Leland Stanford Jr. University. The essay of Professor Conklin was read before the American Philosophical Society. The others are here presented for the first time.

I may add that the present volume is not intended as a text-book in Evolution, although most phases of organic development are in one way or another touched. upon, some of them, however, most briefly. The treatment of different topics is necessarily unequal. The time is long past when any one man can master what is known in any science, least of all the universal science of life. In the supplementary essays I have asked my scientific friends to do for this volume certain work which I could not do except by the unsatisfactory method of compilation.

DAVID STARR JORDAN.

PALO ALTO, CALIFORNIA, January 19, 1898.

ANALYSIS OF CONTENTS.

1. THE KINSHIP OF LIFE.

What is the cause of variety in life? What is a species?
The number of species. The unity of type. Unity in
variety. The meaning of homology. The origin of va-
riety and the origin of homology. The origin of life un-
known. The answer of Linnæus. The answer of Cuvier.
The answer of Lamarck. The answer of Agassiz. What
is special creation? All life from life. Uncertain bound-
aries of species. The species of fishes of North Amer-
ica. The species of the Galapagos. Do species change
with space? The species of South American edentates.
Do species change with time? Darwin's answer. Dar-
win's method. The origin of species. The Darwinian
theory. Artificial selection. Natural selection. The
struggle for existence. Relation of bees to clover. Re-
lation of cats to England's greatness. The equilibrium
of Nature. More organisms born than can mature.
How the hare becomes white. How selection becomes
adaptation. Acceleration of development. How bisex-
ual parentage brings variety. "Vom Vater hab' ich die
Statur." The value of death. The saving of time. Al-
truism and its struggle for existence. Every fact has a
meaning. Geographical distribution. Survival of the
existing. Geological distribution. Epoch-making events.
Change not progress. Vestigial organs. The pineal eye.
Origin of complex structures. The individual repeats
the history of the race. Embryology and evolution (John
Sterling Kingsley). Similarity of early stages in embry-
onic life. The egg of the mammal. Embryonic struc-

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tures in man. Gill slits in man. Objections to the the-
ory of descent. Relation of present heredity to past
environment. Darwin's hope. The species of eel. The
reality of species. The old idea of species has passed
away. The acceptance of the theory of descent. The
philosophy of evolution. Influence of theory of de-
scent. Origin of man. Meaning of homology. Decay-
ing scientific beliefs. Darwin's words. The conception
of God. Darwin's home. Boyesen on evolution.

II.-EVOLUTION: WHAT IT IS AND WHAT IT IS NOT . 54

What evolution is. The science of organic evolution or

bionomics. Meaning of law. Soundness and solvency

of Nature. The indifference of Nature. Evolution as a

theory of organic development. Each fact has a mean-

ing. Evolution as a method of study. Evolution as a

system of cosmic philosophy. Decay of formulæ. What

evolution is not. Man not a developed monkey. Not

progress, but adaptation. Humanity not the goal of evo-

lution. Change by slow divergence. No innate tend-

ency toward progression. Spontaneous generation.

Evolution not a creed. Evolution not a religion. Sci-

ence its own witness.

III. THE ELEMENTS OF ORGANIC EVOLUTION

Heredity. Irritability. Individuality. Natural selec-

tion. Concessions of life. Self-activity. Altruism. Iso-

lation. Nutrition in transmission. Survival of the exist-

ing. Inheritance of acquired characters. The unknown

factors.

IV. THE FACTORS OF EVOLUTION FROM THE STAND-

POINT OF EMBRYOLOGY. By Professor Edwin

Grant Conklin

Embryology shows the method of evolution. Statement
of propositions. Causes of development. Intrinsic causes
dependent on nature of protoplasm. Inherited charac-
ters predetermined in structure of germ cell. Germinal

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100

protoplasm relatively but not absolutely stable. Do ex-

trinsic factors affect germinal protoplasm? Diminished

nutrition. Changes in environment. Use and disuse.

Mechanical conditions. Results of impact. Value of

direct experiment. Return to the position of Darwin.

The final word still far distant.

PAGE

In-

Formation of character. Hereditary tendencies.

heritance of humanity. Inheritance of race characters.

Individual characters. The germ cell. Protoplasm.

Chromatin. Inequality of Nature's divisions. Atavism.

The mid-parent. The thoroughbred. Changes through

experience. Inheritance of acquired characters. Nature

of acquired characters. Prenatal influences. Transmis-

sion of impaired vitality. Ibsen's ghosts. Potentialities

not character. The higher heredity. The unity of the

ego. The ego a co-operation. Fame not greatness.

Counting one's ancestors. Lineage of a little girl. All

Englishmen of noble birth. Effect of primogeniture.

Origin of the English character. Race types and the

survival of the existing.

VI.—THE PHYSICAL BASIS OF HEREDITY. By Professor

Frank Mace McFarland

The cell theory. The meaning of the term "cell." Uni-
cellular and multicellular organisms. The essential
parts of the cell. The protoplasm. The nucleus. Ka-
ryokinesis. The chromosomes. Division of the centro-
some. The spindle. Division of the chromosomes.
Phases of cell division by karyokinesis. Direct division.
Somatic and reproductive tissues. Differentiation of so-
matic and reproductive tissues in Ascaris. Reproduction
in Protozoa. Conjugation. Gradual differentiation of
reproductive cells. Reproduction in Eudorina. Repro-
duction in Metazoa. Fundamental identity of the germ
cells. The egg cell. Maturation. The sperm cell.
Fertilization. Cleavage. The, reduction of the chromo-
somes. Theories as to structure and significance of the

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147

chromosome. The ultimate vital units. Significance of
reduction. Reduction in Ascaris. Reduction in Crusta-
cea. The chromatin as the bearer of hereditary influence.
Indirect evidence. Direct experimental evidence.

VII. THE DISTRIBUTION OF SPECIES

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. 191

Illustrations not arguments. Cumulative evidence.

The fauna of the Galapagos. Island life. Effects of mi-

gration on species. Effects of isolation. Barriers to diffu-

sion. Holarctic realm. Neotropical realm. Ethiopian

realm. Indian realm. Australian realm. Anomalies in

distribution. Adaptation of animals to environment.

Invasion of the Australian realm. Trout in Yellowstone

Park. Two-Ocean Pass. Laws of distribution of ani-

mals. Barriers of land, sea, and climate. Interdepend-

ence of species. The arctic birch. Crossing the bar-

riers. The flying fish. Subspecies or geographical

variations. Doubtful species. Darwin's experience.

The shore larks. Work of Dr. J. A. Allen. Species de-

fined by missing links. Analogy between variations of

species and of words. A fauna like a language. The

survival of the existing. How species change with time.

Physiological isolation.

VIII. LATITUDE AND VERTEBRÆ

Northern fishes have most vertebræ.

Fewest vertebræ

in shore fishes of the tropics. Fewer vertebræ indicates
greater specialization. Analogy of tropical waters to
cities of men. Origin of eels. Coral reefs the centre of
fish competition. Cephalization through competition.

221

Introduction: General evidence of paleontology; in-
completeness of the record. Law of acceleration of de-
velopment. Nomenclature of stages of growth. Paleon-
togeny General statement; Brachiopoda; Crustacea;
Mollusca; Pelecy poda; Cephalopoda; Method of work-