The Story of the Living Machine, by H. W. Conn pptx

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Title: The Story of the Living Machine

A Review of the Conclusions of Modern Biology in Regard

to the Mechanism Which Controls the

A REVIEW OF THE CONCLUSIONS OF MODERN BIOLOGY IN

REGARD TO THE

MECHANISM WHICH CONTROLS THE

PHENOMENA OF LIVING

ACTIVITY BY

H.W CONN

PROFESSOR OF BIOLOGY IN WESLEYAN UNIVERSITY

AUTHOR OF THE STORY OF GERM LIFE, EVOLUTION OF TO-DAY, THE LIVING WORLD, ETC.

WITH FIFTY ILLUSTRATIONS

NEW YORK D APPLETON AND

COMPANY 1903Copyright, 1899,

By D APPLETON AND COMPANY

That the living body is a machine is astatement that is frequently made withoutany very accurate idea as to what itmeans On the one hand it is made with abelief that a strict comparison can bemade between the body and an ordinary,artificial machine, and that living beingsare thus reduced to simple mechanisms; onthe other hand it is made loosely, withoutany special thought as to its significance,and certainly with no conception that itreduces life to a mechanism Theconclusion that the living body is amachine, involving as it does amechanical conception of life, is one of

most extreme philosophical importance,and no one interested in the philosophicalconception of nature can fail to have aninterest in this problem of the strictaccuracy of the statement that the body is amachine Doubtless the complete story ofthe living machine can not yet be told; butthe studies of the last fifty years havebrought us so far along the road toward itscompletion that a review of the progressmade and a glance at the yet unexploredrealms and unanswered questions will beprofitable For this purpose this work isdesigned, with the hope that it may give aclear idea of the trend of recent biologicalscience and of the advances made towardthe solution of the problem of life.

Middletown, Conn., U.S.A

October 1, 1898.

PREFACE.

LIST OF ILLUSTRATIONS THE STORY OF THE LIVING MACHINE.

NEW EDITION OF HUXLEY'S

ESSAYS.

BOOKS FOR NATURE LOVERS.

introduction—Biology a new science—

Historicalbiology—Conservation of energy—Evolution—Cytology—New

aspects of biology—The mechanicalnature of living organisms—Significance

of the newbiological problems—Outline of the

subject 1

PART I

THE RUNNING OF THE LIVING

CHAPTER I

IS THE BODY A MACHINE?

What is a machine?—A generalcomparison of a body and

a machine—Details of the action of the

machine—Physical

explanation of the chief vital functions—

Theliving body is a machine—The living

machineconstructive as well as destructive—The

vital factor 19

CHAPTER II

THE CELL AND PROTOPLASM.

Vital properties—The discovery of cells

—The cell doctrine—The

cell—The cellular structure of organisms

—Thecell wall—Protoplasm—The reign of

protoplasm—Thedecline of the reign of protoplasm—Thestructure of protoplasm—The nucleus—

activities as

of these sources of history—Forces at

work inthe building of the living machine—Reproduction—Heredity—Variation—Inheritance of variations—Method ofmachine building—Migration andisolation—Direct influence ofenvironment—Consciousness—Summary

of Nature's power of building machines—

The origin of the cell

machine—General summary 131

LIST OF ILLUSTRATIONS.

A_bit_of_bark_showing_cellular_structure

Successive_stages_in_the_division_of_the_developing_eggA_typical_cell

Cells_at_a_root_tip

Section_of_a_leaf_showing_cells_of_different_shapes

Two_stages_in_cell_division

The_arm_of_a_bird

The_arm_of_an_ancient_half-bird_half-reptile_animal

Diagram_to_illustrate_the_principle_of_heredity

THE STORY OF THE LIVING MACHINE.

INTRODUCTION.

Biology a New Science.—In recent yearsbiology has been spoken of as a newscience Thirty years ago departments ofbiology were practically unknown ineducational institutions To-day none ofour higher institutions of learningconsiders itself equipped without such adepartment This seems to be somewhatstrange Biology is simply the study ofliving things; and living nature has been

studied as long as mankind has studiedanything Even Aristotle, four hundredyears before Christ, classified livingthings From this foundation down throughthe centuries living phenomena havereceived constant attention Recentcenturies have paid more attention toliving things than to any other objects innature Linnæus erected his systems ofclassification before modern chemistrycame into existence; the systematic study

of zoology antedated that of physics; andlong before geology had been conceived

in its modern form, the animal andvegetable kingdoms had beencomprehended in a scientific system.How, then, can biology be called a newscience When it is older than all theothers?

There must be some reason why this, theoldest of all, has been recently called a

new science, and some explanation of the

fact that it has only recently advanced toform a distinct department in oureducational system The reason is notdifficult to find Biology is a new science,not because the objects it studies are new,but because it has adopted a new relation

to those objects and is studying them from

a new standpoint Animals and plants havebeen studied long enough, but not as wenow study them Perhaps the new attitudeadopted toward living nature may betersely expressed by saying that in the past

it has been studied as at rest, while to-day

it is studied as in motion The older

zoologists and botanists confinedthemselves largely to the study of animals

and plants simply as so many museumspecimens to be arranged on shelves withappropriate names The modern biologist

is studying these same objects as intenselyactive beings and as parts of an ever-changing history To the student of naturalhistory fifty years ago, animals and plants

were objects to be classified; to the

biologist of to-day, they are objects to be

explained.

To understand this new attitude, a briefreview of the history of the fundamentalfeatures of philosophical thought will benecessary When, long ago, man began tothink upon the phenomena of nature, hewas able to understand almost nothing Inhis inability to comprehend the activitiesgoing on around him he came to regard the

forces of nature as manifestations of somesupernatural beings This was eminentlynatural He had a direct consciousness ofhis own power to act, and it was naturalfor him to assume that the activities going

on around him were caused by similarpowers on the part of some being likehimself, only superior to him Thus hecame to fill the unseen universe with godscontrolling the forces of nature The windwas the breath of one god, and thelightning a bolt thrown from the hands ofanother

With advancing thought the ideas ofpolytheism later gave place to the noblerconception of monotheism But for a longtime yet the same ideas of thesupernatural, as related to the natural,

retained their place in man's philosophy.Those phenomena which he thought hecould understand were looked upon asnatural, while those which he could notunderstand were looked upon assupernatural, and as produced by thedirect personal activity of some divineagency As the centuries passed, and man'spower of observation became keener andhis thinking more logical, many of thehitherto mysterious phenomena becameintelligible and subject to simpleexplanations As fast as this occurredthese phenomena were unconsciouslytaken from the realm of the supernaturaland placed among natural phenomenawhich could be explained by natural laws.Among the first mysteries to be thuscomprehended by natural law were those

of astronomy The complicated and yetharmonious motions of the heavenlybodies had hitherto been inexplicable Toexplain them many a sublime conception

of almighty power had arisen, and thestudy of the heavenly bodies ever gaverise to the highest thoughts of Deity ButNewton's law of gravitation reduced thewhole to the greatest simplicity Throughthe law and force of gravitation thesemysteries were brought within the grasp ofhuman understanding They ceased to belooked upon as supernatural, and becamenatural phenomena as soon as the force ofgravitation was accepted as a part ofnature

In other branches of natural phenomena thesame history followed The forces and

laws of chemical affinity were formulatedand studied, and physical laws and forceswere comprehended As these naturalforces were grasped it became, little bylittle, evident that the various phenomena

of nature were simply the result of nature'sforces acting in accordance with nature'slaws Phenomena hitherto mysteriouswere one after another brought within therealm of law, and as this occurred asmaller and smaller portion of them wereleft within the realm of the so-calledsupernatural By the middle of this centurythis advance had reached a point wherescientists, at least, were ready to believethat nature's forces were all-powerful toaccount for nature's phenomena Sciencehad passed from the reign of mysticism tothe reign of law

But after chemistry and physics, with allthe forces that they could muster, hadexhausted their powers in explainingnatural phenomena, there apparentlyremained one class of facts which wasstill left in the realm of the supernaturaland the unexplained The phenomenaassociated with living things remainednearly as mysterious as ever Lifeappeared to be the most inexplicablephenomena of nature, and none of theforces and laws which had been foundsufficient to account for other departments

of nature appeared to have much influence

in rendering intelligible the phenomena oflife Living organisms appeared to beactuated by an entirely unique force Theirshapes and structure showed so manymarvellous adaptations to their

surroundings as to render it apparentlycertain that their adjustment must havebeen the result of some intelligentplanning, and not the outcome of blindforce Who could look upon the adaptation

of the eye to light without seeing in It theresult of intelligent design? Adaptation toconditions is seen in all animals andplants These organisms are evidentlycomplicated machines with their partsintricately adapted to each other and tosurrounding conditions Apart fromanimals and plants the only other similarlyadjusted machines are those which havebeen made by human intelligence; and theinference seemed to be clear that a similarintelligence was needed to account for the

living machine The blind action of

physical forces seemed inadequate Thus

the phenomena of life, which had beenstudied longer than any other phase ofnature, continued to stand aloof from therest and refused to fall into line with thegeneral drift of thought The living worldseemed to give no promise of beingincluded among natural phenomena, butstill persisted in retaining its supernaturalaspect.

It is the attempt to explain the phenomena

of the living world by the same kind ofnatural forces that have been adequate toaccount for other phenomena, that hascreated modern Biology So long asstudents simply studied animals and plants

as objects for classification, as museumobjects, or as objects which had beenstationary in the history of nature, so long

were they simply following along thesame lines in which their predecessorshad been travelling But when once theybegan to ask if living nature were notperhaps subject to an intelligentexplanation, to study living things as part

of a general history and to look upon them

as active moving objects whose motionand whose history might perhaps beaccounted for, then at once was created anew department of thought and a newscience inaugurated

Historical Geology.—Preparation hadbeen made for this new method of studyinglife by the formulation of a number ofimportant scientific discoveries.Prominent among these stood historicalgeology That the earth had left a record of

her history in the rocks in language plainenough to be read appears to have beenimpressed upon scientists in the last of thecentury That the earth has had a historyand that man could read it became moreand more thoroughly understood as thefirst decades of this century passed Thereading of that history proved a somewhatdifficult task It was written in a strangelanguage, and it required many years todiscover the key to the record But underthe influence of the writings of Lyell, justbefore the middle of the century, it began

to appear that the key to this language is to

be found by simply opening the eyes andobserving what is going on around us to-day A more extraordinary and moreimportant discovery has hardly ever beenmade, for it contained the foundation of

nearly all scientific discoveries whichhave been made since This discoveryproclaimed that an application of theforces still at work to-day on the earth'ssurface, but continued throughout longages, will furnish the interpretation of thehistory written in the rocks, and thus anexplanation of the history of the earthitself The slow elevation of the earth'scrust, such as is still going on to-day,would, if continued, produce mountains;and the washing away of the land by rainsand floods, such as we see all around us,would, if continued through the longcenturies, produce the valleys and gorgeswhich so astound us The explanation ofthe past is to be found in the present Butthis geological history told of a history oflife as well as a history of rocks The

history of the rocks has indeed been bound

up in the history of life, and no sooner did

it appear that the earth's crust has had areadable history than it appeared thatliving nature had a parallel history If thepresent is a key to the past in interpretinggeological history, should not the same betrue of this history of life? It wasinevitable that problems of life shouldcome to the front, and that the study of lifefrom the dynamical standpoint, rather than

a statical, should ensue Modern biologywas the child of historical geology

But historical geology alone could neverhave led to the dynamical phase of modernbiology Three other conceptions havecontributed in an even greater degree tothe development of this science

Conservation of Energy.—The first ofthese was the doctrine of conservation ofenergy and the correlation of forces Thisdoctrine is really quite simple, and may beoutlined as follows: In the universe, as weknow it, there exists a certain amount ofenergy or power of doing work Thisamount of energy can neither be increasednor decreased; energy can no more becreated or destroyed than matter It exists,however, in a variety of forms, which may

be either active or passive In the activestate it takes some form of motion Thevarious forces which we recognize innature—heat, light, electricity, chemism,etc.—are simply forms of motion, and thusforms of this energy These various types

of energy, being only expressions of theuniversal energy, are convertible into each

other in such a way that when onedisappears another appears A cannon ballflying through the air exhibits energy ofmotion; but it strikes an obstacle andstops The motion has apparently stopped,but an examination shows that this is notthe case The cannon ball and the object itstrikes have been heated, and thus themotion of the ball has simply beentransformed into a different form ofmotion, which we call heat Or, again, theheat set free under the locomotive boiler

is converted by machinery into the motion

of the locomotive By still differentmechanism it may be converted intoelectric force All forms of motion arereadily convertible into each other, andeach form in which energy appears is only

a phase of the total energy of nature

A second condition of energy is energy atrest, or potential energy A stone on theroof of a house is at rest, but by virtue ofits position it has a certain amount ofpotential energy, since, if dislodged, itwill fall to the ground, and thus developenergy of motion Moreover, it required toraise the stone to the roof the expenditure

of an amount of energy exactly equal tothat which will reappear if the stone isallowed to fall to the ground So in achemical molecule, like fat, there is astore of potential energy which may bemade active by simply breaking themolecule to pieces and setting it free Thisoccurs when the fat burns and the energy

is liberated as heat But it required atsome time the expenditure of an equalamount of energy to make the molecule

When the molecule of fat was built in theplant which produced it, there was used inits construction an amount of solar energyexactly equivalent to the energy whichmay be liberated by breaking the molecule

to pieces The total sum of the active andpotential energy in the universe is thus atall times the same

This magnificent conception has becomethe cornerstone of modern science Assoon as conceived it brought at oncewithin its grasp all forms of energy innature It is primarily a physical doctrine,and has been developed chiefly inconnection with the physical sciences But

it shows at once a possible connectionbetween living and non-living nature Theliving organism also exhibits motion and

heat, and, if the doctrine of theconservation of energy be true, this energymust be correlated with other forms ofenergy Here is a suggestion that the samelaws control the living and the non-livingworld; and a suspicion that if we can find

a natural explanation of the burning of apiece of coal and the motion of alocomotive, so, too, we may find a naturalexplanation of the motion of a livingmachine

Evolution—A second conception, whoseinfluence upon-the development ofbiology was even greater, was thedoctrine of evolution It is true that thedoctrine of evolution was no new doctrinewith the middle of this century, for it hadbeen conceived somewhat vaguely before

But until historical geology had beenformulated, and until the idea of the unity

of nature had dawned upon the minds ofscientists, the doctrine of evolution hadlittle significance It made little difference

in our philosophy whether the livingorganisms were regarded as independentcreations or as descended from eachother, so long as they were looked upon as

a distinct realm of nature withoutconnection with the rest of nature'sactivity If they are distinct from the rest ofnature, and therefore require a distinctorigin, it makes little difference whether

we looked upon that origin as a singleoriginating point or as thousands ofindependent creations But so soon as itappeared that the present condition of theearth's crust was formed by the action of

forces still in existence, and so soon as itappeared that the forces outside of livingforces, including astronomical, physicaland chemical forces, are all correlatedwith each other as parts of the same store

of energy, then the problem of the origin ofliving things assumed a new meaning.Living things became then a part of nature,and demanded to be included in the samegeneral category The reign of law, whichwas claiming that all nature's phenomenaare the result of natural rather thansupernatural powers, demanded someexplanation of the origin of living things.Consequently, when Darwin pointed out apossible way in which living phenomenacould thus be included in the realm ofnatural law, science was ready andanxious to receive his explanation