongst Animals 135

Book III. Of Growth

I. — Of the Processes of Growth 273

II. — Of Growth in the Vegetal Kingdom 276

III. — Of Growth in the Animal Kingdom 285

IV. — Of the General Conditions of Growth 291

OF GENERATION.

I. — Of the Origin of Organised Beings 301

II. — Of Generation in the Two Kingdoms 309

III. — Of Vegetal Generation 315

IV. —Of Animal Generation 320

V. — Of Regeneration 334

CONTENTS.

xi

Book V. Of Motility

CHAP. PAGE

I. — Of the Brownian Movements 339

II. — Of Movements in the Vegetal Kingdom 343

III. — Of Movements in the Animal Kingdom ...... 348

Book VI. Of Innervation

I. — The Nervous System in the Zoological Series . . . . 361

II. — Of Cells and of Nervous Fibres 376

III. — Of Motricity 388

IV. — Properties of Nervous Fibres 394

V. — Of Sensibility in General 402

VI. — Of Touch 406

VII. — Of the Senses of Taste and of Smell ... . . . . . 409

VIII. — Of the Sense of Hearing 415

IX. — Of the Sense of Sight 420

X.— Of Thought 430

Book VII. Of The Physical Forces In Biology

I. — Of Organic Heat 443

IL— Of the Processess of Organic Calorification 449

HI. — The Transformation of Forces in Biology 457

IV. — Of Aliments 465

ERRATA.

P. 230, line 16, for “ pond leech*’ read “pond loach.”

P. 237, line 18, for “ velatory bladder ” read “ natatory bladder.” P. 419, line 5, for “vertebrates” read “ mammifers.”

BIOLOGY.

Chapter I

CONSTITUTION OP MATTER. UNITY OP SUBSTANCE IN THE ORGANIC

WORLD AND IN THE INORGANIC WORLD.

The sciences of observation demand at the outset from him who wishes to cultivate them an act of faith. Though it is perfectly incontestable that the exterior world manifests itself to us solely by exciting in our mind an incessant series of phenomena of consciousness, of phenomena called subjective, we are nevertheless compelled, unless we wish to plunge into the doubt applauded by Pyrrho and Berkeley, to believe our senses as honest and sincere witnesses when they signalise to us the existence, apart from our own being, of a vast material universe, the elements whereof, without pause in movement, awaken in us, by acting on our organism; impressions, sensations, and consequently ideas and desires.

The exterior world exists independently of our conscious life ; it was when as yet we were not ; and it will be when we are no 5

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[Book i.

more. Without stopping, as a few years ago M. Littre did, to discuss the point whether the certitude of the existence of the external world is of first or second quality, leaving aside every metaphysical refinement, we must first firmly believe in the real existence of the external world ; because all our senses cease not to cry to us in every tone that the objective, the Non-Me of the psychologists, is not a chimera, because the contrary opinion would strike with nullity all observation, all experience, all reasoning, all knowledge.

The reality of the exterior world once admitted, and man never having been led to doubt that reality, except through a species of intellectual depravation, people naturally inquired what could be the internal constitution of the substance of the universe. They suspected that behind the appearance infinitely mobile and varied of the exterior phenomena there might exist a general and related force. Our object in this work not being to pass in review the opinions or the reveries of the different philosophical schools, we make haste to expound the most probable theories and systems, those which observation has confirmed, and which by slow degrees have conquered in science their right of citizenship.

Leucippus seems to have been the first to have had the intuition of the most rational theory on the constitution of the universal substance. In his opinion this substance is a discontinuous mass of granules, solid, infinitely small, separated by void spaces. It is “ the void mingled with solid,” according to an expression of Bacon.

Democritus admitted that these primordial granules were full, impenetrable, moreover insecable, and, for this last reason, he called them atoms} But the conception of atoms, full and dis-

1 For what is it that Democritus says? — “That there are substances in infinite number, which are called atoms, because they cannot be divided, which are, however, different, which have no quality whatever, are impassible, which are dispersed here and there in the infinite void, which approach each other, gather themselves together, enter into conjunction ; that from these assemblages one result appears as water, another as fire, another as tree, another

CONSTITUTION OF MATTER.

persed through the limitless void of the universe, did not furnish a sufficiently precise account of the constitution of bodies. Epicurus appeared, whose doctrine was so magnificently sung by the great poet Lucretius. lie immensely improved the atomic theory of Leucippus and Democritus by vivifying atoms, and by supposing them endowed with spontaneous movement. From the mobility of atoms resulted their various aggregations and the dissemblances of bodies. According to Epicurus, atoms of necessity mingled together, intertwined, literally caught and clung to each other. A philosopher who had the talent to preach and to propagate in France the atomic theory without seeming to offend the orthodoxy of his epoch, which was still very suspicious, Gassendi, restored to honour the atomic doctrine of the ancients. He admits, according to the expression of Epicurus, that “that which is moves in that which is not,” that is, that atoms are not in contact, but that they are separated by void spaces.

Thus then, according to this theory, the world is composed of an innumerable quantity of atoms, mobile, infinitely small, distant from each other. These atoms are in a perpetual state of movement, rushing toward each other, repelling each other, for they have their sympathies and antipathies. It is from the diversity of their affinities that result their exceedingly diversified modes of grouping and the variety of the external world. It is by their vibrations, their oscillations that they reveal themselves to man by impressing his organs of sense. They have as essential qualities inalterability, eternity. When they gather together, new bodies are formed ; when they disaggregate, bodies previously existing dissolve and seem to vanish. They are unhewn stones which have passed, pass, and are as man ; that everything consists of atoms, which he also calls ideas, and that nothing else exists, forasmuch as generation cannot arise from that which is not while likewise what exists cannot cease to he, because atoms are so firm that they cannot change nor alter nor suffer.” — Plutarch, Miscellaneous Works: Against the Epicurean Colotes ; Amyot’s translation, Clavier’s

edition, vol. xx., Paris, 1803.

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BIOLOGY.

[Book i.

destined evermore to pass from one edifice to another. Their totality constitutes the general substance of the universe, and, in reality, this general substance undergoes no other changes than modifications in the distribution of its constituent elements. All the phenomena, all the varied aspects, all the revolutions of the universe can be referred essentially to simple atomic displacements.

This grand theory, so admirably simple and seductive, would be nothing but a brilliant speculation, if facts, numerous and rigorously observed, did not now serve it as basis and demonstration.

We rapidly enumerate the most important of these facts, which belong for the most part to the domain of Physics and Chemistry.

Wenzel, Bichter, Proust proved first of all that in chemical compositions and decompositions, bodies combine according to proportions rigorously defined. Dalton formulated the law of multiple proportions, and deduced therefrom naturally that matter is constituted by atoms extended, having a constant weight, and that those atoms are of various species.

When atoms of the same species come into juxtaposition, we have what we call simple bodies, such as hydrogen, oxygen, azote. On the contrary, the bodies called compound result from the juxtaposition of atoms of diversified nature, whence come acids, salts, oxides, and also all the unstable and complex compounds which constitute organic substances.

This is not all : to the law of Dalton the law of Avogadro and of Ampere is adjoined. This last law establishes that all gases, temperature and pressure being equal, have the same elastic force. But as this force is probably due to the shock of atoms or groups of atoms, molecules, on the sides of the vessels which imprison the gases, we must admit that in the conditions aforesaid all gases contain, under the same volume, the same number of molecules or of atoms.

Finally, Dulong and Petit have been able to show, experimentally, that the atoms of simple bodies all possess the same specific heat.

Chap, l]

CONSTITUTION OF MATTER,

5 ■

All these great laws, slowly evolved by observation and experiment, have transformed into a solid scientific theory the brilliant but vague intuition of the thinkers of ancient Greece. With ground so firm to rest on, chemistry has been able to particularise more, to study in some sort the individual character of atoms ; in scientific language, it has arrived at the notion of atomicity.

Atoms have as general characteristics extension, impenetrability, indestructibility, and eternal activity. But these general characteristics exclude not a number of specific differences. The progress of chemistry will no doubt show us what amount of truth there is in the hypotheses of Dumas and of Lockyer, according to which the simple bodies of chemistry as it now exists are merely indecomposed bodies. According to this assumption our metals and our metalloids are simple modifications of a single substance, probably hydrogen, the atoms thereof forming different molecular groupings. In the present state of science, these ideas, as yet purely hypothetical, can be passed by ; and relying for the present on the great laws of Dalton, Ampere, Dulong, and Petit, we have the right to consider the simple bodies of contemporary chemistry as representing groups of atoms identical among themselves in each simple body, but specifically different from one simple body to another. Now each of these atomic species has its individual energy, its own affinities. In the group of the other atomic species it has friends, it has indifferents, it has enemies. It willingly unites itself to the first, neglects the second, refuses, on the contrary, to combine with the last. Moreover, this faculty of attracting and of being attracted attains in each atomic species a different degree of energy. Whence we may conclude that there are in the different atomic species differences of mass and of form. In aggregating themselves thus, according to their affinities, atoms arrange themselves into small systems, having in each body a special structure. These atomic systems are called molecules.

The atoms of alkaline metals, such as potassium and sodium,

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BIOLOGY.

[Book i.

cannot fix each more than one atom of chlorine or of bromine ; they are monoatomic, as, for instance, hydrogen. Calcium, barium, strontium, in order that their attractive power may be saturated, need to fix two atoms of chlorine ; they are diatomic , as, for instance, oxygen. Phosphorus, which in the perchlorure of phosphorus succeeds in fixing five atoms of chlorine, is pentatomic.

It is these inequalities in the mode and the power of combination, in the capacity of saturation, which we call the atomicity of each atomical species, designating specially by that expression the maximum capacity of saturation. However, hereby is by no means implied that a pentatomic species, for instance azote, cannot combine with less than five atoms. Azote, which fixes five atoms in the chlorohydrate of ammonia (AzH4Cl), is not more than triatomic in ammoniac gas (AzH3), and is only diatomic in the bioxide of azote. For the sake of greater clearness, the denomination atomicity is reserved to designate the capacity of absolute saturation. The capacities of inferior saturations aie called quantivalences. Thus then azote is pentatomic, but it is trivalent in gas ammoniac, and so on.

This notion of atomicity has thrown a great light on the ultimate texture of bodies, and also on the march hither and thither of atoms in various combinations. In effect, free or combined, every atom tends to saturate itself by the annexion of other atoms. If, for instance, a tetratomic atom has combined with two atoms only, it ceases not to tend to saturate its attractive force ; it strives to fix two atoms more. But these two atoms once found, no other simple body can combine with our tetratomic atom, unless by displacing one or two of its atoms and becoming their substitute. If, for instance, we take from a carburet of saturated hydrogen an atom of hydrogen, the molecule thus mutilated can unite itself to an atom of chlorine. But the chlorine is monoatomic ; this, however, does not hinder it from fixing the complex molecule of the carburet, impoverished to the extent of an atom of hydrogen. The reason is that certain atomic groups, certain molecules, can play in combinations the part of a single atom. They are what we call com -

CONSTITUTION OF MATTER.

pound radicals. This notion of compound radicals has a predominant importance in the chemistry of organic substances, so called because nearly altogether they constitute the substance of living bodies. It simplifies extremely their apparent complexity. It is thus that, according to Mulder, the formula of albumine is 1 0(C40H31N5O12) + S2Ph. If we limit ourselves to totalising the atoms, this formula gives C400H310!N’50O120 + S2Ph, a molecule of frightful complication. But if we admit a compound radical, proteine (C40H31!N’5O12), comporting itself as a simple atom, the molecular structure of albumine is enormously simplified : it approaches that which we are accustomed to meet in the chemistry called mineral. It is probably also from this notion of compound radicals that we must seek the explanation of what has been called isomeria. If bodies having the same elementary composition, such as the tartaric and paratartaric, malic acid, citric acid, sugars, gums, have nevertheless distinctive properties, we must probably attribute the dissimilarities to differences of molecular structure, to the existence, in the very heart of these isomeric bodies, of dissimilar compound radicals.

There is another notion not less important than that of compound radicals for the easy comprehension of the formulas of the chemistry called organic, the notion, namely, of autosaturation. In effect, the atomicity of a simple body does not always expend itself on atoms of a different species ; it may manifest itself between atoms of the same species. The atoms of carbon, for instance, can saturate themselves. An atom of carbon, which

l

is tetratomic, — c — , may, by expending merely a quarter of its

atomicity, unite itself with another atom of carbon, which, in its turn, will neutralise in this combination a quarter of its attractive energy ; there will result thus therefrom a molecule hexavalent, that is to say, capable of still enchaining six atoms :

8 BIOLOGY. [Book i.

Let a third atom of carbon then unite itself to this molecule, we have an octovalent molecule :

l

I

Finally, the adjunction of a fourth atom of carbon gives a decavalent compound :

I I

I I

This notion of autosaturation has enabled us to systematise a quantity of facts of organic chemistry, to create rationally new compounds, to classify and to seriate groups. We owe to it the theory of alcohols, and that of hydrocarburets.1

The preceding pages contain the principal notions of general chemistry, which as we proceed we propose to apply. We must, however, before ending this chapter say a - few words on what have been called catalyses. Certain bodies brought into contact with other bodies determine by their presence alone, and without taking any other part in the reactions, either combinations or metamorphoses or unfoldings. It seems as if in these cases the body, intervening, by its presence alone, brings into play an attractive force sufficient to disturb the atomicity of the body which it influences, without, however, being able to enter into combination with that body. For instance, platina determines, by its presence alone, the combination of oxygen and hydrogen, the formation of water ; it transforms also alcohol into acetic acid by determining its oxidation.

These are catalyses of combination.

The albuminoidal substances introduced into the stomach impregnate themselves there with gastric juice, expand, and in

1 Consult for further details, Wurtz, Philosophic Chimique, Ghimie nouvelle , etc. Naquet, article, Atomique ( Theorie) in the Encyclopedic Generale.

Chap. i.j

CONSTITUTION OF MATTER.

consequence the organic substance of the gastric juice achieves in these alimentary substances an isomeric modification, which renders them liquid, absorbable, in short, transforms them into albuminose. In the same way, under the influence of sulphuric acid diluted, cane-sugar, cellulose, gums, and fecules are metamorphosed first of all into dextrine, and then into glycose, or grapesugar.

These are isomeric catalyses.

The hippuric acid of the urines of herbivorous animals unfolds itself, under the influence of the mucous elements modified by the air, into hippuric acid and sugar of gelatine or glycocoll.

That is an unfolded catalysis.

In sum, the universe must be regarded as a whole composed of atoms dissimilar, and variously grouped according to their affinities. These active atoms are the foundation, the substance, the cause of all things : to use the expression of Tyndall, they are giants travestied.

The various aspects of bodies result from the various modes of aggregation of the constituent elements.

“ All the changes accomplished on the surface of the globe are due to combinations which are made or to combinations which are unmade.” 1

All chemical phenomena are consequently the expression of atomic combinations, and can .be included in four general types :

1. Simple change of molecular structure, or isomeria.

2. Unfolding of compound molecules.

3. Adjunction, addition of atoms, or of molecules not yet saturated, or, inversely, subtraction of atoms.

4. Substitution of certain atoms, certain molecules for others in a compound body.

These general characteristics manifestly exclude all ultimate, all radical difference between living organised bodies and

1 Dumas, Traite de Chimie , t. viii.

BIOLOGY.

[Book i.

inorganic bodies. Is there sufficient reason, however, for distinguishing between an inorganic world and an organic world? What are the dissimilar qualities of these two grand groups ? This is what we propose to examine in the following chapters.

[Note. — When in this chapter atoms are spoken of as full , it is in the sense of a 'plenum excluding a vacuum. — Translator.]

Chapter II. Anorganic Substances And Organic Substances

If, as results from the preceding exposition, the universe is a whole eternally unstable in form, eternally immutable in substance, it follows as a matter of course that living or organised bodies cannot be constituted of aught essentially special. An integrant part of the medium which environs them, they come forth from it only to return to it, and there is not an atom of their substance which does not participate of the eternity of universal matter, the basis of everything which exists. There is not one of these atoms which has not played an infinite number of parts in an infinity of organic and anorganic combinations, and which is not destined to play an infinite number more. Also, in analysing elementarily the most complex of animals, man, we, in normal conditions, find in him only fourteen simple bodies of mineral chemistry, the list of which is herewith given : —

Oxygen,

Hydrogen.

Azote,

Carbon,

Sulphur,

Phosphorus,

Fluor,

Chlorine,

Sodium,

Potassium,

Calcium, Magnesium, ^ Silicium,

Iron.

Moreover it must be stated that the mass of the human body is especially constituted of four of these "simple bodies, namely, azote, carbon, hydrogen, oxygen.

BIOLOGY.

[Book i.

If the results are accepted of elementary chemical analysis by decomposition, organised beings do not differ in substance from unorganised beings. But the analogy in substance does not exclude very important differences in form ; for we know that the properties of bodies are intimately related to their composition, to the mode of aggregation of the substances which constitute them.

Let us remark, in passing, that of the four simple bodies occupying the first place in the composition of the body of man and of the animals, there are two whose affinities of combination are neither strong nor numerous, and which have a certain degree of chemical inertia. Carbon, which is completely inert in ordinary temperatures, unites itself only to a small number of substances, and often by only a feeble bond. Nevertheless it largely blends with the constitution of plants, and occupies a very important place in the constitution of animals. Azote, more indifferent still than carbon, is found in large quantities in the vegetal kingdom, in quantities still larger in the animal kingdom. It is this very inertia shared, though in a less degree by a third element, hydrogen, which renders these bodies suitable to figure in the chemical constitution of living beings.1 In these beings, in effect, matter is in a state of extreme mobility ; it is subject to a perpetual movement of combination and decombination ; without repose, without truce, its elements go and come, have reciprocities of action, aggregate themselves, disaggregate themselves ; there is a real whirl of atoms, in the very midst of which fixed compounds, with chemical elements solidly cemented together, can only figure in a secondary fashion. Here are needed compounds unstable, of a great molecular mobility, capable of forming, disaggregating, metamorphosing, themselves, of renewing the woof of the living tissues.

At the very outset the ternary compounds non-azotised, the aggregates of hydrogen, of oxygen, and of carbon, that is to say, the fixed oils, the fats, the gums, the starches, the resins, the sugars, and so on, the constituent principles of plants and 1 See H. Spencer, The Principles of Biology , vol. i.

Chap. ii.J ANORGANIC AND ORGANIC SUBSTANCES

animals possess a great inertia and a notable instability ; often they are susceptible of isomeria (sugars, dextrine, and the like).

As regards the more complex compounds, those in which carbon, hydrogen, azote, sulphur, phosphorus ally themselves to form the substances called albuminoidal, molecular instability is carried in them to the maximum ; the unfoldings, the isomeric modifications are effected with extreme facility. Further on we shall, in reference to nutrition and digestion, signalise the important isomeric modifications which transform the insoluble albuminoidal aliments into soluble substances. Let us call attention also, by the way, to the still more curious and typical metamorphoses which the various kinds of virus and miasma produce in the albuminoidal substances of living bodies. It deserves remark, besides, that these last substances, when once modified isomerically, possess the murderous property of transmitting by simple contact to sound organic substances the molecular alteration they have themselves undergone.

But, finally, we may observe that these actions of contact are not peculiar to organic substances. They have, like the isomeric phenomena, their analogues in the chemistry called anorganical. In effect there is no radical difference, no abruptly settled frontier between organic chemistry and inorganic chemistry. The two kinds of chemistry study the same elementary bodies which are subject to the same laws. Organic substances proceed from anorganic substances, and return to them incessantly, to come forth from them anew. For the most part we merely find in organic substances greater complexity and instability. Also we see modern chemistry striving more and more to pluck from living bodies the monopoly of the fabrication of substances called organic.

Moreover, if we place in a graduated series the mineral and organic compounds, we discover between the two classes transitory groups, forming a point of union : these are the carburets of hydrogen, the alcohols, the ethers, ternary acids, fat bodies, the synthesis of which the chemist is now able to accomplish. Neither is there anything inalienable or special in the composition of organic

BIOLOGY.

[Book i.

products. We can succeed in substituting magnesia for lime in the shells of eggs. We can, in fats, replace hydrogen by chlorine, without modifying essentially the properties of the compound. Chemical synthesis has also tried to reproduce the simplest of the azotic organic substances. There has been a direct reproduction of urea, of taurine, of glycocoll in the laboratory ; and if the true albuminoidal bodies have hitherto defied the efforts of synthetic chemistry, we may almost with certainty predict that they will not defy them always. It will then be possible to appropriate direct from the mineral world fibrine, albumine, caseine, and so on, that is to say, the special, the most needful aliments of man. This grand discovery must inaugurate for civilised communities a new era. It must be for man a real enfranchisement, by diminishing in a prodigious measure the sum of muscular labour, to which for more or less duration and progression he is now doomed.