James Francis Abbott.

The elementary principles of general biology online

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Set up and electrotyped. Published January, 1914.


J. S. Cushing Co. Berwick & Smith Co.
Norwood. Mass., U.S.A.

" BEFORE the great problems [of Biology], the cleft between Zoology
and Botany fades away, for the same problems are common to the twin
sciences. When the zoologist becomes a student not of the dead but of
the living, of the vital processes of .the cell rather than of the dry bones
of the body, he becomes once more a physiologist and the gulf between
these two disciplines disappears. When he becomes a physiologist, he
becomes, ipso facto, a student of chemistry and physics."

D'AncY THOMPSON, " Magnalia Naturae."



IN this book I have endeavored to present in an
elementary way some of the fundamental generali-
zations that are the product of modern research in
biology. The artificial division between the study
of plants and that of animals is one that is becom-
ing increasingly difficult to maintain, inasmuch as
some biological principles are best illustrated by
phenomena in the plant world, others by those of
the animal world. I have tried, therefore, to utilize
both aspects of the subject and to draw my illustra-
tive material impartially from both kingdoms.

The practice that insists upon the student getting
his knowledge of natural science at first hand needs
nowadays no justification. The laboratory method
of study has shown itself to be not only the best
means of acquiring a concrete and accurate knowl-
edge of the science studied but also a primary pre-
requisite for those habits of thought that are essential
to what has come to be known as the " scientific
method." Nevertheless in Biology the field is so
broad and so varied that the student is very likely
to lose sight of the fundamental principles that
underlie all living nature. Moreover, these princi-
ples do not grow out of the laboratory work so
obviously nor are they so easily demonstrated by



experiment as is the case with such sciences as
chemistry and physics. This book is accordingly
planned to supply a background for a laboratory
course in Biology and to supplement the facts ac-
quired in such a course, the exact nature of which
will depend upon the convictions or preliminary
training of the individual instructor.

On the other hand, it is believed that the general
reader also will find here a simple statement of the
fundamentals of General Biology, a subject that is
becoming increasingly important in our everyday life.

In covering so much ground I have been compelled
to condense many subjects to paragraphs that might
well have deserved whole chapters to themselves.
The wide-awake teacher, I think, will have no diffi-
culty in amplifying those portions that he esteems
most important or in which he is most interested.
I am conscious, too, of the fact that many generali-
zations have been stated in a much less cautious
way than would have been the case if condensation
had not seemed so essential a feature. But, apart
from this, I think that it is preferable, pedagogically,
that a student should get a few clean-cut funda-
mental ideas which perhaps require subsequent qual-
ification than that he should have vague notions in
which exceptions to rules figure as largely as the
rules themselves. For instance, it is best that he
should acquire the fact that the division of chromo-
somes in mitosis is equal and that in consequence
the number of chromosomes in an individual or a
species is constant, leaving any consideration of the


accessory chromosome, important as it may be, to
a time when the former concept shall have taken
firm root.

A chapter on Animal Behavior was projected but
was abandoned when it was found that its inclusion
would have increased the size of the volume unduly.
For the same reason no apology need be offered for
the constant reference by name without comment
to the various groups of animals and plants. The
first-hand knowledge of the types in the laboratory
will have supplied the descriptive details for which
there is no room in the present work, although text-
figures have been freely used to illustrate the forms

In such a book as the present- one, little can be
claimed for originality except the manner of pre-
senting the subject. I have sought counsel and
criticism in those fields in which my personal knowl-
edge is least dependable, and I hope that such errors
as may have crept in will not be significant ones.
I am particularly indebted to Professor George T.
Moore, Director of the Missouri Botanical Gardens,
who read the whole book in manuscript, and to Pro-
fessor Walter E. Garrey, who read the proof of the
first four chapters. Acknowledgments are also due
to the following for the use of cliches or permission
to copy figures: to Herr Gustav Fischer, Jena, for
permission to use figures 7, 13, 34, 55, 60, and 82;
to Messrs. Henry Holt and Co., for the use of fig-
ures 8, 22, 49, 92, 94, 100, 106, and 112; to Messrs.
Ginn and Co., for the use of figures 31 and 103; to


the American Book Co., for the use of figures 2, 52,

97, and 109; to Messrs. G. P. Putnam's Sons, for
the use of figure 16; to Messrs. D. Appleton and
Co., for the use of figures 19, 58, 62, 67, 70, 90, 93,
95, 96, and 113; to Messrs. Longmans, Green, and
Co., for the use of figure 23 ; to Messrs. P. Blakis-
ton's Son and Co., for the use of figure 64 ; to Pro-
fessor C. B. Davenport and the Editors of the
Popular Science Monthly, for the use of figure 71 ;
to Professor Davenport and Messrs. John Wiley and
Sons, for the use of figure 73 ; to the Columbia
University Press, for the use of figure 110; to Pro-
fessor John Schaffner, for permission to copy figure
66; to Professor C. C. Curtis, for the use of figures
51 and 107; to the Editors of the American Review
of Reviews, for the use of figure 108 ; and to Sir E.
Ray Lankester, for permission to copy figure 112.
For photographs from which were made figures 85,

98, and 99 I am indebted to the kindness of Profes-
sor S. M. Coulter. All the other illustrations, with
the exception of figures 6, 10, 24, 25, 37, 40, 42-44,
50, 54, 56, 57, 63, 74, 77, 88, 89, and 114, are from
publications of The Macmillan Co.

J. F. A.
JANUARY, 1914.




Living and Non-living 2

Life and Death. Elemental Death .... 4

Chemistry of Protoplasm 8

Proteins, Fats, and Carbohydrates .... 10

Physical Structure of Protoplasm* ..... 14
Organization of Protoplasm . ' . . . . .17

The Cell 18

Cellular and Non-cellular Organization .... 26
Functions of a Free Cell . . . . .28
Locomotion, Ingestion, Digestion, Egestion, Assim-
ilation, Irritability, Reproduction ... 29
Specialization in Locomotor Organs .... 32
Specialization in Conducting Organs .... 39
Secretion ......... 41

Specialization in Digestion 42

Summary 45

Specialization and Differentiation .... 45
Tissues, Organs, Systems . . . . .46

Homology and Analogy ...... 47


Oxidation 48

Conservation of Energy ...... 50

Chemical Synthesis in the Organism .... 52

Photosynthesis ....... 54

Production of Fats and Proteins . . .55

Dissimilation 56

Metabolism in Animals ....... 57

Foods in General . . . . . . . . 1 60




Fate of Foods in Higher Animals . . . 61

Role of Oxygen in Metabolism 62

Aerobic and Anaerobic Forms ..... 63

Combustion and Respiration ..... 64

Poisons and Antiseptics . 66

Cycle of the Elements in Organic Nature ... 68

The Nitrogen Cycle 71

Destruction of Organisms ..... 72

Putrefactive Organisms ...... 73

Denitrification and Nitrogen Fixation ... 75

Nature of Energy Transformed ..... 77

Movement ........ 77

Heat 79

Electricity 79

Light 80

Enzymes and Enzymatic Action .... 82

Internal Secretions and Hormones .... 86


Cumulative Integration . . . . . . .91

Amitosis and Mitosis ..... 92

Abnormal Mitosis . . . . . .97

Nature of the Centfosome ..... 98

Influence of External Conditions on Growth . . .100

Light and Heat 101

Chemical Agents . . . . . . .102


Differentiation in Animals .... . 104

Alimentary System 104

Sensory Organs, Cephalization .... 107

Skeletal Structures . 110

Endoskeleton 110

Exoskeleton . 112

Muscular System .113

Circulatory System 114

Excretory Organs . 117

Differentiation in Plants 121

Plant Movement . 123



Supporting Structures 123

Circulatory System 126

Alimentary System 126


Biogenesis and Abiogenesis . . . . . .130

Reproduction as a Growth Process .... 131

Fission in Metazoa . . . . . . .132

Fission in Lower Plants 135

Temporary Budding . . . . . .136

Permanent Budding . . . , . .139
Spore Formation ....... 140

Sexual Reproduction 141

Total Conjugation 142

Isogamy . . . . . . . . 142

Anisogamy . . . . . . . 144

Sexual Differentiation 147

Partial Conjugation 151

Cytoplasmic Conjugation (Plastogamy) . . 151

Nuclear Conjugation (Karyogamy) . . . 152

Nuclear Phenomena of Zygosis in Animals . . 155

Cleavage 158

Gastrulation . . . . . . .161

Further Differentiation 162

Conjugation in Protozoa 164

Parthenogenesis . . . . . .167

Artificial Parthenogenesis . . . . .169

Alternation of Generations in Animals . , 171
Sexual Reproduction in Plants . . . .174

Liverworts and Mosses .... 175

Ferns 176

Seed Plants . . . . . . .177

Germination of the Megaspore . . .179

Germination of the Microspore . . .179

Parthenogenesis in Plants . . . .182

Apogamy ....... 183

The Probable Evolution of the Plant World . .183
Morphogenesis ..-. - . ... 185

Regeneration 185



Regulation 187

Heteromorphosis . . . . . . .189

Theories of Morphogenesis 190

Preformation . 191

Epigenesis ........ 192

" Weismannism " 193

Vitalism and Mechanism . . . . .194

Summary ......... 196


Variation 198

The Law of Frequency of Error .... 200

Types of Variation Curves 202

Asymmetrical Variation .... 204

Discontinuous Variation .... 204

Mutations 207

Correlated Variability 209

Effect of Life Conditions on Variation . . .211

Causes of Variation 212

Heredity 214

Heredity and Inheritance ..... 214

Individual Heredity and Racial Heredity . . 216

Galton's Law of Ancestral Inheritance . . 217

Filial Regression 219

Effect of Selection in Heredity . . . . 220

Pure Lines 221

Unit Characters and Mendelian Inheritance . 223

Sex-limited Inheritance .... 233

Economic Aspects of the Subject . 234
The Inheritance of Disease . . . .236
The Inheritance of Defects . . . .239

Eugenics 240


Environment ........ 243

The Usual Conditions of Environment . . . 244

Temperature 244

Light .245

Chemical Environment ..... 245



Nature of Organic Response ...... 246

Electric Response 247

Individual Response to Unsymmetrical Stimuli . 24H

Adaptive Response 253

Immunity ....... 255

Morphogenetic Response ..... 256

Non-adaptive Morphogenetic Response . . 257

Influence of Food 258

General Adaptation 259

Some Types of Adaptation 260

Aquatic Organisms ...... 260

Aerial Adaptations 262

Subterranean Adaptations .... 263

Protective Adaptations ..... 266

Protective Coloration .... 267

Specific Resemblance .... 268

Aggressive Resemblance .... 269

Mimicry 269

The Care of the Young . . . .272

Environmental Adaptations of Plants . . . 274

Adaptations for Seed Dispersal . . . 278

Associations of Animals ....... 279

Commensalism 280

Parasitism in Protozoa ...... 283

Parasitism in Worms . . . . . . 285

Parasitism- in Insects 287

Sacculina . . ..".*. . . . 289

Associations among Plants ...... 290

Lichens 291

Parasitism in Plants 292

Associations of Plants and Animals .... 293

Grafts , 294


Meaning of Species . 296

Polymorphism 301

Elementary Species and Linnaean Species . . 305



The Origin of Species 306

Evidence for the Evolution of Species in the Past . 307

History of the Elephant 308

Vestigial Structures 312

" Darwinism " 314

Lamarck's Theory 317

Critique of the Darwinian Theory . . . .318

Critique of the Lamarckian Theory . . . 320

Conclusion , 323





BIOLOGY, the "science of life," includes in its
broadest aspects the investigation of all that per-
tains to the structure and functions of living things.
The observing and recording of the wonderful
variety of Nature will always have a fascination
not only for the poet, but for the scientist as well.
But the latter is more especially concerned with
the meaning, the analysis, or the explanation of
natural phenomena. Philosophy tells us that
science can never hope to get the ultimate
explanation of anything which it observes. All
that it can do is to reduce the complexities to simpler
expression, to find the common denominator for
things that seem at first glance unrelated, in the
same way that the mathematician by processes of
factoring reduces elaborate and complex algebraic
expressions to simple statements of relation. And,
just as in mathematics, the greater the number of
variables we have to deal with, the more involved and
difficult becomes our computation, so in physical
and biological science the greater the number of


unknown factors there may be, the greater becomes
our difficulty in reducing them to fundamental
principles. This is why biology is so strikingly an
"inexact" science in comparison with physics or
inorganic chemistry. Yet, it is not necessary even
for the physicist or the chemist to know what is the
ultimate nature of matter or force or electricity or
atoms in order to study such things and formulate
general laws based on such observation; nor is it
necessary for the biologist to concern himself with
the meaning or nature of life in order to find out
what principles govern in the world of living things.

The study and comparison of the structures of
plants and animals, of their methods of growth and
reproduction, their relation to each other and the
world about them, has revealed the fact that there
is an underlying unity in nature that makes it pos-
sible for us to sum up our observations in general
principles, incompletely understood, of course, but
more or less applicable to all living things. The
consideration of these general principles forms the
basis for a General Biology in the sense in which it
will be taken in the present work.

Although we shall not attempt to elucidate life
in any philosophical sense, it is of interest, notwith-
standing, to discover at the start just how much
science can tell us of the nature of life, or of living
things as a whole.

Living and Non-living. If a biologist should
ask the average layman whether he could tell the


difference between something alive and something
that is not, he would hardly be taken seriously.
Yet, if such a layman should be pressed to define
just what he meant by "being alive," he might be
hard put. It might be assumed that some charac-
teristic chemical compounds are to be found in liv-
ing matter which are absent in non-living matter.
But thousands of exact chemical analyses have
been made of every sort of living thing and no ele-
ment or compound has ever been found which is
essentially different from what may exist in the
non-living world. Long ago a distinction used to
be made between "organic" and "inorganic"
substances, the former being the product of
living "organisms." But such a distinction has
broken down. It is possible to synthesize substances
in the test tube, identical in chemical composition
with those formed in Nature's laboratory, the
tissue of plant and animal. Indeed, the ability to
artificially reproduce natural products in this way
has proved of great value commercially, and arti-
ficially synthesized indigo, camphor, etc., now
supplement in large measure Nature's meager store
of such things.

Nor is it easier to discover any unique physical
phenomena in living things. So far as we can
observe, and the more our observations are
extended, the more is the conclusion confirmed,
- living matter obeys the same physical laws that
obtain in the rest of the universe. Again, living
things grow : but so do crystals and clouds. They


reproduce themselves, but, as we shall see later,
this is but a discontinuous form of growth, and may
be paralleled, perhaps, in other " inorganic " bodies.

Life and Death. If we find it so difficult to
point to any one thing as the touchstone of living
matter contrasted with non-living matter, what
shall we say of the difference between that which is
alive and that which has been, but is no longer, in
other words between living matter and dead matter ?
A turtle may justly be called a dead turtle if we cut
off its head, yet, if we cut out the heart of such a
decapitated turtle and suspend it on hooks in a
moist chamber, wet with a weak solution of common
salt, such a heart will go on beating rhythmically for
days. So long as it beats we are forced to consider
the substance composing it as living matter.

We must make a distinction, then, between
general lije and death, which affects the whole or-
ganism and elemental life and death, which affects
only the elements or tissues. This distinction is
much more apparent in animals than in plants on
account of the greater degree of specialization in
the former. Ordinarily, decay and disintegration
in the tissues promptly follow general death, but
experimentally we may avoid this contingency if we
exclude bacterial invasion, 1 and such a piece of
tissue may be kept passively " alive " f or a consider-
able interval of time, regaining its functions when
replaced in a living organism. In this way sections

1 See Chapter IV.


of blood vessels and other organs have been cut out
and later replaced in the same or other animals
without injury. By keeping such a tissue at a
trifle above freezing point the period of suspended
vitality may be extended to weeks or months. 1
Recent experimenters have shown that not only may
the pieces of excised tissue be kept passively alive,
but that under proper conditions they will sprout
and grow like so many plant cuttings. It is only
necessary that they be surrounded by a nutritive
medium drawn from the same animal from which
they came, and that they be kept free from all bac-

If the turtle heart in the experiment described
should after a while cease to beat, but later begin
to do so again, we would of course say that, like the
excised tissues just described, it was still alive during
its period of inactivity, although our only knowledge
of its being alive is derived from its subsequent
beating. For, we say, our idea of life, however
vague .it may be, does not admit of discontinuity.
Once alive, always alive, until dead.

The experimental physiologist is not so sure of
that. Such a suspended heart muscle of the turtle
will not beat except in the presence of salt (or some
sodium compound). But in pure salt solution it
stops beating. The pure salt acts as a poison. We
might now consider the muscle dead, were it not

1 We find an analogous instance in Nature in the fact that many
seeds will retain their vitality unimpaired for years, until proper condi-
tions of warmth and moisture cause them to sprout and grow.


for the fact that if we add a little calcium chloride
to the salt solution, the heart begins to beat again.
The calcium has neutralized the ill effect of the
sodium. If, then, contracting is any criterion of
whether the heart is alive or not, its life would seem


FIG. 1. A tardigrade (Macrobiotus) : a, in the creeping active con-
dition ; b, dried, in the state of apparent death.

to depend upon the presence or absence of something
quite outside the living matter at all !

Under perfectly natural conditions such a state
of "ceasing to live " and then resuming life again is
not uncommon. Some animals that live in shallow
puddles exposed to the chance of drying up are capa-


ble of drying up also, and remaining in an apparently
lifeless condition for long periods of time, blown
about in the dust by the winds (fig. 1). Falling in
a favorable spot where there is sufficient water, they
" come to life again " and resume their activity
as if it had never ceased. The excessively minute
" germs " of bacteria keep the race in existence in
this way.

In seeking an analogy to these phenomena a
German scientist, Preyer, has compared the plant
or animal to a clock, which goes through its charac-
teristic movements so long as the energy in its
mainspring lasts. It may be stopped and remain
so until its pendulum is set swinging again, in which
case it may be compared with a fertile seed. But
if its mainspring be broken or if it run down, even
though externally it be just the same in appearance,
it no longer " goes." Some such a difference as
this may exist, not to push the comparison too
far, between an organism in which life is merely
suspended and one that is dead. 1

Our search, therefore, for the answer to the ancient

1 Waller has shown that in such forms of living substance as nerves,
which do not contract or give any visible evidence of life or death, it is
possible by galvanometric test to show that a "live" nerve deflects the
needle, whereas a "dead" one does not; in other words that the electric
response is a very delicate and accurate sign of life. By this means he
claims to have been able to mark the "beginning of life" in an incubating
hen's egg. A Hindu physiologist, Professor Bose, has claimed, on the
basis of very careful experimental work, that this electrical sign of life
is dependent upon the "molecular mobility" of the matter, and that it
disappears when "molecu]p,r fixation" or strains ensue. Herein may be,
possibly, the simple difference between living and dead matter.


conundrum, " What is Jife? " so long as we attempt
to solve it by processes of analysis, leads us up a
blind alley no matter what clue we follow. Yet,
in spite of our difficulty in defining living matter,
we recognize the existence of it as something real
and not imaginary, and when we compare the in-
numerable kinds of living things from the standpoint
of their physical and chemical composition, we find
that they all have much in common ; that life,
whatever its metaphysical aspects, has also a mate-
rial basis, a " life stuff " or living substance. This
living substance has received various names, but
that which is most commonly used is Protoplasm. 1
This is what Huxley called in enduring phrase " the
physical basis of life."

Chemistry of Protoplasm. In studying the
physics and chemistry of protoplasm we find that
it is exceedingly complex. But its complexity
arises from the almost infinite combinations and
permutations of a very limited series of chemical
elements. Carbon, hydrogen, oxygen, nitrogen, -
these we find in all protoplasm, and they constitute
its bulk. Sulphur and phosphorus are also always
present, but in very much smaller quantities, and
usually chlorine, potassium, sodium, magnesium,
calcium, and iron as well. Many other elements
occur normally, though rarely, in the protoplasm of
certain animals and plants. Iodine occurs in sea-

1 Bioplasm, a term used by many English authors, is perhaps prefer-
able, but protoplasm is firmly established in the literature of biology.


weeds and in the thyroid gland of certain animals.
Zinc and manganese seem to be normal constituents
of the tissues of some mollusks. In other words,
protoplasm is not a definite chemical substance or
compound, like quartz or salt or starch, but is some-
times one thing, sometimes another. Rather, it x is
a mixture of various things, all of them, however,
of an infinite complexity of mutual relations, -
" a mixture, but certainly no jumble." The word

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Online LibraryJames Francis AbbottThe elementary principles of general biology → online text (page 1 of 19)