WONDERS ca ORGANIC LIFE. PHTILIADELPHIA: AMERICAN SUNDAY-SCHOOL UNION, NO. 146 CHESTNUT STREET. L ONDON: RELIGIOUS TRACT SOCIETY. NoTE. —The nAmerican Sunday-school Union have made an arrangement with the London Religious Tract Society, to publish, concurrently with them, such of their valuable works as are best suited to our circulation. In making the selection, reference will be had to the general utility of the volumes, and their sound moral tendency. They will occupy a distinct place on our catalogue, and will constitute a valuable addition to our stock of books for family and general reading. As they will be, substantially, reprints of the London edition, the credit of their general character will belong to our English brethren, and not to us; and we may add, that the republication of them, under our joint imprint, involves us in no responsibility beyond that of a judicious selection. We cheerfully avail ourselves of this arrangement for giving wider influence and value to the labours of a sister institution so catholic in its character and so efficient in its operations as the London Religious Tract Society. *Z- The present volume is issued under the above arrangement. CONTENTS. CHAPTER I. PAOa THE VITAL PRINCIPLE-THE BLOOD.~ ~. 5 CHAPTER II. THE PURIFICATION OF THE BLOOD.... 31 CHAPTER III. ORGANIC AND INORGANIC MATTER COMPARED. 64 CHAPTER IV. REPOSE, OR SLEEP... 9 CHAPTER V. HYBERNATION 9.... I,. 10 iv CONTENTS. CHAPTER VI. PAGE HYBERNATION OF BIRDS-TORPIDITY OF REPTILES. 128 CHAPTER VII. &ISTIVATION, OR SUMMER SLEEP.. 146 CHAPTER VIII. MIGRATION...,,,,153 WONDERS OF ORGANIC LIFE. CHAPTER I. THE VITAL PRINCIPLE-THE BLOOD. IN the consideration of organic beings, we must ever keep before us the great fact, that life is as much life in the monad or animalcule, as in the whale, the elephant, or the rhinoceros —that mass does not add intensity to vitality-that duration of existence is but an infinitesimal portion of time, whether it be counted by minutes or days, or measured by the revolutions of centuries. The elephant, and the ephemera; the banian tree of three thousand years, the sturdy oak, or churchyard yew, and the tender little annual that blooms and withers away, exist all and each according to prefixed laws; and when their extinction takes place, the time is as if it had never been. Startle not; for, 0 man! thou in. the midst of creation standest alone, the sole mighty exception. To thee time will not be as if it had 1 -'* v 6 WONDERS OF ORGANIC LIFE. never been; it is with thee the precursor of a momentous eternity. It has been often said, wherever life can be there life is. The minutest drop of water is to some beings an ample sea; everywhere around us, on the land, in the water, in the air, the results of the creative fiat are made manifest; and the number and diversity of organic beings overwhelm us with astonishment. The huge whales of the ocean present us with the largest of animal forms, and the giant trees of the intertropics with the most stupendous of vegetable productions; but, on the other hand, it has not been determined at what degree of minuteness a boundary is put to organization. The most powerful microscopes are limited in their sphere, yet they have opened to us domains of organic life, the existence of which without their aid would never have been suspected. By the term life, as we here use the word, we mean organized beings in contradistinction to inorganized matter, even in'a state of crystallization. It may, however, be asked in the outset, What do we understand by life in the abstract, that is, irrespective of organization? We shall answer the question as best we can —craving our reader's indulgence, if, in the explanation of subjects of an abstract nature, we are occasionally necessitated to employ language of a scientific character. Life, it must be admitted, prosecute our researches into it as we may, is a deep mystery. Setting man aside, we know not what any THE VITAL PRINCIPLE-THE BLOOD. 7 animal loses when it dies, nor what it had befobre it died; therefore we know not what death is, further than is made manifest to the senses of the living, and that is, a resolution of the frame into the elements around us-dust unto dust. But something once kept this dust together-galve it feelings, passions, and desires — rendered the assumption of nutritive particles imperative, and made reproduction a lawsuch was the fiat of creation. What, then, is this something? —this that makes the infant grow to manhood, the acorn rise into the oak-this that permits man to wither as the flower, and the oak to moulder into ruin. What, we repeat, is life? — or, if the reader like the term better —What is the vital principle? It is obviously either something or nothing; if something, it must be superadded to organization; if nothing, it must be a consequence of organization, and a mere aspect of matter under certain conditions or arrangements. But inert matter cannot vitalize itself, nor can any other than vitalized bodies produce or generate vitalized bodies. From vital organization alone, is vital organization transmitted. Turning for a solution of the difficulties which invest the subject to an examination of the phenomena of death, mystery is still found enshrouding it. The precise mode in which an animal dies we cannot tell; to say that it has ceased to breathe and to feel, is to say nothing-for these things are merely the consequences of death. We may kill by blood-shedding, or by strangu 8 WONDERS OF ORGANIC LIFE. lation, or by the infliction of agony; but even then, the question reverts-:-What has quitted the body, leaving it a prey to the opelrative influence of the laws of chemical dissolution? The whole subject, we are forced again to confess, is shrouded in mystery. This we know, that vitality and organization (a convenient term, if understood in its true sense) are ever associated-that when vitality becomes extinct, organization retains an aspect only, waiting for the laws of chemistry to do their office —and that living beings only can produce living successors. One thing is certain, that between living bodies and the laws of chemical affinity there is, as far as vitality is concerned, a great antagonism, for organic resolution without commensurate reparation is the consequence only of death. Nevertheless, at the same time that we urge this grand principle, we acknowledge that chemical actions are perpetually in operation inl all living bodies, but under the mystic laws of the vital energy. It must be at once apparent, then, that chemical operations or changes, however intricate, however precise, displayed by organic bodies, cannot be the original cause of vitality, nor yet be, in and of themselves, the vital principle. The same observation applies to that recondite agent which we term electricity, galvanic action, or electro-magnetism. No action in the organic living frame takes place without involving galvanic or electric changes. The nervous system is a wonderful galvanic apparatus, but life is TIHE VITAL PRINCIPLE-THE BLOOD. 9 here again a cause, not a consequence; the truly dead Ilerve, when vital warmth has left the body, ceases to respond to the experimental appliances of the physiological anatomist; the sheep, as is often to be seen, may, when just slaughtered, be made to start and struggle, and breathe forcibly, by means of the agency of electric currents skilfully thrown upon certain nerves. The frog, immediately killed, may be made to leap by similar means; but this galvanic irritability (not sensibility) of the nerves, and contractility of muscle, are merely the remains of a power implanted in them by some other principle, and are not inherent in the matter composing these organs; otherwise how could it be lost? This principle we call life, or vitality, terms expressive rather of our ignorance than of our knowledge. We have shown in a few words what life does, rathei than what life is. Let us see if Cuvier, one of the greatest physiological anatomists and philosophers of' any age, has done more. " If, in order," he says, " to obtain a just idea of the essence of life, we will consider it in beings wherein its effects are the most simple, we shall quickly perceive that it con — sists in the faculty which certain organic comnbinations possess of existing, during a certain length of time, and under a determinate form, whilst attracting continually into their composition a portion of surrounding matter, and restoring to the elements portions of their own constituent body. Life is a revolving vortex, 10 WONDERS OF ORGANIC LIFE. more or less rapid, more or less complicated, the direction of which is constant, and which ever draws in molecules of affinity; but at the same time into which individual molecules enter, and from which they are as continually thrown off, insomuch as that the form of a living body is more its essential, than is its constituent matter. As long as this movement subsists, the body in which it is in activity is living -it lives; as soon as the movement ceases for good, the body dies. After death the elements which compose it, rendered up to the ordinary affinities of chemistry, delay not to separate from each other, whence results more or less the dissolution of the body which has been once living. It was, then, by the vital movement that dissolution was restrained, and that the corporeal elements were for a space bound in union. " All living bodies die after a space of time, the extreme limit of which is determined for every species; and death appears to be a necessary effect of life, which, by its own action even, essentially alters the structure of the body in which it operates, so as to render its continuance impossible." Yet again, therefore, the question reverts-What is life, and wherefore should the frame be worn out by the vital actions of its own machinery? Cuvier tells what the results of vitality are, as far as we can appreciate them, but not what causes the ever-changing combinations, the attractions and repulsions which are perpetually going on THE VITAL PRINCIPLE —THE BLOOD. 11 in organic bodies. Life-we are once more forced to the conclusion-is a mystery; nor can we penetrate beyond the revelation which God whas made in the first chapter of the book of Genesis, wherein we learn only this, that living beings arose into existence in obedience to his word. In their Introduction to the French edition of Meckel's Comparative Anatomy, the translators (MM. Riester and Alph. Sanson) ask-"' The principle of life, is it anything more than a modification of the cause of electric forces?" We do not quite understand the meaning of the latter phrase; however, the writers state that this is far from being definitely settled, and then they go on to observe, "' that chemistry has revealed the primitive elements of organic bodies, and that microscopic observation has demonstrated the globular disposition as the essential form of the intimate structure of all tissues under the influence of life." We may here reiterate our observation, that although the vital phenomena may involve a perpetual play of galvanic or electro-galvanic changes and phases, and may agitate the nerves so as to render them efficient in the fulfilment of their multifarious offices, we have no reason thence to assume that the electric fluid under any aspect is identical with the vital principle.* * "Wherever there is organization and life there is also electric tension, or the play of the voltaic pile, as the experiments of Nobili and Alatteucci, and especially the latest admirable labours of Emil du Bois, teach us.'IThe last-named philosopher has succeeded in manifesting the presence of the 12 WONDERS OF ORGANIC LIFE. We read in the Scriptures, " The life of the flesh is in the blood," Lev. xvii. 1; and further on, " The life of all flesh is the blood thereof," v. 14. By this, without straining the point, we may infer that it is in the circulating fluid, blood, sanies, or juice, as the case may be, of all organic bodies, that the living principle exists. Blood is a living fluid, destined to repair the solid body, to afford materials for the building up of every tissue, bone, or muscle, and to recruit itself in a mysterious manner, by the conversion of nutriment into its own character, and by the action of the atmosphere or the water. The very nerves themselves are derived from the contributions afforded by the blood. If the heart ceases to act, we die; if the blood be drained to a certain extent from the system, we (lie; if its waste be not duly repaired, we languish and sink; if the refreshment of the blood, by respiration, be prevented, we die suffocated. Stop the circulation of a plant, ring the bark of a tree with the knife, and every part above fades, withers, and perishes. Some animals of the lower orders electric muscular current in living and wholly uninjured bodies. He shows that the human body, through the medium of a copper wire, can cause a magnetic needle at a distance to be deflected at pleasure, first in one, then in the opposite direction. I have witnessed these movements produced at pleasure, and have had the gratification of seeing thereby great and unexpected light thrown on phenomena, to which I had laboriously and hopefully devoted several years of my youth." —Hlzmboldt. W'ithin the last few years this interesting subject has received great attention, and many curious facts have been elicited, of physiological importance, but into which we cannot here fully enter. THE VITAL PRINCIPLE-THE BLOOD. 13 seem to consist of little else than a quantity of vital fluid. Of such are the large M3iedusce or jelly fish, which we see floating on the surface of the sea. They are composed of a most delicate cellular tissue, filled with fluid; and this being exhaled, as it often is, when individuals are thrown upon the shore, and exposed to the fervid rays of the sun, all that is left is a slight filmy shred, a few grains only in weight. It is evident that the vital principle, in an abstract sense, is beyond our research; we can only study it in its phenomena; we can only watch its effects and trace out its operations. The Scripture, as we have seen, declares that the " life of the flesh is in the blood." It will be interesting, therefore, without entering very abstrusely into the subject, to inquire as to the composition of this fluid, at least in the higher animals, and examine the mode in which its losses are recruited, and its refreshment effected; the more so, as in pursuing our inquiries it will become manifest that both chemical and galvanic changes or agencies are involved in the *phenomena connected with its waste and renewal. The blood of man or quadruped, when poured out from the arteries or veins, is a red viscid fluid, which, if suffered to remain for an hour or two at rest in a vessel, separates, on losing vitality, into two parts, one fluid, called sereAm, the other tolerably solid, called clot or crassamenhtum. Venous and arterial blood differ from each other in colour, the fobrmer being of 2 14 WONDERS OF ORGANIC LIFE. a dark modena-red, the latter of a bright scarlet. The specific gravity of venous blood is greater than that of arterial, and this appears to be owing to the carbon contained in the latter. The specific gravity of the blood, averaging 1050, (water being 1000,) is capable of increase or decrease, according to health and diet; and in the higher animals it always exceeds that of the lower. Its temperature is greater in birds than in any other warm-blooded animals. Tile separation of blood into serum and crassamentum is the result of its death, or perhaps the mode of its dying. During this process a peculiar odour is exhaled, in the form of a vapour, from which we turn away with aversion, and from which the ox instinctively recoils when forced into the slaughterhouse. The quantum amount of serum in proportion to the crassamlentum varies'in different animals, and ill the same animal, according to its condition and state of health. The serum is mrost abundant in small feeble animals, destitute of energy; small in quantity in animals of muscular vigour and ferocious habits. Its general colour is yellowish, often with a tinge of pale green; it is adhesive, and has a saline flavour. In its chemical composition it is essentially albumen, and coagulates by heat. At the temperature of 160~ it is converted into a substance similar in appearance and character to the white of a hard-boiled egg. This fluid albumen contains several earthy and neutral THE VITAL PRINCIPLE-THE BLOOD. 15 salts in a state of solution, such as bydrochloride of soda and potass, subcarbonate and phosphate of soda, sulphate of potass, phosphate of lime, magnesia, and iron, with subcarbonate of lime and magnesia. It also yields an oily and a crystallizable fatty matter. The crassamentum, on its separation from the serum, assumes the form of two layers, not, however, rigidly distinct from each other, but rather blending together. The upper layer appears in the fobrm of a yellowish white glaze, or tenacious skin, and on minute examination will be found to be moderately firml, tough, and elastic, and to consist of a vast number of minute threads or fibres, disposed in various directions, crossing and recrossing each other. From this circumstance it has received the expressive term of fibrin. Under microscopic analysis these fibres are precisely similar to those of a muscle when deprived of its enveloping membrane and its colouring matter. The fact is that the two are identical, for the basis of all muscles, and of the solid parts of the body generally, the bones excepted, consists of fibrin. It is the most important constituent of the blood; whatever other may be absent, this is invariably present in the blood of all animals which possess blood, whether coloured or colourless. Below the glaze of fibrin, which varies in thickness under influencing circumstances, we find a deep red mass, consisting of the colouring particles of the blood, which being of a greater specific gravity than fibrin, 16 WONDERS OF ORGANIC LIFE. have gradually subsided during the progress of coagulation. When examined under a mi-croscope of great power, this mass is found t, be composed of extremely minute corpuscles, varying in size ill different animals. These corpuscles are in the form of flattened discs, circular, oval, or elliptical, and surrounded by a mnost delicate envelope. According to Mir. Lister and Dr. Hodgkin, these red particles are solid flattened bodies, without any envelope. In the lower vertebrate animals, however, there is a distinct and permarnent capsule surrounding a nucleus. In the human subject these blooddiscs are circular, flattened, and rather concave on each side, with a rounded margin. Wollaston estimates them at the five-thousandth part of an inch in diameter; others, however, give different estimates of their admeasurement, and among them Hodgkin and Lister, who set down the size as three thousand. It would appear, however, that some variableness as to size in the blood-discs of the same clot is observable; hence, perhaps, arises the discordance in question. Within the last few years Mr. Gulliver has devoted great attention to this subject;* and it appears, from this gentleman's observations, that in the mammalia generally the blooddiscs are circular, but in some oval. In birds, reptiles, and fishes, their figure is either oval * We refer to the Med. Chir. Trans., vol. xxiii. Dublin Med. Press, Nov. 27, 1839. Annals of Nat. Hist., Dec. 1839. Il3nd. and Edin. Phil. Mag., 1839. Appendix to Gerber's Anatomy. The Proceeds. Zool. Soc. Lond. 1840 to 1846, etc. THE VITAL PRINCIPLE-THE BLOOD. 17 or elliptical; and in fishes they are larger than in any of the other vertebrate classes. It may be observed, that besides the red blood-corpuscles, pale globules present themselves under the microscope —globules of fibrin; and between these two there appears to be a sort of repulsion preventing their union, and thus maintaining the blood in a fluid state. But when drawn from the body, the blood soon coagulates, this self-repulsion ceasing, and cohesion between the corpuscles taking place. The red particles are composed of a substance resembling fibrin, to which the term globuline has been given; they contain a red colouring matter, called hcematosine, and a certain variable quantity of oxide of iron. While fronm the fibrin of the blood the muscles and general tissues of the body are formed, it would seem that the red corpuscles act the part of carriers of oxygen from one part of the system to another, and are thereby the active agents by which animal heat is kept up; and it is observable, that the greater the energy and activity of the animal, the greater is the proportion of this red matter, and also the elevation of the animal temperature. It is well known that there are many animals of a soft or gelatinous consistence, in whose structure no muscles or distinct muscular fibres can be detected, although they are capable of executing decided movements. In such cases it is very probable that motion is produced by changes in the state of the particles of fibrin, in 2* 18 WONDERS OF ORGANIC LIFE. their temporary approximation to each other, or in some alteration which we cannot appreciate, bat which enables them to perform the function of muscles. We have said that the coagulation of the blood is the result of its death, or the inode in which it parts with its vitality. But in the case of animals struck dead by lightning, the blood does not coagulate, the muscles do not become rigid, and decomposition rapidly ensues. Here the vitality of the blood is instantaneously destroyed; no space of time being allowed for it to exhibit the ordinary phenomena attending its gradual death. Of the changes which the blood undergoes in various diseases, or disturbances of the organic functions from unnumbered causes, it is not here our place to speak; our aim is solely to give an explanation of the composition of the vital fluid, of which many persons are ignorant. From the blood the system is nourished and repaired; perspiration and all the secretions tend to its decrease; hence it continually needs recruiting. This is effected by the reception and assimilation of matter which had once lived under an animal or vegetable form, and which having died is now to live again, but also again to die, and perchance enter into another condition of organization. The process termed digestion, by which the blood is recruited, remains to be briefly detailed. All animals do not crush, mince, or nmasticate'the food previously to transferring it to the stomach; reptiles and fishes swallow their prey whole, and the lower animals engulf THE VITAL.PRINCIPLE-THE BLOOD. 19 their victimns at once into their digestive cavity. Granivorous birds, also, swallow their food whole, but the carnivorous tear the flesh into strips or morsels, and swallow it. In the parrot, however, something like mastication is observable, the mobility of the mandibles of its beak enabling it thus to treat the food upon which it naturally subsists. The toucan, too, crushes and squeezes with its beak the unfortunate bird which it has seized before swallowing it, and this may be called a sort of mastication. Among mamlmalia, neither the dog or wolf, nor the lion or tiger, can be said to masticate their food; they rend the flesh into portions, which are bolted at once. The whales and grampuses, also, swallow their prey at once. On the other hand, in such animals as the horse, the ox, the sheep, the deer, and others, mastication is carefully performed, and their teeth are expressly fitted for a grinding action, the salivary glands, too, being large. Man, also, masticates, or ought to masticate his food; for this process, during which the food becomes of a due temperature, and is mixed with a certain portion of saliva, is requisite for its easy digestion. It is to the digestive process, as carried on in the human species, that we shall here confine our attention. In all other animals the process is essentially the same, and involves the agency of a chemical solvent. Tihe food crushed by the teeth, and mixed with saliva, is transferred to the stonmach, where it is maintained at the temperature of 1000 of Fahrenheit, and kept in ~)20 WONDERS OF ORGANIC LIFE. a state of gentle but almost unceasing agitation, by a peculiar motion of that organ, effected by its muscular fibres. This vermicular motion is termed peristaltic. The stomach, we may here observe, is divided into two portions, a cardiac portion, into which the gullet immediately leads; and a pyloric portion, which opens into the commenceiment of the alimentary canal. Now, the food when swallowed passes into the cardiac portion; and the stomach, which when unemployed is one undivided bag, or sacculus, as it is termed, contracts after the fashion of an hour-glass, by the action of the circular fibres of the muscular coat, thus forming two bags, or sacculi, by far the largest of which is the cardiac. Here the food awaits the dissolving influence of the gastric juice. At this juncture a remarkable change takes place in the lining membrane of the stomach. When the stomach is empty, this membrane is of a pale pink colour; but now it becomes of a bright red colour, studded with innumerable minute lucid points, from which a pure limpid and colourless fluid distils, and mingling with the fbod effects its gradual solution. This fluid is the gastric juice, the true solvent of the food, and its action is entirely chenlical; as the food is dissolved, the reduced material is transmitted by means of the peristaltic action of the muscular coat of the stomach into the pyloric portion, where it accumulates. This solution of the food is in no respect analogous to that decomposition by putrefaction which would be effected by the agency THE VITAL PRINCIPLE-THE BLOOD. 21 of warlmth and moisture. It is a true chemical solution, and what is more, the gastric juice is highly antiseptic, and will immediately arrest the putrefactive process, even after it has advanced to a considerable extent. By a wise provision this solvent will not act upon the living stomach, but it will act upon the stomach after death; and many cases are on record in which the coats of the stomach have been more or less extensively eaten away, and the adjacent parts rendered soft and pulpy by its agency, a fict well known to the celebrated John Hunter. With regard to the nature of this fluid, there is now only one opinion-it is acid; this was clearly ascertained by Spallanzani. Dr. Prout was, we believe, the first to prove that this acid is the muriatic; his experiments have been confirmed by those of Tiedemann and Gmelin, and more recently by those of Braconnot and Blondelot; so that it may now be regarded as an established fact, that muriatic acid, or chlorine, (in a diluted state,) is the agent by which the solution of the food is effected. It is a remarkable fact, that if meat be enclosed in a glass tube with diluted muriatic acid, and kept at the temperature of the blood, it will be converted into a uniform semi-fluid mass, closely resembling that formed by the action of the gastric juice on food in the stomach, and which is termed chyme. The muriatic acid or chlorine, which is thus proved to be the essential ingredient of the 22 WONDERS OF ORGANIC LIFE. gastric juice, is with reason supposed to be derived by the secreting agency of minute glands from the common salt (muriate of soda, or more correctly, hydrochloride of sodium) contained in the blood. If this be the case, the salt must undergo a complete decomposition, and its metallic base, sodium, must enter into some new combination. The chyme into which the gastric juice has reduced the food is an acid semi-fluid, or pultaceous mass, usually of a greyish colour; it exhibits, however, some differences according to the nature of the food, both as to colour and consistence, but it is invariably acid. In this state it is gradually transmitted from the pylorus, through the pyloric orifice, into the commencing portion of the alimentary canal, termed the duodenum. Here it undergoes further changes. It becomes mixed with the mucous secretion of the canal, with the pancreatic juice, a fluid somewhat resembling saliva, and with bile poured drop by drop from a fine duct, which thus conveys the secretion of the liver to the duodenum. A singular transformation now begins to take place in the chyme; it gradually separates into two portions, namely, a whitish tenacious fluid, sometimes opaque, and of an alkaline quality, termed chyle, and a pultaceous residuary portion. The chyle is that portion of the food which is destined to become blood; the remainder is useless. By means of the peristaltic action of the small intestines, both the chyle and the resi THE VITAL PRINCIPLE-THE BLOOD. 23 duary matter are gradually carried forwards; the progress of the former is peculiarly slow, for it adheres from its tenacity to the villi (or velvet-like pile) of the inner coat of the intestine, and is, moreover, obstructed by certain valvular folds, termed valvulce conniventes. All this is by design, as it affords time for a system of vessels, termed lacteals, to absorb it. These lacteals, so called from the milky nature of the fluid they contain, commence by innumerable open mouths on the surface of the villi; they then pass through the coats of the intestine, and run through the layers of the mesentery, enter into the first series of mesenteric glands, in which they become extremely convoluted, and communicate freely with each other. After emerging from these glands, the chyliferous vessels continue their course between the layers of the mesentery, and enter a second series of glands, in which they again become convoluted. On freeing themselves from the second set of glands, they converge into a receptacle for the chyle, which constitutes the commencement of the thoracic duct. Here we must observe, that in this receptacle also terminate another set of vessels, termed absorbents, and also lymphatics, (from the colourless and pellucid fluid, or lymph, which they contain.) These absorbents arise from every portion of the frame, and are ever active in removing the materials of which it is composed, the minute arteries depositing fresh materials in their place, so that the body is in a perpetual process of change, by agencies 24 WONDERS OF (,RGANIC LIFE. within itself. The absorbents or lymphatics, as we have said, enter the receptacle for the chyle, and the lymph and chyle become mingled together. The tboracic duct, in its course upwards, receives other lymphatic vessels, the contents of which also mingle with the chyle, and are poured into the venous blood near the heart. This commixed fluid immediately passes into the right cavities of the heart, and is thence sent to travel through the minute vessels which ramify on the cellular tissue of the lungs. HIere the chyle undergoes its last conversionit becomes living arterial blood. What changes the chyle undergoes in the mesenteric glands is not understood, nor is the use of the pancreatic juice satisfactorily ascertained. According to Dr. Prout, this fluid contains albumen, and a curdy substance; it is slightly acid, and holds in solution matters of a saline nature. If the reader asks how the process which we have briefly detailed can turn particles of aliment, dead matter, into living blood, we canl only answer, that we do not know; we know that such is the process; the rest is shrouded in mystery. Here, perhaps, as a sequel to the general details which we have attempted to sketch, is the? most fitting place for some observations respecting a principle in the composition of animal and vegetable organization, and which exists alike in albumen, casein, (cheese,) horn, aninal fibrin, and vegetable fibrin, discovered in 1838 by MBulder, the Dutch chemist, who THE VITAL PRINCIPLE-THE BLOOD. 25 gave to it the term of protein, (from the Greek irpoTFVo, proteu5, I take the first place,) because he regarded it as the basis of all the other substances, or living tissues. In the same year' professor Schleiden, of Jena, " gave the results of his researches on the formation of the cells in plants, and pointed out the existence of a nucleus, or cell bud, from which each cell originated. This nucleus, accordingto Schleiden, is always composed of protein; so that it would appear that the protein is the earliest formed of vegetable substances, and is the seat of that residual power which, in the absence of any intimate knowledge of its nature, is called vitality." Protein is composed of carbon forty — eight parts, hydrogen thirty-six, nitrogen, or azote, six, and oxygen fourteen; but there appears to be some diversity of opinion as to the exact proportions of each of these primlaryelements; at the same time, whether this substance be obtained from animal or vegetable matters, analysis proves that very little difference of elementary composition is in either case to be detected. When either albumen or casein, horn, or animal or vegetable fibrin, is dissolved. in a solution of potass, and this solution, after filtration, is mixed with a slight excess of acid, a greyish white flocculent precipitate is abundantly formed, and a slight smell of hydrosulphuric acid is perceived. This flocculent substance is protein. It exhibits the following properties:-The white flocculi, while moist,. are seli-transparent, but on being dried they 3 Y26 WONDERS OF ORGANIC LIFE. become yellowish, hard, and brittle. Protein is inodorous and tasteless; it absorbs moisture -rapidly from the air, and loses water at 2120. It is insoluble in water, etther, alcohol, or in essential oils. Nevertheless, by long-continued %ooiling in water, it undergoes some change of properties, and is rendered soluble. Protein is, however, dissolved by acetic and phosphoric acids, and also by hydrochloric acid, the solu~tion in this case having a tint of indigo, which changes to black when subjected to heat.'Under the action of concentrated sulphuric acid it produces a jelly, which contracts in *water; and this jelly, after being washed in'water and alcohol, retains a minute portion of acid, though not sufficient to redden litmuspaper. Mulder calls this compound sulphoproteic acid. When protein is boiled in dilute sulphuric acid, it acquires a purple tint. Protein, then, is the essential nutriment which -animals derive from plants or grain, or from other animals. It constitutes, moreove.r, the'basis of albumen, fibrin, casein, etc., substances which differ both from their base, and from each other, in many of their physical properties. For example, albumen is soluble in water; not so, however, fibrin and casein. Albumen coagulates under the influence of heat'; whereas fibrin spontaneously coagulates from the fluids in which it is held in solution, while casein is only precipitated from its solutions by dilute acids, and nmay be re-dissolved by excess of the same acids. These three bodies, thus dif THE VITAL PRINCIPLE —THE BLOOD. 27 fering from one another, and from their basis protein, are found to present the above chemical diversities; not because any such are exhibited by tile protein, their great organic constituent, but because they vary in the quantity of their inorganic constituents, such as sulphur, phosphorus, sodium, chlorine, calcium, etc., mineral elements which are not contained in pure protein. It would thus seem that the varying quantities of these inorganic materials, in albumen, fibrin, and casein, are the influential causes of their respective physical qualities. We have said that chyme is acid, and the chyle alkaline; and we have stated that from the salt of the blood, chlorine, or muriatic acid, is disengaged, as Dr. Prout supposes, by the imlnediate agency of galvanism; for lie regards the principal digestive organs as a kind of galvanic apparatus, of which the mucous membrane of the stomach may be considered as the acid, or positive pole; while the liver, or hepatic system, mnay, on the same view, be considered as the alkaline, or negative pole; and he is of opinion that the greater part of the soda remaining in the blood, after the disengagement of the acid, is probably directed to the liver, and is elicited with bile in the duodenum, where it is again brought into union with the acid which had been previously separated from it. This view " illustrates the importance of common salt in the animal economy, and seems to explain in a satisfactory manner that 28 WONDERS OF ORGANIC LIFE. instinctive craving after this substance which is shown by' all animals." The great object of the digestive apparatus, as we have shown, is to prepare chyle from aliment, the general character and composition of which remains always the same. The stomach, therefore, is endowed with the power of securing this uniformity of composition, by an appropriate action upon the materials subjected to it. With respect to albuminous and oleaginous principles, the chief materials from which the chyle is formed, they require to undergo but little change in order to be fitted for reception into the system. But the saccharine class of aliments, as sugar, honey, starch, arrow-root, (composed of carbon and water,) which, excepting in purely carnivorous animals, enter largely into the food of mammalia and birds, are by no means adapted for such speedy assimilation. They have to undergo a chemical change, and become converted either into albuminous or oleaginous principles, and the stomach is a self-regulating apparatus, in which this conversion is affected. In the conversion of chyme into chyle, the pancreatic juice and the bile exert a decided influence. The chemical composition of the latter is very complex; it contains a peculiar resin, fat, or colouring principle, soda, salts of soda, mucus, and azotized animal substances, picromel, ozmazome, and cholic acid. Bile has the property of dissolving fht; and its bitter resin, which is highly stimulant and antiseptic, excites the secretion THE VITAL PRINCIPLE-THE BLOOD. 29 of the mucous membranes. True chyle cannot be formed without its agency; its constituents for the most part contain a large portion of carbon and hydrogen, which are obtained from the blood. Hence, while the lile is essential to the process of digestion, its elimination is one of the means for maintaining the purity of the blood. It is from venous blood, in minute vessels, termed venous capillary vessels, that bile is secreted, and it is the only known true secretion which is derived from this source, at least as far as the higher animals are concerned. Such, then, are some of the discoveries relative to life and its processes which science has effected. Very limited, however, at the best, are the researches of human philosophy. Thoughtless men have sometimes objected to mysteries in the revealed word of God; but how much greater are those which exist in that department of the natural world to which our attention has just been directed! In it mysteries meet us at every turn. The phenomena of feeling, muscular motion, the antagonism between living bodies and the ordinary laws of chemistry, the conversion of food into blood, and the never-ceasing round of change which takes place in the body itself, are all so many mysteries. In the sight of God, then, let us be clothed with humility, and thankfully receive that revelation of his will which he has given us-a revelation in which he has made the way of redemption so clear that " the wayfaring men, 3* o30 WONDERS OF ORGANIC LIFE. though fools, shall not err therein." Science may be too deep for us; learning may be beyond our reach; brilliancy of intellect may be denied to us: but the truth that " God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life," is adapted to the capacity of all, from that of the lofty philosopher down to the humblest peasant. Here the sage finds himself on a level with the cottager. THE PURIFICATION OF THE BLOOD, ETC. 31 CHAPTER II. THE PURIFICATION OF THE BLOOD, ETC. WHILE the blood suffers exhaustion in consequence of the demands of the system, it at the same time becomes vitiated, and requires purification; and this process is effected by the organs of excretion, namely, by the skin, the lungs, and the kidneys. These remove from the blood its vitiated particles, which, if retained, would soon induce disease. The suppression of any excretion is very dangerous; that of the lungs becomes speedily fatal, for in the latter case the carbon of the venous blood poisons the whole mass of the circulating fluid; the brain dies; the heart struggles feebly for a few minutes, and then ceases, and all the blood will be found to be black. If the excretion of the kidneys be suppressed, urea accumulates in the blood, fever supervenes, and coma and death follow. Let the secretion of bile in the liver be arrested, the same fatal result ensues; let its due excretion be prevented by any obstruction in the bile-duct, and disease, lanIguor, incapability both of mental and bodily exertion, and indifetrence 32 WONDERS OF ORGANIC LIFE. to everything, are the result. Again, let the insensible perspiration of the skin be checked, or suspended, and how soon the lungs and internal organs generally begin to sufflr, and congestion or inflammation takes place. Let the excretion of the mucous membranes become greatly diminished, and manifold are the diseases which immediately supervene. It is, however, to that purifying process in the lungs by which dark carbonized venous blood is converted into bright red arterial blood, that we would here more especially advert. This process is respiration. In animals with lungs, respiration consists of two acts, inspiration (performed in tortoises and frogs by a sort of deglutition) and expiration. Without entering minutely into the structure of the lungs, we mnay state that the bronchial tubes, or branches of the windpipe, pass gradually into a collection of minute vesicles, -consisting of exquisitely fine membranes, over which the capillary branches of the pulmonary artery ramify; and that these membranes and capillary branches are permeable by air, which is brought into immediate contact with the blood. The pulmonary artery brings dark venous blood from the right side of the heart (the right ventricle) to the lungs; the pulmonary veins convey the purified blood from the lungs to the left side of the heart, (the left auricle, whence it passes into the left ventricle,) from which it is sent through all the arteries of the system. At each act of inspiration, as the air rushes THE PURIFICATION OF THE BLOOD, ETC. 33 into, and distends the lungs, they receive a tide of blood which fills all the capillary branches of the pulnlonary artery spread over the walls of the thin air vesicles, and the air and the blood are thus brought into contact, and its purification is effected. At each expiration, the expansion of the lungs is greatly diminished, and a tide of blood, now arterial, and received by venous capillaries from the capillaries of the pulmonary artery, is propelled along the pulmonary veins to the left, side of the heart. The quantity of air received into the lungs during ordinary inspiration is perhaps little more than a pint each time, but it may be increased naturally and without effort to two pints and a half. It must be remembered, however, that the lungs are never, in their natural state, exhausted of air, nor can any effort of expiration utterly exhaust them; when, however, this is effected as far as possible, and followed by as forcible an inspiration as possible, a quantity of air, varying from five to seven pints, will be received. Upwards of nine pints have been so received, but this is beyond the average. About two ounces (by weight) of blood are received by the heart at each dilatation of the auricles respectively, and the same quantity is expelled fiom it at each contraction of the ventricles; consequently, as the heart dilates and contracts four times to one respiration, or seventy-two times on the average in a minutes it sends every minute 144 ounces to the lungs, which in the same space receive about eighteen 4 WWONDERS OF ORGANIC LIFE. pints of air, in addition to ten or twelve pints constantly in the vesicles. The blood is estimated to perform three complete circuits through the body every eight minutes of time, and the average quantity of blood in the body, in health, is reckoned to be 384 ounces, or twenty-four pounds avoirdupois, being nearly twenty imperial pints. We have now to ascertain the result of the action of the air upon the blood, and of the blood upon the air; and in following out this subject we shall see how the laws of chemistry are carried out, under the governance of a vital principle. Oxygen is the great agent in rendering the blood, whatever be the character of that blood, fitted fo)r the purposes of the animal economy. No animal, whether it respires air or water, whether it is furnished with lungs or gills, or vibratile cilia, or whether the external surface alone acts as a respiratory organ, can live, unless a certain portion of oxygen be present in the fluid, whether air or water, which it respires. Every other gas in a pure state, such as azote or nitrogen, and hydrogen, and also carbonic acid gas, soon destroys the life of an animal forced by way of experiment to inhale it. Pure oxygen alone, although it will support life for a considerable period, is, when unmixed, too great, a stimulant, and tends to exhaust the vital energies; oxygen must be diluted with azote; and of such is the atmosphere of our globe'composed, with certain non-essentials, as carbonic acid, vapour, and exhalations from THE PURIFICATION OF THE BLOOD, ETC. 35 animal, vegetable, and mineral bodies. The water of the ocean, or of rivers, or of lakes, is by the atmospheric pressure replete with air, -and is moreover composed of oxygen and hydrogen. Of one million of cubic inches of pure air, the weight of the oxygen is 71,809'3, of azote 238,307'7, total 310,117'0. Oxygen, then, is *the food of life, and every animal destroys vast:quantities of this fo6d, insomuch that if the great vegetable kingdom did not produce oxygen, and fix carbonic acid, the atmosphere itself would in due time be incapable of sustain-.ing life. As a proof of this, we may state that if any air-breathing animal, especially quadruped or bird, (for lower animals do not consume oxygen so rapidly,) be placed in a vessel of atmospheric air, so sealed up as to prevent all ~communication with the circumambient atmosphere, the animal, after a given lapse of time, perishes, and the oxygen of the air in which it was confined will be found exchanged for carbonic acid. This leads us to the point in hand. The.venous blood, having passed through the arterial system, and fulfilled the demands of that system, becomes replete with carbon, the presence of,which renders it unfit for the purposes of life. Whence it acquired this carbon, or carbonic acid, is not very clear. " Some observations lately made," says Dr. Prout, "have induced us to believe that the conversion of albuminous matters into gelatine is one great source of the carbonic acid in venous blood. Gelatine contains three or ;36 WONDERnS OF ORGANIC LIFE. four per cent. less of carbon than albumen contains. Now gelatine enters into the structure of every part of the animal frame, and especially of the skin; the skin, indeed, consists of little else besides gelatine. It is most probable,'therefore, that a large portion of the carbonic acid of venous blood is fornmedin the skin and in the analogous textures. Indeed, we know that the skin of many animals gives off carbonic acid, and absorbs oxygen; or, in, other words, performs all the offices of the- lungs; a function of the skin perfectly intelligible, on the supposition that near the surface of the body the albuminous portions of the blood are always converted into gelatine." It is- the presence of carbonic acid that gives darkness of colour to the venous blood, and on the removal of this it resumes its hue of scarlet. Carbonic acid is composed of pure carbon and oxygen, but the oxygen is not in a maximum proportion;a and it has been demonstrated that between oxygen and carbonic acid a very powerful attraction exists. When, therefore, the atmospheric air is admitted into the lungs, the oxygen of that air unites with the carbonic acid of the blood, and, as experiments prove, is expired in the form of a gas, which will render lime-water turbid, and cause a precipitate of carbonate of lime. Thus freed from carbon, the blood becomes scarlet or vermilion, a colour due to the action of the salts it contains on the blocd discs. It would appear, however, that the blood retains in itself a portion of pure oxygen, THE PURIFICATION OF THE BLOOD, ETC. 37 perhaps to become combined with carbon during its progress through the system. According to the experiments of Dr. Prout, the generation and expiration of carbonic acid gas vary according to different conditions of the system, and also according to the hours of the day. For example, the lungs give out more carbonic acid during those of sunlight than those of darkness. The increase commences at daybreak, and at noon arrives at its maximum, decreasing as the shades of evening approach. With respect to the azote of the atmospheric air, it is returned unchanged, but generally diminished in volume, a portion of it having been absorbed into the system. With the carbonic acid and azote expired from the lungs, a large quantity of watery vapour is also thrown off, which appears, in a great measure, to be derived from the chyle which has recently been admitted into the venous system, and to constitute a means of its perfect purification. It is thus that the essential oil of various substances taken as aliment, and useless to the blood, although mixed with the chyle, is thrown out. For example, onions, garlic, rum, etc., impart their peculiar odour to the breath, and in indigestion, and during various diseases, the blood becoming loaded with deleterious particles, really poisonous, thus gets rid of them by a self-purifying process. The quantity of carbon thrown off from the lungs of a man during the twenty-four hours of the total day, has been estimated at about eleven ounces-a quantity, 4 WONDERS OF ORGANIC LIFE.:as Dr. Prout observes, more than equal to that,contained in six pounds of beef. Nor can the;generation of this quantity be easily accounted!for, even on the supposition that it is owing to the conversion of albuminous matters into gelatine. A wide field of experiment is here open;