Science teachings in living nature : a popular introduction to the study of physiological chemistry and sanitary science

Introduction

The present is, especially, an age of enquiry, for we do not now rest content with mere assertions, but accept them only when actually proved. How vast is the field of nature, and how immense, therefore, must be the domain of science ! As in nature there are man)^ different parts combined, or running closely together, to form an immense whole, so no particular science can fully explain the vast range of creation ; and just as the light of the sun consists of several different lights combined, and as this combination is most suitable for the promotion of the various functions in the living section of nature, so the light which best enables us to explain the working of the universe, is composed not only of the light of one science, but of the radiations from all sciences combined.

“ One science only will one genius fit,

So vast is art, so narrow human wit.”

Notwithstanding the remark of a recent writer, who says — “ We are staggered by the great shouting of men of science, who place a scientific above every other kind of education,” it must be acknowledged that science is the only real foundation for true knowledge. The laws of nature are discovered by science, while art applies

Vlll hib'odtiction.

them to useful purposes, and thus enlarges her field. Art is, therefore (as probably all things are), dependant first upon nature, and then upon science as a medium. Whatever the pursuit, whether agricultural or manufacturing, Science is the driving wheel, put into place by Art, and turned by the hand of Nature.

Of all sciences, perhaps chemistry is the most important, and should, therefore, be the most familiar, for (as one separated from the rest) it would explain the most things with which we are generally connected ; and yet I believe the word chemistry is one which, to an ordinary person, frequently gives a very imperfect idea of that which it really represents. Instead of impressing him with its value, its general importance, and the connection which it bears to the many things, and phenomena occurring around us, it more frequently gives the idea of glass bottles up-side down ; bad smells ; explosives, which when touched destroy ; or noxious substances, that always mean mischief. -

A friend once said to me — “ Chemistry is dry — positively dry ; the words organic and inorganic, for instance, are words with very jarring sounds, and the whole science is composed of inharmonious language ; ” and, lest the well-known condemnation of those who have no music in themselves was presented as a fitting cap, to some extent the assertion may be admitted, but the argument is superficial and hardly worthy of note. It shows, however, what, I believe, is a very general idea in the minds of the general community, although chemistry is gradually becoming a subject in ordinary hitroduction.

IX school curriculum. Humboldt, in the great work of his declining years — Cosmos: a Sketch of a Physical Description of the Universe — says, “ I take pleasure in persuading myself that scientific subjects may be treated of in language at once dignified, grave, and animated, and that those who are restricted within the circumscribed limits of ordinary life, and have long remained strangers to an intimate communion with nature, may thus have opened to them one of the richest sources of enjoyment of which the mind is invigorated by the acquisition of new ideas. Communion with nature awakens within us perceptive faculties that had long lain dormant ; and we thus comprehend at a single glance the influence exercised by physical discoveries on the enlargement of the sphere of intellect, and perceive how a judicious application of mechanics, chemistry, and other sciences may be made conducive to national prosperity.”

Chemistry has a dictionary which is becoming more and more comprehensive : the words it contains convey appropriate meanings, and when combined form the foundation for a true knowledge of the processes continuall}^ going on in nature. Everything in earth, in air, or sea, belongs to chemistry, and is constantly working under her dictation, to promote those familiar changes which we all admire. The rock which darts from beneath ' its verdant covering ; the stream which dashes over the different coloured stones ; the trees which hang over the stream reflecting upon it the varied tints of foliage ; the bird singing its merry song upon its branches ; and the fish which sports in its natural element as it winds its

X

Introduction.

way round the shaded nook, are each dealt with by that science whose title conveys such a dark and gloomy impression. As it deals with the composition of the air, the water, the rock, and the trees in the landscape, so it deals with the composition of man. The brain of the wise, the muscle of the strong, the bone of the skeleton, and the complexion of the beauty, are explained by the necessary application of chemical science ; while the nature of the food which is taken to support them, the changes which it goes through before it does actually support them, and the decay after the life is separated from them by death, are explained by the same science.

“ On earth there is nothing great but man,” was the proud expression of the middle ages, and yet he is only a temporary being ; one which in death promotes the .same functions as the lowest creature he tramples beneath his feet. The degraded worm which crawls beneath the soil derives its substance from the eartfu; the offensive weed, or the cultivated plant that grows upon the earth, derives a necessary part of its structure directly from it ; while “ man, proud man,” is an ultimate conglomeration of earthly dust. Thus, Lucretius writes, that “ With good reason the earth has gotten the name of mother, since all things are produced out of the earth.”

The earth, the air, the ocean, and the living bodies which inhabit the earth, are popularly considered as distinct divisions of nature, but nature cannot be divided ; it is one immense system of mutual accommodation ;

Introditction.

XI they cannot exist separated, for one is absolutely dependent upon another for its existence. The plant, as it grows, acquires from the soil and the air those various particles which, when united, form its complete structure : man, as he lives, acquires from the plant those particles which go to form his structure, but nothing flourishes for ever, and, when he fades away into the dim vista of the past, his substance returns to the earth.

Man is unquestionably the highest organism, and has the powers of thought most fully developed, for " the highest degree of organisation gives the highest degree of thought,” but while possessing this advantage he is not independent, and cannot even say that the ephemeral insect lives without a purpose, since the humble creatures we so frequently despise are no doubt constructed to perform their part in nature. The many different forms of insects which crawl upon the earth, and which at first appear to us to deteriorate either the soil or the crop which grows upon it, may, on the other hand, be working out beneficial results ; they may, for instance, at a particular time in their lives, be destroying certain plants or weeds which we do not desire to cultivate, and when they have so performed their duty, birds or other forms of life may destroy them to give place to future generations, or they may die naturally and return their component parts directly to the soil. While we try to imagine the desolate appearance of the earth without *the beauty conveyed to it by the various and wonderful arrangements of colour which plant life

Xll

Introduction.

affords, and, as we notice its importance in the preparation of our food, let us not forget that it serves a most important purpose in the preparation of clothing for us. As the cotton plant forms a crop of cotton it purifies the air from noxious gases injurious to animal life. Wool is the product of animals fed solely upon plants. It may be truly said that from the earth each living body, whether plant or animal, comprises a step in the immense ladder of life that leads up to the highest form, which we ourselves comprise ; and, as everything sooner or later comes to an end, we must descend the ladder, not step by step, but by one stride, and return to the earth from which we were formed,

*

In the following pages I propose to consider the chemistry of life, though by no means in full, for that would be an undertaking difficult to accomplish, and far beyond my present purpose, but rather to demonstrate some of the more important facts connected with everj^day life, with which we should all be familiar, remembering that we are not independent units, but beings simply gifted with understanding, whose happiness largely depends upon the cultivation of it,

“ What is man,

If his chief good, and market of his time,

Be but to sleep and feed 1 A beast — no more.

Sure, He that made us with such large discourse.

Looking before and after, gave us not That capability and godlike reason To fust in us unused,”

W. H. W.

Braystones, near Whitehaven,

CHAPTER I. “You that seek what life is in death

Now find it air that once was breath.

New names unknown — old names gone :

Till time end bodies but souls none.”

Byron.

The origin of life, and the order in which its various forms have been observed upon the earth have been for long, and especially of late, the subject of much scientific enquiry and controversy, resulting in many different theories and speculations ; but with the almost general feeling that the absolute genesis of living matter is beyond human comprehension ; yet it is obviously impossible to say how far the mystery in which it is now obscured might be removed by scientific research ; for, in the words of Sir John Herschel, the character of the true philosopher is to hope all things not impossible, and to believe all things not unreasonable

In the chemistry of life, however, we have a more tangible foundation to work upon, and in its elementary study it offers a field as useful and interesting as does the primal origin of it. To the scientific enquirer the action of foreign substances on the phenomena of life affords a continuous range for experiment, while it is difficult to conceive any one uninterested in the causes

B

2 Sciejice Teachings in Living Nature.

and the effects of those actions upon which his own life depends.

The more common actions, and those which are of most interest to the ordinary observ^er, have now been pretty fully considered, and our knowledge may be said to be definite upon many of them, though on others there is much room for further investigation and proof. The facts at present known concerning living action have been obtained by the joint efforts of the physiologist and the chemist from very early times ; so, we must look forward for an extension of our knowledge to the same source, as Professor M'Kendrick remarked in his address to the British Association at Glasgow in 1876, thus : — “ The physiologist must go hand in hand with the chemist. The chemist in his laboratory preparing certain substances, and building up new compounds, by those wonderful synthetic processes which are now the glory of his science, while the physiologist investigates the action of these. By united work who can tell what may be accomplished.”

What are the characteristics of life 1

Firstly, the reproduction of all living bodies from previously existing living germs, so that Hamlet’s assertion that “ the sun breeds maggots in a dead dog,” — and that by Helmont, in 1662, that mice may be produced from saw-dust and an old shirt, have finally been rejected in favour of the conclusions arrived at by Redi in 1668. Although 210 years have elapsed since this Italian philosopher asserted that there could be “ no life without antecedent life,” yet many years passed before

The Origin of Life, c2fc.

this opinion became anything like popular ; and, indeed, quite recently the matter of “ spontaneous generation ” has been brought forward and advocated by Dr. Bastian, though well refuted by the experiments of Professor Tyndall and others. Redi’s opinions were based upon experiment, and he looked upon speculative ideas, or theories without experiment, as not allowable in scientific investigation. His crude experiment with reference to the subject of the generation of life was a most simple one, one which is -frequently performed in everyday life ; and although not now considered sufficient in itself to warrant a precise conclusion, yet in those days it was ; and fortunately the conclusion which Redi arrived at from it was one which is now generally accepted and confirmed by more accurate methods of research. He says, “ Here is a piece of dead flesh. I simply expose it to the air during the warm weather of summer, and in a few days a number of maggots are produced upon it. It would therefore appear that these are generated by dead flesh. But if I take a piece of meat, as before, and expose it to the same conditions, but cover it by very fine wire-gauze, the meat may become putrid, but not a single maggot will be produced. This proves that I have kept something away from the meat which was the cause of the map-ffots being produced in the first case.” Such was Redi’s method of experimenting and reasoning. The blowflies, whose olfactory nerves are evidently most acute, smell the meat, they go to it, and, if possible, deposit their eggs, which are the germs from which the

4 Science Teachmgs in Living N attire.

maggots are produced. Redi, finding these germs deposited upon his wire-gauze, came to the natural conclusion that they were what the gauze intercepted, and which produced the maggots in the first instance (when the meat was simply exposed to the air), and he infers from this experiment, and others similar to it, that there can be no development of life without life previously existing. From these experiments the covers made of wire-gauze, now so generally used for covering meat, were originated, which, although allowing the air free access to it, prevent those other conditions which hasten its decay.

Taking a rapid leap over many theories and experiments bearing upon this subject, from the time of Redi to the present, and coming to the experiments of recent years, what do we find as a result Practically the same conclusions. Over two hundred years ago, when Redi was busily engaged upon his researches into the origin of life, the appliances necessary for accurate experiments were not constructed. The microscope at that time was of a most elementary and inferior kind, so that while his experiments were necessarily upon those giant forms of life which we have just noticed, the microscope of the present day makes us familiar with those minute organisms which were then unknown, and of which there may even be many thousands in one single drop of water. Therefore, although Redi found that maggots were not produced in meat from which the flies were kept off by means of wire-gauze, we now find that although maggots are not produced, smaller

The Oi'igin of Life ^ (2fc.

forms of life are ; even in dead matter exposed to the air for a very short time. This fact by itself would lead us to reject Redi’s conclusion, and to believe in “ spontaneous generation,” i.e. the production of living bodies from lifeless matter ; but we have continued our investigations further. Dr. Bastian recently asserted that fungi may be produced from solutions containing only definite chemical compounds. Professor Tyndall’s reply to this may be taken also as a reason for the production of organisms in meat exposed to the air and apparently kept from everything else. He shows that the air contains minute living organisms, cells of both plants and animals, in immense numbers, and that the fungi produced in the “ solutions of chemical compounds ” are due to the intervention of these — for the organisms are destroyed by heat, or they may be filtered out of the air by passing it through such a substance as cottonwool, and when air, so purified, is alone allowed access to the solutions no living bodies are produced in them.

The name of Redi must ever stand most prominent in connection with the knowledge we possess of the development of living bodies, for he was the first who made it the subject of correct experiment, and upon his results the mass of work done in this direction up to the present day has been founded. It is not necessary to detail other arguments in connection with this subject, but to give it as the generally accepted opinion that one of the characteristics of living bodies is their reproduction only from living bodies previously existing.

Science Teachings in Living Nature.

Many diseases are spread by infection alone. This “ infection ” consists of living organisms which have the property of reproducing themselves to an enormous extent in the blood of human beings ; while we suppose, further, that each individual infectious disease is spread by a particular kind of germ, just as a particular kind of animal or plant is produced from a germ or seed of its own kind.

Secondly^ the germs from which all living bodies are produced are, in the first instance, minute ; but, by the property which they possess of appropriating and assimilating matter from without, they increase in size by the formation of various organs, and this possession of organs being a general feature in the existence of living bodies they are commonly designated organised bodies, and thus distinguished from those containing the same elements in the world of lifeless matter.

Thirdly, after a time they lose the power which they previously possessed of appropriating the substances which surround them ; their organised structures being gradually destroyed, while the combinations of the elementary substances of which they are composed are changed and become subject to the laws of inorganic chemistry. There are many other features by which bodies which are endowed with life may be distinguished from those which are not, but those already given are the more important ; so that we now pass on to the consideration of some of the differences to be observed between the two divisions of life — animal and vegetable. They are these : —

The Origin of Life, &c.

1. The food of plants consists of inorganic substances, such as carbonic acid, ammonia, and water ; while, on the contrary, that of animals consists of organic substances such as albumen, fibrin, fats, and starches, associated, as they are in nature, with small, though important, proportions of inorganic salts.

2. Plants contain considerable quantities of a substance called cellulose, while in animals this exact compound is only seldom found, and then in comparatively small quantities. It is the principal constituent of cotton fibre, and consists of Cg Hjg O5.

3. Plants are not provided with a nervous system, while animals, with the exception of the very lowest forms, are.

We cannot fail to notice, as we observe the things around us, that certain definite conditions are absolutely necessary for the continuance of life in its various forms, and that it is to the absence of one or more of such conditions that the end of life is due. There must be in every instance a fluid, capable of nourishing the body ; in constant circulation — a fluid containing the different substances requisite for the formation and sustenance of the various organs and tissues of the body. In the instance of animals such a fluid is called blood, and in plants it is called sap. The quantity and quality of this fluid is kept up by a supply of substances as food.

A constant supply of air is, as we all know, a necessary of life. If we “ hold our breath ” for a short time even, this is made painfully evident. It is not, however, so very generally remembered that air should be pure when breathed, and especially, free from organic putrescent matters, to which the “ close ” smell of the air in confined rooms is due. The nature and action of these will be described hereafter. To the air we breathe the blood is frequently exposed, by which various substances no longer of value are cast out of the body ; we are always more or less impure, and are thus constantly being purified. These impurities are evolved in the form of carbonic acid gas and watery vapour, from which plants derive much of their sustenance. The influence of plants on the atmosphere is, therefore, directly the opposite to that of animals, and it is owing to this important natural law that the atmosphere as a whole remains of one uniform composition — a composition which is more suitable than any other for the support of living bodies. This leads us to mention the fact that the actions involved in the respirations of plants and animals (but more especially plants) are considerably influenced by the external conditions, light and heat ; indeed, the chief nutritive functions of plant-life are only exercised under the influence of solar light.

Apart, then, from the value of this as a medium by which we are enabled to see, solar light is of the greatest importance to us from a physiological point of view, and it is therefore spoken of as the

“ Prime cheerer

Of all material things, first and best.”

Solar light, and that derived from the burning of

The Origin of Life, dfc.

gas, oil, or candles, must not be confounded. Light, as we have it direct from the sun, consists in reality of a number of different coloured lights (as they are seen in the rainbow), which, when combined, as they are, form a uniform white light. That derived from the burning of gas or oils is not so composed.

There are in the rainbow a number of different colours, which are separated from each other and made visible, but, so far as is at present known, it is only by one or two of these coloured lights that the nutritive functions of vegetation are promoted ; namely, by the blue and violet rays, which are those possessing chemical action. Although these particular rays are supposed to be alone necessary in promoting the important vital functions just named, yet it is necessary that they should be diluted as they are in the day-light ; so that if without action, the other rays are none the less important, and thus we have here one instance among many, of wonderful design in the whole of Nature’s works. Ordinary artificial illumination, which we are obliged to resort to occasionally, does not contain the chemically active rays. It is therefore of no value in the promotion of healthy vital action, and in point of fact, when living in a room artificially lighted, we are, as regards health, living almost in absolute darkness. From what has been said, it follows that the value of light in relation to life depends, up to a certain point, upon the amount of the blue and violet rays which it contains. Solar light contains the largest proportion of these rays in the spring. Physiologists tell us that tadpoles, although supplied with every other necessary of life except light, never become perfect frogs, and that people who live in dark rooms are more subject than others to nervous diseases. What is the effect of light upon the development of life } When decaying organic matter is infused in water, and the infusion set at rest for some time, minute animal bodies — animalculse — begin to make their appearance, and may be easily seen in the infusion by the aid of a microscope of ordinary power. If a part of such an infusion be poured into a glass and exposed to the light, and another part kept in the dark, it will be found, after exposure for a day or two, that w'hile that exposed to the light has developed a number of living bodies (than the motion of which nothing is more interesting when seen under the microscope), that kept in the dark has not. This shows that a longer time is necessary for the development of these living bodies in the dark than when exposed to the light.^

It has already been shown that daylight consists of different coloured lights combined together ; but it should be added, that although it is considered that the blue and violet rays are those which are important in relation to life, yet the precise action of these and the others have been by no means fully investigated. As regards their action upon plant-life, one or two points

^ It was shown, however, by Messrs. A. Downes and T. P. Blunt, in a paper read before the Royal Society on 6th December 1877, that light is prejudicial to the development of one of the lower forms of life called bacteria ; a few hours’ exposure to the daylight being in some instances sufficient to destroy the germs existing in an organic solution, while a similar solution kept in darkness developed bacteria freely.

have been made the subject of research by various experimenters, with the following general results : — ^

a. The luminous rays retard the germination of seeds,

b. The rays having chemical action, to some extent,

quicken germination.

c. Both the chemically active and the luminous rays

are essential to the formation of chlorophyll (the green colouring matter of plants).

d. The chemical rays and’ luminous rays, without

those affording heat, retard or prevent the development of the reproductive organs of plants.

e. The heat-giving rays facilitate the flowering of

plants and the development of their reproductive organs.

Corresponding experiments on animal life are, I believe, at present wanting ; but there is every reason to suppose that, to the lower forms, the results just given may be, to a certain extent, applicable.

With regard to heat as an external influence, its importance and effect are very evident from the increased vegetation in warm climates as compared with that in colder regions. In plants the sap ceases to perform its various functions under the influence of cold, and, as a result, leaves and other green herbage wither and decay ; thus the bloom of summer gives place to the decay of winter.

Without considerable w^armth no fruit or vegetable

would ripen ; the corn fields without the heat of summer would never produce that grandeur of colour we all so much admire ; the bird’s egg without the prolonged application of warmth would not produce the chicken ; while the breeze which aids in carrying the air, vitiated by animal life, to the forests of purification, and which produces to the delight of the angler a ripple on the clear country stream, is produced by variation of temperature at different parts of the atmosphere. The sun, which provides us with that life-sustaining agent, light, supplies at the same time the heat, which, when required, promotes the germination of the seed, or ripens the full ear of corn for the harvest. How wonderfully are they connected ! Artificially they can be separated, but the direct rays of the sun contain both, for they have mutual, though distinct, functions to perform.

The fireside in winter has a natural attraction for us when the cold is most severe, while even the sight of it has a pleasing effect.

Living bodies consist of a number of chemical substances, which have been derived from the atmosphere and the soil, but these substances, while forming part of living bodies, are more or less governed by living action — that is, they are not directly subject to the laws of ordinary chemistry as we understand them in the laboratory. There we can decompose and recompose substances almost as we desire ; taking, for instance, sulphur and oxygen, we can easily combine them together, getting as a result the corrosive oil of vitriol, or

The Origin of Life, dfc. 13

taking the metal copper we may unite it with oxygen to form the powdery oxide of copper, and finally this oxide of copper with oil of vitriol to form a neutral salt — sulphate of copper. But in our bodies substances

do not always, as in this case, associate themselves according to the laws of chemical affinity, for chemistry, as we understand it, is here the servant of a superior power which regulates it.^

When studying the composition of animals from a chemical point of view, the human body is naturally selected, as that most perfect of all organised structures, for our conclusions apply to the lower forms equally, and indeed to a great extent to plants. As various as the different forms of animal life are, the zoology of almost every species being different, yet the chemistry of them is peculiarly uniform, for our bodies comprise the same elements as those of the fishes of the sea, the birds of the air, or the insects which crawl upon the earth, so that man may truly say to the worm, “ Thou art my sister and my mother.” Strangely, again, the science of nutrition in each class is not widely different, and man, elevated by his position in the scale of life, is humbled as he compares his similarity to and depend-

^ I do not say that certain substances can only be formed by the inter\'entiou of vital force, which was an opinion held years gone by ; on the other hand, it is only reasonable to suppose that all organic chemical substances may be artificially prepared by synthesis, but I say that there is a certain power (of which we at present know very little) which modifies ordinary chemical action in the arrangement of our component parts, and prevents their mutual decomposition as it would occur when the same substances were mixed together independently of a living organism.