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W. T. (William Thompson) Sedgwick.

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AMERICAN SCIENCE SERIES



AN INTRODUCTION



TO



GENERAL BIOLOGY



BY

WILLIAM T. SEDGWICK, Ph.D.

i'ro/essor of Biology in the Massachusetts Institute of Technology^ Boston

AND

EDMUND B. WILSON, Ph.D.

Professor of Zoology in Columbia College, New York



SECOND EDITION, REVISED AND ENLARGED




NEW YORK

HENRY HOLT AND COMPANY

1899



Copyright, 1886, 1895,

BY

HENRY HOLT & CO.



PEEFACE TO THE FIRST EDITION.



Several years ago it was our good fortune to follow, as grad-
uate students, a course of lectures and practical study in General
Biology under the direction of Professor Martin, at Jolins Hop-
kins University. So interesting and suggestive was the general
method employed in this course which, in its main outlines, had
been marked out by Huxley and Martin ten years before, that
we were persuaded that beginners in biology should always be in-
troduced to the subject in some similar way. The present work
thus owes its origin to the influence of the autliors of the
' ' Elementary Biology, ' ' our deep indebtedness to whom we
gratefully acknowledge.

It is still an open question whether tlie beginner should pur-
sue the logical but difficult course of working upwards from tlie
simple to the complex, or adopt the easier and more practical
method of working downwards from famihar higlier forms.
Every teacher of the subject knows how great are the practical
difficulties besetting the novice, who, provided for tlie lirst time
with a compound microscope, is confronted with Yeast, Proto-
coccus, or Amoeba ; and on the other hand, how hard it is to sift
out what is general and essential from the heterogeneous details
of a mammal or a flowering plant. In the hope of lessening the
practical difficulties of the logical method we venture to submit a
course of preliminary study, which we have used for some time
with our own classes, and have found practical and effective.

It has not been our ambition to prepare an exhaustive trea-
tise. We have sought only "to lead beginners in biology from
familiar facts to a better knowledge of how living things are
built and how they act, such as may rightly take a place in gen-






^ ^fS /■



111



IV PREFACE TO THE FIRST EDITION.

eral education or may afford a basis for further studies in General
Biology, Zoology, Botany, Physiology, or Medicine.

Believing that biology should follow the example of physics
and chemistry in discussing at the outset the fundamental prop-
erties of matter and energy, we have devoted the first three
chapters to an elementary account of living matter and vital en-
ergy. In the chapters which follo^v, these facts are applied by
a fairly exhaustive study of a representative animal and plant, of
considerable, though not extreme, complexity — a method which
we believe affords, in a given tune, a better knowledge of vital
phenomena than can be acquired by more superficial study of a
larger number of forms. We are satisfied that the fern and the
earthworm are for this purpose the best available organisms, and
that their study can be made fruitful and interesting. The last
chapter comprises a lirief account of the j)rinciples and outlines
of classification as a guide in subsequent studies.

After this introductory study the student will be well pre-
pared to take up the one-celled organisms, and can pass rapidly
over the ground covered by such works as Huxley and Martin's
''Practical Biology," Brooks's "Handbook of Invertebrate
Zoology," Arthur, Barnes and Coulter's "Plant Dissection," or
the second part of this book, which is well in hand and will
probably be ready in the course of the following year.

The directions for practical study are intended as suggestions,
not substitutes, for individual effort. We have striven to make
the work useful as well in the class-room as in the laboratory,
and to this end have introduced many illustrations. The gener-
ositv of a friend has enabled us to enlist the skill of our friend
Mr. James H. Emerton, who has drawn most of the original
figures from nature, under our direction. We have also been
greatly aided in the preparation of the figures by Mr, William
Claus of Boston.

September, 1886.



PKEFACE TO THE SECOND EDITION.



It was originally our intention to publish this work in two
parts, the first, which appeared in 1886, being intended as an
introduction, while the second was to form the main body of tlie
work and to include the study of a series of type-forms. The
pressure of other work, however, delayed the completion of tb.e
second part, and meanwhile several laboratory manuals appeared
which in larsie measure obviated the need of it. Nevertheless
the use of the introductory volume by teachers of Biology,
and its sale, slowly but steadily increased. It soon appeared,
however, that in some cases the work was being employed not
merely as an introduction, as its authors intended, but as a
complete course in itself; though the wish was often expressed
that the number of types were somewhat larger. These facts,
and the many obvious defects in the original volume, induced
us to undertake the preparation of a second and extended editioiu

"With increased experience our ideas have undergone some
change. We are as firmly convinced as ever that General Biol-
ogy, as an introductory subject, is of the very first impoi-tance ;
but we are equally persuaded that it must not trespass too far
upon the special provinces of Zoology and Botany . The present
edition, therefore, differs from the original in these respects:
first, while the introduction has been extended so as to in-
clude representatives of the unicellular organisms {Amoeha,
Infusoria^ Protococcus^ Yeasts, Bacteria), the publication of a
second volume has been abandoned. It is lioped tliat tlie work
as thus extended may serve a double purpose, viz., either to
be used as an introduction to subsequent study in Zoology, Bota-
ny, or Physiology; or as a complete elementary course for
general students to whom the minutiae of tliese more special sub-
jects are of less importance than the fundamental facts of vital
structure and function. We believe that a sound knowledge of



\i PREFACE TO THE SECOND EDITION.

these facts can be conveyed by tlie metliod of study liere out-
lined ; but we must emphatically insist that neither this nor any
Xother method will give good results unless rightly used, and that
C this work is not designed to be a complete text-book. Probably
few teachers will find it desirable to go over the whole of the
ground here laid out, and we hope that still fewer will be inclined
to confine their work strictly to it. Even in a brief course the
student may, after going over certain portions of this work, be
made acquainted with the leading types of plants and animals ;
and this may be rapidly accomplished if the introductory work,
however limited, has been carefully done. In extended courses
we have sometimes found it desirable to postpone certain parts of
the introductory work, returning to them at a later period.

A second modification consists in placing the study of the
animal before that of the plant, which plan on the whole appears
desirable, especially for students who have not been well trained
in other branches of science. The main reason for this lies in the
greater ease with which the physiology of the animal can be ap-
proached ; for there is no doubt that beginners find the nutritive
problems of the plant abstruse and difiicult to grasp until a cer-
tain familiarity with vital phenomena has been attained ; while
most of the physiological activities of the animal can be readily
illustrated by well-known operations of the human body.

The third change is the omission of the laboratory directions,
these" havih^~beentound "TmsuitabTe! The needs~of different
teachers differ so widely that it is impossible to draw up a scheme
that shall answer for all. In place of the laboratory directio ns for
students we have therefore given, in an appendix, a series (fTprac-
ticaFsucrffestions to teachers, leaving^ it to them to work OTxde-
taHed directions, if desirecT/ by the help of the standard labora-
tory manuals. These suggestions are the result of a good deal of
experience on the part of many teachers besides ourselves, and
we hope they will be found useful in procuring and preparing
material (often a matter of considerable difficulty), and in decid-
ing just what the student may reasonably be expected to do.

For the rest, the original matter has been thoroughly re^dsed,
numerous errors have been corrected, and many additions made,
particularly on the physiological side.

September, 1895.



TABLE OF CONTENTa



CHAPTER I,

INTBODVCTOBY.

Living things and lifeless things. The contrast and the likeness hetweea
living matter and lifeless matter. The journey of lifeless matter
through living things. Analogy between a fountain, a flame or a
whirlpool, and a living organism. Living matter is lifeless matter in
a peculiar state or condition. Its characteristic properties. Biology,
its scope and its subdivisions. The Biological sciences. The relations
of -Biology to Zoology and Botany, Morphology and Physiology.
Definitions and inter-relations of the biological sciences. Psychol-
ogy, Sociology. Definition of General Biology. .,...<,,„..., 1



CHAPTER n,

THE STRUCTURE OF LiriNG THINGS.

Their occurrence and their size Organisms composed of organs. Func-
tions. Organs composed of tissues. Differentiation. Tissues com-
posed of cells, DefinitionSo Unicellular organisms. Living organ-
isms contain lifeless matter. Lifeless matter occurs in living
tissues and cells. Examples, Lifeless matter increases relatively
with age. Summary statement of the structure of living things.
The organism as a whole — the Body — more important than any of its
parts <> o 9

CHAPTER III.

PROTOPLASM AND THE CELL,

Protoplasm "the physical basis of life." Historical sketch. The com-
pound microscope and the discovery of cells in cork. The achromatic
objective. The cell-theory of Schlelden and Schwann, Virchow
and Max Schultze. Modern meaning of the term "cell/* The dis-
covery of protoplasm and sarcode and of their essential similarity.

• •

Vll



nii TABLE OF CONTENTS.

PAQB

Purkinje. Von Mohl. Cohn. Schiiltze. Appearance and structure
of protoplasm, A typical cell. Its parts. Cytoplasm and the nucleus.
The origin of cells. Segmentation of the egg, differentiation of the
tissues, the genesis of the " body," and the physiological division of
iabor. Protoplasm at work. Muscular contractions. Amo&ba on its
travels. "Rotation" in Nitella and AnacJtaris. "Circulation" of
the protoplasm in hair- cells of spiderwort. Ciliary motion. The
sources of protoplasmic energy. Metabolism and its phases. Vital
energy does not imply a*' vital force.'* The chemical relations of
protoplasm: proteids, carbohydrates, and fats. Physical Relations:
temperature, moisture, electricity, etc. The protoplasm of plants and
A animals similar but not identical c 20



CHAPTER IV.
THE BIOLOGY OF AN ANIMAL: THE COMMON EARTHWORM.

4. representative animal. Earthworms taken as a type. Their wide dis-
tribution. The common earthworm. Its name ; habitat ; habits ;
food ; castings ; influence on soils ; burial of objects ; senses. Its
differentiation: antero-posterior and dorso-ventral. Its symmetry:
bilateral and serial. Plan of the earthworm's body. Organs of the
body and the details of their arrangement in systems: alimentary;
circulatory; excretory; respiratory; motor; nervous; sensitive; etc,. 41

CHAPTER V.

THE BIOLOGY OF AN ANIMAL: THE COMMON EARTHWORM {Continued).

Definition of reproduction. The germ-cells. Sexual and asexual repro-
duction. Regeneration. The reproductive system of the earthworm.
Its copulation and egg-laying. The process of fertilization, and the
segmentation or cleavage of the egg. The making of the body. The
gastrula. The three germ-layers : ectoblast, entoblast, mesoblast.
Brief statement of the phenomena of cell-division, and of nuclear
division or karyokinesis. The making of the organs. The fate of
the germ-layers. The germ-plasm » . » 72

CHAPTER VL

THE BIOLOGY OF AN ANIMAL: THE COMMON EARTHWORM {Continued),

The microscopic anatomy or histology of the earthworm. The funda-
mental animal tissues and their constituent cellular elements. Epi-
thelial, muscular, nervous, germinal, blood, and connective tissues,
and their distribution in the various organs. Microscopic structure
of the body-wall ; of the alimentary canal ; of the blood-vessels ; of
the dissepiments ; of the nervous system, ganglia ; etc. .. 90



TABLE OF CONTENTS ix

CHAPTER VII.

TEE BIOLOGY OF AN ANIMAL: THE COMMON EARTHWORM iContinued.)

PAGS

General Physiology. The animal and its environment. Definitions.
Adaptation, structural and functional, of organism to environmento
Origia of adaptations. Elfect of their persistence and accumulation.
Natural selection through the survival of the fittest. The need of an
income of food to supply matter and energy. Nature of the income.
The food and its journey through the body. Alimentation. Diges-
tion and absorption. Circulation. Metabolism. The outgo. Inter-
action of the animal and the environment. Summary 97

CHAPTER VIII.

THE BIOLOGY OF A PLANT: THE COMMON BRAKE OR FERN.

A representative plant. Ferns taken as a type. Their w^ide distribution.
The common brake. Its name, habitat, size, etc. General morphol-
ogy of its body. Its differentiation, antero-posterior and dorso-ventral.
Its bilateral symmetry. The underground stem. Origin and arrange-
ment of the leaves. Internal structure of the rhizome and the three
great tissue-systems. The elementary tissues of plants. Histology of
the rhizome. Roots and branches. Embryonic tissue and the apical
cell. How the rhizome grows. The frond or leaf of Pieris and its
structure. Chlorophyll-bodies. Stomata. Veins 105

CHAPTER IX.

THE BIOLOGY OF A PLANT: THE COMMON BRAKE (Continued).

The various methods of reproduction in Pteris. Sporophore' and
oophore. Alternation of generations. Sporangia. Spores. Ger-
mination of the spores. Protonema. Prothallium. The sexual
organs. Antheridia. Male germ-cells. Archegonia. Female germ-
cells. Fertilization. Segmentation. Differentiation of the tissues.
The making of the body » 130

CHAPTER X.

THE BIOLOGY OF A PLANT: THE COMMON BRAKE (Continued).

Physiology. The fern and its environment. Its adaptation. A defini-
tion of life. The need of an income of matter and energy. Income
of Pteris. Its power of making foods, especially starch. The circu-
lation of foods through the plant-body. Metabolism. Outgo. Res-
piration. Interaction of the fern and the environment. Special



TABLE OF CONTENTS.

PAGB

physiology of the tissue-systems and of reproduction. The question
of old age. A comparison of the fern with the earthworm, and of
plants in general with animals in general. The physiological im-
portance of the chlorophylless plants 144



CHAPTER XI.

THE UNICELLULAR ORGANISMS.

The multicellular body. Its origin in continued, but incomplete, cell-
division. The unicellular body. Its origin traced to complete cell-
division. The multicellular body and the unicellular body as
individuals. Unicellular forms physiologically " organisms." Special
importance of their structural simplicity. "Organisms reduced to
their lowest terms. " 156



CHAPTER XII.

UNICELLULAR ANIMALS.
A. Amceba.

General Account. Habitat. Form. The " Proteus animalcule.'* Ap-
pearance. Pseudopodia. Locomotion. Foods. The encysted state.
Structure of the unicellular body. Cytoplasm. Nucleus. Vacuoles.
Reproduction by fission. Physiology. The fundamental physiological
properties of protoplasm as displayed in Aynoeba. The (question of
■old age. Related forms. The Rhizopoda or pseudopodial Protozoa.
Arcella. Difflugia. The "sun-animalcule." The Foramenifera.
The Radiolaria , 158



CHAPTER XIII.

UNICELLULAR ANIMALS {Continued).

B. Infusoria.

General account. Habitat. The "slipper-animalcule." The "bell-
animalcule." Paramcecium. Its form, structure, and habits. Cyto-
plasm; trichocysts; vacuoles; nuclei; mouth; oesophagus; anal spot.
The encysted state. Reproduction by agamogenesis; by conjugation;
amphimixis. Voriicella. Its form, structure, etc. Its reproduction
by fission, endogenous division, and conjugation. Microgamete and
macrogamete. Related forms= Euglena; Zoothamnion; CarcJiesium;
Epistylis; etc. Physiology of the Infusoria. Herbivorous, carniv-
orous, and omnivorous infusoria. Analogy with higher forms. The
problem of chlorophyll in animals. S3^mbiosis. Vegetating animals.
The claim of unicellular animals to be regarded as unicellular "or-
ganisms"; organs in the cell; etc o 168



TABLE OF CONTENTS. XI

CHAPTER XIV.

UNICELLULAR PLANTS.
A. Pbotococcus.

PAGB

General account. Habitat. Morphology. Structure. Motile and non-
motile states. Reproduction by fission. Cell-aggregates. Physi-
ology. Income and outgo. The making of starch from inorganic
matters. The fundamental physiological properties of protoplasm as
displayed by plants. Comparison of Proiococcus with Aniosba, and
chlorophyll-bearing plants in general with animals in general. Other
unicellular chlorophyll-bearing plants: diatoms; desmids; Ghroocoo
cus; Glceocapsa; etc 178

CHAPTER XV.

UNICELLULAR PLANTS {Continued).
B. Yeast.

General account. Wild yeast and domesticated yeast. Microscopical
examination of a yeast-cake. Morphology of the yeast cell. Cyto-
plasm and nucleus. Reproduction by budding and by spores. Physi-
ology. Yeast and the environment. Dried yeast. Income. Meta-
bolism. Oiitgo. The minimal nutrients of yeast compared with
those of Proiococcus and Amoeba. Why yeast is regarded as a plant.
Top yeast Bottom yeast. Wild yeasts. Red yeast. Fermentation
and ferments. Unicellular plants not necessarily at the bottom of
the scale of life; etc 184

CHAPTER XVI.

UNICELLULAR PLANTS (Continued).
C. Bacteria.

The smallest, most numerous, and most ubiquitous of known living
things. Their abundance in earth, air, milk, water, etc. Comparison
of their work in soils with that of earthworms. Parasitic and sapro-
phytic bacteria. Their botanical position. Sanitary and economic
importance. Morphology. Structure. Cytoplasm and nucleus.
Cilia. Their size. Swarming and the resting stages. Reproduction.
Endospores. Arthrospores. Physiology. Income. Metabolism.
Outgo. Ferments. Fermentation, Putrefaction. Disease. One
species capable of living upon inorganic matter. Related forms.
Why bacteria are regarded as plants. The relations of bacteria to
temperature, moisture, poisons, etc. Sterilization, Pasteurizing,
disinfection, filtration, etc , 192



XU TABLE OF CONTENTS.

CHAPTER XVII

A HAY INFUSION.

PAGB

General account. Results of microscopical examination. Turbidity.
Odor. Color. Coustituents. The scene of important pliysical,
chemical, and biological phenomena. Previous history of the hay
and the water. Efiect of bringiug them together. Causes of tur-
bidity, color, odor, etc. Aerobic and anaerobic bacteria thrive.
Infusoria multiply and devour them. Carnivorous mfusoria attack
the herbivorous. The struggle for existence. Hay a green plant
and the source of food. Quiet finally supervenes. How nutritive
equilibrium may be preserved or disturbed. The hay-infusion an
epitome of the living world 201

APPENDIX.

SUGGESTIONS FOR LABORATORY STUDIES AND DEMONSTRATIONS.

Books for the laboratoiy. Time required for General Biology . , 205

Special suggestions for laboratory work, etc., upon the subjects treated
in the several chapters as outlined above, viz.:

Chapter I. Introductory 205

II. Structures of Living Organisms , 206

III. Protoplasm and the Cell. o. 207

IV. -VIII. The Earthworm ,.. 2)0

IX.-XI. The Fern , ,.... 213

XII. Amoeba 216

XIII. Infusoria 217

XIV. Protococcus 220

XV. Yeast o = ..o 221

XVI. Bacteria 222

XVII. AHay Infusion 223

Instruments and Utensils o o 220

Reagents and Technical Methods c « . . 221

Index. 227



GENERAL BIOLOGY.



CHAPTER I.

INTRODUCTORY.



"We know from common experience that all material things
are either dead or alive, or, more accurately, that all matter is
either lifeless or living ; and so far as we know, life exists only
as a manifestation of living matter. Living matter and lifeless
matter are everywhere totally distinct, though often closely as-
sociated. The most careful studies have on the whole rendered
the distinction more clear and striking, and have demonstrated
that living matter never arises spontaneously from lifeless matter,
but only through the immediate influence of living matter already
existing. And so, whatever may have been the case at an earlier
period of the earth's history, we are justified in regarding the
present line between living and lifeless as one of the most
clearly defined and important of natural boundaries.

The Contrast between Living Matter and Lifeless Matter is made
the ground for a division of the natural sciences into two great
groups, viz. : the Biological Sciences and the Physical Sciences,
dealing respectively with living matter and lifeless matter. The
biological sciences (p. 7) are known collectively as Biology
{/3io5, life; Xoyos, a discourse), which is therefore often de-
fined as the science of life, or of living things, or of living mat-
ter. But living matter, so far as we know, is only ordinary
matter which has entered into a peculiar state or condition.



..A A



2 INTRODUCTORY.

And hence biology is more precisely defined as tJie science ichich
treats of viciUer in the living state.

The Relationship between Living and Lifeless Matter. Al-
though living matter and lifeless matter present this remarkable
contrast to one another, they are most intimately related, as a
moment's reflection will show. The living substance of the human
body, or of any animal or plant, is only the transformed lifeless
matter of the food which has been taken into the body and has
there assumed, for a time, the living state. Lifeless matter in
the shape of food is continually streaming into all living things
on the one hand and passing out again as waste on the other.
In its journey through the organism some of this matter enters
into the living state and lingers for a tune as part of the body
substance. But sooner or later it dies, and is then for the most
part cast out of the body (though a part may be retained within
it, either as an accumulation of waste material, or to serve some
•aseful purpose). Matter may thus pass from the lifeless into the
living state and back again to the lifeless, over and over in never-
ending cycles. A living plant or animal is like a fountain or a
flame into which, and out of which, matter is constantly stream-
ing, while the fountain or the flame maintains its characteristic
form and individuality. It is " nothing but the constant form of
a similar turmoil of material molecules, which are constantly
flowing into the organism on the one side and streaming out on
the other. . . . It is a sort of focus to which certain material par-
ticles converge, in which they move for a time, and from which
they are afterward expelled in new combinations. The parallel
between a whirlpool in a stream and a living being, which has
often been drawn, is as just as it is striking. The whirlpool is
permanent, but the particles of water which constitute it are in-
cessantly changing. Those which enter it on the one side are
w^hirled around and temporarily constitute a part of its mdi-
viduality ; and as they leave it on the other side, their jDlaces are
made good by newcomers." (Huxley.)

How then is living matter different from lifeless matter ?
The question cannot be fully answered by chemical analysis, for
the reason that this process necessarily kills living matter, and
the results therefore teach us little of the chemical conditions ex-
isting in the matter when alive. Analyses, nevertheless, bring



LIVING MATTER. S

to light several liiglilj important facts. It is likely that livino-
matter is a tolerably detinite compound of a nnmljer of the


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Online LibraryW. T. (William Thompson) SedgwickAn introduction to general biology → online text (page 1 of 20)