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Elementary Zoology
Pp. xv + 492, 172 figs., 12mo, 1901, $1.35.

First Lessons in Zoology
Pp. x + 363, 257 figs., 12mo, 1903, $1.12.

American Insects
Pp. vii + 671, 812 figs., 11 colored plates, 8vo,
1905 (American Nature Series, Group I), $5.00.
Students’ edition, $4.00.

Darwinism To-Day
Pp. xii +- 403, 8vo, 1907, $2.00.

Insect Stories

Pp. vi + 298, illustrated, 12mo, 1908 (A meri-
can Nature Series, Group V), $1.50.

Henry Hort anp Company

PUBLISHERS New York

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THE ANIMALS AND MAN:

AN ELEMENTARY TEXTBOOK OF ZOOLOGY

AND HUMAN PHYSIOLOGY

BY

VERNON LYMAN KELLOGG

PROFESSOR IN STANFORD UNIVERSITY

fi. 2 ZH *
cp

NEW YORK
HENRY HOLT AND COMP

IQII

CopyRIGHT, IgII,

BY

HENRY HOLT AND COMPANY

PREFATORY NOTE

This book is a simple introduction to the study of the
structure, physiology, behavior and classification of animals
and to the study of the make-up and physiology of the
human body. It makes use of some of what have been
proved by experience to be the most useful parts—specially
revised for this book—of the author’s “ Elementary Zoology”’
and ‘‘First Lessons in Zoology,” to which have been added
new chapters on human structure and physiology and on
certain special relations between animals and man. ‘The
whole book has been written and arranged from the point
of view of a biologist intent on making our knowledge of
the make-up and life of the lower animals help in under-
standing human structure and physiology and in contributing
to human welfare. I believe that this point of view need not
militate in the least against the disciplinary or informational
value of a text-book of zoology. I believe, indeed, that it
will enhance these values.

Chapters XXI to XXVIII, on human structure and
physiology, were written by Assistant Professor Isabel
McCracken of this University, and to that extent Miss
McCracken is joint author of the book.

I wish to acknowledge my indebtedness to those numerous
zoologists who have accorded me permission to use illustra-
tions original with them. The sources of these repeated
illustrations are indicated in the captions of the pictures.
The drawings for the figures original with me have mostly
been made by Miss Mary Wellman and Mr. Sekko Shimada
to both of whom I am under obligation for their intelligent
and skilful help.

Vaal Based <S
STANFORD UNIVERSITY, January, 1911.

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CONTENTS

PART [I

THE PARTS OF ANIMALS AND HOW THEY ARE USED

CHAPTER
I.
iT.
EIT:

nV:
Vs
VI.

VIE:
VIII.
x:

THE GRASSHOPPER AND THE SNAIL (External Structure)

THE SUNFISH AND THE SPARROW (External Structure)

THE GARDEN TOAD (BUFO LENTIGINOSUS) (External and
Internal Structure)

THE CRAYFISH meng SP.) (External and Internal

Structure)

AMCEBA, PARAMCECIUM AND VoRTICELLA (Structure and

Behavior)
ANIMAL PHYSIOLOGY
PART Ti
THE LIFE-HISTORY OF ANIMALS
MULTIPLICATION AND DEVELOPMENT

MosQuliITOES AND CATERPILLARS
FRoGS AND BIRDS

PART tit

PAGE
1
8

79
85
97

DIFFERENT KINDS .OF ANIMALS, THEIR CLASSIFICATION,

HABITS AND SPECIAL RELATION TO MAN

. THE CLASSIFICATION OF ANIMALS
. THE SIMPLEST, OR ONE-CELLED, ANIMALS (PROTOZOA)
. HuMAN DISEASES CAUSED BY ONE- CELLED ANIMALS .

. THE INVERTEBRATES : ; : : ; :
. THE INVERTEBRATES (continued): ARTHROPODS AND MOL-
: : . 149

LUSCS

. FIGHTING INSECT PEsts ; :
. THE VERTEBRATES: FISHES, BATRACHIANS, AND REPTILES 191
. THE VERTEBRATES (continued): BIRDS

. THE VERTEBRATES (continued): MAMMALS
. DOMESTICATED ANIMALS .

. Fosstt ANIMALS

107

118
_ 424

132

180

2 OA4
5237
58
275

CHAPTER

XXI.
XXII.
ROTI:
XXIV.
XXV.
XXVI.
XXVIT.
XXVIII.
XXIX.

CONTENTS

PART TLV

HUMAN STRUCTURE AND PHYSIOLOGY
(Chapters XXI-XXVIII by Isabel McCracken)

PAGE
INTRODUCTION, AND THE CHEMISTRY OF PHYSIOLOGY Bee call
DIGESTION AND ABSORPTION 03
THE BLOOD AND CIRCULATION ~~ oL6
THE SKELETON AND MUSCLES 2329
RESPIRATION AND EXCRETION . 343
NERVOUS SYSTEM . 354
THE SPECIAL SENSES : : . 368
MICRO-ORGANISMS AND SANITATION or
ANCIENT AND MODERN MAN . . 384

PART V

ANIMALS IN RELATION TO EACH OTHER, TO PLANTS, AND

XXX.
XXXI-.
XXXII.
XXXITII.
XXXIV.

Ne

INDEX

TLOSLHES OUTSIDE, WORLD

THE STRUGGLE TO LIVE, ADAPTATION, DISTRIBUTION, ETc. 399
PARASITISM AND DEGENERATION : : . 411
MuTuAL AID AND COMMUNAL LIFE : 3 Al
THE COLORS AND MARKINGS OF ANIMALS, AND THEIR USES 438

INSECTS AND FLOWERS . 450
APPENDICES

. STUDENT AND CLASSROOM EQUIPMENT AND METHODS AGE

. REARING ANIMALS AND MAKING COLLECTIONS . 469

. 483

THE ANIMALS AND MAN

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The Animals and Man

PART J

THE°-PARTS OF ANIMALS“AND
HOW (/LHEY ARE USED

CHAPTER 1

THE GRASSHOPPER AND THE:SNAIL

An animal’s body composed of parts.—The body of every
animal, even the very simplest ones, is composed of a
few or many parts, each part having some special use or
thing to do. A dog has its body made up of head, trunk,
legs, and tail—the head comprising skull with brain inside,
jaws with teeth, tongue, eyes, ears, etc.; the trunk com-
prising a host of internal parts, as the backbone, heart,
lungs, stomach, intestines, etc., and the legs in turn composed
of a series of bones to which are attached muscles, among
which run nerves and blood-vessels, the whole being covered
with a hairy skin. The study of the parts, external and
internal, of an animal is called anatemy, and the study of
the uses or functions of the parts is called physiology. In
earlier years anatomy and physiology were studied wholly
separately, as they still sometimes are. But we know that
the things animals do, and the ways in which they do them,
depend upon the parts of the body and upon the special
character of these parts. We know also that these parts
are specially developed and fitted to do certain things or
perform certain functions in special ways. That is, the

£

2 THE ANIMALS AND MAN

structure of a part and its
function or business are close-
ly related. A grasshopper’s
hind legs are specially long
and strong so as to enable the
grasshopper to hop; or we
may put it differently and
say that the grasshopper can
hop because its hind legs are
specially long and strong. In
whichever way we look at this
relation between the power of
an animal to do something in
ees a special way and its posses-
wild oats. Sslon of parts specially fitted
(Natural size; for doing this something,
from life.) Whether it be hopping, or
flying, or singing, or breathing
under water, it must be kept always plainly
in mind that such a close relation does
exist. | Dhetetore when we estudy) sure
make-up of an animal, examining care-
fully the various parts of the body, we
should always remember that this partic-
ular make-up or structure is closely con-
nected with the things the animal can do,
and the special manner in which it does
them.

The grasshopper.—Grasshoppers, better
called locusts, of some kind can be readily
found along roadsides or in fields (fig. 1).
Collect several specimens, keeping some
alive and dropping the others into the
killing-bottle (see p. 472). Examine care-
fully a dead specimen. Note that the body

THE GRASSHOPPER AND THE SNAIL 3

is made up of rings or segments. In what part of the body
are these rings plainest? ‘The legs are attached to the
middle part of the body called the thorax, of which the front
part (to which the fore legs are attached) is movable and is
covered over by a sort of saddle-shaped hood, while the
hinder part is solid and box-like. How many pairs of legs
are there? Examine a single leg and make a drawing of it,
showing of how many parts it is composed and how each
part appears. Of what use are the claws and the little pads
on the under surface of the foot? ‘To what part of the body
are the wings attached? Note how the narrow thicker fore
wings cover and protect the plaited delicate hind wings when
the wings are folded. When the locust flies for long dis-
tances it rises high into the air, until it finds an air current;
then it simply lets its large outspread hind wings act as flat
sails to hold it up, thus allowing it to float for many miles.
In this way the Rocky Mountain locusts sail or fly some-
times a thousand miles; all the way from Wyoming to
Kansas. Note the many veins in the wings. What are
these for? Draw a front wing and a hind wing.

On the head find two large compound eyes (see fig. 2),
three very small simple eyes, a pair of many-jointed feelers
or antenne, used both for feeling and probably also for
smelling, and a set of mouth-parts consisting of an upper
lip, a pair of hard, blackish-brown jaws or mandibles, a
second pair of jaw-like parts called maxille, each made up
of several small pieces and a small palpus or feeler, and an
under lip bearing two more small palpi. With the mandi-
bles the locust bites off, and with the help of the other parts,
chews bits of leaves, green stems, etc. The palpi are be-
lieved to be organs for feeling and tasting the food. Draw
the front of the head, naming the different parts.

Note that almost the whole outer surface of the body is
covered with a firm, smooth coat, the chitinized cuticle,
that is, the horny outer layer of the skin. The skin of the

4 THE ANIMALS AND MAN

neck, however, and that at the bases of the legs and wings
is soft. Why is this necessary? Note that the soft skin of
the neck is well protected by the projecting saddle-shaped
horny piece on the front thoracic body-ring. Another use of
the firm cuticle, or exo-skeleton, as it is called, is to afford
solid points of attachment for the many muscles of the
body, the locust having no bones or any kind of internal
skeleton. (In a few places there are processes or continua-

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tarsal segments
Fic. 2. Locust, with external parts named.

tions of the exo-skeleton projecting internally and these are
sometimes called the endo-skeleton.)

That part of the body behind the thorax is called the
abdomen. Examine the upper side of the first (nearest
the thorax) body-ring of the abdomen, and find two small,
nearly circular, thin places looking like little windows.
These are the hearing organs, or tympana, of the locust.
The sound-waves striking against these thin tightly stretched
bits of the body wall, set them into vibration, and these
vibrations stimulate a tiny vesicle and_nerve-ganglion

THE GRASSHOPPER AND THE SNAIL 5

on the inside from which a nerve leads to one of the internal
nerve-centers. This is a much simpler kind of ear than we
possess, and the locust probably cannot hear nearly as well
as we can. Note on each side of each abdominal body-ring
(except the last) a tiny blackish spot. These are breathing
pores or spiracles which open into a system of internal tubes
that carry the air to all parts of the body. The locust does
not take in air through nostrils on the head nor through the
mouth, but by means of these many lateral openings in the
body-wall. There is a spiracle near each tympanum, and
one on each side of the thorax near the insertion of the mid-
dle legs. At the very tip of the abdomen are several small
projecting parts which differ in the male and female. ‘The
female has two pairs of strong, curved, pointed pieces called
the ovipositor or egg-laying organ. When the locust is ready
to lay its eggs, by means of this strong ovipositor it bores a
hole in the ground into which the abdomen is pushed and the
eggs laid at the bottom. The male locust has a swollen,
rounded, abdominal tip, with a few short inconspicuous
pieces on the upper surface.

Examine now a live locust and see how it uses its legs
in walking and hopping; how it moves its jaws sidewise,
not up and down as with us; how its antenne keep “feeling”
about in front of it when it is walking; how the abdomen
keeps up a slight but distinct and regular expanding and
contracting. This movement forces air in and out of the
body through the spiracles; it is the breathing motion.

Make a drawing from lateral view of the whole body of
the locust, showing and naming all the parts studied.

(A more detailed study of the external structure of the locust can
easily be arranged for by reference to Comstock and Kellogg’s ‘‘Ele-
ments of Insect Anatomy,” 5th ed.)

The pond snail.—Pond snails may be found in almost
any pond, and live specimens may be easily kept in the
schoolroom aquarium or simply in bowls or glass jars of

6 THE ANIMALS AND MAN

water (fig. 3). They should be fed pieces of lettuce or
cabbage leaves. Observe the habits of the snails; how
they come to the surface to breathe; how they crawl about;
how they eat by rasping off bits of the leaves with the rough,
horny tongue; how they protrude from and withdraw into
the shell; how the feelers move in and out.

Examine a specimen with body extended from the shell,
and note that it is not made up of segments or rings, as the
locust, but is a soft, un-
segmented mass with
a firm, muscular, flat-
tish disk on its lower
side called the foot.
How does the snail
“walk” by means of
this “foot”? The body
is covered by the man-
tle, an edge of which
may be seen just at
the “Mmarem™ of mane
shell. The soft, flex-
ible body and firmer
muscular foot can
both be withdrawn
into the protecting
shell.

Fic.3. Pond snails ina battery jar aquarium. Find on the head
(One-third natural size; from life.) a pair of extensible
tentacles, the feelers,

with the eyes (dark spots) at their bases. Most other snails
and slugs have two pairs of tentacles or horns, the eyes being
on the tip of the second pair. Find also the mouth, and
examine with a lens the peculiar ribbon-like radula or
tongue, which is covered with fine curved teeth. The
radula is drawn back and forth across the food. and by it

|
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|

THE GRASSHOPPER AND THE SNAIL 7

small particles of the leaf are rasped off. Leaves which have
been fed on will show the rasped or scraped places.

Find also, usually just at the surface of the water, when
the snail has come up to breathe, a small hole on the right
side of the body; this is the breathing pore, and air entering
here passes into a small sac-like space, a simple kind of
lung.

Examine a shell and note the following parts: the aperture
at the large end, the apex or pointed end, the lip or outer
edge of the aperture, the lines of growth parallel with the lip,
the suture or spiral groove on the outside, the spire compris-
ing all the whorls or turns, and the columella or inner axis
of the spire. Do the whorls of all the shells turn the same
way? What is the use of the shell?

Make a drawing of the right-hand side of a snail and its
shell representing the animal fully extended; name all the
parts of the snail and shell.

If pond snails cannot be found, garden snails or slugs
may be studied. The slug is a snail-like animal without
a shell.

CHAPTER If

THE SUNFISH AND THE SPARROW

The two animals whose external structure we have studied
are both backboneless or invertebrate animals. Most of the
smaller animals are without internal bony skeletons and
hence without backbones. ‘This is true of the sponges and
sea-anemones, the starfishes, the worms, the crayfishes,
crabs and lobsters, the centipedes, and the spiders, as well
as of the insects and the snails, slugs, and clams. Con-
trasted with these backboneless animals are the backboned
ones, or vertebrates, including the fishes, amphibians, rep-
tiles, birds, and mammals or quadrupeds. We shall now
examine the external structure of two backboned animals, a
fish and a bird.

The sunfish (fig. 4).—Some kind of sunfish can be found
in the streams of any part of the United States, except in
Washington and Oregon, and in the higher Rocky Moun-
tains. Where sunfishes cannot be obtained, bass or perch
or gold-fish may be used for study. Specimens should be
taken alive if possible, and kept in a large jar or tub of fresh
water.

Examine a live sunfish. Note the deep, flattened trunk
of the body, and the paddle-like tail. The head is closely
fitted to the trunk without any neck. How are the scales
arranged? Remove a scale and examine it under a hand
lens. What sort of an edge has it? Examine the fin, called
the dorsal fin, on the back. Note that its front part is com-
posed of spines, and its posterior part of soft rays jointed
and branched, both spines and rays being connected by and
supporting a thin skin. At the end of the tail is the caudal

8

Fic. 4. A sunfish, Eu pomotis sp.

(One-half natural size. )

10 THE ANIMALS AND MAN

fin; in front of the tail on the under surface is the anal fin,
while still in front of this is the pair of ventral fins, and on
the sides of the body back of the mouth are the pectoral fins.
How is each of these fins composed? ‘The ventral fins cor-
respond to the hind legs of other backboned animals, while
the pectoral fins correspond to the forelegs, wings, or arms.
Watch the fish swim and determine the use of each kind of
fin. Professor Needham gives the following directions for
doing this: ‘“To learn the use of the pectoral and ventral
fins catch the fish with the hand, avoiding the sharp spines
at the front of the pectoral and anterior dorsal fins; fold the
pectoral fins backwards, flat against the sides of the hody;
pass a rubber band back over the head and around these
fins to keep them so. Keep the fish under water while at-
tempting to depress the pectoral spines, for in air it will
keep them rigidly erect. Pass another rubber band about
the ventral fins. ‘Then liberate the fish and watch it. What
position does its body assume? Release the paired fins and
fasten down the dorsal and anal fins with rubber bands.
Liberate the fish again, and observe how it gets along with-
out the use of these fins. What kind of a course does it take
through the water ?”’

ixamime the eyes. “Are there eyelids? in fromt ot the
eyes are two pairs of nostrils. Examine the inside of the
mouth. Is there a tongue? Where are the teeth situated,
and in what direction do they point? What advantage to
the fish is it to have the teeth pointing as they do?

Lift up the flap, called opercular flap, in front ofone of
the pectoral fins and bend it forward. Under it are four
gill arches, each with a double fringe of gills. The cavities
enclosed by the gills are called gill-pouches. Note the gill-
rakers, short and blunt, on the first gill arch. Note also, on
the under side of the flaps turned back, delicate red gill-like
structures covered by a membrane. ‘These are the false
gills. The true gills are organs by means of which the fish

THE SUNFISH AND THE SPARROW II

breathes under water. Note the fish continually gulping
water. This water with air dissolved in it passes through
the mouth into the gill-pouches and out under the operculum.
Thus the dissolved air in the water comes in contact with the
gills, passes through the delicate gill membranes and into
the blood, which runs in many fine capillaries through the
giJls, while at the same time the blood itself gives up carbon
dioxide, which passes out through the gill membranes into
the water. In this way the blood is purified.

Make a drawing from lateral view of the sunfish, showing
and naming the parts studied.

Professor Needham gives the following directions for
seeing the flow or circulation of the blood in the caudal fin
of a fish:

“Wrap the fish in a wet towel, leaving the caudal fin
exposed, and place it on a low box beside the microscope,
with its caudal fin extending across the center of the micro-
scope stage. Spread the fin out flat on a glass slip upon the
stage, so as to bring a thin portion of it into the field, and
examine it with low power. If the fish refuses to lie quietly,
pour a little chloroform on the towel near its mouth.

“Observe the conspicuous, dark, irregular pigment cells
scattered throughout the epidermis of the fin.

‘The larger blood-vessels are of two kinds: (1) arteries,
bringing blood out into the fin, and (2) veins, conveying the
blood back to the body again. ‘The smaller ones are the
capillaries connecting the arteries with the veins, and dis-
tributing the blood throughout the tissues of the fin.

“Observe that the blood consists of a fluid plasma, in
which float numerous corpuscles. Observe that the blood
appears red in the arteries and veins, where the corpuscles
are accumulated, but only slightly reddish or yellowish in
the capillaries, where the corpuscles form but a thin layer.

“Does the blood travel faster in the arteries and veins,
or in the capillaries?

12 THE ANIMALS AND MAN

“Place a bit of cover-glass over a very thin portion of the
fin and study it with higher power. Find two kinds of
corpuscles in the blood: (1) red corpuscles (red only when
a number are seen together), very numerous, and carried
along in the center of the larger currents closely packed
tofether-\ “and (2) “white *“corpuscles,;ji4 9 = mot. very
numerous, and usually seen trailing along the edges of
the blood currents, or escaping out into the tissues.”

Sunfishes eat insects, shellfish, spawn of other fishes, but
not other fishes themselves.

The females lay their eggs in shallow saucer-like depres-
sions on the stream bed, which are scooped out and cleared
of pebbles by the males. After laying her eggs the female
departs, leaving the nest to the exclusive care of the male.
The males are very active and pugnacious, defending the
nest with great bravery. This attention lasts, however, only
until the eggs hatch, which happens in a week or more,
depending on the temperature. The young fry are left to
care for themselves.

The English sparrow (fig. 5).—As the English sparrows,
which have spread over the whole country, are almost
universally held to be pests, the shooting of a few to serve
as specimens for the study of the external parts of a bird
may be looked on more leniently than the killing of other
birds should be. The habits of the live birds may be studied
as the pupils go and come from school or in the school
yard.

Examine a dead specimen. Note the division of the
body into head, trunk, and appendages—namely, wings
and legs. Note that the sparrow is covered with feathers,
some long, some short, in some places thick and in others
thin, but all fitting together to form a complete covering
for the body. Only the bill and feet are exposed, and
these are covered in one case (bill) with a horny sheath,
and in the other (feet) with horny scales. The feathers

THE SUNFISH AND THE SPARROW 13

Fic. 5. English sparrows; note the black cheeks and throat which dis-
tinguish the males. (One-half natural size; from life.)

14 THE ANIMALS AND MAN

and the horny covering of bill and feet are simply modified
portions of the skin. Of what uses are the feathers to the
bird ?

The feathers are of several kinds or types, each of which
has a name. In the wings and tail are long, stiff feathers
called quill feathers; those which overlie the whole body
and bear the color pattern are called contour feathers; the
small soft ones which cover the body more or less com-
pletely (being, however, mostly hidden by the contour
feathers) are called down feathers or plumules, while,
finally, the scattered, slender, soft, or stiff hair-like ones,
with thin bare stem and small
terminal tuft of branches,
are called thread feathers
or filoplumes.

Pull a quill feather from
the wing and examine it in
detail. Note the central stem
or shaft, composed of two
parts, a basal hollow trans-
parent quill, which bears no
web and by which the feath-
er is inserted in the skin, and
Fic. 6. Bit of bird’s feather, great- a longer terminal four-sided

ly magnified; s, shaft; b, barb; part, the rachis, which bears

bl, barbule; h, hamule. on either side a web or vane.
Examine the vane with a

lens and see that it is composed of many narrow linear plates
called barbs, and that each barb is fringed in turn with smaller
branches called barbules. Finally, each barbule bears many
fine barbicels or hamules, which can be seen with a micro-
scope. The barbs comprising the vanes are interlocked
with each other (fig. 6), thus forming a true web and giving
the vanes, composed of small, weak parts, much strength
and power of resistance. Rub the feathers from tip to base,

THE SUNFISH AND THE SPARROW 15

and, examining the vanes with the lens, find out what has
happened; now rub from base to tip, and note, under a
lens, the result.

Examine a plucked-out contour feather. How does it
differ from the quill feather? Can you understand its
structure from your study of the quill feather? Note that
the tip of the feather is colored and marked while the base
is not especially patterned. Why is this? Examine a down
feather. How does it differ in make-up from a quill feather ?
From a contour feather? What is the special use of the
down feathers? Finally, pluck out one of the hair-like
thread feathers from the base of the bill and examine it with
the lens to determine its structure.

Make a careful drawing of each of the four kinds of
feathers, naming all the parts.

In classifying birds reference is made in the manuals of
classification to differences in the shape and character
of many parts of the body and to differences in the plumage
of various body-regions. ‘To understand these references it
is necessary to become acquainted with the names applied
to these various small parts and regions, and so in fig. 7
the names of them are given.

Examine the bill or beak. It is composed of an upper
and a lower mandible or jaw; the meeting line of the man-
dibles is called the commissure, and the corner of the
mouth is called the rictus; the bristles at the rictus are the
rictal bristles; the median ridge of the upper mandible is
the culmen, and the median keel of the lower mandible
the gonys. Note just above the bill two openings. What
are they? How are they connected with the mouth? Note
the eyes, and at the inner angle of each the delicate nictitat-
ing membrane, which can be drawn over the ball. Does
the bird have external ears? The names of the regions of
the head which are commonly referred to in describing its
markings will be learned from fig. 7.

THE ANIMALS AND MAN

16

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THE SUNFISH AND THE SPARROW |

Examine a wing; determine by reference to fig. 7 what
feathers compose the primaries, secondaries, tertiaries,
greater, middle, and lesser coverts. How many primaries
are there? How many secondaries? At the bend of the
wing and lying partly over the upper greater coverts is a
tuft of short quills, the spurious quills; underneath the wing
at its junction with the body are some long, narrow feathers,
the axillars.

Spread the wing out and note where the quill feathers are
inserted. Note how perfectly the feathers fit together and
overlap, both when the wing is outspread and when folded.
The wing corresponds to our arm and hand, the primaries
being inserted on the hand (in the bird there is only one
large finger, two very small ones not showing except in the
skeleton), the secondaries on the forearm and the tertiaries
on the upper arm. With what part of the fish does the wing
of the bird correspond? If a cleaned and mounted skeleton
of a bird can be had for examination the bones of the wing
should be studied and drawn.

The names of the various regions of the trunk can be
learned by reference to fig. 7.

How many rectrices or tail feathers are there? What is
the use of the tail? Note the oil gland above the base of
the tail. What is the use of the oil? How is it put on the
feathers? Observe this in a chicken.

Examine a leg. It is composed of thigh, shank, and foot,
the foot comprising the long slender tarsus and four toes
with claws. What parts of the leg are feathered? Note
the covering on the unfeathered parts. What are the toes
well fitted for? ‘There is much variety in the shape and
character of birds’ legs, including differences in the length
of the various parts, in the covering, in the number and
position of the toes, and in the size of the claws. All these
differences, as well as the many in the shape and character
of the bill, are correlated with habits, especially the feeding

18 THE ANIMALS AND MAN

habits of the birds, and offer a most interesting subject for
study.

The English sparrow was first introduced into the United
States in 1850, and since that time has rapidly populated
most of the cities and towns of the country. On account of
its extreme adaptability to surroundings, its omnivorous
food-habits, and its fecundity, it survives where other birds
would die out. It also crowds out and has caused the dis-
appearance or death of other birds more attractive and more
useful. The sparrow annually rears five or six broods of
young, laying from six to ten eggs at each sitting. Unmo-
lested a single pair would multiply to a most astonishing
number. It has, however, many enemies, most common
among them perhaps being the “‘small boy,” but birds and
mammals play the chief part in the destruction. The
smaller hawks prey upon it, and rats and mice destroy
sreat numbers of its young and of its eggs whenever the
nests can be reached. The sparrow is omnivorous, and
when driven to it is a loathsome scavenger, though at other
times its tastes are for dainty fruits. Its senses of perception
are of the keenest; it can determine friend or foe at long
range. The nesting habits are simple, the nests being
roughly made of any sort of twigs and stems mixed with
hair and feathers and placed in cornices or trees. A maple-
tree in a small Missouri town contained at one time thirty-
seven of these nests.

CHAPTER. ITE*
THE GARDEN TOAD (Bufo lentiginosus)

TecunicaAL Note.—Although this description is written for the
toad it will fit for the dissection of the frog. It will be found, after
casting aside a few ungrounded prejudices, that the toad is the better
for class dissection. Toads are best collected about dusk, when they
can be picked up in almost any garden in town or in the country. Dur-
ing the spring many can be found in the ponds where they are breeding.
To kill the toad place it in an air-tight vessel with a piece of cotton or
cloth saturated in chloroform or ether. When the toad is dead, wash
off the specimen and put in a dissecting-pan for study. Several speci-
mens should be placed in a nitric acid solution for a day or so (for
directions for preparing, see p. 25) to be used later for the study of the
nervous system. Also several specimens should be injected for the
better study of the circulatory system. With an injecting mass made
as directed in Appendix I, introduce through a small canula into the
ventricle of the heart. This will inject the arterial system, and with
increased pressure the injecting mass may be forced through the valves
of the heart, thus passing into the auricles and throughout the venous
system. After injecting use the specimen fresh or after it has been
preserved in 4% formalin.

External structure.—Note that the body of the toad is
divided into several principal regions or parts, correspond-
ing to those of the human body. Indeed, all through the
study of the toad’s anatomy a general correspondence of the
body-parts and their arrangement with the parts of the
human body and their arrangement will be manifest. The
toad and ourselves belong to the same great animal branch.

*If preferred, or the school is not equipped for dissections by pupils, the
teacher may substitute demonstrations of already dissected specimens for
the dissections by students called for by this and the following chapter.

19

20 THE ANIMALS AND MAN

As you look at the toad note the similarity of the parts
on one side to those of the other, as right leg correspond-
ing to left leg, right eye to left eye, etc. This arrangement
of the body in similar halves among animals is known as
bilateral symmetry. As a rule animals which show bilateral
symmetry move in a definite direction. ‘The part that moves
forward is the anterior end, while the opposite extremity is
the posterior end. In most animals we note two other views
or aspects; that which is called the “back” and with most
animals is, under ordinary conditions, uppermost is called
the dorsum or dorsal aspect, while that which hes below is the
venter or ventral aspect. When referring to a view from one
side we speak of it as a right or left lateral aspect. These
terms hold good for most of the animals that we shall study.

Note on the head of the toad the wide, transverse mouth.
What other openings are on the head? Note the two large
eyes, the organs of sight. Just back of each eye find an
elliptical, smooth membrane. ‘This is the tympanum of
the outer ear, and through this membrane the vibrations
produced by sound-waves are transferred to the imner
ear, which receives sensations and transmits them to the
brain. Open the mouth by drawing down the lower jaw.
Note just within the angle of the lower jaw the /fongue.
How is it attached to the wall of the mouth? On the tongue
are a great many fine papille in which is located the sense
of taste. It has now been seen that most of the special senses
of the toad have their seat in the head. Pass a straw or bris-
tle into one of the nostrils. Where does it come out? These
internal openings to the nose are the zmner nares. Note in
the roof of the mouth just posterior to each of the eyeballs
an opening. These are the internal openings to the wide
Eustachian tubes, which lead to the mouth from the chamber
of the ear behind the tympanum.

Note far back in the mouth an opening through which
food passes. This is the wsophagus or gullet. Note just

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below this gullet an elevation in which is a perpendicular
slit, the glottis. This is the upper end of the laryngotracheal
chamber, and the flaps within on either side of the slit are
the vocal cords.

Note at the posterior end of the body in the median line
an opening. This is the anal opening or anus. Note the
general make-up of the toad. How do its arms compare
with our own? How do its fore feet (hands) differ from its
hind feet? Note that the body is covered by a tough envel-
oping membrane, the skim. In the skin are many glands
which by their excretion keep it soft and moist.

Internal Structure.—Trcunicat Note.—With a fine pair of
scissors make a longitudinal median cut through the skin of the venter
from the anal opening to the angle of the lower jaw. Spread the cut
edges apart and pin back in the dissecting-pan.

Note the complex system of muscles which govern the
movements of the tongue. Observe a number of pairs of
muscles overlying the bones which support the arms. ‘These
are attached to the pectoral or shoulder-girdle. Note the
large sheet of muscles covering the ventral aspect of the
toad. These are the abdominal muscles, which consist of
two sets, an outer and an inner layer. Note that posteriorly
the abdominal muscles are attached to a bone. ‘This is the
pubic bone of the pelvic girdle which supports the hind legs.

TecunicaAL Note.—With the scissors cut through the muscles of
the body-wall at the pubic bone and pass the points forward to the
shoulder-girdle. Separate the bones of the shoulder-girdle and pin
out the flaps of skin and muscle to right and left in the dissecting-pan
(see fig. 8). Cover the dissection with clear water or weak alcohol.

Note two large conspicuous soft brown lobes of tissue.
These form the Jiver, an organ which produces a secretion
that assists in the process of digestion. Note just anterior
to the liver and extending between its two lobes a pear-
shaped organ, the heart. The lower end or apex of the

22 THE ANIMALS AND MAN

heart, ventricle, undergoes a contraction, forcing blood out
into the blood-vessels. This is followed by a relaxation of
the apex and a contraction of the basal portion, the auricle.
The heart is surrounded by a delicate semi-transparent sac,
the pericardium. ‘The pericardium is filled with a watery
fluid, body-lymph, which bathes the heart. Note between
the lobes of the liver a small bladder-shaped transparent
organ of a pinkish color. This is the gall-bladder, a reser-
voir for the bile, the secretion from the liver. Separate the
lobes of the liver and note, beneath, the long convoluted
tube which fills most of the body-cavity. This is part of
the alimentary canal. ‘The most anterior portion of the
canal, the gullet or esophagus, leads to a large U-shaped
enlargement, the stomach. From the lower end of the
stomach there extends a long, slender, very much convo-
luted tube, the small intestine, which is followed by a much
larger one, the large intestine. This large intestine after
one or two turns passes directly back into the rectum, which
opens at last to the exterior through the anus. Note just
ventral to the rectum a large thin-walled membranous
sac. ‘This is the urinary bladder which acts as a reservoir for
the secretion from the kidneys. Notice a many-branched
yellow structure with a glistening appearance, the fat-body
(corpus adiposum). Now push liver and intestine to one
side and note the pinkish sac-like bodies (perhaps filled with
air), the /ungs. The lungs are paired bodies which open into
the laryngotracheal chamber. ‘The toad takes air into its
mouth through its nostrils, and then forces it, by a kind of
swallowing action, through the laryngotracheal chamber
into the lungs.

Now lift the stomach and note in the loop between its
lower end and the small intestine a thin transparent tissue.
This is a part of the mesentery, which will be found to sus-
pend the whole alimentary canal and its attached organs to
the dorsal wall of the body. Note in the loop of the stomach

THE GARDEN TOAD 23

in the mesentery an irregular pinkish glandular structure
which leads by a small duct into the intestine. This gland
is the pancreas, and the duct is the pancreatic duct. From it
comes a secretion which aids in the digestion of food. Near
the upper end of the pancreas note a round nodular structure,
generally dark red. This is the spleen, a ductless gland, the
use of which is not altogether known.

Make a drawing which will show as many of the organs
noted as possible.

TECHNICAL NotTE.—Pass two pieces of thread under the rectum
near the pubic bone. Tie these threads tightly a short distance apart
and then cut the rectum in two between the threads. Now carefully
lift up the alimentary canal with attached organs (liver, etc.), and cut
it off near the region of the heart.

How is the heart situated with regard to the lungs? The
heart consists of a lower chamber with thick muscular walls,
the tip, called the ventricle, and two upper thin-walled
chambers, the right and left auricles. Can you make out
these three chambers? ‘The purified blood from the lungs
flows into the left auricle, while the venous blood from all
over the body laden with its carbon dioxid enters the right
auricle. From these two chambers the blood enters the
ventricle. Here the pure and impure blood are mixed.
From the ventricle the blood enters a large muscular tube
on the ventral side of the heart. This is the conus arteriosus,
which gives off three branches on each side; the anterior
ones, the carotid arteries, supply the head, the next ones, the
systemic arteries, or aorte, carry blood to the rest of the body,
while the posterior vessels, the pulmonary arteries, go directly
to the lungs and there break up into fine vessels (capillaries)
where the carbon dioxid is given off and oxygen is taken
from the air. From the lungs the blood returns through the
pulmonary vein to the left auricle. Meanwhile the blood
which has passed through the systemic arteries and body
capillaries is collected again into other vessels going back

24 THE ANIMALS AND MAN

to the heart; these are the veins, which empty into a large
thin-walled reservoir, the stmus venosus, which in turn con-
nects with the right auricle of the heart. Three large veins
enter the sinus venosus, namely, two pre-caval veins at the
anterior end, and a single post-caval vein at the posterior
end. ‘Trace out the larger arteries and veins from the heart
to their division into or origin from the smaller vessels.

TECHNICAL Note.—Carefully remove the heart together with the
lungs. The lungs may be inflated by blowing into them through the
laryngotracheal chamber with a quill and tying them tightly, after
which they should be left for several days to dry. When perfectly dry,
sections may be cut through them in various places with a sharp knife,
and by this means a very good idea of the simple lung structure of the
lower backboned animals can be obtained. With a sharp knife cut
the heart open, beginning at the tip (ventricle) and cutting up through
the conus arteriosus and the two auricles. Note the valves in the
heart which separate the different compartments.

Note on either side of the median line in the dorsal region
a pair of reddish glandular bodies, the kidneys. Attached
to the kidneys of the male are two white ovoid glandular
masses. These are the reproductive organs. From each
kidney trace a tube, wreter, posteriorly toward the region
of the anus. The kidneys are the principal excretory organs
of the body. The blood which flows through the delicate
blood-vessels in the kidney gives up there much of its waste
products. These pass out through small tubules of the
kidneys into the ureters, which carry the wastes toward the
anus. Along one side of each kidney may be seen a
yellowish glistening mass, the adrenal body.

In some of the specimens studied, the body cavity may be
filled with thousands of little black spherical bodies. ‘These
are undeveloped eggs lying in the female reproductive or-
gans situated on each side of the post caval vein. ‘They are
deposited by the mother toad in the water in long strings
of transparent jelly, which are usually wound around sticks
or plant-stems at the bottom of the pond near the shore.

THE GARDEN TOAD 25

From these eggs the young toads hatch as tadpoles and in
their life-history pass through an interesting metamorphosis.
(See Chapter IX.)

TECHNICAL NotE.—The teacher should be provided with several
well-cleaned skeletons of the toad in order that the bones may be care-
fully studied. Boil in a soap solution a toad from which most of the
muscles and skin have been removed (see Appendix I). Leave in this
solution until the muscles are quite soft and then pick off all bits of mus-
cles and tissue from the bones. If this is carefully done, the ligaments
which bind the bones will be left intact and the skeleton will hold
together.

Note that the skeleton (fig. 9) consists of a head portion
which is composed of many bones joined together to form
a bony box, the skull; of a series of small segments, the
vertebre, forming the vertebral column, which with the skull
forms the axial skeleton; and of the appendicular skeleton,
consisting of the bones of the fore and hind limbs. Note
that the skull is composed of many bones joined together,
some by sutures, while others are fused. The anterior limbs
(arms) articulate with the pectoral or shoulder-girdle. ‘The
arms will be seen to be made up of a number of bones placed
end to end. Note that the uppermost, the /umerus, is
attached to the pectoral girdle, while at its lower end it
articulates with the radio-ulna. At the lower end of the
radio-ulna is a small series of carpal bones which afford
attachments for the slender finger-bones, the fialanges or
digital bones. The bones of the leg are articulated with a
closely fused set of bones, the pelvic girdle. ‘The leg-bones,
proceeding from the pelvic girdle, are named femur, tibio-
fibula, tarsal bones, and phalanges or digits. ‘To what bones
of the arm do these correspond? Determine the other prin-
cipal bones of the skeleton by reference to figure 9.

TECHNICAL Note.—In a specimen which has been macerated for
some time in 20% nitric acid dissect out the nervous system. Place
the specimen in a pan, ventral side uppermost, and pin out. Carefully
pick away the vertebrae and the roof of the mouth-cavity, thereby
exposing the central nervous system, which will appear light yellow.

26 THE ANIMALS AND MAN

nasal

palatine. . spheno-ethmoid

maxillary

ee) _.-radio-ulna

bs

S
&

XQ)

. ~ Calcaneunr

tibio-fibula
astragalus

Fic. 9. Skeleton of the garden toad.

THE GARDEN TOAD 27

Examine the brain. In front of the true brain are the
olfactory lobes, the nervous centre for the sense of smell.
The brain itself is composed of several parts. ‘The anterior
portion consists of two elongated parts, the cerebral hemis-
pheres; just back of these are the optic lobes or midbrain,
consisting of two short lobes, which are followed by the
small cerebellum, which in turn is followed by a long part,
the medulla oblongata, which runs imperceptibly into the
long dorsal nerve, the spinal cord. Note the large optic
nerves running out to each eye. How far backward does
the spinal cord extend? Note the many pairs of nerves
given off from the brain and spinal cord. ‘These nerves
branch and subdivide until they end in very fine fibres.
Some end in the muscle-fibres, and through them the cen-
tral nervous system innervates the muscles. These are
motor endings. Still others pass to the surface and receive
impressions from the outside. These last are sensory end-
ings. Note that the spinal nerves arise from the spinal cord
by two roots, an anterior or ventral, and a posterior or dorsal
root. ‘Trace the principal spinal nerves to the body-parts
innervated by them. ‘These nerves are numbered as first,
second, etc., according to the number of the vertebree (count-
ing from the head backward) from behind which they arise.

For a more detailed account of the anatomy of the toad
(frog) the student may refer to Parker and Haswell’s Text-
book of Zoology, Vol. II.

CHAP LER: 1y

THE CRAYFISH (Cambarus sp.)

TECHNICAL Note.—The crayfish, or crawfish, is found in most of
the fresh-water ponds and streams of the United States. (It is not
found east of the Hoosatonic River, Mass. In this region the lobster
may be used. On the Pacific coast the crayfishes belong to the genus
Astacus.) Crayfishes may be taken by a net baited with dead fish,
or they may be caught in a trap made from a box with ends which
open in, and baited with dead fish or animal refuse of any sort. This
box should be placed in a pond or stream frequented by crayfish. If
possible the student should study the living animal and observe its
habits. Crayfish which are to be kept alive should be placed in a
moist chamber in a cool place. They will keep for a longer time in a
moist chamber than in water. Some fresh specimens should be in-
jected by the teacher for the study of the circulatory system. A watery
solution of coloring matter or, better, of an injecting mass of gelatine
(see Appendix I) is injected into the heart through the needle of a hypo-
dermic syringe. For the purpcse of injecting, a small bit of the shell may
be removed from the cephalothorax above the heart. Specimens which
are to be kept for some time should be placed in alcohol or 4% formalin.

External structure (fig. ro).—Place a specimen in a pan
for study. Note that the body, which of course differs much
in shape from that of the toad, is also unlike that of the
toad in being covered by a hard calcareous exo-skeleton,
which acts as a covering for the soft parts and also as a place
of attachment for the muscles, just as the internal skeleton
does in the case of the toad. The body is composed of an
anterior part, the cephalothorax, and a posterior part, the
abdomen. ‘The cephalothorax is covered above and on the
sides by the carapace, which is divided into parts correspond-
ing to the head and thorax of the toad by the transverse

28

THE CRAYFISH 29

antennule

opening of green gland
\

genital aperture -~ 7

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a

5} 7 pleopods

--"
-<-
--

. Z
Ss by Ee?

Fic. 10. Ventral aspect of crayfish, Cambarus sp. with the appendages
of one side disarticulated.

30 THE ANIMALS AND MAN

cervical suture. ‘The abdomen is composed of segments.
How many? ‘The flattened terminal segment is called the
telson. Is the cephalothorax composed of segments? Where
is the mouth of the crayfish? Where is the anal opening?

At the anterior end of the cephalothorax note a sharp
projection, the rostrum. Where are the eyes? Remove one
of them and examine its outer surface with a microscope. A
bit of the outer wall should be torn off and mounted on a
glass slide. Note that it is made up of a great many little
facets placed side by side. Each of these facets is the exter-
nal window of an eye element or ommatidium. An eye com-
posed in this way is called a compound eye. In front of the
eye note two pairs of slender many-segmented appendages.
The shorter pair, the antennules, are two-branched. Remove
one of them and note at its base a small slit along the upper
surface. This slit opens into a small bag-like structure
which contains fine sand-grains. ‘The bag is protected by a
series of fine bristles along the edge of the slit. This bag-
like structure is believed to be an auditory organ. The
longer pair of appendages are the antenne, and the sense
of smell is believed to be located in the fine hair-like pro-
jections upon the joints. ‘Thus it is seen that the sense-
organs of the crayfish, like those of the toad, are located on
the head. Beneath the basal portion of each antenna there
is a flat plate-like projection, at the base of which on the
upper edge will be noted a small opening, the exit of the
kidney, or green gland.

Make a drawing of the surface of part of an eye; also of
an antennule; and of an antenna.

TECHNICAL Note.—Stick one point of the scissors under the pos-
terior end of the carapace on the right side, and cut forward, thus
exposing a large cavity, the gill-chamber. Remove all of the mouth-
parts, legs and abdominal appendages from the right side, being careful
to leave the fringe-like parts, the gills, attached to their respective
legs. Place all of the appendages in order on a piece of cardboard.

THE, CRAYFISH 31

Examine the abdominal appendages, called pleopods, or
swimming feet. How many pairs are there? Each is com-
posed of a basal part, the protopodite, and two terminal seg-
ments, an inner one, the endopodite, and an outer, the exo-
podite. In the males the first and second pleopods of the
abdomen are larger and less flexible than the others. In the
female the pleopods serve to carry the eggs and the first two
pairs are very small or absent. Note the last set of abdomi-
nal appendages. These are the uropods, which together
with the telson form the tail.

Make a drawing of the pleopods of one side.

Examine the appendages of the cephalothorax. Like the
appendages of the abdomen the typical composition of each
includes a protopodite, an exopodite and an endopodite, but
some of these appendages are much modified, and show a
loss of one of these parts, or the addition of an extra part.
The cephalothoracic appendages may be divided into three
groups, an anterior group of three pairs of mouth-parts
(belonging to the head) of which the first pair is the mandi-
bles and the others are the maxille; a second group of three
pairs of foot-jaws or mawxillipeds, belonging to the thorax,
and a third group of five pairs of walking-legs. ‘The man-
dibles, lying next to the mouth-opening, are hard and jaw-
like and lack the exopodite; the first maxillz are small and
also lack the exopodite; the second maxilla have a large
paddle-like structure which extends back over the gills on
each side within the space, the branchial chamber, above the
gills. It is by means of this paddle-like structure (the
scaphognathite) that currents of water are kept up through
the gill-chambers. The maxillipeds increase in size from
first to third pair. Each pair of walking-legs except the
last bears gills. These gills are the organs by which the
blood is purified. The blood of the crayfish flows into the
large vessels on the outer sides of the gill and thence into
the fine vessels in the little leaf-like lamella. At the same

32 THE ANIMALS AND MAN

time the air which is mixed with the water bathing the gills
passes freely through the thin membranous walls of these
lamellz and blood-vessels, and the blood gives off its car-
bon dioxide to the water and takes up oxygen from the air
in the water. Thus it will be seen that the office of the
gill is like that of the lung in the toad, namely, to act as an
organ for the elimination of carbon dioxide and the taking
up of oxygen.

Note the pincer-like appendages of the first pair of legs.
These pincers are the chel@, with which food is torn into bits
and placed in the mouth. In the basal segment of each of
the last pair of legs of the male note the genital pore. In the
female the genital pores are in the basal segments of the next
to last pair of legs. Is the crayfish bilaterally symmetrical ?
Note the repetition of parts in the crayfish, that is, the recur-
rence of similar parts in successive segments. ‘This serial
repetition of parts among animals is called metamerism.

Internal Structure (fig. 11)—TrcunicaL Nore.—With a pair
of scissors cut through the dorsal wall of the cephalothorax into the
body-cavity. Cut the body-wall away from both sides and remove
the middle portion.

At the anterior end of the cephalothorax note the large
membranous sac, the stomach. Attached to each end of this
are sets of muscles which control its movements. ‘To the
right and left of the stomach notice attached to the shell
large muscles which connect by stout ligaments at their
lower ends with the mandibles. Note a yellow fringe-like
structure, the digestive gland, which fills most of the region
about the stomach. It connects by a pair of small tubes, the
bile-ducts, with the alimentary canal. Within the posterior
portion of the cephalothorax note a pentagonal sac, the
heart, contained within a delicate membrane, the fericar-
dium. Remove the pericardium and note a pair of dorsal
openings into the heart, called ostia. (There are also two

33

THE CRAYFISH

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34 THE ANIMALS AND MAN

lateral pairs and a ventral pair of ostia.) Note passing
anteriorly from the heart along the median line to the eyes
a blood-vessel, the ophthalmic artery. Arising from the
anterior portion of the heart are the antennary arteries, run-
ning to the antenne. Yet another pair running anteriorly
from the heart to the stomach and digestive glands are called
the hepatic arteries. From the posterior end cf the heart
arises the dorsal abdominal artery, running back to the telson.
Below this arises the sternal artery, which will be seen later.

In the region below the heart are located the reproductive
organs. They are whitish glandular masses from each of
which runs a tube which opens at the base of the last pair
of walking-legs in the male, and at the base of the third pair
of walking-legs in the female.

TrecunicaAL Notre.—Cut longitudinally through the dorsal wall of
the abdomen on either side of the median line and remove the piece
of shell.

Note the powerful muscles within which flex and extend
the abdomen. By a rapid contraction of these muscles the
tail is brought beneath the body, propelling the animal
strongly backwards. When the crayfish crawls it generally
goes forward, but in swimming it reverses this direction.

Make a drawing showing, in their natural position, the
internal organs which have been studied.

Examine the alimentary canal for its whole length. Note
that the large bladder-shaped stomach is attached to the
mouth-opening by a short tube. What part of the canal is
this? From the posterior end of the stomach is a short
thick-walled part, the small intestine, followed by a long
straight tube, the large intestine, which opens to the exterior
through the anus.

TrecunicaL Note.—Remove the alimentary canal, detaching it
from the anal end first, and working forward.

PRE SCRAYEFSH 35

Cut the stomach open. Note an interior portion, the
cardiac chamber, and a smaller posterior portion, the pyloric
chamber. Examine its inner surface. What do you find
here? This structure is called the gastric mill. Food, which
for the most part consists of any dead organic matter, is
chewed by the ‘“‘stomach-teeth” into fine bits, and is then
passed into the pyloric chamber. It is here that the diges-
tive glands empty their secretion into the food. These glands
have the same office as have the liver and pancreas combined
in the toad, and so they are often called the hepato-pancreas.
When the stomach has been removed there will be noted in
the anterior portion of the body paired, flattened bodies,
already mentioned, which connect with openings at the base
of each of the antennze by means of wide thin-walled sacs,
the ureters. ‘These organs are the kidneys, or green glands.
Their office is similar to that of the kidneys in the toad,
namely, the elimination of waste from the body.

TECHNICAL NotEe.—Carefully remove all of the alimentary canal,
digestive glands, and reproductive organs. This process will expose
the floor of the cephalothorax. Now cut away from either side the
horny floor or bridge at the bottom of the cephalothorax. If the
specimen has not already been immersed, place it in clear water for
further dissection.

The foregoing dissection will expose the central nervous
system. It extends as a series of paired ganglia connected
by a double nerve-cord along the ventral median line from
the cesophagus to the last segment of the abdomen. From
what points do the lateral nerves arise? Anteriorly the
double nerve-cord divides, the two parts passing upward on
each side of the cesophagus, where they again meet to form
the supra-esophageal ganglion or brain. Where do the
nerves tun which rise from the brain? What is the differ-
ence between the position of the central nervous system in
the crayfish and in the toad?

36 THE ANIMALS AND MAN

Make a drawing of the nervous system.

Just beneath the nerve-cord note a blood-vessel extending
the length of the body. ‘This is the sternal artery, which
arises from the posterior end of the heart and passes ventrally
at one side of the alimentary canal and between the nerve-
cords. Here the sternal artery divides into an anterior and
a posterior branch, from which lesser branches are given
off to each one of the appendages. ‘The various arteries
running to all parts of the body finally pour out the blood
into the body-cavity, where it flows freely in the spaces
among the various tissues and organs. After the blood has
bathed the body tissues it flows to the gills on either side
passing up the outer side of the gill through delicate thin-
walled vessels, where it is oxygenated as has already been
described. From the gills the purified blood flows back on
the inner side through a large chamber, sznus, into the peri-
cardium, through the ostia of the heart, whence it is driven
into the arteries once more. ‘This sort of a circulatory sys-
tem in which the blood in places is not enclosed in a definite
vessel is known as an open system. In the toad we find the
blood in a closed system, i.e., arteries leading into capillaries
which in turn lead into veins, in no case allowing the blood
to pass freely through the spaces of the body.

For a detailed account of the life and structure of the
crayfish see Huxley’s ‘‘The Crayfish: an Introduction to
the Study of Zoology.”

CHAPTER V

AMCBA, PARAMGCIUM AND VORTICELLA

Ameceba.—TecunicaL Note.—Amebe are found in stagnant pools
of water on the dead leaves, sticks and slime at the bottom. To obtain
them, collect slime and water from various puddles in separate bottles
and take them to the laboratory. Place a small drop of slime on a slide
under a cover-glass. Examine under the low power first and note any
small transparent or opalescent objects in the field. Examine these ob-
jects with the higher power and note that some are mere granular
jelly-like specks, which slowly (but constantly) change their form.
These are Amebe.

A teacher of zoology recommends the following method of obtaining
a large supply of Amebe: ‘For rearing Amebe place two or three
inches of sand in a common tub, which is then filled with water and
placed some feet from a north window; three or four opened mussels,
with merest trace of the mud from the stream in which they are taken,
are partially buried in the sand and a handful of Nz/ella and a couple
of crayfish cut in two are added; as decomposition goes on a very gentle
stream is allowed to flow into the tub, and after from two to four weeks
abundant Amebe are to be found on the surface of the sand and in
the scum on the sides of the tub; small Amebe appear at first, and
later the large ones.”

Having found an Ameba (fig. 12) note its irregular shape,
and if it moves actively observe its method of moving. How
is this accomplished? The viscous, jelly-like substance
which composes the whole body of an Ameba is called
protoplasm. The little processes which stick out in various
directions are the ‘‘false feet” (pseudopodia). Note that the
outer portion, the ectosarc, of the protoplasmic body is clear,
while the inner, the endosarc, is more or less granular in .
structure. Has Ameba a definite body-wall? Do the
pseudopodia protrude only from certain parts of the body?

37

38 THE ANIMALS AND MAN

Within the endosarc note a clear globular spot which con-
tracts and expands, or pulsates, more or less regularly. This
is the contractile vacuole. Note the small granules which
move about within the endosare. ‘These are food-particles

Fic. 12. An Amceba, showing forms assumed by a single individual in
four successiv> changes. (Greatly magnified; from life.)

which have been taken in through the body-wall. Note how
pseudopodia flow about food-particles in the water and how
these are digested by the protoplasm. If an Ameba comes
into contact with a particle of sand, note how it at once
retreats. Note within the endosarc an oval transparent body

AMC@BA, PARAMCCIUM AND VORTICELLA 39

which shows no pulsations. This is the nucleus, a very com-
plex little structure of great importance in the make-up of
Ameba.

Note that Ameba has no mouth or alimentary canal; no
nostrils or lungs, no heart or blood-vessels, no muscles, no
glands. It is an animal body not made up of numerous dis-
tinct organs and diverse tissues. Its whole body is a minute
speck of protoplasm, and forms a single animal cell. But it
takes in food, it moves, it excretes waste matter from the
body, is sensitive to the touch of surrounding objects, and,
as we may be able to see, it can reproduce itself, ie.,
produce new Amabe. Ameba is one of the simplest living
animals.

It is only rarely that we can find an Ameba actually repro-
ducing. ‘The process, in its gross features, is very simple.
First the Ameba draws in all of its pseudopodia and remains
dormant fora time. Next, certain changes take place in the
nucleus, which divides into equal portions, one part with-
drawing to one end of the protoplasmic body, the other to
the opposite end. Soon the body protoplasm itself begins
to divide into two parts, each part collecting about its own
half of the nucleus. Finally the two halves pull entirely
away from each other and form two new Amebe, each like
the original, but only half as large. This is the simplest kind
of reproduction found among animals.

Amebe continue to live and multiply as long as the con-
ditions surrounding them are favorable. But when the pond
dries up the Amebe in it would be exterminated were it not
for a careful provision of nature. When the pond begins to
dry up each Ameba contracts its pseudopodia and the pro-
toplasm secretes a horny capsule about itself. It is now
protected from dry weather and can be blown by the winds
from place to place until the rains begin, when it expands,
throws off the capsule and commences active life again in
some new pond.

40 THE ANIMALS AND MAN

The Slipper Animalcule (Paramecium sp.).—TECHNICAL NOTE.—
Paramecia can be secured in most pond-water where leaves or other
vegetation are decaying. However, if specimens are not readily se-
cured place some hay or finely cut dry clover in a glass dish, cover with
water and leave in the sun for several days. In this mixture specimens
will develop by thousands. Place a drop of water containing Paramecia
on a slide with cover-glass over it. Using a low power, note the many
small animals darting hither and thither in the field. Run a thin
mixture of cherry gum in water under the cover-glass. In this mixture
they can be kept more quiet and be better studied.

How does Paramecium (fig. 13)
differ from Ameba in form and
movement? Has the bedy an
anterior and a posterior end? The
delicate, short, thread-like pro-
cesses, on the surface of the body,
which beat about very rapidly in
the water are called cilia, and they
are simply fine prolongations of the
body protoplasm. What is their
function? Note a fine cuticle cov-
ering the body. Note also many
minute oval sacs lying side by side
in the ectosarc. ‘These are called
trichocysts and from each a fine
thread can be thrust out.

Note on one side, beginning at
the anterior end, the buccal groove
leading into the interior through
the gullet. Observe also that by
the action of the cilia in the buc-
Bret As we Parambconmess cal groove food-particles are swept

note the body-wall, cilia, into the gullet. Rejected or waste
buccal groove, gullet, con- particles are ejected from the body
tractile vacuoles and nu- Occasionally. Where? Note about

clei. (Greatly magnified; ~~ : ;
from life.) midway of the Parameciuman ovoid

AMCBA, PARAMCGCIUM AND VORTICELLA 4I

body with a smaller oval one attached to its side, the former
being the macronucleus, the latter the micronucleus. Note
that there are two contractile vacuoles in the Paramecium;
also that the food-vacuoles have a definite course in their
movement inside the endosarc.

Make a drawing of a Paramecium.

In comparing Paramecium with Ameba it is apparent
that the body of the first is less simple than that of the second.
The definite opening for the ingress of food, the two nuclei,
the fixed cilia, and the definite cell-wall giving a fixed shape
to the body, are all specializations which make Paramecium
more complex than Ameba. But the whole body is still
composed of a single cell, and there is, as in Ameba, no
differentiation of the body-substance into different tis-
sues, and no arrangement of body-parts as systems of
organs.

Paramecium may occasionally be found reproducing.
This process takes place very much as in Ameba. The
animal remains dormant for a while, the micronucleus then
divides, the macronucleus elongates and finally divides in
two, the protoplasm of the body becomes constricted into
two parts, each part massing itelf about the withdrawn
halves of the macro- and micronuclei, and lastly the whole
breaks into two smaller organisms which grow to be like the
original. After multiplication or reproduction has gone on
in this way for numerous generations (from one to two
hundred), a fusion of two Paramecia seems necessary before
further divisions take place. (This is probably true of Am-
wba also.) ‘This process of fusion, called conjugation, may
be noted at some seasons. Two Paramecia unite with
their buccal grooves together, part of the macronucleus
and micronucleus of each passes over to the other, and the
mixed elements fuse together to form a new macro- and
micronucleus in each half. ‘The conjugating Paramecia
now separate, and each divides to form two new individuals.

42 THE ANIMALS AND MAN

The Bell Animalcule (Vorticella sp.)—Trcunicat Notre.—
Specimens of Vorticella may usually be found in the same water with

Ameba and Paramecium.

The individuals live together in colonies,

a single colony appearing to the naked eye as a tiny whitish mound-like

Fic. 14. Vorticella sp.; one
individual with stalk
coiled and one with
stalk extended; note
the peristome, epis-
tome, vestibule, nucle-
us, contractile vesicle,
food particles, etc.
(Greatly magnified;
from life.)

tuft or spot on the surface of some leaf or
stem or root in the water. Touch sucha
spot with a needle, and if it is a Vorticellid
colony it will contract instantly. Bring bits
of leaves, stems, etc., bearing Vorticellid
colonies into the laboratory and keep in a
small stagnant-water aquarium (a battery-
jar of pond-water will do).

Examine a colony of Vorticella in
a watch-glass of water or in a drop
of water ona glass slide under the
microscope. Note the stemmed bell-
shaped bodies which compose the
colony. Each bell and stem _to-
gether form an individual Vorticella
(fig. 14). How are the members of —
the colony fastened together? Tap
the slide and note the sudden con-
traction of the animals; also the
details of contraction in the case of
an individual. Watch the colony
expand; note the details of this move-
ment in the case of an individual.

Make drawings showing the col-
ony expanded and contracted.

With higher power examine a
single individual. Note the thick-
ened, bent-out, upper margin of the
bell. This margin is called the
peristome. With what is it fringed ?
The iree “end' or the ellis mear=
ly filled by a central disk, the epzs-

AMCBA, PARAMCECIUM AND VORTICELLA 43

tome, with arched upper surface and a circlet of cilia.
Between the epistome and peristome is a groove, the mouth
or vestibule, which leads into the body. Study the internal
structure of the transparent, bell-shaped body. Note the
differentiation of the protoplasm comprising the body into
an inner transparent colorless endosarc containing various
dark-colored granules, vacuoles, oil-drops, etc., and an
outer uniformly granular ectosarc not containing vacuoles.
Is the stalk formed of ectosarc or endosarc or of both? Note
the curved nucleus lying in the endosarc. (This may be
difficult to distinguish in some specimens.) Note the nu-
numerous large circular granules, the food particles. Note the
contractile vesicle, larger and clearer than the food vacuoles.
Note the thin cuticle lining the whole body externally. A
high magnification will show fine transverse ridges or rows
of dots on the cuticle.

Make a drawing showing the internal structure.

Observe a living specimen carefully for some time to
determine all of its movements. Note the contraction and
extension of the stalk, the movements of the cilia of peri-
stome and epistome, the flowing or streaming of the fluid
endosare (indicated by the movements of the food particles),
the behavior of the contractile vesicle.

Make notes and drawings explaining these motions.

Specimens of Vorticella may perhaps be found dividing,
or two bell-shaped bodies may be found on a single stem,
one of the bodies being sometimes smaller than the other.
These two bodies have been produced by the longitudinal
division or fission of a single body. In this process a cleft
first appears at the distal end of the bell-shaped body, and
gradually deepens until the original body is divided quite
in two. The stalk divides for a very short distance. One
of the new bell-shaped bodies develops a circlet of cilia near
the stalked end. After a while it breaks away and swims
about by means of this basal circlet of cilia. Later it settles

44 THE ANIMALS AND MAN

down, becomes attached by its basal end, loses its basal
cilia and develops a stalk.

“Conjugation occurs sometimes, but it is unlike the con-
jugation of Paramecium in two important points: Firstly,
the conjugation is between two dissimilar forms; an ordi-
nary large-stalked form, and a much smaller free-swimming
form which has originated by repeated division of a large
form. Secondly, the union of the two is a compiete
and permanent fusion, the smaller being absorbed into
the larger. This permanent fusion of a small active
cell with a relatively large fixed cell, followed by divis-
ion of the fused mass, presents a striking analogy to
the process of sexual reproduction occurring in_ higher
animals.”

The single-celled body.—The study of Ameba, Para-
mecium and Vorticella has made us acquainted with a type of
animal body very different from that of the toad or the cray-
fish. These extraordinarily minute animals have a body so
simple in its composition, compared with the toad’s, that if
the toad’s body be taken for the type of the animal body,
Ameba might readily be thought not to be an animal at all.
The body of Ameba is not composed of organs, each with a
particular function or work to perform. Whatever an Ameba
does is done, we may say, with its whole body. But as we
learn the things that this formless viscid speck of matter
does, we see that it is truly an animal; that it really does
those things which we have learned are the necessary life-
processes of an animal. Ameba takes up and digests food
composed of organic particles; it has the power of motion;
it knows when its body comes in contact with some external
object, that is, it can feel or has the power of sensation.
Ameba takes in oxygen and gives out carbon dioxide, and
it can produce new individuals like itself, that is, it has the
power of reproduction. But for the performance of these
various life-processes or functions it has no widely differing

AMCEBA, PARAMECIUM AND VORTICELLA 45

special parts or organs, no mouth or alimentary canal, no
lungs or gills, no legs, no special reproductive organs. We
have here to do with one of the “simplest animals.” With a
minute, organless, soft speck of viscous matter called pro-
toplasm for a body, the simplest structural condition to be
found among living beings, Ameba nevertheless is capable
of performing in the simplest way in which they may be
performed, those processes which are essential to animal
life.

Paramecium has a body a little less simple than Ameba.
The food-particles are taken into the body always at a cer-
tain spot; this might be spoken of as a mouth. And the
body has some special locomotory organs, if they may be so
called, in the presence of the cilia. The body, too, has a
definite shape or form. But, as in Ameba, there is no
alimentary canal, nor nervous system, nor respiratory sys-
tem, nor reproductive system. ‘The whole body feels and
breathes and takes part in reproduction.

A long jump has been made from the toad and crayfish
to Ameba and Paramecium; from the complex to the
simplest animals. But, as will later be seen, the great
difference between the bodies of these simplest animals and
those of the highly complex ones is only a difference of
degree; there are animals of all grades and stages of struc-
tural condition connecting the simplest with the most com-
plex. When animals are studied systematically, as it is
called, we begin with the simplest and proceed from them
to the slightly complex, from these to the more complex, and
finally to the most complex. There are hundreds of thou-
sands of different kinds of animals, and they represent all
the degrees of complexity which lie between the extremes
we have so far studied.

The cell.—The characteristic thing about the body of
Ameba and Paramecium and the other ‘simplest animals”
—for there are many members of the group of “simplest

46 THE ANIMALS AND MAN

99

animals,’ or Protozoa—is that it is composed, for the ani-
mal’s whole lifetime, of a single cell. A cell is the structural
unit of the animal body. The bodies of all other animals ex-
cept the Protozoa, the simplest animals, are composed of
many cells. These cells are of many kinds, but the simplest
kind of animal cell is that shown by the body of an Ameba, a
tiny speck of viscous, nearly colorless protoplasm without
fixed form. The protoplasm composing the cell is differenti-
ated to form two parts or regions of the cell, an inner denser
part, called the nucleus, and an outer clearer part, called the
cytoplasm. Sometimes, as in the Paramecium, the cell is en-
closed by a cell-wall which may be simply a denser outer layer
of the cytoplasm, or may be a thin membrane secreted by the
protoplasm. Thus the cell is not what its name might lead us
to expect, typically cellular in character; that is, it is not
(or only rarely is) a tiny sac or box of symmetrical shape.
While the cell is composed essentially of protoplasm, yet it
may contain certain so-called cell-products, small quantities
of various substances produced by the life-processes of the
protoplasm. ‘These cell-products are held in the proto-
plasmic body-mass of the cell, and may consist of droplets
of water or oil or resin, or tiny particles of starch or pigment,
etc. The cell cannot be said to be composed of organs, be-
cause the word organ, as it is commonly used in the study
of an animal, is understood to mean a part of the animal
body which is composed of many cells. But the single cell
can be somewhat differentiated into parts or special regions,
each part or special region being especially associated with
some one of the life-processes. In Paramecium, for exam-
ple, the food is always taken in through the so-called mouth-
opening; the fine protoplasmic cilia enable the cell to swim
freely in the water, the waste products of the body are
always cast out through a certain part, and so on. But this
is a very simple sort of differentiation, and the whole body
is only one of those structural units, the cells, of which so

AMCEBA, PARAMCECIUM AND VORTICELLA Aq

many are included in the body of any one of the complex
animals.

Protoplasm.—The protoplasm, which is the essential liv-
ing substance of the typical animal cell and hence of the
whole animal body, is a substance of very complex chemical
and physical make-up. The most important thing about
the chemical constitution of protoplasm is that there are
always present in it certain complex albuminous substances
called proteids which are never found in inorganic bodies,
although the elements that compose these substances as well
as all the rest of the protoplasm are the familiar ones, car-
bon, nitrogen, hydrogen, oxygen, sulphur, phosphorus,
potassium, sodium, etc. The atoms in a single proteid
molecule often number more than a thousand, and the mole-
cules are very large. But chemists have yet to find out a
great deal about these complex albuminous compounds.

In addition to the proteids protoplasm usually contains
certain native albumins and certain other characteristic
compounds known as carbohydrates and fats (which differ
essentially from the albuminous substances in lacking nitro-
gen as a composing element). ‘There are also various salts
and gases and always water to be found in living substances.
Water is absolutely necessary to the physical condition of
half fluidity which gives to protoplasm its essential capacity
for motion on itself. The commoner salts found in living
substances are compounds of chlorine as well as the car-
bonates, sulphates, and phosphates of the alkalies and al-
kali earths, especially common salt (sodium chloride),
potassium chloride, ammonium chloride, and the carbon-
ates, sulphides, and sulphates of sodium, potassium, magne-
sium, ammonium, and calcium. The gases found in living
matter are oxygen and carbon dioxide. These, when not
in chemical combination, are almost always dissolved in
water, although rarely they may be in the form of gas bubbles.

The physical constitution of protoplasm seems to be that

48 THE ANIMALS AND MAN

of a viscous liquid containing many fine globules of a liquid
of different density. It is a sort of liquid foam. Some
naturalists however, believe the fine globules to be solid
granules while still others believe that numerous fine threads
of dense protoplasm lie coiled and tangled in the clearer
viscous protoplasm. The difficulty in determining the
physical structure is due to the limitations of the microscope.
The ultimate structure of protoplasm is ultra-microscopic.

What little is known of the chemistry and physics of proto-
plasm certainly is far from explaining its wonderful properties.
It should be held clearly in mind also that the full life capacity
of protoplasm is realized only when it is in that differ-
entiated and organized condition typical of the structural
unit or cell. The essential thing about the cell is not that
it has a definite shape or size or that it is truly cell- or sac-
like, but that it is a tiny but definitely organized mass of
protoplasm with various substances secreted by or held in
it. The protoplasm itself is differentiated into at least
two parts, an inner, denser, smaller part called the nucleus,
and an outer surrounding, usually larger, portion called
the cytoplasm. Such a differentiated or organized proto-
plasmic unit can perform all of the essential functions of
life and persist in this performance indefinitely unless de-
stroyed by extrinsic causes. The cell itself may not have
an indefinite existence as a unit, but it will be the progenitor
of an indefinitely prolonged series of cells. A single part
of this cell, that is, a bit of protoplasm either of the nucleus
or the cytoplasm, or the whole of either can perform for a
while most of the activities of life; but such a part always
lacks the capacity for reproduction, that is, for persistence
as living matter.

CHAPTER, VI

ANIMAL PHYSIOLOGY

Motions and locomotion.—Our attention is usually first
attracted to an animal by the movements it makes. ‘These
are the plainest proof that it is alive. For the animal itself
the ability to move is essential to existence. Most animals
move in search of food, to escape from their enemies, to find
and build their homes, to seek their mates, and care for
their young. In the higher forms the organs of motion
constitute the great bulk of the body. The shape and
size of such an animal are determined largely by these
organs.

The heart and blood-vessels, the lungs and digestive sys-
tem, are principally concerned with supplying the organs of

REPRE RF IRF

Fic. 15. Scorpion walking, showing the successive positions of body
and legs. (After instantaneous photographs by Marey.)

motion with materials necessary for their working, and by
far the larger part of the work of the sense organs and ner-
vous system is to put these organs into action, and to direct
and control them. We can see therefore that they have
much to do with both the structure and physiology of ani-
mals. Indeed the most marked usual difference between
animals and plants is the possession by the former of the
organs of motion and their nerves. True, plants have the

a“

50 THE ANIMALS AND MAN

power of motion and are sensitive to light, heat, and other
influences as are animals, but to a far less degree.

Among the movements made by animals, the moving of
the body from place to place, usually spoken of as locomo-
tion, generally requires the greatest energy or power. The
other motions are those of parts of the body, as the arms,
lees mena. etc:

There are three different ways in which locomotion takes
place, namely, by swimming in water, crawling or walking or
leaping on some solid object, as the ground or the trunk of a
tree, and by flying in the air. In each of these three cases
the body must first be supported, then either pushed or
pulled along or perhaps both pushed and pulled.

In swimming the body is supported by the water. In
animals that swim it is either lighter than water, as in the
duck, or just as heavy or only a little heavier, as in fishes, so
that it is wholly or almost wholly held up by the water, and
the full power of the leg, fin, or tail used in the motion can
be devoted to pushing the animal along. Animals crawling
on the bottom in water also have very little to do in holding
up the body, the water supporting them. But those that
move on land or fly with their bodies immersed in air
alone have the body only very slightly supported by the air.
These animals must therefore devote energy to supporting
the body as well as to moving it along, and they have special
means for this.

As already said the body is moved by pushes or pulls.
In by far the most cases motion results from pushes given
by a part of the body against something outside. Now it is
plain that air is a very poor thing to push against as com-
pared with water or a solid. Naturally since water is a
liquid it gives way readily to a push, but its heaviness offers
much greater resistance to motion than does the air. The
solid ground, of course, offers most of all. Currents in wa-
ter and air are of peculiar help in this matter. Water cur-

ANIMAL PHYSIOLOGY 51

rents may carry an animal for great distances without any
work on its part; while air currents make it possible for
birds to soar with little effort. Flight by the vibration of
wings, as in birds and insects, requires the greatest expen-
diture of energy, since the pushes against the thin air must
be made quickly and with great force and be rapidly re-
peated to be effective for support and locomotion. Man in
making locomotive machines, railway engines, automobiles,
steamships, etc., has met the same conditions as the animals;
but the difficulties of aerial locomotion are so great that he
has only now succeeded in making a beginning toward
achieving a mechanism for it.

The simplest and what may be called the most imperfect
modes of locomotion are shown by the simplest animals.
These modes we have already studied in Amceba, Para-
moecium, and Vorticella. The living elements in the body
of the higher animals are the many individual cells, and they
show many kinds of move-
ment. But motion in the
higher animals is produced
chiefly by the contraction of
muscles, each of which is
h -m made up of contractile fibres
which may be thought to be
modifications of such a fibre

} Jas = as exists in the stalk of Vor-
Nl le ticella.

The muscles require firm

V.n.¢. points of attachment to pull

Fic. 16. Diagram of cross-section against and the complex

h h the th x of i a
emo orax of an insect + ovements of most animals
to show the exo-skeleton and the

leg and wing muscles attaching require also rigid levers and
to it; h, heart; al.c, alimentary fylcra. These firm solid

canal; v. n.c, ventral nerve cord; :
68) parts of an animal’s body
w, wing; J, leg; m, muscles.

(Much enlarged; after Graber.) COMPOSE its skeleton,

52 THE ANIMALS AND MAN

The skeleton of a backboneless or invertebrate animal
differs from that of a backboned or vertebrate animal (as
we have seen in comparing the frog and crayfish) not in the
use made of it but in its arrangement and in the part of the
body from which it is mainly developed. The skeleton of
the invertebrate is developed from the skin, and forms a
hard casing over the whole or part of the body (fig. 16). It
is therefore called an exo-skeleton.

In the vertebrates the skeleton is
mainly developed from tissues within
the body and is called in consequence
the endo-skeleton. Even more than
in the invertebrates it is a system
(fig. 17) of levers, fulcra, and points
of attachment for muscles to work
with, and is as important a part of the Fic.17. Skeleton of arm
organs of motion as is the muscular Oe ae
system itself. bones and muscle act

To illustrate the use of the skeleton as levers. (After Jen-
of a vertebrate we may examine the a
bones of the hind legs of a cat (fig. 18). The upper bone,
the femur, is attached by a joint to the large irregularly
shaped bone called
the ilium, which is
firmly bound to the
backbone. Below the
femur are two bones,
the largest, called
tibia, being bound
by, a) Yjommt to the
Fic. 18. Skeleton of cat. (After Reighard and femur. Below the

Jennings.) tibias 18:98.) psroup
of bones, the tarsal bones, pretty firmly fastened together.
The largest makes a joint with the tibia. Each of the
four tarsal bones toward the toes makes a joint with a

ANIMAL PHYSIOLOGY 53

slender bone in the body of the foot. These are the
metatarsals. At the end of each metatarsal is a series
of three bones which forms the skeleton of each toe.
All of these bones together constitute a system of levers
which the muscles of the leg can draw up in a some-
what folded position, and then straighten out with quick-
ness and force. Since during such movements the toes
rest on the solid ground, the body is lifted and thrown for-
ward. There are several strong muscles which make the
pulls for these motions, but a single pair may be studied as
an example of the method of attachment and action of all.
Fig. 19 shows the large muscles of the
fore leg of acat. Each consists of a large
central mass formed of the muscular or
contractile substance proper bound up
into a compact body by connective tis-
sues, with strings or bands of connective
tissue at the ends fastening the muscular
mass to the bones. ‘These fastenings are
tendons. When the muscular substance
contracts it of course pulls on the two ten-
donous ends. If one end of a muscle
in the hind leg is attached to the hip-
bone it cannot move, but the one fastened
to the tibia moves this bone as a lever,
Hed “Martieson Wita its fulerum? ate the end’ of the® fe-
side of fore leg of mur. ‘The tibia is brought toward the
cat. (After Reigh- femur, and we say that the limb is flexed.
ard and Jennings.) 2 : :
°° Another muscle in contracting will act on
the tibia as a lever also, but it brings the tibia back again
into a straight line with the femur. This motion is called
extension. For each part of the limb from hip to toe are
groups of muscles which flex and extend that part, the
bones being levers and fulcra and points of attachment.
Most of these levers are of the kind called in mechanics

54 THE ANIMALS AND MAN

levers of the third class. By them quickness of motion
is magnified.

Thus by noting first what motions an animal makes, and
then, by dissection, examining the muscles, the bones, and
their points and means of attachment, we may come to
understand clearly the uses of the muscles and skeleton in
any animal.

Necessity of oxygen and food.—In the organs of motion
just studied, the muscles and bones are only the machinery
for motion. They make use of energy but cannot them-
selves provide it. Just as an engine and all the wheels and
levers connected with it make use of heat, which is one of
the forms of energy, to produce the needed motions, so the
muscles and bones make use of some form of energy to
produce the motions of the animal body. In the steam-
engine the special form used is heat, generated by the burn-
ing of coal, oil, or wood; by means of this heat, which
expands the steam, i.e., the vapor of water, energy is applied
to the piston in the form of a push. The motion of the
piston is passed over to the wheels and levers of the shop,
and by them are given all the different directions and veloci-
ties required by the different machines of that particular
shop.

In the animal body the muscle is the engine, for in it the
energy is generated. In a way we do not yet exactly under-
stand this energy makes the muscular substance contract
and give a pull on the tendon, with the same effect as the
push of the steam on the piston, that is, to set the rest of
the machinery, the bones, in motion. The bones apply the
motion in the way required for the movement of the animal.
A striking difference, however, between the animal body and
a shop is this, that while in even a very large shop there may
be but one engine generating energy to run all the different
machines, in the body every muscle is a separate engine, and
one bone may be connected with a number of them. Never-

ANIMAL PHYSIOLOGY 55

theless the essential facts are the same in both cases. ‘The
muscle-engine, like the steam-engine, produces a form of
energy and applies it to machines so as to lift weights or to
move things from place to place. But we learn in physics
that we can get any form of energy only by changing some
other form into the one desired. ‘The forms of energy are
heat, light, electricity, chemical energy, and tnat of a body
in motion. Now the only way to get heat, for example, is
by a change from one of the others. We can make a piece
of iron hot by striking it with a hammer; here the energy
of a moving body is converted into heat. Or the energy of
the electric current may be converted into heat or motion.
Man’s most common way of getting heat is to take coal,
wood, or oil, and apply some heat to start with, when the
oxygen of the air will unite with carbon and hydrogen, sub-
stances in the coal, wood, or oil, to make two new substances,
one of these being carbon dioxide, the other water. This is
chemical action; it results in changing chemical energy into
heat. In ordinary language this union of oxygen with car-
bon or hydrogen is spoken of as ‘“‘burning” or “‘combustion.”’

An animal cannot make the least motion without using
a certain amount of energy. And it has been shown by
investigation that the energy possessed by an animal is
derived from the chemical energy resulting from the union
of oxygen with the carbon, hydrogen, and nitrogen in other
substances. The muscles are the engines in which this
energy is made use of for motion. ‘This brings us now to
see how essential it is that the animal should have in its
body oxygen and substances for the oxygen to combine with.

Respiration.—Respiration is the name commonly used
in books for the process of obtaining oxygen. ‘The pro-
cess has, however, another object in addition to procuring
oxygen. When oxygen combines with carbon a poisonous
gas, carbon dioxide, is formed. If this remains in the
muscle or other tissue cells it interferes with the activity

56 THE ANIMALS AND MAN

of those cells. It is, therefore, just as-necessary for the
carbon dioxide to be removed from the body as for
oxygen to be supplied to it. Carbon dioxide, like oxygen,
is soluble in water. Blood, which is composed largely of
water, can carry off carbon dioxide as well as bring oxygen.
Also, since carbon dioxide is made by a combination with
oxygen it arises just where it can be carried away by the
very means that brings the necessary oxygen. Thus the
respiratory, aided by the circulatory apparatus manages
both the bringing of a supply of oxygen and the disposal of
the carbon dioxide.

The fundamental fact in the process of respiration is that
gases whether free or dissolved in water will readily pass
through a thin, moist membrane. Thus, if a closed sac
made of thin membrane filled with water in which carbon
dioxide is dissolved be immersed in water in which oxygen
is dissolved, carbon dioxide will pass out of the sac and
oxygen into it until there is the same amount of each outside
and inside. If the water outside is constantly replaced all
the carbon dioxide will be finally removed. Ii the oxygen
inside the sac is constantly used up and the supply outside
is always renewed, oxygen will be constantly going in and
carbon dioxide going out. This is just what happens in
the living animal. Animals get their oxygen from the air,
of which it is a part. The air may be free or dissolved in
water. Carbon dioxide is made in the cells of the body.
Respiration takes place through the membranes covering
all or part of the surface of the body. It requires the con-
stant renewal of free air or water containing air on the out-
side, and the constant passage of fresh blood on the inside
surface of the membrane. This end is attained in a great
variety of ways among animals.

In the simplest forms, the Protozoa, where we have the
most primitive means of motion, we find also the simplest
means of respiration. The Amoeba, as we have seen,

ANIMAL PHYSIOLOGY ay

simply relies on its whole external surface for breathing, the
thin outside layer of the body acting as a membrane through
which the oxygen passes in and the carbon dioxide out.
During periods of activity the processes protruding from the
body increase the amount of respiratory surface sufficiently
to provide for theincreased respiration demanded by the
activity. In ciliated forms the cilia greatly increase the
surface area and respiration is further assisted by the con-
stant contact of the moving body with fresher water. Even
in more complex animals, the common earthworm and the
larvee of some insects, for example, the whole external skin
is sometimes the only respiratory surface. However, such
animals have only sluggish and weak motions. Much
increase in size and activity make certain demands on the
surface of the body which unfit it for respiraton. The hard
covering of insects, crabs, and other animals necessary in
connection with locomotion and for protection from inju-
ries illustrates this. Again, while in a minute form like
Amoeba, the slight increase of surface attained by its pro-
truded processes answers the increased respiratory needs,
the surface of a large animal would fall far short of doing
so, because, according to a familiar law of physics, the mass
or bulk of a body increases as the cube of the diameter while
the surface increases only as the square. ‘Therefore the
larger animals must have special respiratory surfaces with
special respiratory apparatus to move the air or water over
these surfaces externally, and special circulatory apparatus
to move the blood over them internally.

Special respiratory surface is provided for in two ways.
One is by the extension of a portion of the surface exter-
ally; thus gills are formed. The other is by the extension
of the surface within the body in the form of tubes, as the
trachez in insects, or of sacs, as the lungs in the vertebrates.
Water-breathers have gills and air-breathers have trachez or
lungs.

58 THE ANIMALS AND MAN

In the higher vertebrates the exterior skin surface is not
at all adapted for respiration, which, together with the
generally greater activity of these animals, necessitates a
much greater development of the lungs. ‘Thus instead of
the two simple lung sacs of the frog the lizard has a com-
plex double sac enlarged by tube-like extensions into the
body-cavity. This arrangement gives a much increased
respiratory surface. In birds and mammals the extent
of surface is immensely increased. It is estimated that
the inner surface of a man’s lungs amounts to a thousand
square feet in area, or one hundred times the external sur-
face of the body. ‘The windpipe gives off one large branch
to each lung; these branches divide again and again, the
last divisions bearing on their ends very small sacs of thin
membrane about which is clustered a net-work of capillary
blood-vessels. Through the walls of these small sacs the
oxygen and carbon dioxide pass.

So far we have seen only
how increase of surface is
brought about. Accompany-
ing this we find improved
means for passing the air
_ over the exterior and bringing
the blood to the interior sur-
face. A frog or salamander
breathing quietly enlarges the
mouth-cavity by lowering its
floor, and the air comes in Fic. 20. Tracheal tube, lungs, heart
through the nostrils; this air arcadia brag eco 2 Ose:
is then squeezed by the upward pressure of the floor
of the mouth, the valves in the nostrils close, and it
is thus pushed down into the lungs. The muscles in
the walls of the body now contract and squeeze upon
the air in the lungs, the nostril valves open, and the
air is forced out. This method is gradually improved

ANIMAL PHYSIOLOGY 59

upon in the vertebrates until in the mammals we
find a bony basket of ribs and sternum, the thorax (fig.
20), containing the lungs, with two sets of muscles
between the ribs, which by their alternate contractions and
expansions first elevate and extend the ribs, then lower
and draw them in, thus enlarging and diminishing the
thoracic cavity. We find further a muscular partition in
the thorax, the diaphragm, separating it from the abdominal
cavity. When the diaphragm, which is convex on the
upper side, contracts, it lowers the floor of the thorax, thus
enlarging the thoracic cavity; the muscles in the waiis of
the abdomen then contract and press upon the stomach,
intestines, and liver, pushing up the floor of the thorax and
so diminishing the thoracic cavity. Thus in two ways this
is enlarged, and in two ways diminished. As it enlarges,
the pressure of the outside air expands the elastic sacs of
the lungs; as it diminishes, the air is pressed out again.
Along with great increase of surface and great complexity
of mechanism for moving, the air go, as has been pointed
out, a perfecting of the circulatory apparatus for bringing
the blood to the respiratory surface, and a proportionate
complexity of the nervous system for producing and regu-
lating the necessary movements. It is to be kept in mind,
however, that the respiratory apparatus only brings oxygen
to the respiratory surface, and before the real respiration
at the tissue-cell can take place the oxygen must be carried
by the blood to the cell. This process we shall later discuss
under the head of circulation.

Now having seen how animals get the necessary oxygen
we may next inquire how they obtain and make use of
the equally necessary substances to be oxidized and to
build the body out of, that is, their food.

How animals obtain and digest food.——Amceba eats
without a mouth. It extends any part of its soft body
over the little plant or animal it feeds upon. In many

60 THE ANIMALS AND MAN

Protozoa, however, there is a definite mouth-place, as in
Paramcecium, where the food-particles are gathered to-
gether in a little ball by the cilia, and then pushed through
the body-wall. The body of the fresh-water hydra (see
Chapter XIII), incloses a digestive cavity, the mouth being
but an opening to this. In the higher animals we find
mouths arranged for cutting, filing, sucking, crushing,
gnawing, grinding, chiseling, piercing, sawing; in fact
almost every device one could think of for working in wood,
bone, shell, flesh, liquid, soft and hard material of many
forms.

To understand the process of digestion some knowledge
of the nature of food substances is necessary. In con-
sidering the production of energy and making of body
material we saw that the same substances provided for both.
In fact whatever the form of food, animal or plant, the
elementary substances are the same, being conveniently
classified into two great groups, organic and inorganic
substances.

Inorganic food substances are water and certain minerals
of which common salt is one. Organic food substances
are of three kinds or groups. The first group, called the
proteids, of which the white of egg is an example, forms
a large part of the tissues of animals; the second group
is made up of the fats and oils; the third, known as the
carbohydrates, consists of the starches and sugars.

Digestion consists in changing all these substances into
soluble form so that they can be absorbed into the body,
circulate with the blood, if there be any, and then pass
into the “ying “cells for them use. “This echanee issac-
complished by certain liquids called digestive fluids. The
digestive apparatus varies like other parts of the animal
organism, being very simple in some forms and very com-
plex in others. In Amceba the food-particles are retained
in spaces in the cell until they are digested. So in other

ANIMAL PHYSIOLOGY 61

Protozoa. The simple digestive cavity of the hydra has
been referred to. In the polyps and jelly-fishes (see Chap-
ter XIII), this cavity is extended, the digestive surface
being much increased by partitions, tubes, etc. Worms,
crabs, and snails have a definite alimentary canal with certain
parts set apart for special processes. In the vertebrates
the digestive apparatus varies from a relatively simple
straight tube to the very long and complex alimentary canal
of the cow. All this variety depends much on the nature
of the food of the individual animal, and the processes
necessary to turn it into body material.

We have now to consider that process which has to do
with carrying oxygen and food from the respiratory and
digestive surfaces to all parts of the body. This process
is the circulation, and the organs for performing it com-
pose the circulatory system.

How the blood circulates.—It has already been shown
that increase of size and activity in animals necessitates
blood and a means of circulating it through the body. The
uses of the circulation are: to bring oxygen from the respi-
ratory surface to every cell, to take carbon dioxide from
every cell to the respiratory surface, to carry digested food
substances from the absorbing surface of the alimentary
canal to every cell, and, further, to remove from every cell
the injurious and waste substances formed by its activity
to where they may be either excreted from the body or dis-
posed of in some other way. Circulation is accomplished
by the moving of a liquid through a system of tubes and
spaces channeling the whole body.

In the very smallest and most sluggish of animals there is
no circulatory system. In those which are of compara-
tively large size and very active, and which therefore need
a great amount of energy, much oxygen and food must be
supplied. Also a large amount of waste substance is pro-
duced which must be removed. In such animals the cir-

62 THE ANIMALS AND MAN

culatory system is found to be highly developed and to
work with great efficiency.

In Amceba, because of its small size and the constant
flowing of the body-substance, there is no circulatory system.
In some Protozoa the contents of the body-cell seem to have
a definite movement, but there are no such organs as heart
and blood-vessels. In most animals we
find blood and a system of tubes and
spaces for it to circulate in. In some,
as the insects (fig. 21), only part of the
circulatory system consists of definite
tubes; these open into loose ill-defined
spaces in the body-cavity. In these
spaces the blood moves _ gradually
throughout the animal, but not so
definitely and quickly as in others
where the blood runs in definite vessels.
In the earthworm there is no “heart”’
as in higher animals, but the blood- Fic. 21. Diagram of
vessel along the dorsal line and some ‘“Mulatory system of

, : a young dragon-fly;
otuts: pranches“around) they sidesshave.) a aie madione the
muscular walls and “beat”? by a wave chambered dorsal
of contraction running toward the Yess! with single

; artery; the arrows
heads sin “insectssthe = dorsalablood=— Seataeeaediecton
vessel beats in the same way, but of blood - currents.
generally more vigorously. Inthe young tter Kolbe.)
larva of a mosquito or nymph of a May-fly with transparent
skin the beating can be easily seen under the microscope. In
molluscs there is a well-developed heart; it can be well seen
in the fresh-water mussel. The crustaceans also have a heart.
This can be seen at work in a water-flea under the micro-
scope, or can be readily demonstrated in a crab or crayfish
killed with chloroform or ether.

In vertebrates the blood circulates in a definite system of
tubes through which it is pumped by a heart. The fishes

ANIMAL PHYSIOLOGY 63

(fig. 22) have the heart consisting of two parts, with mus-
cular walls, a single auricle and a single ventricle. The
auricle receives the blood pouring from all the tissues of
the body through the veins. It contracts and forces the
blood into the ventricle. ‘This then contracts and drives it
into a short vessel called the ventral aorta, which gives off a
branch artery for each gill-arch. The gill-arteries divide

Fic. 22. Diagram of the circulatory system of a fish; wv, ventricle; a,
auricle. (After Parker and Haswell.)

into capillaries in the gills, whence, after aeration, the
blood is gathered by another artery and carried to the dor-
sal aorta, from which branch arteries distribute it to the
capillaries of the general body-tissues. From these it is
gathered by the veins and carried back to the auricle to be-
gin again. In the course of circulation the blood reaches
every. part of the body, picking up certain substances here,
leaving others there, thus accomplishing the results already
pointed out as the objects of the circulation.

In the circulation of the higher vertebrates the most
striking difference from that of the fish is in the structure of
the heart, which adapts the circulation to lungs instead of
gills, and in the more perfect control and regulation of the
action of heart and blood-vessels by the nervous system.

It may be asked how, since the blood remains in vessels
during circulation, the tissue-cells receive anything from it.
The blood as such does not reach the tissue-cells. These

64 THE ANIMALS AND MAN

are surrounded by a liquid, called lymph, which fills the
spaces between them. The capillary blood-vessels run
through this liquid and may not actually touch the cells
themselves at all, or at only a few points. The walls
of the capillaries being very thin, however, the substances
needed by the cells diffuse from the blood through the walls
into the liquid and thence to the cells themselves. On the
other hand, substances from the cells—carbon dioxide and
other waste matters—diffuse into the liquid and from this to
the blood through the capillary walls. In fact each tissue-
cell feeds, like certain one-celled animals, by absorption
from a liquid medium, but by means of the circulation this
liquid has a prepared food constantly brought to it.

We may ask how the blood carries the oxygen. In the
vertebrates part of the blood consists of little bodies called
the red corpuscles. The color of these is due to a chemical
substance called hemoglobin. This has the capacity of ab-
sorbing oxygen at the lungs and of giving it up to the tissues.

How animals know things and control their motions.—
Thus far we have considered the mechanisms animals have
for motion and for obtaining oxygen and food. A more
difficult but more interesting subject is how motions take
place in the animal, how they are guided, how they are
stopped; in short, how the whole conduct of the life of the
animal is carried on. To understand better what these
processes consist of, let us consider as an example the life
of a common bird. We know that after hatching from the
ege it takes food, learns the notes of the parent bird, learns
to fly, learns to fight or to avoid enemies, all these including
motions guided by sight, hearing, touch, and smell. On
the approach of winter it migrates to the south; in spring
it returns, chooses a mate, builds a nest, and rears young
to which it teaches in turn the ways of bird life. While
the full explanation of these processes is far from being
reached, and while we cannot here discuss them at length,

ANIMAL PHYSIOLOGY 65

yet we may at least examine some of the parts of the body
specially concerned with these processes. In the higher
animals they are determined and directed by means of the
sense-organs and the nervous system. In vertebrates the
special senses, as they are called, are those of sight, hearing,
smell, taste, touch, cold, heat, and one called the muscular

Sunfish. Toad. Snake. Sparrow. Mouse.

Oi bes ee

cbr.

md. br.

cbl.

med. ob.

sp. cd.

Fic. 23. Diagram of brains of vertebrates; olf. l., olfactory lobes; cbr.,
cerebrum; md. b ., midbrain (optic lobes); cb/., cerebellum; med.
ob., medulla oblongata; sp. cd., spinal cord.

sense. A part of the eye known as the retina is specially
sensitive to light; in the internal ear there are certain cells
which are affected by sound vibrations; in the nasal passages
there is a region in which are cells sensitive to odors; in the
skin of the tongue are cells that react to sweet, sour, and
bitter liquids; in various parts of the skin are cells sensitive
to pressure, heat, and cold. These different kinds of cells
affected by different influences are called sense-cells.

Now what the animal sees, hears, touches, etc., deter-
mines its motions, and we find that the sense-cells are con-
nected with the muscles by means of the nervous system.
Through this connection light, heat, sound, etc., guide
muscular action.

The nervous system of a vertebrate (fig. 24), consists of a
central portion, the brain (figs. 23, 25), and spinal cord, from

66 THE ANIMALS AND MAN

which branches called nerves extend in pairs; the nerves then
branch and branch again until their divisions reach every part
of the body in the shape of very numerous white threads, too
small to be detected by the naked eye. ‘These very small
nerve-threads or fibers end at last in connection with cer-
tain of the tissue-cells. All the sense-cells of the retina,

Fic. 24. Central nervous system of a dog. (After Ritzema-Bos.)

ear, nose, tongue, and skin are connected with minute
nerve-fibers as are also all the muscle-fibers. Now all the
nerve-fibers from both sense-cells and muscle-cells run to
the central portions of the nervous system, the brain and
spinal cord, and are there in some way definitely connected
with one another, thus making pathways over which every-
thing that affects the eye, ear, and other sense-organs may
affect the muscles.

The nervous system of all vertebrates is on the same
general plan, being, however, less complex in the lower
forms. All animals with a definite nervous system have
nerve-fibers connecting both sense-cells and muscle-cells
with certain central parts. They differ, however, in the
arrangement of these parts. And since they differ also in
muscular arrangement, and in the kind and position of the
sense-organs, the arrangement of the nerve-fibers connecting

“ANIMAL PHYSIOLOGY 67

muscles and sense-organs with these central parts differs
accordingly.

In the worms, crustacea, and insects, which have much-
the same body-plan, the central nervous system (fig. 26) con-
sists of a chain of ganglia(small nerve-centers) along the ventral
portion of the body, this chain being
connected at the anterior end by a
cord on each side of the gullet,
with a large head ganglion which
stands in the position of the
vertebrate brain. In the starfishes
and sea-urchins, the central nerv-
ous system has the form of a ring
with radiating branches, but with
no head ganglia. In sea-anemones
and jellyfishes it is somewhat sim-
ilar, but is less distinctly set apart
from the other tissue-cells. In the
one-celled animals we recognize
Fic. 25. Brain of a cat, dor- no trace of a nervous system any

a surface, ee more than we do of a muscular

bulbs; 1 cecbral Fem or bony system. In Amozba the

IV, medulla oblongata. Whole cell is in a weak way sensi-

(After Reighard and Jen- tive to light, heat, jars, odors, acids,

me?) alkalis, and the various other things
that affect the sense-organs of higher animals. ‘The cell as
a whole conducts the effects of these to all its parts and the
response of the animal is slow and _ indefinite.

In recent years a great deal of careful observation and
experimentation has been done on the behavior of the
simplest animals. The conclusions of the naturalists who
have done this work are not yet in sufficient harmony to
make possibie any satisfactory generalizations, but it seems
certain that much of the behavior of the simpler animals is
determined and controlled by agencies outside of the body.

68 THE ANIMALS AND MAN

if Pane eae

lo

Fic. 26. Diagrams showing fundamental structure of types of several
animal phyla: 1, sea-anemone; 2, starfish; 3, worm; 4, centiped;
5, clam; 6, honeybee; 7, salamander. In each figure the central
nervous system is indicated by the black lines. (After Haeckel.)

ANIMAL PHYSIOLOGY 69

Light, for example, has always a definite influence on certain
simple animals compelling them to move in certain ways
and to continue moving until they have arranged their
bodies in a fixed position with regard to the direction of the
light rays. Certain chemical substances, as well as gravita-
tion, magnetism and other external agencies exert similarly
definite influences. These externally controlled movements
are called tropisms. Various other animal motions are of
such a definite character, always recurring in exactly the
same way under the same conditions of stimulation, that
they are called reflexes; and these also go to show, as do the
tropisms, that much of the behavior of the simpler animals,
and even more or less of that of the higher animals, is beyond
the control of the animal itself.

As we proceed upward in the animal scale we find a
gradual grouping into definite positions of a number of
cells that are specially sensitive to the different influences
acting on the organisms, and along with this definite groups
of muscular cells and definite nerve pathways for impulses
to pass from the sensitive to the motor cells, and more and
more complex connections of groups with groups. In the
highest organisms we have sense-organs which make us
exactly acquainted with the outside world; we have brain,
spinal cord, and nerves, which receive the impulses from
these and turn them through the muscles into all the motions
our bodies are capable of; besides we have all those wonder-
ful processes included under the names instinct, memory,
and reason.

The special senses and their organs.—The organs of
sight, the eyes, are the only organs of special sense generally
conspicuous and unmistakably recognizable when present.
In the vertebrates the eyes, ears, nose, and taste organs are
always situated on the head, but in the invertebrates the
sense-organs corresponding to these are often scattered over
the body, and certain other organs are found which from

70 THE ANIMALS AND MAN

their structure seem to be sense-organs although we are by
no means sure what kind of sense they serve.

In some of the lower animals, as the polyps, there are
on the skin certain sense-cells, either isolated or in small
groups that are not limited to a single special sense. They
seem to be stimulated not alone by the touching of foreign
substances, but also by warmth and light. These simple
sense-cells from which the more complex or special ones
may develop are called primitive or generalized sense-
organs.

The tactile sense or sense of touch is the simplest and
most wide-spread of the special senses, with the simplest
organs. The special organs are usually simple hairs or
papilla connecting with a nerve. They may be distributed
pretty evenly over most of the body or may be mainly con-
centrated upon certain parts in crowded groups. Many
of the lower animals have projecting parts, like the feeling
tentacles of many marine invertebrates, or the antenne
(feelers) of crabs and insects, which are the special seat of
the tactile organs. Among the vertebrates
the tactile organs are either like those
of the invertebrates, or are little sac-like
bodies of connective tissue in which the
end of a nerve is curiously folded and
convoluted. These little touch-corpuscles
(fig. 27) lie in the cell layer of the skin,

covered over thinly by the cuticle. Some-
ae ee ae “°F times they are simply free, branched nerve-
puscle of the skin é : ; :

Gf isan’) 7) nerve, endings im) the skin. iin> einer tease they

(Greatly magni- are especially abundant in those parts of

oe atter Koll the body which can be best used for feel-

ing. In man the finger-tips are thus es-
pecially supplied, in certain tailed monkeys the tip of the
tail, and in hogs the end of the snout.

The taste organs are much like the tactile organs except

ANIMAL PHYSIOLOGY 75

that the special taste cell must be exposed or covered
only by a thin osmotic membrane, so that small particles
of the substance to be tasted can come into actual con-
tact with it. The taste organs (fig. 28) of man and the
other air-breathing animals are located in the mouth or on
the mouth parts. It is
also necessary that the
food substance to be
tasted be dissolved. This
is accomplished by the
fluids poured into the
mouth from the salivary
glands. With the lower Fic. 28. Papilla with taste buds (¢. b.)
A : wet fic from the tongue of a calf. (Greatly
aquatic animals it is not ie euinedotattar Honea ;
improbable that taste or-
gans are situated on other parts of the body besides the
mouth, and that taste or a sense akin to it is used not only
to test food substances but also the chemical character of
the fluid medium in which they live.

Smelling and tasting are closely allied, the one testing
substances dissolved, the other substances vaporized. The
organs of the sense of smell are, like those of taste, simple
nerve-endings in papille or pits. By smell animals can
discover food, avoid enemies, and find their mates. With
the strictly aquatic animals the sense of smell is probably
but little developed. ‘There is little opportunity for a gas
or vapor to reach them, and only as gas or vapor can a sub-
stance be smelled. With these animals the sense of taste
must take the place of the olfactory sense. But among the
insects, mostly terrestrial animals, there is an extraordinary
development of the sense of smell. Insects must depend on
smell far more than on sight or hearing for the discovery
of food, and for becoming aware of the presence of their
enemies and the proximity of their mates and companions.
The organs of smell of insects are situated principally on

72 THE

ANIMALS AND MAN

the antennee or feelers (fig. 29), a single pair of which is borne
on the head of every insect. That many insects have an
amazingly keen sense of smell has been shown by numerous
experiments, and is constantly proved by well-known habits.

HG. 929) The vantenna of
a carrion beetle, with
the terminal three seg-
ments enlarged and flat-
tened and bearing many
‘““smelling-pits.”” (Much
enlarged; photo-micro-
graph by Geo. O. Mitch-
ell.)

for perceiving or being stimu-
lated by vibrations ranging from
16 to 40,000 a second—that is,

Hearing is the perception of cer-
tain vibrations of bodies. These vi-
brations give rise to waves—sound-
waves as they are called—which
proceed from the vibrating body in
all directions, and which, coming to
an animal, stimulate the special au-
ditory organs, which transmit this
stimulation along the auditory nerve
to the brain, or nerve ganglion,
where it is translated as sound. These
sound-waves come to animals usu-
ally through the air, or, in the case
of aquatic animals, through water, or
through both air and water. The
organs of hearing are of very com-
plex structure in the case of man and
the high-
er Viet Ue=
biates:
Our ears
(fig. 30),
which are
adapted

Fie. 30; Diagram ‘of? thexin-
ternal part of the human ear;

for hearing all those sounds pro- 0, external opening; b, bones
duced by vibrations of arapidity of the ear; /, labyrinth; ¢,

not less than 16 to a second nor

cochlea or “snail shell”; x,
auditory nerve. (After Head-

greater than 40,000 to a second jy.)

ANIMAL PHYSIOLOGY 73

—are of such complexity of structure that many pages
would be required for their description. But among the
lower or less highly organized animals the ears, or audi-
tory organs, are much simpler.

In most animals the auditory organs show the common
characteristic of being wholly composed of, or having,

Fic. 31. The auditory organ of a locust (Melanoplus sp. ). The large
clear part in the center of the figure is the thin tympanum, with the
auditory vesicle (small, black, pear-shaped spot) and auditory ganglion
(at left of vesicle and connected with it by a nerve) on its inner sur-
face. A spiracle at the side of the tympanum allows air to pass into
a chamber behind the tympanum so that the air pressure is the same
on both outer and inner surfaces of the tympanum. (Greatly magni-
fied; photo-micrograph by Geo. O. Mitchell.)

as an essential part, a small sac filled with liquid in which
one or more tiny spherical hard bodies called otoliths are

held. This auditory sac is formed of, or lined internally
by, auditory cells, specialized nerve-cells, which often bear

"4 THE ANIMALS AND MAN

delicate vibratile hairs. Auditory organs of this general
character are known among the polyps, the worms, the
crustaceans, and the molluscs. Recent studies seem to
show that the otoliths have a special use as organs which
help the animal to keep its equilibrium. In the common
crayfish the “‘ears”’ are situated in the basal segment of the
inner antennz or feelers. They consist each of a small
sac filled with hquid, in which are suspended several grains
of sand or other hard bodies. The inner surface of the
sac is lined with fine auditory hairs. The sound-waves
coming through the air or water outside strike against this
sac, which lies in a hollow on the upper or outer side of the
antenne. ‘The sound-waves are taken up by the contents of
the sac and stimulate the fine hairs, which in turn give this
stimulus to the nerves which run from them to the principal
auditory nerve and thus to the brain of the crayfish. Among
the insects other kinds of auditory organs exist. The com-
mon locust or grasshopper has on the upper surface of the
first abdominal segment a pair of tympana or ear-drums (fig.
31), composed simply of the thinned, tightly-stretched
chitinous cuticle of the body. On the inner surface of this
ear-drum there are a tiny auditory sac, a fine nerve leading
from it toa small auditory ganglion lying near the tympanum,
and a large nerve leading from this ganglion to one of the
larger ganglia situated on the floor of the thorax. In the
crickets and katydids, insects related to the locusts, the
auditory organs or ears are situated in the fore legs.

Certain other insects, as the mosquitoes and other midges
or gnats, undoubtedly hear by means of numerous delicate
hairs. borne on the antenne. The male mosquitoes have
many hundreds of these long, fine antennal hairs, and on
the sounding of a tuning-fork they have been observed to
vibrate strongly. In the base of each antenna there is a
most elaborate organ, composed of fine chitinous rods, and
accompanying nerves and nerve-cells whose function it is to

ANIMAL PHYSIOLOGY 75

take up and transmit through the auditory nerve to the
brain the stimuli received from the external auditory hairs.
Not all animals have eyes. The moles, which live under-
ground, insects and other animals that live in caves, and the
deep-sea fishes which live in waters so deep that the light of
the sun never comes to them, have no eyes at all, or have
eyes of so rudimentary a character that they can no longer
be used for seeing. But all these animals have no eyes or
only rudimentary ones because they live under conditions
where eyes are useless. They have lost their eyes by degen-
eration. There are, however, many animals that have no
eyes, nor have they or their ancestors
ever had eyes. These are the sim-
plest, most lowly organized animals.
Many, perhaps all eyeless animals.
are, however, capable of distin-
guishing light from darkness. They pyc. 32. Simple eye cf a
are sensitive to light. An investiga- jellyfish. (Greatly magni-
tor placed several individuals of ds after Hertwig.)
the common, tiny fresh-water polyp (Hydra) in a
glass cylinder the walls of which were painted black.
He left a small part of the cylinder unpainted, and
in this part of the cylinder where the light pene-
trated the Hydras all gathered. The eyeless maggots
or larve of flies, when placed in the light will wriggle
and squirm away into dark crevices. They are conscious
of light when exposed to it, and endeavor to shun it. Most
plants turn their leaves toward the light; the sunflower turns
on its stem to face the sun. Light seems to stimulate organ-
isms whether they have eyes or not, and the organisms either
try to get into the light or to avoid it. But this is not seeing.
The simplest eyes, if we may call them eyes, are not
capable of forming an image or picture of external objects.
They only make the animal better capable of distinguish-
ing between light and darkness or shadow. Many lowly

76

THE ANIMALS AND MAN

organized animals, as some polyps, and worms, have cer-
tain cells of the skin specially provided with pigment.
These cells grouped together form what is called a pig-

MM

<

Za

\
il

Y,

Fic. 33. Diagram of vertebrate
eye; c, choroid; 2, iris; /, lens;
n,. optic metve;. 7 retina; —s,
sclerotic. (From Kingsley.)

ment-fleck, which can, because
of the presence of the pig-
ment, absorb more light than
the skin-cells, and are more
Sensitive to the “leht, jBy
such pigment-flecks, or eye-
spots, the animals can detect,
by their shadows, the passing
near them of moving bodies,
and thus be in some measure
informed of the approach of
enemies or of prey. Some of
these eye-flecks are provided
not simply with pigment but
with a simple sort of lens that
serves to concentrate rays of
light and make this simplest

sort of eye even more sensitive to changes in the intensity of

light (fig. 32).

Most of the many-celled ani-

mals possess eyes by means of
which a picture of external ob-
jects more or less nearly com-
plete and perfect can be formed.
There is great variety in the
finer structure of these picture-
forming eyes, but each consists
essentially of an inner delicate
or sensitive nervous surface called
the retina, which is stimulated by
light, and is connected with the
brain by a large optic nerve, and

Fic. 34. Part of cornea, show-
ing facets, of the compound
eye of a horse-fly. (Greatly
magnified; photo-microgra-
phy by Geo. O. Mitchell.)

ANIMAL PHYSIOLOGY

ad

of a transparent light-refracting lens lying outside of the

retina and exposed to the light.

These are the constant

essential parts of an image-forming and image-perceiving
eye. In most eyes there are other accessory parts which

may make the whole eye an organ of ex-
cessively complicated structure and of re-
markably perfect seeing capacity. Our
own eyes (fig. 33) are organs of extreme
structural complexity and of high devel-
opment, although some of the other ver-
tebrates have undoubtedly a keener and
more highly perfected sight.

The crustaceans and insects have
eyes of a peculiar character called com-
pound eyes (figs. 34 and 35). In ad-
dition most insects have smaller simple
eyes. Each of the compound eyes is
composed of many (from a few, as in
certain ants, to as many as twenty-
five thousand, as in certain beetles)
eye elements, each eye element seeing
largely independently of the others and
seeing only a very small part of any ob-
ject in front of the whole eye. All the
small parts of the external object seen
by the many distinct eye elements
combine so as to form an image in mo-
saic, that is, made up of separate small
parts of the external object. If the head
of a dragon-fly be examined it will be
seen that two-thirds or more of the whole

Fic.35. Section through

a few facets and eye
elements(ommatidia)
of the compound eye
of a moth; /f, corneal
facets; c.c, crystalline
cones; p, pigment; r,
retinal parts; o. 1.,
optic nerve. (Greatly
magnified; after Ex-
ner.)

head is made up of the two large compound eyes, and with a
lens it may be seen that the outer surface of each of these eyes
is composed of many small spacesor facets, which are the out-
er lenses of the many eye elements composing the whole eye.

‘-

)

PT

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Av

PART II

THE LIFE-HISTORY OF ANIMALS

CHAPTER VII

MULTIPLICATION AND DEVELOPMENT

Multiplication.—We know that any living animal has
parents; that is, has been produced by other animals which
may still be living or be now dead or, as with Ameba, may
have changed, by division, into new individuals. Individuals
die, but before death, they produce other individuals like
themselves. If they did not, their kind or species would
die with them. This production of new animals constantly
going on is called the reproduction or multiplication of
animals. ‘The process is well called multiplication, because
each female animal normally produces more than one new
individual. She may produce only one at a time, one a
year, aS many of the sea-birds do or as the elephant does,
but she lives many years. Or she may produce hundreds,
or thousands, or even millions of young in a very short time.
A lobster lays 10,000 eggs at a time. Nearly nine millions
of eggs have been taken from the body of a thirty-pound
female codfish. As a matter of fact but very, very few of
these eggs produce new animals which reach maturity.
From the 10,000 eggs produced by the lobster each year
an average of but two new mature lobsters is produced.
There is always a struggle for food and for place going on
among animals, for many more are produced than there
are food and room for, and so of all the new or young animals

79

80 THE ANIMALS AND MAN

which are born the great majority are killed before they
reach maturity. In a later chapter more attention will
be given to this great struggle for life.

In the preceding paragraph it has been stated that “we
know that any living animal has parents; that is, has been
produced by other animals which may still be living or be
now dead.” ‘This is a statement, however, which has found
complete acceptance only in modern times. It is a familiar
fact that a new kitten comes into the world only through
being born; that it is the offspring of parents of its kind.
But we may not be personally familiar with the fact that a
new starfish comes into the world only as the production
of parent starfish, or that a new earthworm can be produced
only by other earthworms. But naturalists have proved
these statements. All life comes from life; all organisms
are produced by other organisms. And new individuals
are produced by other individuals of the same kind. That
these statements are true all modern observations and
investigations of the origin of new individuals prove. But
in the days of the earlier naturalists the life of the microscopic
organisms like Ameba and Paramecium, and even that of
many of the larger but unfamiliar animals, was shrouded
in mystery. And various and strange beliefs were held
regarding the origin of new individuals.

Spontaneous generation.—The ancients believed that
many animals were spontaneously generated. The early
naturalists thought that flies arose by spontaneous generation
from the decaying matter of dead animals. Frogs and
many insects were thought to be generated spontaneously
from mud, and horse-hairs in water were thought to change
into water-snakes. But such beliefs were easily shown
to be based on error, and have been long discarded by
zoologists. But the belief that the microscopic organisms,
such as bacteria and infusoria, were spontaneously generated
in stagnant water or decaying organic liquids was held by

MULTIPLICATION AND DEVELOPMENT 81

some naturalists until very recent times. And it was not
so easy to disprove the assertions of such believers. If
some water in which there are apparently no living organisms,
however minute, be allowed to stand for a few days, it will
come to swarm with microscopic plants and animals. Any
organic liquid, as a broth or a vegetable infusion, exposed to
the air for a short time becomes foul through the presence
of innumerable microscopic organisms. But it has been
certainly proved that these organisms are not spontaneously
produced in the water or organic fluid. A few of them enter
the water from the air, in which there are always greater or
less numbers of spores of microscopic organisms. ‘These
spores germinate quickly when they fall into water or some
organic liquid, and the rapid succession of generations soon
gives rise to the hosts of bacteria and one-celled animals
which infest all standing water. If all the active organisms
and inactive spores in a glass of water are killed by boiling
the water, and this sterilized water be put into a sterilized
glass, and this glass be so well closed that germs or spores
cannot pass from the air without into the sterilized liquid,
no living animals will ever appear in it. We know of no
instance of the spontaneous generation of animals, and all
the animals whose life-history we know are produced by
other animals of the same kind.

Simplest multiplication and development.—The sim-
plest method of multiplication and the simplest kind of
development shown among animals are exhibited by such
simple animals as Ameba and Paramecium. ‘This method
we have already studied. The production of new in-
dividuals is accomplished by a simple division or fission of
the body (a single cell) into two practically equivalent parts.
The only change necessary for the young or new Ameba to
become like its parent, is that of simple growth to a size
about twice its present size. The development here is
reduced to a minimum. Just as the simplest animals per-

82 THE ANIMALS AND MAN

form the other life-processes, such as taking and digesting
food, breathing and feeling, in an extremely primitive simple
way, so do they perform the necessary life-process of re-
production or multiplication in the simplest way shown
among animals.

In the case of Paramecium the process of multiplication
is slightly more complex than that of Ameba in the fact
that sometimes before the simple fission of the body takes
place the interesting phenomenon of conjugation occurs.
If the two conjugating individuals differ at all—and they
always do differ, because no two individual animals, al-
though belonging to the same species, are exactly alike—
the new individual, made up of parts of each of them, will
differ slightly from both. Nature seems intent on making
every new individual differ slightly from the individual
which precedes it. And the method of multiplication which
Nature has adopted to produce the result is the method which
we have seen exhibited in its simplest form in the case of
Paramecium—the method of having two individuals take
part in the production of a new one.

The development of the new Paramecia is a little more
complex than that of Ameba. Not only must the new
Paramecium grow to the size of the original one, but it
must develop those slight, but apparent, modifications of
the parts of its body which we can recognize in the full-
grown, fully developed Paramecium individual. A new
mouth-opening must develop on the new individual formed
of the hinder half of the original Paramecium and new
cilia must be developed. And the recent studies of a careful
naturalist have shown that altogether the new Paramcecia
undergo considerable change during their growth to full size.
Thus there is a slight advance in complexity of development,
just as there is in complexity of structure in Paramecium as
compared with Amaba. In the many-celled animals this
complexity of development is carried to. an. extreme. ue

MULTIPLICATION AND DEVELOPMENT 83

Birth and hatching—When a young animal is born
alive, it usually resembles in appearance and structure the
parent, although of course it is much smaller, and requires
always a certain time to complete its development and be-
come mature. A young kangaroo or opossum Is carried
for some time after its birth in an external pouch on the
mother’s body and is a very helpless animal. A young
kitten is born with eyes not yet opened and must be fed by
the mother for several weeks. On the other hand young
Rocky Mountain sheep are able to run about swiftly within
a few hours after birth.

Most animals appear first as eggs laid by the mother.
This is true of the birds, the reptiles, the fishes, the insects,
and most of the hosts of invertebrate animals. ‘This
egg may be cared for by the parent as with the birds, or
simply deposited in a safe place as with most insects, or
perhaps dropped without care into the water as with most
marine invertebrates. The young animal which _ issues
from the egg may at the time of its hatching resemble the
parent in appearance and structural character (although
always much smaller) as with the birds, some of the insects,
and many of the other animals. Or it may issue in a so-
called Jarval condition, in which it resembles the parent
but slightly or not at all, as is the case with the gill-bearing,
legless, tailed tadpole of the frog or the crawling, wingless,
wormlike caterpillar of the butterfly, or the maggot of the
house-fly.

Life-history—Any animal which hatches from an egg
has undergone a longer or shorter period of development
within the egg-shell before hatching. The development
of an animal from first germ-cell to the time it leaves the
egg, for example, the development of the embryo chick
from the first cell to time of hatching, is called its embryonic
development; and the development from then on, for ex-
ample, that of the chick to adult hen or rooster, or that of

84 THE ANIMALS AND MAN

tadpole to frog, is called the post-embryonic development.
Beginning students of animals cannot study the embryonic
development (embryology) of animals readily, but they can
in many cases easily follow the course of the post-embryonic
development, and this study will always be interesting and
valuable.

CHAPTER VIII

MOSQUITOES AND CATERPILLARS

In the following* studies of insect life-histories the growth
and development of the insects from hatching to maturity
can be readily observed in the schoolroom. The particular
insects chosen are selected because they can be easily ob-
tained and reared indoors, and because they present especially
interesting changes in their development. But other insect
life-histories may be observed, either completely or in part,
if it is so desired. Various caterpillars and chrysalids can
be kept alive and watched as they develop into moths or
butterflies, and various grubs that live in the ground can be
kept until they become beetles. Flesh-flies may be allowed
to lay their eggs on decaying meat, and the hatching of the
maggots, their change into brown seed-like pup, and
the final emergence from these of the blue and green flies
all carefully noted.

MOSQUITOES

The eggs and hatching.—Mosquitoes’ eggs are usually
laid in small blackish masses, which float on the surface
of water. (In the case of some species the eggs are laid
in groups of only a few, or even deposited singly.) These
sooty egg-masses are composed of a single layer of slender
elongate eggs standing on end and loosely fastened to-

*Most of the work outlined in this chapter, as also that of the succeeding
chapter, can be done only in the spring or summer, so that this part of the
book although devoted to a subject which should logically be treated imme-
diately after,—if indeed not before—the structure and general physiology,
may be postponed until after the next part (classification) is studied.

85

86 THE ANIMALS AND MAN

gether to form a narrow, irregular, little raft, slightly concave
on the upper surface, and wholly unsinkable. They are
to be found on small pools of standing water, or in water-
ing-troughs or exposed barrels—wherever indeed there is
quiet or stagnant water. ‘These egg-masses should be
brought into the schoolroom and kept in glass tumblers,
with some of the water on which they are found floating
(fig. 36). Examine an egg-mass with a hand lens to note
the arrangement and appearance of the eggs. How many
are there in the mass?

The eggs should be kept under pretty constant observation
for hatching is likely to take place soon after they are brought
into the schoolroom. Ordinarily they hatch in from twelve
to twenty-four hours after they are laid. They may, of
course, hatch at night. But if the hatching occurs during
the day it can be easily observed. From which end of the
egg does the young mosquito emerge? It may not be easy
to find the egg-masses on the pools; in that case the wrigglers
or larvee (described in the next paragraph) should be sought
for and brought into the schoolroom in tumblers or jars
containing water taken from the pool in which they are
found. The life-history can be studied from this point on.
The tumblers must not be kept in places too cool or dark,
or the young mosquitoes will develop abnormally slowly.

The “‘wrigglers” or larve.—The newly hatched mosquito
bears no resemblance to the familiar winged fly which we
call by that name. In this first stage of its life, or second
stage, if we call the egg stage the first, it is familiarly known
as a “wriggler,” but is called larva by naturalists. The
active young stage of any insect which differs markedly
from the fully developed or mature one is called the larval
stage.

The larvee swim actively about. By what means do they
swim? If they cease swimming do they sink deeper in the
water or rise to the surface? Is the body of the larva denser

MOSQUITOES AND CATERPILLARS 87

or less dense than the water? that is, is it heavier or lighter
than water? Note that some of them hang quietly from
the surface, and that each one comes occasionally to the

surface and rests
there for a while to
breathe. Every ani-
mal has to breathe;
that is, to take up
oxygen from the air
and to give off from
its body carbon di-
oxide (CO,): There
is always some air
mixed with or dis-
solved in water,
and most aquatic
animals—fishes for
exam ple—have
special structures
called gills which
enable them to take
up this dissolved
oxygen, and thus to
breathe under wa-
ter, sbut the. gills
of most mosquito
larvee are too un-
developed, and
therefore they have
to come occasional-
ly to the surface to
breathe.

Fic. 36. A mosquito, Culex sp.; showing eggs
(on surface of the water), larvae (long and
slender, in the water), pupa (large-headed at
surface), and adult (in the air). (About three-
times natural size; from living specimens.)

Examine with a hand lens one of the larve in a watch-
glass of water. Distinguish the head end of the. bedy;
note the eyes (two small black spots), the feelers, or antenne,

88 THE ANIMALS AND MAN

and a pair of tufts or brushes of hair on the head which
vibrate rapidly and constantly. These brushes by their
vibration create currents in the water setting toward the
mouth, which lies between them, and thus bring food to it.
This food consists of any tiny animalcules and microscopic
bits of organic matter in the water. Are there any legs or
wings? Examine the posterior end of the body and note
its division into two parts—one the end of the hind body
or abdomen, the other a breathing-tube projecting from
the next to last body-ring. Make a drawing of the larva,
showing and naming all these parts.

Observe again the larve in the jar. When they hang
from the surface note that only the tip of the breathing-
tube reaches it. Note the vibration of the mouth-brushes.
The larve feed busily for most of the time. If they sink
in the water when they stop ‘wriggling,’ 1.e., swimming,
how is it that they can rest quietly at the surface? For
this reason: the tip of the stem-like breathing-tube pro-
jects slightly above the surface when the wriggler comes up
to breathe, so that the expanded edges of its mouth are
caught by the tense surface film and the wriggler’s body
being but slightly heavier than water, is thus supported or
suspended by the film. It is easier to prove the existence
of this film than to explain it. If you carefully lay a clean
needle on the surface of the water it will not sink, although
much denser, i.e., heavier than water, but will be supported
by the surface film. If you fill a tumbler to its brim you
can still add more water carefully and so heap it up above
the level of the brim. ‘This is because the surface film ex-
tending over the water from edge to edge holds it in place.
If you dip your finger in and then lift it up the water does
not all run off, but a large drop will remain hanging to your
finger. The tense surface film holds the little mass _ to-
gether in the form of a drop. The mosquito larva takes
advantage of the surface film and is able to keep itself at

MOSQUITOES AND CATERPILLARS 89

the surface when breathing by hanging from it. Water-
striders and the numerous little flies which run quickly and
safely about on the surface of the water are supported by
the film. Their feet make little dents or depressions on the
water’s surface, but do not break through.

It is probable that the movements of the feeding-brushes
also help to keep the wriggler at the surface, as the wrigglers
seem to be able to balance themselves, i. e., keep from sinking,
in the water by these movements.

Observing the larve or “‘wrigglers’’ from day to day it
will be noted that they increase in size, that is, are growing.
They breathe and feed and swim and grow. And some
keenly observant pupil may see that they occasionally cast
their skin, or moult. That the larve do moult one or more
times is certain; how many times, however, has not yet been
found out for many kinds.

The pupz.—After several days—just how many each
pupil should determine for himself—the long slender larve
enter upon another stage in the mosquito’s life called the
pupal stage, and the young mosquitoes are now called pupe.
In this stage the head end is large and bulbous, the hind body
is usually curled underneath the head, and the creature
spends most of its time floating at the surface. It can swim,
and does so when disturbed, by a peculiar straightening and
folding of its body. When it stops swimming what happens
to it?) In what way must the pupa differ from the larva in
its relation to the density of water ?

Examine with a hand lens one of the pupz in a watch-
glass of water. Note the two tubes or horns which project
upwards from the back or dorsal part of the bulbous head
end of the body, and the pair of flaps at its posterior tip.
What are the dorsal tubes for? With what do they cor-
respond in the larve? The mouthless pupa takes no food
and usually floats quietly at the surface. Why then does it
swim at all? What is the use of the flaps at the end of the »

90 THE ANIMALS AND MAN

body? Note the indications of legs and wings folded on
the under side of the head end. Make a drawing showing
and naming these parts.

In two or three days the pupa suddenly changes into the
full-fledged winged mosquito. ‘That is, the cuticle or outer
skin wall of the body splits along the middle line of the
back, and the winged mosquito emerges through this open-
ing. What part of the body appears first? What parts
next? While the mosquito is emerging the pupal skin
serves as a raft upon which the soft-bodied damp insect is
partly supported until its wings and legs are unfolded and
dried and hardened, and it is ready to fly away. Some-
times the body rests simply on the surface of the water,
being supported by the surface film. ‘This transformation
of pupa into fully developed mosquito can be readily ob-
served, and each pupil should see it.

The winged or imago stage.—The mosquito is now
full-grown and fully developed; and in this fully developed
stage it is called an zmago to distinguish it from larva and
pupa. It is of course the same insect, a mosquito all the
time, but we commonly apply that name only to the winged
stage or imago. A few of the winged mosquitoes should
be killed in a “‘killing-bottle” (see Appendix I), and examined
under a hand lens. Two kinds may be distinguished;
one with many long hairs on their feelers or antenne, the
other with fewer and much shorter hairs; the latter are
females, the ones with bushy antenne males. These
antenn are the mosquito’s organs of hearing. How many
wings has the mosquito? How many pairs of legs? Can
you find behind the wings a pair of delicate little knobbed
processes projecting from the body? ‘These are called
balancers and they aid the mosquito in directing its flight.
Note the long, piercing and sucking beak (fig. 37) by means
of which the mosquito gets its food, which is either the blood
of animals or the sap of plants. The male mosquitoes

MOSQUITOES AND CATERPILLARS QI

never (or very rarely) suck blood. On each side of the
beak, and arising at its base, is a pair of feelers or palpi,
presumably organs for smelling and tasting, or which at
least aid in determining the character of the food. These
palpi are as long as the beak
in the males, but less than
half as long as in the females.
What are the large black spots
on the head? Make a drawing
of a mosquito, showing and
naming these parts. an

If some of the mosquitoes
are kept alive in jars filled
with water and covered with
netting the females may per-
haps lay eggs on the surface
of the’ water. But it is not
at all certain that they will;
indeed, they seem to lay eggs Fic. 37. Beak of female mos-
only rarely when thus Kept aul, dtl how th
in confinement. If a slice of their sheath; mx. p., the max-
banana be put in the jar the illary palpi, or feelers of the
mosquitoes may be seen to suck OU early aeeaned )
the sap from it, and they may be kept alive for many days
if given fresh banana every three or four days. If the egg-
laying occurs, the life-history of our mosquitoes is com-
pleted. A new cycle is about to begin.

Distribution of mosquitoes.—Mosquitoes are distributed
all over the world, being found in enormous numbers in
arctic regions and on high moutain ranges as well as in
the tropics, and in swamps and marshy valleys. About
four hundred and fifty species, or different kinds, of mos-
quitoes are known, nearly seventy of which are found in
North America. Besides the irritation caused by their
“bite,” i.e., piercing with the sucking beak, it has been

92 THE ANIMALS AND MAN

proved that mosquitoes are the conveyers and distributors
of the germs of malarial fever (see Chapter XII). Only
certain kinds of mosquitoes, however, are malaria-carriers.
These all belong to the genus Anopheles; they may be
distinguished by the possession of spotted wings, as most of
the innocuous kinds have the wings clear. There are a few
innocuous or non-malarial kinds with spotted wings, how-
ever, but no malaria-carrying kinds with wholly clear wings.
The malaria-bearing kinds have the maxillary palpi long in
both male and female, while in the other kinds the females
have short palpi (fig. 37). Other kinds of mosquitoes are
certainly the distributors of the germs of yellow fever, and
the same kinds convey a terrible tropical disease called
elephantiasis.

The most effective remedy against mosquitoes is to pour a
little kerosene on the surface of the pool in which the larvee
and pupz live. The kerosene will spread out and form a
thin, oily film over the surface of the water, and no winged
mosquito will be able to emerge alive through this film,
contact with kerosene being fatal to almost all insects, and
and especially so just after a moult.

For full accounts of the life of mosquitoes see ‘‘Mosquitoes,”’ by
Dr. L. O. Howard or ‘“‘ Mosquito Life” by Evelyn G. Mitchell.

CATERPILLARS

Caterpillars are the larve of moths and butterflies. While
larva is the entomologist’s name for the young of any kind
of insect that has a complete metamorphosis, most persons
call the larvee of different kinds of insects by different names,
as grubs for the larve of beetles, maggots for those of many
flies, wrigglers for those of mosquitoes, slugs for those of
saw-flies and caterpillars for those of moths and butterflies.

Most caterpillars are readily distinguishable by the five
pairs of short, blunt, fleshy abdominal legs which they
possess in addition to the three pairs of jointed thoracic legs.

MOSQUITOES AND CATERPILLARS 93

The different kinds also are often easily recognizable by
well-marked color patterns, or by coverings of colored hair
or the presence of conspicuous tubercles and the like.
They may be found from late spring to early fall usually
busily feeding in their favorite plants. “The best hunting
grounds are the sides of country roads, the edges of woods,

\
al

eae e

Fic. 38. Larva of the achemon sphinx moth, Philampelus achemon.
(Natural size; after Lugger.)

half-cleared fields and gardens. Low fresh second growths
of oak, poplar or elm will pay investigation. . . . A low
growth of wild cherry is almost sure to yield a harvest.”
Virginia creeper, sassafras, bayberry, hop-vines, appletrees,
nettles, milkweeds and wild carrot are all favorite feeding
grounds of butterfly caterpillars.

The important thing to note at the time of collecting
a live caterpillar, which you wish to rear indoors, is the
kind of plant it is feeding on. For these are the best leaves
to bring in to it. Indeed some kinds of caterpillars will

ah ‘THE ANIMALS AND MAN

eat the leaves of only certain few kinds of plants. Indoors
the live caterpillars should be kept in clean cages (see
Appendix II for directions for making cages) and given
plenty of fresh food. They will then eat, grow, moult,
pupate and finally turn into perfect moth or butterfly.

The observations to be made on the caterpillars are of

peer? — oe ma He — oe 2 a tn ea

f .
eS

t 1

oP =
* . *. ~

|
|
|

Fic. 39. Larva of the violet-tipped butterfly, Polygonia interrogationis,
pupating. (Slightly enlarged; photograph from life by the author.)
two general categories: (1) observations of structure; (2)
observations of behavior. ‘To record the first make drawings;
for the second make notes. ed a
Of structural characteristics note the segmental make-up
of the body and number of the segments; number, position
and character of the legs, the mouth-parts, eyes and antenne
on head; presence and arrangement of hairs or tubercles,
and position and number of spiracles (breathing pores).

MOSQUITOES AND CATERPILLARS 95

All of these points may be shown in a single drawing. A
colored drawing should be made showing the colors and
color pattern.

Among the characteristics of behavior to be noted are
the manner of walking, manner of eating, attitudes when
disturbed or frightened, and the processes of movlting and
pupating.

If an inch worm (caterpillar of a Geometrid moth) can
be found, note its different methods of walking and the dif-
ference in the number of legs. Is there a relation between the
different number of legs and the different mode of walking?

Some caterpillars go into the ground to pupate, some
spin silken cocoons, some simply attach themselves freely
exposed. The spinning of cocoons should be watched
closely and described fully in the notes.

A fully spun cocoon should be cut open several days
after it is made, in order to see the chrysalid within. If
some caterpillars have burrowed into the ground one or
two should be dug up after several days in order to see
what has happened. If the chrysalid has been made freely
exposed note whether its colors and patterns are such as
would tend to conceal it if it were hanging against bark or
among leaves. °

Make a drawing of the chrysalid showing and naming all
the parts that can be observed. Look for spiracles and
for the wings, legs, mouth-parts and antenne of the future
moth or butterfly.

Make drawings and notes describing in detail the issuance
of the moth or butterfly from the chrysalid case. Pay
special attention to the unfolding and expanding of the wings.
By what means does this expansion probably take place?

Make drawings of the fully expanded moth or butterfly
showing not only its general shape but all of its parts. Note
all of the details in which it differs from the caterpillar.
These include number, character and arrangement of the

96 THE ANIMALS AND MAN

segments, number and character of the legs, presence of
the wings, difference of the wings, difference in antenne,
eyes and mouth-parts, clothing of scales over wings and
body, color and color patterns, etc.

Frc. 40. Pupa or chrysalid of the violet-tipped butterfly, Polygonia in-
terrogationis. (Slightly enlarged; photograph from life by the author.)

There is no limit to the possibilities of pleasure and in-
terest in the field study and collecting of moths and butter-
flies. ‘The study should include observations on their flight,
their resting attitudes, their feeding habits, their play with
each other, and their mating and egg-laying.

Directions for collecting and preserving these and other
insects will be found in Appendix II.

Butterflies can be named by referring to some such book as Com-
stock’s ‘‘How to Know the Butterflies,” Holland’s ‘‘The Butterfly
Book,” or Scudder’s ‘‘Everyday Butterflies.’”” The more common
and conspicuous moths can be named from Holland’s “The Moth Book. ”’

CHAPTER IX

FROGS AND BIRDS

While the life-history of most of the backboned animals
shows no such startling transformations or metamorphoses
as that of the insects we have studied, yet among toads,
frogs, and salamanders, forming the class of backboned
animals known as amphibians or batrachians, there is an
interesting and well-marked metamorphosis. A newly
hatched bird is much smaller and weaker than its parents,
its feathers are different, and it usually has to be cared for
and fed for some time, but it is unmistakably birdlike in
appearance, and its development to adult form is gradual
and without startling changes. The same is true of kittens
and puppies, or young lions or camels, and true, also, for
the most part, of fishes and of snakes and lizards. But the
young toad or frog, which we call tadpole, looks, and truly
is, much more like a fish than like its parent, and therefore
in its growth and development it undergoes a marked trans-
formation.

The eggs and hatching.—In the spring, April and May,
the frogs and toads begin their croaking and trilling, and
then is the time to look in the ponds for the eggs. Indeed
the ponds had better be watched as soon as the ice goes out.
Hunt in the shallow water along the banks. Toads’ eggs lie
in long strings of a gelatinous, jelly-like substance, usually
wound about submerged sticks or the stems of water-plants,
while those of the frog are found in small bunches or masses
of the jelly. They are small, shining, black, and bead-
like, and in the toad strings are arranged in single rows.

97

98 THE ANIMALS AND MAN

If they have been recently laid, the enclosing jelly mass will
be clean and clear, but it soon becomes partly covered with
fine mud, when the eggs are not so easily seen. Bring some
egg-masses to the schoolroom and keep them in water in a
light warm place but not in the direct sunlight.

Examine the eggs several times a day, as hatching occurs
in two or three days after they are laid. The developing
embryo. can be
clearly seen through
the transparent jel-
ly> = W ateh stor
their first move-
ments and note
their change in
form. Finally they
wriggle out from
the jelly mass and
swim freely in the
Water, ‘or “attach
themselves. 7by
means of a little
V-shaped sucker on the head, to some solid object. They
are not like adult frogs or toads at all, but are the famil-
iar little fish-like tadpoles (fig. 42).

The tadpoles.—To rear tadpoles successfully in the school-
room requires some pains. First, a proper little artificial
pond must be made. Professor Gage, of Cornell University,
who has sucessfully reared many broods, gives the following
directions for caring for them:

“To feed the tadpoles it is necessary to imitate nature as
closely as possible. To do this a visit to the pond where
the eggs were found will give the clue. Many plants are
present, and the bottom will be seen to slope gradually
from the shore. The food of the tadpole is the minute
plant-life on the stones, the surface of the mud, or on the

Fic. 41. Garden toad.

FROGS AND BIRDS 99

outside of the larger plants. Make an artificial pond in a
small milk-pan, or a large basin or earthenware dish. Put
some of the mud and stones and small plants in the dish,
arranging all to imitate the pond, that is, so it will be shallow
on one side and deeper on the other. ‘Take a small pail of
clear water from the pond to the schoolhouse and pour it
into the dish to complete the artificial pond. The next

Fic. 42. Tadpoles. (Photograph from life by Cherry Kearton; _per-
mission of Cassell and Co.)

morning when all the mud has settled and the water is clear,
put thirty or forty of the little tadpoles which hatched from
the egg string, into the artificial pond. Keep this in the
light, but not very long at any one time in the sun.

“One must not attempt to raise too many tadpoles in
the artificial pond or there will not be enough food, and
all will be half-starved. While there may be thousands
of tadpoles in a natural pond, it will be readily seen that,
compared with the amount of water present, there are
really rather few.

“Every week, or oftener, a little of the mud, and perhaps.

100 THE ANIMALS AND MAN

a small stone covered with the growth of microscopic plants,
and some water should be taken from the pond to the arti-
ficial pond. ‘The water will supply the place of that which
has evaporated, and the mud and stones will carry a new
supply of feed.”

The tadpoles will begin to change very soon. Make a
drawing of one just hatched from the egg, examining it
with a hand lens. Note the gills on the sides of the neck,
the V-shaped sucker on the head, and the absence of legs
and eyes. Watch sharply for the first changes. What are
they?

It takes a tadpole about two months from the time of
hatching to complete its development and hop out of the
water as a little toad or frog. In this process of develop-
ment the following changes occur: eyes appear; the gills are
lost; four legs develop; the tail is gradually lost, and lungs
are formed inside the body. The development of the lungs
cannot be actually seen, but its course is made apparent by
the behavior of the tadpoles. While at first they remain
under the water nearly all the time, breathing by means
of their gills the air dissolved in the water, as they grow
older they come more and more often to the surface and gulp
down air through the mouth. Lungs are developing, and
are being more and more used for breathing air from the
limitless supply above.

Observe carefully the process of the disappearance of
the tail. Does it drop off suddenly? Is it lost before the
legs develop? Which pair of legs appears first? The order
of their appearance differs in the toad tadpoles and the frog
tadpoles; if both kinds are being reared determine this by
observation.

Make a drawing of a tadpole just after its legs appear,
and compare with the drawing of the newly hatched tadpole;
make also a drawing of a little toad or frog when it first
finishes the tailed tadpole stage and hops out of the water.

FROGS AND BIRDS IOI

While the development of the tadpoles is going on in the
schoolroom observations on the growth and changes of
those in the natural ponds outdoors should be made. Does
development go on more rapidly indoors than out? Where
do the little toads and frogs go after they leave the outdoor
ponds ?

Toads and frogs.—Adult toads and frogs are carniv-
orous, instead of feeding on tiny plants as in their tadpole
stage. They snap up all
kinds of insects, worms, and
snails; when full grown they
will eat younger frogs, cray-
fish, small turtles, and fish,
and may also occasionally
capture small birds. A few
grown-up toads and_ frogs
should be kept in the school-
room in a box with at least
one glass-side and covered over with netting. Keep a dish of
water in the box, and the bottom covered with clean moist
sand. Feed the toads live insects, worms, and snails, or
bits of raw meat. How does the toad catch its prey or
seize the offered food ?

Both toads and frogs do much good by destroying many
insects. One observer, quoted by Professor Gage, reports
that a single toad disposed of twenty-four caterpillars in
ten minutes, and that another ate thirty-five celery-worms
within three hours. This observer estimates that a good-
sized toad will destroy nearly ten thousand insects and worms
inasinglesummer. ‘The garden can have no more desirable
animal inhabitants than toads; not only should they not be
killed but it would be worth while to introduce them into flower
and vegetable gardens where they are not naturally present.

——

Fic. 43. Garden toad.

For a good account of tadpole-rearing see ‘‘The Life of a Toad,”
by Professor S. H. Gage.

102 THE ANIMALS AND MAN

BIRDS

The animals whose life-history we have so far studied
do not take care of their young, though making certain
provision for them nevertheless. The female mosquito,
although an aerial creature, is careful to lay her eggs on
the surface of water so that the young will find themselves
at the moment of hatching in their proper element; the
female moth or butterfly, although she never eats leaves her-
self, always lays her eggs on the plants or trees where
the young, on hatching, can find at hand their proper
leaf food. Such is the habit of all moths and butterflies.
Some of them indeed take no food in their adult stage;
others do, but this is always liquid nectar from flowers, or
other sweet juices, and water, and their mouth-parts are
formed into a long flexible, coiling, sucking proboscis. They
could not eat green leaves if they would; and yet each moth
and butterfly mother seeks out, at egg-laying time, that par-
ticular plant, unknown to her as food, the green leaves of
which, the young caterpillars must live upon; truly a re-
markable instinct! But beyond this care in laying their
eggs in suitable places the butterflies and moths have nothing
to do with their young.

And so it is with most of the lower or simpler animals,
and with many of the vertebrates (backboned animals),
most of the fishes for instance, the amphibians, and the
reptiles. ‘These animals pay little or no attention to their
young after birth; indeed many of the lower ones die before
the young are hatched, and those that do not may have gone
a long distance away before that time. But among the
higher vertebrates, the birds and mammals, and among a
few particularly interesting invertebrates, as the social
insects and others, the parents give much care and pro-
tection to their young, building homes for them, providing
them with food, and teaching them to help themselves.
Almost all animal homes are built primarily for the pro-

FROGS AND BIRDS 103

tection and housing of the young, although the parents,
may, and during the rearing of the young, naturally do,
largely live in them themselves. As an example of an ani-
mal home, we may observe the construction of a bird’s
nest, together with the egg-laying and incubation and the
care of Oe fledglings.

A bird’s nest.—In spring (iy Yy Vi, JI
and early summer, the nesting- \X“*7 oe iio,
times, find close to the school- Maile 1 “yj I)
room a pair of birds that have
begun a nest. By keeping
sharp watch in trees and
bushes they will surely be
found, though most birds hide
their nests as effectively as
possible. Robins are especially
good birds to watch, because
they are not easily frightened
from their work, because they
build a large nest, and be-
cause they gather their nesting
materials mostly in the near
vicinity of thenest. Because
the robin’s nest is in a tree, Fic. 44. Nest of humming-bird,
it may not be so easy to watch made of sycamore down.
as the nest of some bird that ea a
builds in hedges or bushes. Find a robin or other bird
carrying a straw in its bill and trace it “home.”

In observing the nest-building, egg-laying, and incu-
bation try to answer the following questions: Do both
birds take active part in building, or but one, and if one,
which one, the male or female, and what does the other do?
What materials are used? Is the nest composed chiefly of
one kind of material, or nearly equally of several? What
“tools” of the bird are used in building? When does build-

Vy, 7 NR .
Hey
By,

Yy

Y

104 THE ANIMALS AND MAN

ing begin? How long does it last? How soon after finish-
ing the nest are the eggs laid? Are all the eggs laid at one
sitting? Do both birds take part in incubation, i. e., sitting,
or but one, and if but one, is it the male or female? What
does the other do? How long before the eggs hatch? Do
they all hatch at the same time?

After hatching the care of the fledglings should be well

Fic. 45. Oriole’s nest with skeleton of bluejay suspended from it; the
bluejay probably came to the nest to eat the eggs, became entangled
in the strings composing the nest, and died by hanging. (Photo-
graph by S. J. Hunter.)

watched. Do both parents bring food? How many times
is food brought in one hour, or if so much time can be given
to continuous watching, in two or three? What is the food?
Is the nest cleaned? If so, how often? When are the first
flying lessons given? How long do the young birds con-
tinue to come back to the nest at night after they first leave
ite

FROGS AND BIRDS 105

Other incidents in the course of nest-building, incubation,
and care of the young birds will certainly be noted if sufficient
observation to answer the above questions is given. Attacks
by cats and bluejays (fig. 45), disputes between the parent
birds, accidents from high winds or other causes are all
likely to enter into the course of nesting. And the behavior
of the parent birds under such more or less unnatural cir-
cumstances will be interesting to observe and record.

While some pupils are watching a robin’s nest others
should observe the nesting of other kinds of birds—the blue-
bird, wren, groundbird, catbird—any familiar kind that
can be found at work.

See Chapters XVII-XXI in Baskett’s ‘The Story of the Birds,”
and Chapter VI in Chapman’s ‘‘Bird-life.”’

H 7
A Pata (

4 ib

J ¢ J

MTs WN eEAY,
ag Mi ae phe)

PAR TERI

DIFFERENT KINDS OF ANIMALS, THEIR
CLASSTPICATION. HABITS CAND
SPECIAL RELATION TO MAN

CHAPTER:
THE CLASSIFICATION OF. ANEMALS

Basis and significance of classification.—It is the com-
mon knowledge of all of us that animals are classified:
that is, that the different kinds are arranged in the mind
of the zoologist and in the books of natural histroy, in various
groups, and that these various groups are of different rank
or degree of comprehensiveness. A group of high rank
or great comprehensiveness includes groups of lower rank,
and each of these includes groups of still lower rank, and
so on, for several degrees. For example, we have already
learned that the toad belongs to the great group of back-
boned animals, the Vertebrates, as the group is called.
So do the fishes and the birds, the reptiles and the mammals
or quadrupeds. But each of these constitutes a lesser
group, and each may in turn be subdivided into still lesser
groups.

In the early days of the study of animals and plants their
classification or division into groups was based on the re-
semblances and the differences which the early naturalists
found among the organisms they knew. At first all of the
classifying was done by paying attention to external re-

107

108 THE ANIMALS AND MAN

semblances and differences, but later when naturalists began
to dissect animals and to get acquainted with the structure
of the whole body, the differences and likenesses of inner
parts, such as the skeleton and the organs of circulation
and respiration, were taken into account. At the present
time and ever since the theory of descent began to be accepted
by naturalists (and there is practically no one who does
not now accept it), the classification of animals, while still
largely based on resemblances and differences among them,
tells more than the simple fact that animals of the same
group resemble each other in certain structural characters.
It means that the members of a group are related to each
other by descent, that is, genealogically. They are all the
descendants of a common ancestor; they are all sprung
from acommon stock. And this added meaning of classifica-
tion explains the older meaning; it explains why the animals
are alike. ‘The members of a group resemble each other in
structure because they are actually blood relations. But as
their common ancestor lived ages ago, we can learn the
history of this descent, and find out these blood-relationships
among animals only by the study of forms existing now,
or through the fragmentary remains of extinct animals pre-
served in the rocks as fossils. As a matter of fact we usually
learn of the existence of this actual blood-relationship, or
the fact of common ancestry among animals, by studying
their structure and finding out the resemblances and dif-
ferences among them. If much alike we believe them
closely related; if less alike we believe them less closely
related, and so on. So after all, though the present-day
classification means something more, means a great deal
more, in fact, than the classification of the earlier naturalists
it is still largely based on and determined by resemblances
and differences just as was the old classification. Some-
times the fossil remains of ancient animals tell us much
about the ancestry and descent of existing forms. For

THE CLASSIFICATION OF ANIMALS 10g

example, the present-day one-toed horse has been clearly
shown by series of fossils to be descended from a small
five-toed horse-like animal which lived in the Tertiary age.

Importance of development in determining classifica-
tion.—A very important means of determining the relation-
ships among animals is by studying their. development.
If two kinds of animals undergo very similar development,
that is, if in their development and growth from egg-cell to
adult they pass through similar stages, they are nearly
related. And by the correspondence or lack of correspon-
dence, by the similarity or dissimilarity of the course of
development of different animals much regarding their
relationship to each other is revealed. Sometimes two
kinds of animals which are really nearly related come to
differ very much in appearance in their fully developed adult
condition because of the widely different life-habits the two
may have. But if they are nearly related their developmental
stages will be closely similar until the animals are almost
fully developed. For example, certain animals belonging
to the group which includes the crabs, lobsters, and cray-
fishes, have adopted a parasitic habit of life, and in their
adult condition live attached to the bodies of certain kinds
of true crabs. As these parasites have no need of moving
about, being carried by their hosts, they have lost their
legs by degeneration, and the body has come to be a mere
sac-like pulsating mass, attached to the host by slender
root-like’ processes, and not resembling at all the bodies of
their relatives, the crabs and crayfishes. If we had to trust,
in making out our classification, solely to structural re-
remblances and differences, we should never classify the
Sacculina (the parasite) in the group Crustacea, which is
the group including the crabs and lobsters and crayfishes.
But the young Sacculina is an active free-swimming creature
resembling the young crabs and young shrimps. By a study
of the development of Sacculina we find that it is more

110 THE ANIMALS AND MAN

closely related to the crabs and crayfishes and the other
Crustaceans than to any other animals, although in adult
condition it does not at all, at least in external appearance,
resemble a crab or lobster.

Scientific names.—To classify animals then, is to deter-
mine their true relationships and to express these relation-
ships by a scheme of groups. ‘To these groups proper names
are given for convenience in referring to them. These
proper names are all Latin or Greek, simply because these
classic languages are taught in the schools and colleges of
almost all the countries in the world, and are thus intelligible
to naturalists of all nationalities. In the older days, indeed,
all the scientific books, the descriptions and accounts of
animals and plants, were written in Latin, and now most of
the technical words used in naming the parts of animals and
plants are Latin. So that Latin may be called the language
of science. For most of the groups of animals we have
English names as well as Greek or Latin ones and when
talking with an English-speaking person we can use these
names. But when scientific men write of animals they use
the names which have been agreed on by naturalists of all
nationalities and which are understood by ail of these natural-
ists. These Latin and Greek names of animals laughed at
by non-scientific persons as ‘‘jaw-breakers,” are really a
great convenience, and save much circumlocution and
misunderstanding.

AN EXAMPLE OF CLASSIFICATION.

TECHNICAL Note.—There should be provided a small set of bird-
skins which will serve just as well as freshly killed birds, and which
may be used for successive classes, thus doing away with the neces-
sity of shooting birds. The birds suggested for use are among the
commonest and most easily recognizable and obtainable. ‘They may
be found in any locality at any time of the year. The skins can be
made by some boy interested in birds and acquainted with making
skins, or by the teacher, or can be purchased from a naturalists’ sup-
ply store, or dealer in bird skins. The skins will cost about 25 cents

THE CLASSIFICATION OF ANIMALS III

each. This example or lesson in classification can be given just as
well of course with other species of birds, or with a set of some other
kinds of animals, if the teacher prefers. Insects are especially avail-
able, butterflies perhaps offering the most readily appreciated resem-
blances and differences.

Species.—Examine specimens of two male downy wood-
peckers (the males have a scarlet band on the back of the
head). (In the western States use Gardiner’s downy
woodpecker.) Note that the two birds are of the same size,
have the same colors and markings, and are in all respects
alike. ‘They are of the same kind; simply two individuals
of the same kind of animal. There are hosts of other
individuals of this kind of bird, all alike. This one kind
of animal is called a species. ‘The species is the smallest*
group recognized among animals. No attempt is made to
distinguish among the different individuals of one kind or
species of animal as we do in our own case.

Examine a specimen of the female downy woodpecker.
It is like the male except that it does not have the scarlet
neck-band. But despite this difference we know that it
belongs to the same species as the male downy because
they mate together and produce young woodpeckers, male
and female, like themselves. There are thus two sorts of
individuals, male and female, comprised in each species
of animal. A species is a group of animals comprising simi-
lar individuals which produce new individuals of the same
kind usually after the mating together of individuals of two
sexes which may differ somewhat in appearance and structure.

Examine a male hairy woodpecker and a female; (in
western States substitute a Harris’s hairy woodpecker).
Note the similarity in markings and structure to the downy.
Note the marked difference in size. Make notes of meas-

*The lesser group called variety, or subspecies, we may leave out of
consideration for the present.

{Some species of animals are not represented by male individuals; and
in some all the individuals are hermaphrodites.

112 THE ANIMALS AND MAN

urements, colors and markings, and drawings of bill and
feet, showing the resemblances and the differences between
the downy woodpecker and the hairy woodpecker. These
two kinds of woodpeckers are very much alike, but the
hairy woodpeckers are always much larger (nearly a half)
than the downy woodpeckers and the two kinds never
mate together. The hairy woodpeckers constitute another
species of bird.

Genus.—Examine now a flicker (the yellow-shafted or
golden-winged flicker in the East, the red-shafted flicker in
the West). Compare it with the downy woodpecker and
the hairy woodpecker. Make notes referring to the differ-
ences, also the resemblances. ‘The flicker is very differently
marked and colored and is also much larger than the downy
woodpecker, but its bill and feet and general make-up are
similar and it is obviously a ‘“‘woodpecker.”’ It is, however,
evidently another species of woodpecker, and a species
which differs from either the downy or the hairy wood-
pecker much more than these two species differ from each
other. There are two other species of flickers in North
America which, although different from the yellow-shafted
flicker, yet resemble it much more than they do the downy
and hairy woodpeckers or any other woodpeckers. We
can obviously make two groups of our woodpeckers so far
studied, putting the downy and hairy woodpeckers (together
with half a dozen other species very much like them) into
one group and the three flickers together into another group.
Each of these groups is called a genus, and genus is thus the
name of the next group above the species. A genus usually
includes several, or if there be such, many, similar species.
Sometimes it includes but a single known species. ‘That
is, a species may not have any other species resembling it
sufficiently to group with it, and so it constitutes a genus by
itself. If later naturalists should find other species re-
sembling it they would put these new species into the genus

THE CLASSIFICATION OF ANIMALS ide,

with the solitary species. Each genus of animals is given a
Greek or Latin name, of a single word. ‘Thus the genus
including the hairy and downy woodpeckers is called
Dryobates; and the genus including the flickers is called
Colaptes. But it is necessary to distinguish the various
species which compose the genus Colaptes, and so each
species is given a name which is composed of two words, first
the word which is the name of the genus to which it be-
longs, and, second, a word which may be called the species
word. The species word of the yellow-shafted flicker is
auratus (the Latin word for golden), so that its scientific
name is Colaptes auratus. ‘The natural question, Why not
have a single word for the name of each species? may be
answered thus: There are already known more than 500,000
distinct species of living animals; it is certain that there are
no less than several millions of species of living animals; new
species are being found, described and named constantly;
with all the possible ingenuity of the wordmakers it would
be an extremely difficult task to find or to build up enough
words to give each of these species a separate name. ‘This
is not attempted. The same species word is often used for
several different species of animals, but never for more than
one species belonging to a given genus. And the names of
the genera are never duplicated. (There are, of course,
much fewer genera than species, and the difficulty of finding
words for them is not so serious.) Thus the genus word in
the two-word name of a species indicates at once to just
what particular genus in the whole animal kingdom the
species belongs, while the second or species word distin-
guishes it from the few or many other species which are
included in the same genus. This manner of naming
species of animals and plants (for plants are given their
scientific names according to the same plan) was devised by
the great Swedish naturalist Linneus in the middle of the
eighteenth century and has been in use ever since.

114 THE ANIMALS AND MAN

Family.—Examine a _ red-headed woodpecker (Mela-
ner pes erythrocephalus) and a_ sapsucker (Sphyrapicus
varius) and any other kinds of woodpeckers which can be
got. Find out in what ways the hairy and downy wood-
peckers (genus Dryobates), the flickers (genus Cola tes),
and the other woodpeckers resemble each other. Examine
especially the bill, feet, wings and tail. These birds differ
in size, color and markings, but they are obviously all alike
in certain important structural respects. We recognize
them all as woodpeckers. We can group all the wood-
peckers together, including several different genera, to form
a group which is called a family. A family is a group of
genera which have a considerable number of common struc-
tural features. Each family is given a proper name consisting
of a single word. ‘The family of woodpeckers is named
Picide.

We have already learned that resemblances between
animals indicate (usually) relationship, and that classify-
ing animals is simply expressing or indicating these relation-
ships. When we group several species together to form
a genus we indicate that these species are closely related.
And similarly a family is a group of related genera.

Order.—There are other groups* higher or more com-
prehensive than families, but the principle on which they
are constituted is exactly the same as that already explained.
Thus a number of related families are grouped together to
form an order. All the fowl-like birds, including the families
of pheasants, turkeys, grouse and quail, all obviously re-
lated, constitute the order of gallinaceous birds called
Galline. The families of vultures, hawks and owls con-
stitute the order of birds of prey, the Raptores, and the fami-

lies of the thrushes, wrens, warblers, sparrows, black-birds,

*Each of these higher groups has a proper name composed of a single
word. In the case of no group except the species is a name-word ever
duplicated. Each genus, family, order, or higher group has a name-word
peculiar to it, and belonging to it alone,

THE CLASSIFICATION OF ANIMALS II5

and many others constitute the great order of perching birds
(including all the singing birds) called the Passeres.

Class and branch.—But it is evident that all of these
orders, together with the other bird orders, ought to be
combined into a great group, which shall include all the
birds, as distinguished from all other animals, as the fishes,
insects, etc. Such a group of related orders is called a class.
The class of birds is named Aves. There is a class of fishes,
Pisces, and one of frogs and salamanders, Batrachia, one
of snakes and lizards called Reptilia, and one of the quad-
rupeds which give milk to their young called Mammalia.
Each of these classes is composed of several orders, each of
which includes several families and so on down. But these
five classes of Pisces, Batrachia, Reptilia, Aves and Mammals
agree in being composed of animals which have a backbone
or a backbone-like structure, while there are many other
animals which do not have a backbone, such as the insects,
the starfishes, etc. Hence these five backboned classes may
be brought together into a higher group called a branch
or phylum. ‘They compose the branch of backboned ani-
mals, the branch Vertebrata (now usually looked on as a
sub-branch of the great branch Chordata); all the animals
like the star-fishes, sea-urchins and sea-lilies which have the
parts of their bodies arranged in a radiate manner compose
the branch Echinodermata; all the animals like the insects
and spiders and centipedes and crabs and crayfishes, which
have the body composed of a series of segments or rings and
have legs or appendages each composed of a series of joints
or segments, make up the branch Arthropoda. And so might
be enumerated all the great branches or principal groups
into which the animal kingdom is divided.

TABLE OF BRANCHES AND CLASSES OF ANIMALS

As the animals referred to in this book are not taken up
In a rigorous systematic or classificatory order, but are

116

THE ANIMALS AND MAN

grouped together to some extent rather according to simi-
larities of habit or habitat, the following table of classifica-
tion* of animals to branches and classes is introduced to
show the relationships of the various large groups.

Class i
Class =) 40:
Class: Et:
Glassa LV:
Class Wp
Class 16
Class IE
Class) sll.
Class’ 2 LE
Chass.) LV
Class 1.

@lassy sf.
Class” 21:
Class iff
Classe -ade
Glass. Ue
Class ie
Class.: ell.
@lass* LEP
Class ie
Glass- =L1
Class, ELL:

KINGDOM ANIMALIA.

Branco I. PROTOZO’A.
Rhizop’oda.
M ycétoz0’a.
Mastigo ph’ ora.
Sporoz0’a.
Injuso’ria.

Brancu II. PORIF’ERA.
Porifera.

BraNncu III. CCELEN’TERA’TA (sé-lén-te-ra-ta).

H¥droz0'a.

Scyphozoa (si-f5-z0’-a).
Actinoz0’a.

Cténé ph’ora (tén-dph’-o-ra).

Branco IV. PLATYHELMIN’THES.
Turbella’ria.
Trémato’da.
Césto’da.

Branco V. NEMATHELMIN’THES.
Némato'da.
Acanthocéph’ala.
Chetog/natha (ké-tdg’-na-tha)

Branco VI. TROCHELMIN’THES.

Rotij’era.

Dino phi'lea.

Gastrot’richa.

BrancH VII. MOLLUSCOI’DA.

Polyz0’a.

Phoro’nida.

Brachi6 p’oda.

*The classification here used is that adopted by Parker and Haswell’s
Text-book of Zoology (1897).

Class i td
Class’: ak:
Class, PI:
@lass:» “EV;
Class V.
Glass’ “WL:
Class VEL.
@lass = 91:
Glass: -* bie
Class hie
Class, =TV2
Class Ec
Glass, Vii
Class: LE
Class: TV.
Class ava
Class 1
Class iio
Class~ “Lik
Class. “LV:
Sub-branch
Sub-branch
Sub-branch

THE CLASSIFICATION: OF ANIMALS

BrAncH VIII. ECHINODER’MATA.
Asterot’ dea.
O phiuroi’ dea.
Echinot’ dea.
Holothurot’ dea.
Crinov’ dea.
Cystot’ dea.
Blastoi’ dea.

BrancH IX. ANNULA’TA.
Chetop’oda (ké-top’o-da).
Géphyré’a (jéf-e-ré’-a).
Archi-annél'ida.
Hirudin’ea.

BrancH X. ARTHROP’ODA.
Crusta’cea.
Onychoph’ora (6n-y-k6f’-o-ra).
Myria p’oda.
Inséc’ta.
Ardch’nida.

Branco XI. MOLLUS’CA.

Pélecy p’oda.
Amphineu’ra.
Gastro p’ oda.
Céphalép’oda.

BrancH XII. CHORDA/‘TA.
I. Adélochor’da.
Class Adélochor’da.
II. Urochor’da.
Class Urochor’da.
III. Vertebra’ta.

Division A. Acrda’/nia.
Class Acra’nia

Division B. Crania’ta.
Class I. Cyclostém’ata.
Class II. Pisces (pis-séz).
Class III. Amphib’ia.
Class IV. Reptil’ia
Class V. A’ves.
Class VI. Médmmal’ia,

16 |

CEUAP ARERR Xt

THE SIMPLEST, OR ONE-CELLED, ANIMALS
(PROTOZOA)

Besides the Ameba, Paramecium and Vorticella (de-
scribed in Chapter V) there are thousands of other kinds
of Protozoa. Most of them live in water, but a few live
in damp sand or moss, and some live inside the bodies of
other animals as parasites. Of those which live in water
some are marine, while others are found only in fresh-water
streams and lakes.

Form of body.—The Protozoa all agree in having the
body composed for its whole lifetime of a single cell, * but
they differ much in shape and appearance. Some of them
are of the general shape and character of Ameba, sending
out and retracting blunt; finger-like pseudopodia, the body-
mass itself having no fixed form or outline but constantly
changing. Others have the body of definite form, spherical,
elliptical, or flattened, enclosed by a thin cuticle, and having
a definite number of fine thread-like or hair-like protoplasmic
prolongations called flagella or cilia. Many of the familiar
Protozoa of the fresh-water ponds always have two whiplash-
like flagella projecting from one end of the body. By means
of the lashing of these flagella in the water the tiny creature
swims about. Others have many hundreds of fine short
cilia scattered, sometimes in regular rows, over the body-
surface. The Protozoan swims by the vibration of these
cilia in the water.

There is no stagnant pool, no water standing exposed in

*In some Protozoa a number of similar cells temporarily unite to form
a colony, but each cell may still be regarded as an individual animal.

118

THE SIMPLEST, OR ONE-CELLED ANIMALS II9Q

watering-trough or barrel which does not contain thousands
of individuals of the one-celled animals. And in any such
stagnant water there may always be found several or many
different kinds or species. A drop of this water examined
with the compound microscope will prove to be a tiny world

/

Fic. 46. Sun animalcule, a fresh-water Protozoan with a siliceous skeleton
and long thread-like protoplasmic prolongations. (From life.)

(all an ocean) with most of its animals and plants one-celled
in structure. A few many-celled animals will be found in it
preying on the one-celled ones. ‘There are sudden and
violent deaths here, and births (by fission of the parent) and
active locomotion and food-getting and growth and all of the
businesses and functions of life which we are accustomed
to see in the more familiar world of larger animals.

120 THE ANIMALS AND MAN

Marine Protozoa.—One usually thinks of the ocean as
the home of the whales and the seals and the sea-lions, and
of the countless fishes, the cod, and the herring, and the
mackerel. Those who have been on the seashore will
recall the sea-urchins and starfishes and the sea~-anemones
which live in the tide-pools. On the beach there are the
innumerable shells, too, each representing an animal which
has lived in the ocean. But more abundant than all of
these, and in one way more important than all, are the
myriads of the marine Protozoa.

Although the water at the surface of the ocean appears
clear and on superficial examination seems to contain no
animals, yet in certain parts of the ocean (especially in the
southern seas) a microscopical examination of this water
shows it to be swarming with Protozoa. And not only is
the water just at the surface inhabited by one-celled animals,
but they can be found in all the water from the surface to a
great depth below it. In a pint of this ocean-water there
may be millions of these minute animals. In the oceans of
the world the number of them is inconceivable. And these
myriads of Protozoa represent a great host of different species
grouped in various families and orders. All of this wealth of
animal life was unknown to the earlier naturalists, for but few
of the Protozoa are visible without the aid of the microscope.

Among all these ocean Protozoa none are more interesting
than those belonging to the two orders Foraminifera (fig. 48)
and Radiolaria. ‘The many kinds belonging to these orders
secrete a tiny shell (of lime in the Foraminifera, of silica
in the Radiolaria) which encloses most of the one-celled
body. These minute shells present a great variety of shape
and pattern, many being of the most exquisite symmetry
and beauty. The shells are perforated by many small
holes through which project long, delicate, protoplasmic
pseudopodia. ‘These fine pseudopodia often interlace and
fuse when they touch each other, thus forming a sort of

THE SIMPLEST, OR ONE-CELLED ANIMALS rar

protoplasmic network outside of the shell.

In some cases

there is a complete layer of protoplasm—part of the body
protoplasm of the Protozoan—surrounding the cell externally.

When these tiny animals die their hard shells sink to
the bottom of the ocean, and accumulate slowly, in incon-

ceivable numbers, until they
form a thick bed on the
ocean floor. Large areas of
the bottom of the Atlantic
Ocean are covered with
this slimy ooze, called Fora-
minifera ooze or Radiolaria
ooze, depending on the kinds
of animals which have form-
edadtea2 Nor is; it. -only7 im
present times that there has
been a forming of such
beds by the marine Pro-
tozoa. All over the world
there are thick rock strata
composed almost exclusively
of the fossil shells of these
simplest animals. The chalk-
beds and cliffs of England,
and of France, Greece,
Spain, and America, were
made by Foraminifera.
Where now island were
once oceans the bottoms of
which have been gradually
lifted above the water’s sur-
face. =) similarity, the. rock

Fic. 47. Stentor sp.; a Protozoan

which may be fixed, like Vort-
cella, or free-swimming, and
which has the nucleus in the
shape of a string or chain of
bead-like bodies. The figure
shows a single individual as it
appeared when fixed, with elcn-
gate stalked body, and as it ap-
peared when swimming about,
with contracted body. (From life.)

called Tripoli found in Sicily and the Barbadoes earth
from the island of Barbadoes are composed of the shells

of ancient Radiolaria.

122 THE ANIMALS AND MAN

It is thus evident that the Protozoa are an ancient group
of animals. As a matter of fact zoologists are certain that
it is the most ancient of all animal groups. All of the animals
of the ocean depend upon the marine Protozoa and the
marine Protophyta,
one-celled plants, for
food. Either they
feed on them directly,
or prey on animals
which in turn prey
on these simplest
organisms. <A _ well-
known zoologist has
said: “The food-sup-
ply of marine ani-
mals consists of a
few species of micro-
scopic organisms
which are inexhausti-

ble> and: the onily

Fic. 48. Rosalina varians,a marine Proto- source of food for all
zoan (Foraminifera) with calcareous : .
shell. (After Schultz.) the inhabitants of

the ocean. The sup-
ply is primeval as well as inexhaustible, and all the
life of the ocean has gradually taken shape in direct
dependences oneit-)) Lhe manner Protozoa are the only
animals which live independently; they alone can _ live
or could have lived in earlier ages without depending on
other animals. They must therefore be the oldest of
marine animals. By oldest is meant that their kind
appeared earliest in the history of the world, and as it
is certain that ocean life is older than terrestrial life—that
is, that the first animals lived in the ocean—it is obvious that
the marine Protozoa are the most ancient of all animal
groups.

THE SIMPLEST, OR ONE-CELLED ANIMALS 123

As already learned in the examination of examples of
one-celled animals, it is evident that life may be success-
fully maintained without a complex body composed of
many organs performing their functions in a specialized
way. The marine Protozoa illustrate this fact admirably.
Despite their lack of special organs and their primitive
way of performing the life-processes, that they live success-
fully is shown by their existence in such extraordinary
numbers. They outnumber all other animals. The con-
ditions of life in the surface-waters of the ocean are easy
and constant, and a simple structure and simple method
of performing the necessary life-processes are wholly ade-
quate for successful life under these conditions.

CHAPTER XII

HUMAN DISEASES CAUSED BY ONE-CELLED
ANIMALS

Long ago when it was first discovered that various para-
sitic worms lived in our bodies and were the causes of pain
and injury and even certain diseases physicians rapidly
came to believe that all our ills were in some way caused by
such parasites, known or unknown. Later there came a
reaction against this belief as the search for the supposed
parasites causing various diseases was unsuccessful in re-
vealing them; but again with the later discovery, by means
of perfected microscopes and methods of investigation, of
bacterial germs in the body tissues the parasite or germ
theory of disease was rehabilitated, and this time to endure.

These first known and first studied “germs” were all
bacteria, which are extremely small, simple, one-celled
plants. ‘They are indeed probably the simplest of all living
plants. But with the continued study of germs and con-
tagious and infectious diseases it was found that certain
of these diseases were produced not by bacteria or bacilli
but by one-celled microscopic animals, organisms belonging
to the branch Protozoa, or simplest animals. So today
just as we recognize that typhoid, cholera and tuberculosis
are diseases caused by the presence and growth in our body
of bacteria, we recognize that malaria, sleeping sickness, re-
lapsing fever and other related diseases are caused by the
presence and growth of Protozoa.

A marked difference between the bacteria-caused and the
Protozoa-caused diseases is the manner of the development
and of the inoculation of the disease germs. While bacteria

124

DISEASES CAUSED BY ONE-CELLED ANIMALS | 125

have a very simple sort of life-history, the disease-producing
Protozoa have usually a very complicated life-history and
one that requires two kinds of hosts for its completion.
The bacteria or bacilli that cause typhoid fever for example,
multiply in the body by simple division repeated indefi-
nitely, forming generation after generation of bacilli all alike
and of the same habits. The Protozoa that cause malaria
multiply for a number of generations in the body, somewhat
as the bacteria do, but then gradually cease multiplying and
either die or lie more or less inert in the blood until they are
sucked up with some of this blood into the stomach of a
mosquito when they renew their active life and their process
of multiplication but in a way very different from their
former way. ‘The very shape and appearance of the germs
become so changed that they could not be recognized as
belonging to the same kind if the actual process of the
changes had not been clearly observed.

In the mosquito’s stomach some of the little round in-
active bodies suddenly put forth five or six long slender
lash-like processes that break off and go swimming about
like little snakes. These find some of the inactive bodies
which have become somewhat swollen and fuse with them
and the new body formed by this fusion becomes active
and moves toward the wall of the stomach and there burrows
into this wall as far as its outer coating. Here the parasite
comes to rest and begins to grow rapidly until it forms a
little nodule on the outer surface of the stomach. Inside
this nodule the body stuff of the parasite divides into many
hundred minute spindle-shaped bodies. Finally the walls
of the nodule, which now projects into the body-cavity of
the mosquito, break and the hundreds of new active germs
escape into the blood of the insect which flows freely all
through its body-cavity. From the blood they migrate
forward into the neck and head and finally lodge in the
salivary glands where they remain.

126 THE ANIMALS AND MAN

1 Bs 6) eS Some may be taken
into the stomach

\ 4 of the Mosquito when

Development of it bites
x Parasite in ie
0 “9 20
o. &
\»)

6 Human Blood acy

aot as

0)

when Mosquito
bites

InSalivary Development
Gland

Transmitted to Human Blood

in the

os0WN PWPRUOI UI WEUIdo/ 9,

Fic. 49. Diagram to illustrate the life-history of the malarial parasite.
1 is a red blood-corpuscle, 2 to 7 shows the development of the parasite
in the corpuscle, a b ¢ d and a’ b’ c’ and e the development of the para-
site in the stomach of the mosquito, f g h i the development in the
capsule on the outer wall of the stomach of the mosquito, k in the
salivary gland.

DISEASES CAUSED BY ONE-CELLED ANIMALS 127

When a mosquito ‘‘bites,” that is, pierces the skin with
its needle-like mouth-parts, so as to suck blood, it always
pours a little of the fluid from the salivary glands into the
wound. ‘The reason for this is not certainly known, but the
fluid, perhaps, keeps the blood from coagulating and thus
from refusing to flow. However, one of the results of this
habit is to inoculate the bitten person with the germs of

Fic. 50. Diagrammatic figure of stages in the development of the malaria-
producing Haemamoeba (Plasmodium) in a red blood-corpuscle of
the human body.

malaria, for some of the many quiet little spindle-shaped
germs flow into the blood with the salivary fluid.

As soon as they enter the blood they become active and
attach themselves to the red blood-corpuscles and burrow
into them. As they work their way into the corpuscles
they change their shape gradually, getting shorter and
thicker, until by the time a germ is well lodged within a
blood-corpuscle it is nearly spherical.

128 THE ANIMALS AND MAN

The germ now feeds and grows at the expense of the
corpuscle. It may become nearly as large as the whole
corpuscle. Then its body stuff divides into about six parts,
the corpuscle breaks down, and the six new germs escape

Fic. 51. Malarial mosquito, Anopheles maculipennis, on the wall. (Photo
graph from life by R. W. Doane.)

into the blood to find new blood-corpuscles to attack.

This kind of simple multiplying goes on for a number of
generations but ceases after a while, and the germs of the
last generation lie inert in the blood until they can be taken
into a mosquito’s body. Then a new life-cycle is started,
according to the processes already described.

This, in brief and most general terms, is the story of the
relation of the minute Protozoan animals called Hematozoa,

DISEASES CAUSED BY ONE-CELLED ANIMALS 129

or, popularly, malarial germs, with man and the mosquito.
Not all kinds of mosquitoes—and over a hundred species of
mosquitoes live in the United States—carry malaria germs.
In only a few kinds, certain ones belonging to the spotted-
winged genus Anopheles, can the malarial germs live and
multiply. But it is difficult for the non-expert to tell one
kind of mosquito from another and as the malaria-spreading
kinds are scattered over the whole country, all mosquitoes
should be avoided or fought. How mosquitoes live is told
in Chapter VIII and how to fight them in Chapter XV.

The way in which quinine cures malaria is by its power of
killing the germs when they are in our blood. But we do
not know that they are there until a great many have been
produced by their rapid method of multiplication, and then
it takes some time for the quinine to make headway against
them. We should be saved much suffering by preventing
their getting a lodgment into the body at all.

As the germs are not created in the mosquito’s body but
only get into it by the sucking up of blood by the insect from
some person already suffering from the disease, another way
of fighting malaria is to prevent mosquitoes from having
access to malarial patients, in other words to isolate and
quarantine from mosquitoes any person suffering from
malaria.

While malaria in America is not looked on as a fatal
disease—although in fact about 10,000 persons die each
year from its effects—elsewhere in the world, as in the
Mediterranean countries and especially in India, it is a very
terrible disease indeed, carrying off hundreds of thousands,
even millions of victims every year. In some of these
countries, notably in Italy, mosquito fighting is done on a
large scale under governmental control and expense.

The malarial fevers are the principal diseases which in
our own country are produced by one-celled animals living
in our bodies, But elsewhere in the world other even more

130 THE ANIMALS AND MAN

serious diseases are caused by Protozoan germs. The
terrible sleeping sickness of Africa is one of these and, as
with malaria, the germs are spread from man to man by a
-blood-sucking insect. This is not the mosquito but a
larger heavier fly called the ¢se-tse, which is rather like a
small horse-fly in general appearance.

Yellow fever is also almost certainly caused by a Protozoan
parasite, which is
distributed exclu-
sively by mosqui-
toes. Several infec-
tious diseases of
domestic animals
are caused by Pro-
tozoas, “he? best
known of these in
this country is the
Texas ‘or “sp lenive
cattle fever, the
germs of which pass
part of their life in
the bodies of ticks
Fic. 52. Texas fever tick, Margaropus an- and. are distributed

eee adult not fully gorged. by them from ani-

mali sto “animal:
These germs, called Piroplasma, have the interesting power
of entering the eggs in the body of the female tick so that
when the young ticks hatch from these eggs, which are laid
on the ground when the old ticks drop off from the cattle
upon which they have been holding while sucking
their blood, these young ticks are already inoculated
with germs. When cattle are attacked by these young
ticks they become inoculated with the fever by the escape
of the germs from the bodies of the ticks into their blood.

The characteristic common to all these Protozoa-caused

DISEASES CAUSED BY ONE-CELLED ANIMALS 131

diseases that they are disseminated by insects in whose
bodies the germs live for part of their life and undergo a
special part of their multiplication is one that distinguishes
them from the diseases caused by bacteria. However,
several of the bacterial diseases are undoubtedly partly
spread by insects, as cholera and typhoid fever by house-
flies, plague by fleas, etc. But the germs do not have to live
in the insects’ bodies in order to complete their life-history.
However, the germs of some bacterial diseases can be, and
are, taken into the stomachs of the insects and passed out
of the body alive and virulent. The bacilli of both typhoid
fever and cholera have been found in “flyspecks,” which
are the excrement from the alimentary canal of the fly.

CHAPTER: Xi

TEE INVERTEBRATES

The invertebrate or backboneless animals include all of
the great branches, or phyla, into which the animal king-
dom is. divided, except one, the branch Chordata. Ac:
cording to our table of animal classification (see pp. 116, 117)
there are twelve of these invertebrate branches, one of
which, the Protozoa, or one-celled animals, we have already
briefly discussed. Included in the other eleven branches
are all the sponges, sea-anemones, corals and _ jellyfishes,
all the animals we commonly know as worms and a host of
less familiar worm-like others, all the starfishes, sea-urchins
and sea-cucumbers, the crabs, the centipedes, the insects
and spiders and all the shell-fish and other creatures grouped
together as molluscs. The backboneless animals out-
number by far in species and in individuals the backboned
animals. ‘The insects alone, which compose but a single
class, the Insecta, of the great branch Arthropoda, include
a greater number of kinds than all the other animal classes
and branches together. But just the same the interest of
most of us is held more by the backboned animals, the fishes,
batrachians, reptiles, birds and animals; those animals
with which our own bodies may be most readily compared
and among whom we find our most valuable and entertaining
and friendly companions and aids in life.

However, the five hundred thousand known species,
more or less, of invertebrate animals now living include a
host of kinds whose lives are of great interest and of great
immediate importance to us. Some of them help build

132

THE INVERTEBRATES 133

islands on which men live; others live parasitically in our
bodies to our great discomfort and danger; many are per-
sistent enemies of our crops and domestic animals. Finally,
all in their structure, their physiology, their development
and growth, their extraordinary adaptations to the con-
ditions of their life, their marvelous modes of distribution,
their beauty of color and pattern, and symmetry of outline,
appeal to that inborn love of knowledge in us, as subjects to
study, admire and enjoy.

Sponges.—A bath or slate sponge is simply the skeleton, or
part of it, of a sponge
animal. In life all
of this skeleton is in-
closed or covered by
a soft, tough mass
Di sponge. —aesh.
Sponges are fixed, ex-
cept when very young,
when they swim freely
about. Phey= are
found at all depths
and in all seas, grow-
ing especially abun-
dantly in the Atlan- Fic. 53. A simple sponge, Grantia sp.;
fie 1@Ocean "and, the at right a longitudinal section, showing
Mediterranean. A the simple body-cavity. (One-half natu-
very femelandenliver i ral size; after Jordan and Kellogg.)
fresh water, being found in lakes, rivers, and canals, in
all parts of the world. The shape of the simplest sponges
is that of a small vase, or nearly cylindrical cup, attached
at its base, and having at the free end a large opening
(fig. 53). But most sponges are very unsymmetrical and
srow more like a low, compact, bushy plant than like the
animals we are familiar with. The smallest sponges are
only 1 mm. (1-25 in.) high, while the largest may be over

134 THE ANIMALS AND MAN

a meter (39 in.) in height.

In color they may be red,

purple, orange, gray, and sometimes blue.
Examine a bath sponge and note the holes in it. These

Fic. 54. The skeleton of a glass
sponge, composed of siliceous
spicules; from Japan. (Natu-
ral size.)

are to let in and out the sea-
water, in which float the minute
bits of animal or plant sub-
stance on which the sponge
feeds. This water also brings
oxygen for the breathing of
the sponge, and carries away
the carbon dioxide given off
by it. But the sponge has no
special organs, its soft flesh
being able to digest food and
take up oxygen without stom-
ach or lungs.

The living sponges are col-
lected by divers, or are dragged
up by men in boats with long-
poled hooks or dredges.

They are: arst- killed’ by
exposure to the air, and then
thrown into tanks of water.
Here the flesh decays away,
leaving the tough, horny, or
leathery skeleton, which, when
cleaned, bleached, and _ trim-
med, is ready for market.
Some sponges have a lime and
some a glass skeleton instead

of a horny one, and the glass skeletons are often very
beautiful (see fig. 54). All the sponges compose the animal

branch called Porifera.

Hydra.—One of the most interesting of the simple animals
found in fresh-water ponds is Hydra (fig. 55). Though

THE INVERTEBRATES 135

very small compared with most animals we know, it is much
larger than any of the Protozoa, being when expanded
nearly one-fourth of an inch long. It is also not composed
of a single cell but of hundreds of cells. It is one of the
simplest of the many-cell-
ed animals, i.e., Metazoa.
Hydra may be found at-
tached to bits of sticks,
stones, and leaves in pools
not too stagnant. There
are two common kinds,
one brown and one green.
Specimens shouwld= be
brought into the school-
room alive, and kept in
a dish of water in the
irehts » Vor observes the
habits of Hydra, examine
a live specimen, attached
to a bit of leaf or stick, in
a watchglass, under the
low power of a compound
microscope, or with a good
magnifier.
Note the cylindrical a

body, attached at its base, 7 SS. vms, note two. tents
and with a series of ten- budding young Hydra. (Natural
tacles projecting from its size, one sixth of an inch high;
free end. How many ten- pone

tacles are® there? They. -arise ‘in a circle anout the
mouth. Have some small water-fleas in the water
and observe Hydra’s method of catching and eating food.
Note that when it captures one of the water-fleas with its
tentacles the flea soon ceases to struggle. It is paralyzed.
On the tentacles are many extremely fine, little, stinging

136 THE ANIMALS AND MAN

threads, which lie coiled up in small pockets until prey is
captured, when they uncoil, shoot out, and sting. If Hydra
catches an animal too large to be crowded into its mouth
it releases it.

Note that Hydra can contract its tentacles and its whole
body until it looks like a small egg with a rosette of short
blunt fingers at one end. Sometimes Hydra may be seen
with another much smaller one growing out from it (fig. 55).
This is a new one, forming by the process of ‘‘budding.”’
It will grow and develop until about as large as the parent,
when it will break off, and attaching itself elsewhere will
begin an independent existence. Hydra has the interesting
power of being able to regenerate itself if cut in two. In
such a case each half will usually develop into a new com-
plete Hydra.

Sea-anemones, corals and jellyfishes.—'The sea-anemones
which are common in tide-pools, and the coral animals
which live in tropic and sub-tropic oceans, have the same
type of body as that shown by Hydra, but are much larger.
When the tide is out, exposing the dripping seaweed-covered
rocks, and the little basins are left filled with clear sea-
water, the brown and green and purple “sea-flowers”’
may beseen fixed to the rocks by the base, with the
mouth opening and circlet of slowly moving tentacles
hungrily ready for food. ‘Touch the fringe of tentacles
with your finger-tip and feel how they cling to it. If it
were a small animal, like a sea-snail, these deadly ten-
tacles would hold it fast and slowly carry it into the
mouth. Inside the body is a cylindrical hollow, which 1s
really a primitive kind of stomach. But there is no heart
nor brain nor lungs in this simple body. It is only a
thick-walled sac, with the mouth surrounded by food-
catching tentacles.

The coral animals, or coral polyps, are simply a kind
of sea-anemone which secretes in its otherwise soft body-

THE INVERTEBRATES E37

wall a stony skeleton of carbonate of lime which persists
after the polyp is dead. We know these animals chiefly
by their skeletons, which we see in masses in collections,
or made into ornaments. But in tropical oceans there are
whole islands of coral, or long coral reefs fringing the shores
of continents, formed by the skeletons of millions of polyps.
For as they live closely massed together in great colonies
their skeletons form solid stony banks. Coral islands have
a great variety of form, but the elongated, circular, ring-
shaped, and crescent forms predominate. In the Atlantic
Ocean they are found along the coasts of Southern Florida,
Brazil, and the West Indies; in the Pacific and Indian
oceans there are great coral reefs on the coasts of Australia,
Madagascar, and elsewhere; and certain large groups of
inhabited islands, as the Fiji, Society, and Friendly Islands
are almost exclusively of coral formation.

There are over 2000 kinds of coral polyps known, and
their skeletons vary much in appearance. Because of the
suggestive appearance of some of these they have received
common names, as the organ-pipe coral, brain coral, etc.
The red coral of which jewelry is made grows chiefly in the
Mediterranean Sea. It is gathered specially on the western
coast of Italy, and on the coasts of Sicily and Sardinia.
Most of this coral is sent to Naples, where it is cut into orna-
ments.

By walking along the sea-beach soon after a storm one
may find many shapeless masses of a clear and jelly-like
substance scattered here and there on the sand. These
are the bodies or parts of bodies of jellyfishes which have
been cast up by the waves. Exposed to the sun and wind
they soon die or evaporate away to a small shrivelled mass.
The flesh of a jellyfish contains hardly more than one per
cent of solid matter, all the rest of it being water.

Jellyfishes, although closely related to the fixed polyps,
some indeed being the immediate offspring of them, have

138 THE ANIMALS AND MAN

a body of quite different appearance. It corresponds in
general to an umbrella or bell (fig. 56), around the edge
of which are disposed numerous threads or tentacles (cor-
responding to the tentacles of the polyp). The mouth-
opening is at the end of a longer or shorter projection which
hangs from the middle of the under side of the umbrella,

Fic. 56. <A jellyfish or medusa, Gonionema vertens, eating
two small fishes. (Natural size.)

like a short, thick handle. The body-cavity, or primitive
stomach, extends out into the umbrella-shaped part of the
body. By alternately clapping shut and opening the um-
brella the jellyfish swims about.

Jellyfishes occur in great numbers on the surface of the
ocean, and are familiar to sailors under the name of “‘sea-
blubs.”” Some live in the deeper waters; a few specimens

THE INVERTEBRATES 139

have been dredged up from depths of a mile below the sur-
face. ‘They range in size from ‘‘umbrellas” or disks a few
millimeters in diameter to disks of a diameter of two meters
(24 yards). They are all carnivorous, preying on other
small ocean animals, which they catch by means of their
tentacles, provided with stinging-threads. The tentacles
of some of the largest jellyfishes, ‘‘reach the astonishing
length of 4o meters, or about 130 feet.”” Many of the jelly-
fishes are beautifully colored, although all are nearly trans-
parent. Almost all of them are phosphorescent, and when
irritated some emit a very strong light.

The so-called ‘“‘colonial jellyfishes” are floating or swim-
ming colonies of jellyfishes and polyps composed of many
individuals closely joined. These individuals are all of
one species, but are of different forms or kinds, each kind
having a special function to perform in the life of the colony.
For example, some individuals catch ali the food for the
colony; some make the motions; some are especially sen-
sitive to the presence of enemies or prey, and some produce
all the young. These various individuals act like the
separate organs of our own body. The beautiful Portu-
guese ‘“‘man-of-war’’ is one of these colonial jellyfishes. It
appears as a delicate bladder-like float, brilliant blue or
orange in color, usually about six inches long, and bearing
on its upper surface, which projects above the water, a
raised parti-colored crest, and on its under surface a tangle
of various appendages, thread-like, with grape-like clusters
of little bell- or pear-shaped bodies. Each of these parts
is a specially modified individual, produced by budding
from an original central polyp. The Portuguese man-of-
war iS very common in tropical oceans, and sometimes
vast numbers swimming together make the surface look
like a splendid flower-garden.

The sea-anemones, corals, and jellyfishes compose Be
animal branch Celenterata.

140 THE ANIMALS AND MAN

Starfishes and sea-urchins.—Among the most easily found
and most readily recognized seashore invertebrates are the
starfishes and sea-urchins, which belong to the animal branch
called Echinodermata. Although these animals do not
look at all alike, the starfishes having a body composed of

Fic. 57. Starfishes of various kinds in a tide-pool on the Bay of Monterey,
California; note two with five rays, three pentagonal, and two with
many rays. (Photograph by the author, from living specimens 77
situ.)

central disk and long rays or radiating arms, and the sea-
urchins looking like spiny flattened balls, they are really
closely related. In each the body, with its various organs,
is built on a radiate plan of structure, the mouth being in
the center of the under side and all the body parts radiating
out from this center.

THE INVERTEBRATES I4I

If a starfish, either fresh or preserved in alcohol, can be
had for examination, note that the body is covered by a

muscles of the pyloric caeca
:

madreporic plate

“cardiac stomach

~~--intestinal caecum

pyloric caecum

’
‘muscles of the pyloric caeca

Fic. 58. Dissection of a starfish (Asterias sp.).

skeleton composed of little plates, on which are short stout
spines arranged in irregular-rows. At the tip of each arm
or ray there is a small red speck, the very simple eye of the

©
a

142 THE ANIMALS AND MAN

animal. The starfish cannot see with this ‘‘eye;” it can
only distinguish between light and darkness. On the under
side the mouth is in the center, and from it along each ray
runs a groove. In each groove may be seen two double
rows of soft, tubular processes with sucker-like tips called
the tube-feet. These are the organs of locomotion. If
live starfishes can be watched the slow locomotion by means
of the tube-feet may be seen, and perhaps also the peculiar
mode of taking food. Starfishes are carnivorous, feeding
on crabs, snails, and the like. If the live prey is too large
to be taken into the mouth it is surrounded by the stomach,
which is pushed outward for this purpose. It secrets fluids
which kill the prey, after which the soft parts are digested.

In size starfishes vary from a fraction of an inch in diameter
to three feet. They are yellow or red, or brown or purple,
and the number of rays varies from five to thirty or more in
different kinds (fig. 57). Some have the spaces between
the rays filled out nearly to the tips of the arms, making
the animal simply a pentagonal disk. Starfishes are able
to regenerate a lost ray—that is, if one or more rays are
bitten off by enemies, new ones grow out in their places. I
once found a starfish in Samoa which was regenerating
four new rays and the central disk from a single old ray!

Starfishes hatch from eggs, and in their early stages are
very different in appearance from the adults, being more
or less ellipsoidal in shape, and having many cilia on the
outer surface. ‘They swim freely about in the sea, feeding
on microscopic organisms.

The sea-urchins, of which more than three hundred
species are known, while without arms or rays yet show
their radiate structure in having the tube-feet arranged in
five rows radiating from the center. This can be seen in a
“shell” or body-wall, from which the spines have been
removed. Around the mouth, which is at the center of the
under side, are five strong teeth. Like the starfishes, the

THE INVERTEBRATES 143

young sea-urchins are free swimming creatures of very
different appearance from the adults. Their food consists
of small marine animals and of bits of organic matter which
they collect from the sand and débris of the ocean floor.
Many of the sea-urchins are gregarious, living together in
great numbers. Some have the habit of boring into the
rocks of the shore between tide-lines. I have seen thousands
of small, beautifully colored purple sea-urchins lying each in a
spherical pit or hole in hard conglomerate rock on the
California coast. How they are enabled to bore these
holes is not yet known. ‘There is great variety in size and
color among these animals. The colors are brown, olive,
purple red, greenish blue, etc.

A few kinds of sea-urchins have a flexible shell or test.
The Challenger expedition dredged up from the sea bottom
some sea-urchins, and when placed on the ship’s deck
“the test moved and shrank from touch when handled, and
felt like a starfish.’’ The cake-urchins or sand-dollars are
sea-urchins having a very flat body with short spines. They
lie buried in the sand, and are often very brightly colored.
Their hard bleached tests with the spines all rubbed off
are common on the sands of both the Atlantic and Pacific
coasts.

Worms.—In the older classifications the branch Vermes
included all the animals which are now divided into
four branches of terrible names (Platyhelnfinthes, Nema-
thelminthes, Trochelminthes and Annulata). Vermes were
worms; that was easy to remember. But with the discovery
of many new worm-like creatures and of new things about
some of the old ones called worms naturalists have decided
that the old easy grouping was not a correct one. Hence
the new one.

Bring into the schoolroom large live earthworms. ‘They
may be found in the daytime by digging, or at night by
searching with a lantern. They often come above ground

144 THE ANIMALS AND MAN

cerebral ganglion

| “ante

gesophagus
retractor and protractor se)

muscles of the pharyne _-

esophageal pouches.---
seminal receptacles =

seminal vesicles=z ==

crop <

nephridium --'

Se

gizzard-- Tes

intestine --

Fic. 59. Dissection of the earthworm, Lumbricus sp

THE INVERTEBRATES 145

.
in the daytime after a heavy rain. They may be kept in
flower-pots filled with damp soil, and should be fed bits of
raw meat, preferably fat, bits of onion, celery, cabbage, etc.

Examine a live specimen put on a piece of moist paper.
Note that the body is made up of rings or segments. Are
there any legs? How does the earthworm move along?
Can you find some short fine bristles, called sete, on the
body? The broad thickened ring or girdle, including several
segments near the head, is called the clitellum. It secretes
the cases in which the eggs are laid. Make a drawing of
the worm, showing all the external features you can make
out.

Earthworms live in soft moist soil which is rich in organic
matter. Their food is taken into the mouth mixed with
dirt and sand. As this mixture passes through the long
alimentary canal the organic particles are taken up and
digested. The eggs are laid in a horny capsule which lies
in the earth until the young worms emerge. Only a part
of the eggs develop in each capsule, the rest being eaten by
the growing young. Earthworms of various kinds are
found in all parts of the world except in desert or arid re-
gions. In size these different kinds vary from 1 mm. (,', in.)
to 2 meters (2% yards) in length.

Leeches are familiar to boys who go in swimming. Some
live specimens should be brought into the schoolroom. ‘The
body of a leech is flattened instead of being cylindrical as in
the earthworm, and tapers at both ends. In the live animal
it can be greatly elongated and narrowed, or much shortened
and broadened. It is composed of many segments (not as
many as there are cross lines, however, each segment being
transversely annulated), and bears at each end on the ven-
tral surface a sucker, the posterior one being the larger.
These suckers enable the leech to cling firmly to other
animals. The mouth is at the front end of the body on the
ventral surface and is provided with sharp jaws. Leeches

146 THE ANIMALS AND MAN

live mostly on the blood of other animals. The common
leech fastens itself upon its victim by means of its suckers,
then cuts the skin, fastens its oral sucker over the wound,
and pumps away until it has completely gorged itself with
blood, distending enormously its elastic body, when it
loosens its hold and drops off. Its biting and sucking
cause very little pain, and in olden days physicians used
the leeches when they wanted to “bleed” a person. A
common European species much used for this purpose is
known as the “medicinal leech.” Most of the leeches lay
their eggs in small packets or cocoons. ‘These cocoons are
dropped in soil on the banks of a pond or stream so that
the young may have a moist but not too wet environment.
The young issue from the eggs in four or five weeks, but
they grow very slowly and it is several years before they
attain their full size. Leeches are long-lived animals, some
being said to live for twenty years.

The group of roundworms, so called from their slender,
smooth, cylindrical bodies, contains some interesting ani-
mals. Familiar examples are the vinegar-eels, which can
be found in mouldy vinegar, and the hairworms or horse-
hair snakes which are often seen in fresh-water pools after
a rain. Some people believe these worms to be horsehairs
which have turned into animals, and others believe that they
come down with the rain. ‘They have in reality come from
the bodies of insects in which they pass their young or
larval stages as parasites. The hairworms all live as para-
sites during their larval stages, and as free independent ani-
mals in the adult. A parasite is an animal which lives for
part or all of its life in or on the body of another animal
called the host, and which feeds on the blood or other tissues
of this host. Some of the hairworms require two distinct
hosts for the completion of their larval life, living for a while
in the body of one, and later in the body of another. The
first host is usually a kind of insect which is eaten by the

THE INVERTEBRATES 147

second. The eggs are deposited by the free adult female in
slender strings twisted around the stems of water-plants.
The young hairworm on hatching sinks to the bottom of
the pond, where it moves about hunting for a host in which
to take up its abode.

The terrible Trichina spiralis, which produces the disease
called trichinosis, is another roundworm of which much is
heard. This very small oP
worm lives in its adult con-
dition in the intestine of man
as well as in the pig and other
mammals. The young,
which are born alive, burrow
through the walls of the
intestine, and are either car-
ried by the blood, or force
their way, all over the body,
lodging usually in the mus-
cles blere “theya form. “for
themselves little cells or
cysts in which they lie.
The forming of these thou-
sands of tiny cysts injures

:)

Kin eS
ane .

{mm
Ti

Le

Fic. 60. Tapeworm; head, magni-

ne muscles and oper fied, at left; the whole worm
great pain, sometimes death may be several yards long.
to the host. Such infested (After Leuckart.)

muscle or flesh is said to be ‘“‘trichinosed,”’ and the flesh
of a trichinosed human subject has been estimated to con-
tain 100,000,000 encysted worms. To complete the devel-
opment of the encysted and sexless Trichine the infested
flesh of the host must be eaten by another animal in which
the worm can live, e.g., the flesh of man by a pig or rat,
and that of a pig by man. In such a case the cysts being
dissolved by the digestive juices, the worms escape, develop
reproductive organs and produce young, which then migrate

148 THE ANIMALS AND MAN

into the muscles and induce trichinosis as before. But,
however badly trichinosed a piece of pork may be, tho-
rough cooking of it will kill the encysted trichine, so that
it may be eaten without danger. Some people, however,
are accustomed to eat ham, which is simply smoked pork,
without cooking it, and in such cases there is always great
danger.

CHAPTER XIV

THE INVERTEBRATES (continued): ARTHROPODS
AND MOLLUSCS

The jointed-legged animals.—None of the invertebrates
we have studied so far has any organs which are really of
the nature of legs, in the meaning commonly ascribed to the
word. In fact the animals of only one out of the eleven
invertebrate branches have organs which show any analogy
with the jointed legs of our own body and of the other ter-
restrial vertebrates. This branch is that of the Arthropoda
which includes in its five classes a great host of familiar

/ 4 J a bo at a
Ta acielents ne a [ae OE ee id
“ a SeWren Nts Ppl Rasa hey BAN wh Pe eNO Ne NET ms nal
yitld ont OT a a aR TAO
ire en a i i re setae! - i y;, =.
Ses chee a tieebiebanb ls Da ee ge GERM .
> ie eS PLP Pe ee nets as = a ~- >> ee.

f 7 ‘ ‘
a i “2 Saree

Fic. 61 Peripatus etseni. Mexico.)

animals, namely, all the crabs, shrimps, sand-fleas, barnacles,
etc., (class Crustacea); the thousand-legged worms (bad
name; they are not worms at all) and centipeds (class
Myriapoda); all the insects (class Jmsecta); the scorpions,
spiders, mites and ticks (class Arachnida); and one other
class, the Onychophora, containing but a single genus
(Peripatus) of curious half worm-like, half centipede-like
animals found in the tropics which seem to be a sort of con-
necting link between the true worms and the myriapods.
All of these animals agree in possessing legs composed of
several distinct articulated segments.

The crayfish, or crawfish (whose structure is described
in Chapter IV) is a good example of the Crustaceans. It

149

150 THE ANIMALS AND MAN

is found in most fresh-water ponds and streams of the United
States west of Massachusetts. Crayfishes may be taken
by a net baited with dead fish, or may be caught in a trap
made from a box with ends which open in, and baited with
dead fish or animal refuse of any sort. They should be
brought alive into the schoolroom and kept in a moist
chamber. Observe live specimens to see the characteristics
of locomotion, and the use of the pincers and the mouth-
parts in taking food.

In meadows where water stands for certain seasons of
the year there may be noticed many scattered holes with
slight elevations of mud about them. ‘These are mostly
the burrows of crayfish. During the dry season the ani-
mal digs down until it reaches water, or at least a damp
place, where it rests until wet weather brings it to the sur-
face once more. One of these burrows followed in the
process of digging a mining shaft extended vertically down
to a distance of twenty-six feet, where the crayfish was
tucked snugly away.

The eggs are carried by the female on her abdominal
appendages. Previous to laying them she rubs off, with
the fifth pair of legs, all the dirt from the appendages and
smears them with a sticky secretion. When the eggs are
laid, which is during the last of March or April in the Cen-
tral States, they are caught on the sticky pleopods, where
they remain attached in clusters. After some weeks the
young crayfishes issue from the eggs. In general appearance
they are not very unlike the adults. They grow very rapidly
at this stage. As the animal is enclosed in a hard shell,
growth can take place only during the period just following
the moult, for the crayfish casts its hard shell periodically,
and it is while the new shell is forming that it does its grow-
ing. When it moults it casts not only the exo-skeleton, but
also the lining of part of the alimentary canal. After the
females have hatched their young many of them die in the

ARTHROPODS AND MOLLUSCS 151

shallow pools, in which places the dried-up skeletons are
noticeable during the summer months.

For an exhaustive account of the biology of the crayfish see Huxley’s
“The Crayfish: An Introduction to Zoology.”’

Lobsters are very much like crayfish in all structural char-
acters, although much larger. They live on the rocky
sandy ocean-bottom at shallow depths. They are caught
in great numbers in so-called “lobster-pots,”’ a kind of
wooden trap baited with refuse. The number thus taken
upon the shores of New England and Canada amounts to
between twenty and thirty million annually. Live lobsiers
are brownish or greenish, with bluish mottling; they turn
red when boiled. A single female will lay several thou-
sand eggs. They are greenish, and are carried about by
the mother until the young hatch. The young are free-
swimming larve until they reach a length of half an inch.

Most crabs (fig. 62) differ from the lobsters, crayfishes,
and shrimps in having the body short and broad, instead
of elongate. This is due to the special widening of the
carapace and the marked shortening of the abdomen.
The abdomen, moreover, is permanently bent under the
body, so that but little of it is visible from the dorsal aspect.
The number of abdominal legs or appendages is reduced.
When the tide is out the rocks and tide-pools of the ocean
are alive with crabs. They “scuttle” about noisily over
the rocks, withdrawing into crevices or sinking to the bottom
of the pools when disturbed. They move as readily back-
ward or sidewise, ‘‘crab-fashion,’’ as forward. They are
of various colors and markings, often so patterned as to
harmonize very perfectly with the general color and appear-
ance of the rocks and sea-weeds among which they live.
The spider-crabs are especially strange-looking creatures,
with unusually long and slender legs and a comparatively
small body-trunk. They include the Macrocheira of Japan,
the largest of the crustaceans. Specimens of this crab are

152 THE ANIMALS AND MAN

known measuring twelve to sixteen feet from tip to tip of
extended legs; the carapace is only as many inches in width
or length. ‘The soft-shelled crab is a species common along

Fic. 62. Some crabs and barnacles of the Pacific Coast; the short sessile
acorn barnacles in the upper left-hand corner belong to the genus
Balanus; the stalked barnacles in the upper right-hand corner are of
the species Pollicipes polymenus; the largest crab (upper left-hand)
is Brachynotus nudus; the one in left lower corner is a young rock-
crab, Cancer productus; the one in the seaweed at the right is a kelp
crab, Epialtus productus; while the two in snail-shells in the right
lower corner are hermit-crabs, Pagurus samuelis. (About one-half
natural size; from living specimens in a tide-pool on the Bay of Mon-
terey, California.)

ARTHROPODS AND MOLLUSCS 153

our Atlantic coast. It is “soft-shelled’”’ only at the time of
moulting, and has to be caught in the few days intervening
between the shedding of the old hard shell and the hardening
of the new body-wall. The little oyster-crabs (Pinnotheres)
which live with the live oyster in the cavity enclosed by the
oyster shell are well-known and interesting creatures. They
are not parasites preying on the body of the oyster, but are
simply messmates feeding on particles of food brought into
the shell by the currents of water created by the oysters.
The hermit crabs all have the habit of carrying about with
them, as a protective covering into which to withdraw, the
spiral shell of some gastropod mollusc. The abdomen of the
crab remains always in the cavity of the shell; the head,
thorax, and legs projecting from the opening, to be with-
drawn into it when the animal is alarmed or at rest. The
abdomen being always in the shell, and thus protected,
loses the hard body-wall, and is soft, often curiously shaped
and twisted to correspond to the spiral cavity of the shell.
It has on it no legs or appendages except a pair for the hind-
most segment, which are modified into hooks for holding
fast to the interior of the shell. As the hermit-crab grows it
takes up its abode in larger and larger shells, sometimes kill-
ing and removing piecemeal the original inhabitant. Certain
hermit-crabs spend much of their time on land, traveling
far inland, and making burrows in the ground. These
“land-crabs”’ are common in the South Pacific islands.
Crustaceans which at first glance are hardly recognizable
as such are the stalked or sessile barnacles (fig. 62), which
live fixed in great numbers on the rocks between tide lines,
or on the piles supporting wharves, or on the bottom of
ships or even on the bodies of whales. The body of the
stalked barnacle is enclosed in a sort of bi-valved shell
formed by a fold of the skin and stiffened by five calcareous
plates. ‘The legs of which there are usually six pairs are
long and feathery and divided nearly to the base. These

154 THE ANIMALS AND MAN

feathery feet project from the opened shell when the animal
is undisturbed and, waving about in the water, catch small
animals which serve as the barnacle’s food. The acorn
barnacle has no stalk but looks like a low bluntly pointed
pyramid, this appearance being due to the convergence of
the six calcareous plates in its body-wall. Barnacles have
no heart nor any blood-vessels and show other degenerate
features. ‘This degeneration is due to their fixed life. The
young barnacles when hatched from the egg are free-swim-
ming larve as with most other Crustaceans.

Pill-bugs, wood-lice, or damp-bugs
(fig. 63), as they are variously called,
may be readily found in concealed
moist places, under stones or boards,
on damp soil, ete; They sunabout
quickly, and feed chiefly on decaying
vegetable matter. ‘They are night-
scavengers. Although commonly called
“bugs” and supposed to be insects,
they really belong to the Crustacea,
that class of animals which includes
Fic. 63. A damp-bug, the crayfish, lobster, and crabs. Ex-

Isopod. (Four times amine the body of a dead pill-bug. It

pa ey is oval and convex above, rather pur-
plish or grayish brown, and smooth. Note its division into
head, thorax, and abdomen. Find the eyes, the antenne, and
the mouth-parts. All the locomotory appendages are adapted
for walking or running, not swimming. How many pairs
of legs are there? Find gills and gill covers. Although the
pil-bugs do not live in the water they breathe partly at
least by means of gills (though they may breathe partly
through the skin). It is therefore necessary for them to
live in a damp atmosphere, so that the gill membranes
may be kept damp. If these are not moist, they will not
permit the exchange of gases.

ARTHROPODS AND

MOLLUSCS 155

Millipeds and centipeds (class Myriapoda).—-The Mpyria-
poda are land-animals breathing by means of trachee
like the insects. In them the body-segments are nearly
uniform in character with the exception of the head, which,
as in the insects, bears the mouth-parts and antenne. There
is no grouping of the body-segments into regions except as

the head is distinct
from the rest of the
body. (In a few
myriapods there
are indications of a
division of the hind
body into thorax
and abdomen.)
‘hes “presence” or
true legs on all the
segments of the
hinder region of
the body and the
lack of the three-
region division of
2 the body are the
Fic. 64. A galley. principal external

worm(milliped) structural charac-

IE. teristics which dis-
tinguish myriapods from insects.
The internal anatomy corresponds
in general character with that of
insects.

The most familiar myriapods
are the millipeds, and the litho-
bians and centipeds. The mil-
lipeds are cylindrical in shape,
have two pairs of legs on most of
the body-segments and are vege-

Fic. 65. The skein centiped,
Scutigera forceps, common
in houses and conservato-
ries. (Natural size; after
Marlatt.)

156 THE ANIMALS AND MAN

table feeders, though some may feed on dead animal
matter. The galley-worms (Julus) (fig. 64), large, black-
ish, cylindrical millipeds found under stones and logs
and leaves and in loose soil, are familiar forms. They
crawl slowly and when disturbed curl up and emit a mal-
odorous fluid. They can easily be
.. kept alive in shallow glass vessels
) with a layer of earth in the bottom,
* and their habits and life-history may
thus be studied. They should be
fed sliced apples, green leaves, grass,
strawberries, fresh ears of corn, etc.
They are not poisonous and may
be handled with impunity. They lay
their eggs in little spherical cells or
nests in the ground. An English
species of which the life-history has
been studied lays from 60 to I00
eees at a. mie, Ahe exes <on this
species hatch in about twelve days.
The lithobians and centipeds are
flattened and have but a single pair
of legs on each body-ring. ‘They are
predaceous in habit, catching and
killing insects, snails, earthworms,
etc. They can run rapidly, and
Fic. 66. Acentiped, Scolo- have the first pair of legs modified
pendre sp- (Niaiucal into a.) pain Ol) poisom-claws.aaniiel
s1ze.) 3
are bent forward so as to lie near the
mouth. The common “skein” centiped (Scutigera for-
ceps) (fig. 65) is yellowish and has fifteen pairs of
legs, long 4o-segmented antenne, and nine large and
six smaller dorsal segmental plates. The true centipeds
(Scolopendra) (fig. 66) have twenty-one to twenty-three
body-rings, each with a pair of legs, and the antennz have

ARTHROPODS AND MOLLUSCS 84)

seventeen to twenty joints. They live in warm regions,
some growing to be very large, as long as twelve inches or
more. The “bite” or wound made by the poison-claws is
fatal to insects and other small animals, their prey, and
painful or even dangerous to man. The popular notion
that a centiped “stings” with all of its feet is fallacious.
It is recorded by Humboldt that centipeds are eaten by
some of the South American Indians.

Insects (class Insecta).—Insects are the most familiar
and abundant of land animals, and number more species
than are known of all other kinds of animals together.
Nearly 400,000 different species of living insects have so
far been found, and thousands of new ones are discovered
each year. Beetles, moths and butterflies, flies, wasps, bees
and ants, dragon-flies, plant-bugs and grasshoppers are to be
found in the vicinity of any schoolroom, and the interesting
habits of insects, their great variety and abundance, and the
readiness with which they may be collected, kept alive, and
studied, make them unusually fit animals for the special
attention of beginning students of zoology.

Our studies with the grasshopper, mosquito, and cater-
pillars have already made us acquainted with the elementary
facts concerning insect body-form, structure, and _life-
history, and elsewhere in this book are accounts of the
special relations of insects to flowers, to other animals and
also to man.

Insects are classified into various groups called orders,
of which all the beetles constitute one, the moths and butter-
flies one, the two-winged flies one, the ants, bees, wasps,
etc., one, and so on. But to learn much about this classi-
fication, which constitutes systematic entomology, requires
a great deal of time and persistence on account of the great
numbers of species concerned. A good way to begin the
study of the kinds and classifications of insects is to make
a collection. Directions for this are given in Appendix I].

158 THE ANIMALS AND MAN

Books of insect classification are Comstock’s “Manual of
Insects” and Kelloge’s “American Insects.”

Insects live both on land and in water, but the aquatic
kinds are almost wholly limited to fresh water. A few
species live on the surface of the ocean, however, and a few
others on the water-drenched rocks and seaweeds between
the tide-lines.

Among the most interesting insects to study in the field
andi'to='-keep-* alive
and observe in the
schoolroom are the
water-bugs and _ bee-
tles to be found in
almost any brook or
pond. Collect various
kinds alive and keep
in the schoolroom aq-
uarium (Appendix IT).
Running’ swiftly
about on the surface
may be seen rather
large, blackish, nar-
row-bodied, long-leg-
: ged insects known as
Fic. 67. A water-strider, Hygrotrechus sp., water-striders or pond

adult. (Twice natural size.) skaters (fig. 67).
When at rest they hold the front pair of legs, which
are short and stout, projecting forward close to the
head, ready to grasp and hold small insects, the blood of
which they suck by means of a sharp, strong, piercing beak.
Their feet make small dents or dimples in the surface film,
but do not break through. Do they ever dive or swim in
the water? Can they leap? Are they winged or wingless?
The immature water-striders have the body much shorter
than that of the adult. To be found also at the surface of

ARTHROPODS AND MOLLUSCS 159

the pool are small, oval, flattened, shining black insects
that dart swiftly about in curving paths on the water. ‘These
are whirligig beetles. Do they run on the water or swim?
Do they ever dive and swim beneath the surface? Examine
one with a magnifier, and note that it has four compound
eyes instead of two, the usual number in insects. Where

Fic. 68. Predaceous diving beetles, Dyticus, and back-swimmers, N ota-
secta. (Slightly less than natural size; from living specimens.)

is the extra pair situated? Note the peculiar shape of the
legs. What are the legs specially fitted for?

Swimming about below the surface may sometimes be
found large, shining, black beetles (fig. 68) from half an
inch to an inch and a half long. There are two principal
kinds, the predaceous diving-beetles, which kill and eat other
insects, and the water scavenger-beetles which feed on decay-

160 THE ANIMALS AND MAN

ing vegetation in the water. ‘The first have slender thread-
like antennz, while the second have antenne with thickened
or club-like tips. As neither kind has gills both have to
come to the surface to get air, but they always carry down
with them a supply sufficient to last some time. They do
this in two different ways. ‘The predaceous diving-beetles
force the posterior tip of the body above the surface (they
always hang head downward when at the surface) and
slightly lift the tips of the horny black
wing-covers which lie on the back. Air
rushes in under the wing-covers and is
held Qby- tthe: sclosines orethe ips. an ile
breathing pores or spiracles of the beetle
are situated along each side of its back,
underneath the wing-covers, so that the
air held there readily enters the body. The
water scavenger-beetle when at the surface
keeps its head uppermost. It carries most
of its air supply on its under or ventral
surface, where it is held in a coat of fine
short hairs. The air gives the under side
of the beetle a shining silvery appearance.
It is held by the fine hairs by virtue of the
surface film. If you dip a bit of cloth hav-
Fic. 69. Water- jing a pile, as velvet, into water, you will see

tiger, the latva that it retains underneath the water a

of the predace- é F

ous watembee. nearly complete coating of air, he under

tle, Dyticus sp. side of the water scavenger-beetle is cov-

(Natural size.) ered in places with a fine pubescence
which acts like the pile of the velvet.

The water-bugs are about half an inch long, and are
grayish or black and white in color. ‘There are two common
kinds, one called back-swimmers (fig. 68), which swim with
under side uppermost, and have the back black with large
creamy patches, the other called water-boatmen (fig. 70),

ARTHROPODS AND MOLLUSCS 161

which swim with back uppermost, and are greenish gray,
with fine black mottling. Both kinds come to the surface
for air, and carry a supply of it down with them. Observe
this, and note the difference in the disposition of the air
(revealed by its silvery appearance) in the two kinds. What
is the favorite resting position of each? Which pair of
legs do the back-swimmers use for oars? Which pair do
the water-boatmen use? Water-bugs are predaceous, suck-
ing the blood of captured insects by means of a piercing beak.
On the under side of stones, in brook ‘“‘riifles,’? and in
pools and watering-troughs
not too frequently used are
to be found commonly the
nymphs, -1. €:, <younps. (ig:
71), of Mayflies, recognizable
by the rapidly vibrating
flap-like tracheal gills along
each side of the flattened
delicate body, three pairs of
legs, and two or three long, Fic. 70. Water-boatman, Corisa
slender filaments projecting a ae ia ae
from the tip of the abdomen.
Those found in ponds or other quiet water can easily
be kept alive in the school aquarium (see Appendix II).
Examine a live specimen in water in a _ watch-glass
with a magnifier. The body-wall is so transparent that
many of the internal organs can be seen. Note especially
the beating of the heart, a slender tube running along
the middle of the back. See the dark air-tubes (trachee)
running out into the thin gills, and note the rapid vibration
of these gills to keep in contact with fresh water. The
young Mayflies feed on minute organisms such as dia-
toms and other alge. They live as nymphs for a year,
or even two or three years in some species, and then crawl
out of the water on a stone or plant-stem, or come

162 THE ANIMALS AND MAN

simply to the surface when the delicate, gauzy-winged
adult quickly issues. The adult Mayfly takes no food and
lives only a few hours, or at most a few days. The May-
flies have the shortest adult stage of all insects. The
female drops her eggs into the water.

Moths and butterflies are among the most attractive and
instructive insects to collect and classify and to rear as
caterpillars and chrysalids in the
schoolroom or at home. Some
of the most beautiful butterflies
and largest and most striking
moths are common all over the
country and their eggs, or cater-
pillars at least, can certainly be
found and reared in simple
breeding-cages (for directions for
making see Appendix ITI) in the
schoolroom. Directions for the
study of caterpillars have already
been given in Chapter VIII.

Scudder’s ‘‘Every-day Butterflies,”’
Mary Dickerson’s “Moths and Butter-
flies,” and Eliot and Soule’s ‘Cater-
pillars and their Moths,” are admirable
books. Reference to them will give
suggestions for an unlimited amount of
Fic, 71. Young (nymph) of observation. Scudder’s “Life of a

aE showing (3) Butterfly” is a detailed account of the
tracheal gills. (Three i eG
Gina heats th cic after monarch butterfly. Comstock’s How
Jenkins andliKeloce> to Know the Butterflies,’’ and Holland's
“The Butterfly Book,” are finely illus-
trated manuals of butterfly classification.

7]

Scorpions, spiders, mites, and ticks (class Arachnida).—
The class Arachnida is composed of Arthropods whose body-
segments are grouped into two regions, a cephalothorax bear-
ing the mouth-parts, eyes, and legs, and an abdomen. ‘The

ARTHROPODS AND MOLLUSCS 163

Fic. 72. Swallow-tail butterflies, Papilio rutulus. (One-
half natural size; drawn from life.)

164 THE ANIMALS AND MAN

segments composing each of these two parts are so fused that,
except in the scorpions, they are usually indistinguishable.
There are no antenne, the eyes are simple, the mouth-parts
fitted for biting, and there are four pairs of legs. In their
internal anatomy the arachnids show in some forms a peculiar
modification of the respiratory organs, the trachee being
flat and leaf-like and massed together in a few groups rather
than being tubular and ramifying through the body.

The dorsal vessel or heart usually
has a few blood-vessels or arteries
running from it. This class is divid-
ed into three orders, the Arthrogastra,
or scorpions, the Acarina, or mites
and: ticks, and, the Aranemas. or
spiders.

The scorpions (fig. 73) have the
posterior six segments of the abdo-
men much narrower than the seven
anterior segments and forming a tail
which bears at its tip a poison-fang
or sting. This sting is used to kill
prey, such as insects and other small
animals. The tail can be darted
| forwards over the body to strike prey
Fic. 73. A scorpion, Cen- Which has been previously seized by

trurus sp., from Cali- the large pincer-like maxillary palpi.

fornia. (Natural size.) Seorpions are common in warm
regions, about twenty species being known in_ south-
ern North America. Their sting though painful is
not dangerous to man. ‘The young are born alive and are
carried about’ by their mother © tor {some “time alter
birth.

The mites (fig. 74) and ticks (fig. 75) are mostly small
obscure animals, which live more or less parasitically. The
common red spider of house-plants as well as the sugar- and

ARTHROPODS AND MOLLUSCS 165

cheese-mites, the dreaded itch-mite and the chigger are
familiar examples of these degraded arachnids, and the
wood-ticks, dog- and chicken-ticks are common examples of
the larger blood-sucking forms. The body in both mites
and ticks is very compact, the two body-regions, cephalo-
thorax and abdomen, being closely fused. Various species
of ticks have been proved to be the carriers of the germs of
certain diseases of human beings
and domesticated animals (see
Chapter XII).

The spiders have the abdomen
distinctly set off from the cepha-
lotherax. “The \-eyes,” (ig. 70)
vary in number and _ arrange-
ment, the mandibles are large,
each being composed of two
parts, a basal hair-covered part,
the falx, and a terminal smooth,
shining, slender, sharp-pointed
part, the fang, which is mova-
bly articulated with the falx
(fig. 76). In the falx is a poison-
sac from which poison flows Fic. 74. The cheese-mite,
through the hollow fang and out = T'yroglyphus stro. (Greatly
at its tip. The legs vary in rela- °ml@teeds ater Berlese.)
tive length in different spiders, and each is made up of seven
joints. The spinnerets (fig. 77), which are situated at the
tip of the abdomen, are six in number (a few spiders have
only four), and are like little short fingers. They have at
their tips many fine little spinning-tubes from each of which
a fine silken thread issues when the spider is spinning.
These many fine threads fuse as they issue to form a single
strong cable or sometimes a flat rather broad band. The
spinnerets are movable, and by their manipulation the
desired kind of line is produced. The silk comes from

166

THE ANIMALS AND MAN

many silk-glands in the abdomen, from each of which a
fine duct runs to a spinning-tube.
The spiders may be divided into two groups according to

Fic. 75. The dog- or wood-tick, Dermacentor americanus, male, the most
abundant tick in the Northern States. (Natural size indicated by
line; after Osborn.)

iG: 4/0.) ) he
Eyes aad
mandibles of
ay Sip uidie a
(Much en-
larged; after
Jenkins and

Kellogg.)

their habits, viz., the wandering or hunt-
ing spiders, which do not spin webs_ to
catch thew <sprey, and.) the sedentary sor
web-weaving spiders, which spin snares to
catch their prey. The wandering spiders
can spin silk, however, and often do so to
limes) theiz” burrows, sto: aumakern mesic. or
to make egg-sacs. The: hairy tarantulas
and the trap-door spiders of similar appear-
ance are among the most interesting of the
hunting /) spiders.) *“Bhey olives m= vertical
burrows or tunnels in the ground which

ARTHROPODS AND MOLLUSCS 167

are lined with silk, and which in the case of the trap-
door spider are covered with a door or lid made
of silk and soil. The top of this door is always covered
with soil or bits of leaves or twigs so that it is nearly indis-
tinguishable from the surface of the ground about it.

The common rather large swift black spiders found under
stones and boards are
hunting spiders, be-
longing to the family
Lycosidz and are call-
ed therunning spiders.
They live in burrows yy¢. 77, The spinner-
in the ground, coming _ ets of a spider, with

out to stalk and chase ©D© SPimmeret enlarg-
ed to show the “‘spin-

their prey. The eggs ning spools” or tubes. (Much enlarged; after
are laid in globular Jenkins and Kellogg )
egg-sacs which are
often carried about,
attached toy the
spinnerets, by the
Females Chey: 76)..
The young spider-
lings after hatch-
ing, insome species,
climb on to the
mother’s back and
are carried by her
POE RSOMe site’.
Other kinds of
wandering or hunt-
ing spiders are the
crab-spiders (Tho-
Fic. 78. Trap-door spider (California), and two miside) (fig. 80),
burrows, one with door open, one with door . . .
closed. (Natural size; from living spider in which run sidewise
field,) or backward as well

168 THE ANIMALS AND MAN

as forward, and the black and red, fierce-eyed, stout-bodied
little jumping spiders (Attide) (fig. 81), which leap on their
prey.

The sedentary or web-weaving spiders are of various
kinds) 9 hrey
may be grouped
accordine to
their spinning
habits into cob-
web weavers
Fic. 79. A female running spider (Lycosid), Cis eridide ye

carrying its egg-sac attached to its spinnerets. gma]l] slim-leg-
(Slightly enlarged; after Jenkins and Kellogg.)

Fed) (Spices
which make the familiar unsymmetrical cobwebs of
houses and outbuildings; funnel-web weavers (Agalenide),
larger long-legged spiders of meadow and field which spin a
flat or concave horizontal web in the grass with a silken
tube leading down
to the ground; the
curled-thread wea-
vers (Dictynide),
which use in addi-
tion to the usual
lines peculiar broad
lines: sntadie om

waved or curled ees
Fic. 81. A jumping

Fic. 80. A crab-spi- i: alan eels aeuee
dern( a) vo nas 1a); threads in their 1r- S pastes ame see tclic)e
(Slightly enlarged; regular webs made (Slightly — enlarged;

after Jenkins and
Kellogg.)

after Jenkins and

ones in fence-corners

and on plants; and
finally orb-weavers (Epeiridz) (fig. 82), the host of variously
colored and patterned stout-bodied garden-spiders which
spin the beautiful symmetrical circular webs familiar to all.
If a complete uninjured orb web be examined it will be
found to consist of a small central hub either open or closed,

ARTHROPODS AND MOLLUSCS 169

from which run radii to the outer edges of the web. Around
the hub is an open or free zone, and farther out a spiral zone,
so called because a line running in close spiral turns fills in
the space between the radu. This is the real prey-catching
part of the snare, and the silken line here is sticky, while the
radii and some other parts of the web are made of silk that
is not sticky. ‘The web is supported by strong foundation-
lines, attached to

leaves, stems, or what-

ever. is. firm in” the y
neighborhood of the , ie
Wen. . whe ‘sprder: (MN % vs
° . ~ Pe.
either rests on the web me Sip ee Lae a
usually in the centre, 4 i ec
or lies concealed in Roy

oa gPtdhp a
a Nest. Or,-tent near a g SAS a a
at hand from which ; Lf Pa ~<a
a special path-line cc
runs’ to..the ‘centre h XS A

Of be. Webs Lhe

building of one of

these orb webs is a Fic. 82. Argiope sp., a large orb-weaver
creat work, and is (Epeirid). (Natural size; after Jenkins
done with extraordi- ee ee

nary nicety of manipulation by the use of feet and spinnerets.

For an account of web-making, etc., see McCook’s ‘American
Spiders and their Spinning Work.”’

The habits and instincts of spiders in connection with the care of
the young, the building of webs and nests, ballooning by means of silken
lines, the active stalking and catching of prey, etc., are very interesting
and offer a good field for independent observation and study by the
student. McCook’s book will be the best guide for this study.

Mussels, oysters, snails, ‘‘sea shells’ and cuttlefish
(Branch Mollusca).—The molluscs are not to be mistaken
for any other of the lower animals; they have a structure

170 THE ANIMALS AND MAN

peculiarly their own. In them the body is not articulated or
segmented as with the worms and arthropods, nor radiate
as in the echinoderms, nor plant-like as with the sponges
and polyps. Where the typical molluscan body is well
developed it is composed of four principal parts: a head,
with the mouth, feelers, eyes, and other organs of special
sense; a trunk containing the internal organs; a foot which is
a muscular mass not at all foot- or leg-like in shape, but which
is the organ of locomotion by means of which the mollusc
crawls; and a mantle which is a fold of the skin enclosing
most of the body and which produces the shell. Such a
typical molluscan body is possessed by most of the snails.
But in most of the other molluscs one or more of these
four body-regions are so fused with some other region
as to be indistinguishable. In the mussels and clams the
head is not at all set off from the rest of the body, the cuttle-
fishes and octopi have no foot, the slugs have no shell. In
the case of some of the molluscs without external shell
there are inside the body the rudiments or vestiges of a
shell.

With regard to the internal organs we note the constant
presence of three pairs of ganglia, viz., the brain, lying
above the pharynx, which sends nerves to the feelers, eyes,
and auditory organs; the pedal ganglion, which sends
nerves to the foot, and the visceral ganglion, which sends
nerves to the viscera. This is a condition of the nervous
system characteristic of all molluscs. The heart is a well-
developed pulsating sac in the upper part of the body, com-
posed of either two or three chambers, and there is a well-
defined closed system of arteries and veins, specially com-
plete in the cuttlefishes and octopi. This highly developed
condition of the circulatory system also distinguishes the
molluscs from the other invertebrates.

The shell is composed of carbonate of lime and may be
in two pieces, bivalved as in the oyster and clams, or in one

ARTHROPODS AND MOLLUSCS 171
piece, univalved, as in the usual spiral snail and sea shell
type. The eggs are usually laid in a mass held together by
a gelatinous substance. In most species the young mollusc
on hatching from the egg does not resemble its parents,
but is a free-swimming larva called a veliger. It is pro-
vided with cilia for organs of locomotion. It must undergo a
radical change in order to reach the adult stage. Thus
metamorphosis occurs in this branch as well as among the
Arthropods and Echinoderms. In the development of some
molluscs, however, there is little or no metamorphosis, the
young being hatched in a condition much resembling, except
in size, the parent.

The branch Mollusca is divided into five classes, three of
which include the more familiar kinds. These three classes
are the Pelecypoda, including the mussels, cockles, clams,
scallops, oysters, etc., molluscs with a shell composed of
two pieces, one on each side of the body and hinged to-
gether; the Gastropoda, including the snails, slugs, peri-
winkles, whelks, and a host of other univalved shell-fish,
that is, molluscs which have a shell composed of a single
piece; and the Cephalopoda, including the squids, cuttle-
fishes, octopi, and the pearly nautilus.

Clams show a range in size from the little fresh-water
Cyclas about 1 cm. long to the giant clam of the Indian and
Pacific islands “which is sometimes 60 cm. (2 feet) in length
and 500 pounds in weight.”? They show also some variety in
the form and appearance of the shell, but not anything like
the degree of variety shown by the shells of the Gastropods.

The edible clams are of several different species. The
hard-shell clam (Venus mercenaria), or “quohog” as it
is often called, is found along the Atlantic Coast from Texas
to Cape Cod. It is ‘““common on sandy shores, living chiefly
on the sandy and muddy plots, just beyond low-water
mark. . . . It also inhabits estuaries, where it most
abounds. It burrows a short distance below the surface,

142 THE ANIMALS AND MAN

but is frequently found crawling at the surface with the shell
partly exposed.” ‘The shells of this edible clam are white. °
The soft-shell clam (Wya arenaria), “‘the clam par excellence,
which figures so largely in the celebrated New England clam-
bake, is found in all the northern seas of the world.

Fic. 83. California mussels and barnacles on rocks, exposed at low
tide. (Photograph by the author.)
:
All along the coasts of the eastern States, every sandy shore,
every mud flat, is full of them, and from every village and
hamlet the clam-digger goes forth at low tide to dig these
esculent bivalves. The clams live in deep burrows in the
firm mud or sand, the shells sometimes being a foot or
fifteen inches beneath the surface. When the flats are
covered with water his clamship extends his long siphons
up through the burrow to the surface of the sand, and
through one of these tubes the water and its myriads of
animalcules is drawn down into the shell, furnishing the
gills with oxygen and the mouth with food, and then the
water charged with carbonic acid and feecal refuse is forced
out of the other siphon. When the tide ebbs the siphons
are closed and partly withdrawn.’ Ocean clams and
mussels have furnished food for man for ages, and along
coasts are found here and there great mounds made of heaps
of clam-shells which have become covered over with soil

ARTHROPODS AND MOLLUSCS 173

and vegetation. Such mounds are the old feasting-places
of the early coast inhabitants, and the archeologist often
finds in these “‘kitchen-middens,” as they are called, various
relics of the early natives of the continent.

Even more widely known than the clams are the oysters
(Ostrea virginiana), also members of this class of mol-

Fic. 84. An Eastern oyster, Ostrea virginiana. (After photograph by
W. H. C. Pynchon.)

luscs. ‘The oyster is carefully cultivated by man in many
countries. It has its two shells or two shell-halves dis-
similar, one valve being hollowed out to receive the body,
while the other is nearly flat. The oyster is attached to
the sea-bottom by the outside of the hollowed-out valve.
When first hatched the young oyster swims freely by means
of its cilia; after a few days it attaches itself to some solid
object and grows truly oyster-like. Much care has to be
taken in cultivating oysters to furnish proper conditions
for growth and development. The young oysters when
first attached are called “‘spat’’; when a little older this
“spat,” now called ‘‘seed,” may be transplanted to new beds,
which are stocked in this way. In fact some beds have
constantly to be thus restocked, the young oysters produced
on them not finding good places to attach themselves, and
so swimming away. Sometimes pieces of slate, pottery, etc.,
are strewed about the oyster-beds to serve as ‘“‘collectors,”’
that is, as places for the attachment of the young oysters.

174 THE ANIMALS AND MAN

The extent of the acreage of the American oyster-beds is
larger than that of any other country. “The Baltimore
oyster-beds on the Chesapeake River and its tributaries
cover 3,000 acres, and produce an annual crop of 25,000,000
bushels.”

The “‘pearl-oyster’” is not a true oyster, that is, not a
member of the family to which the edible oysters belong,
but it is a member of the same class, that is, it is a bivalve

Fic. 85. Pholas sp., a mollusc burrowing in sandstone. (Photograph
by C. H. Snow; permission of the American Society of Civil Engineers.)

mollusc. Pearls are obtained from a number of different
“nearl-oysters,” but the finest pearls and mother-of-pearl
come from the tropical species Meleagrina margaritifera.
This pearl-oyster has an extensive distribution, being
found in Madagascar, the Persian Gulf, Ceylon, Australia,
Philippine Islands, South Sea Islands, Panama, West
Indies, etc. Mother-of-pearl is simply the inner lining
of the shell, which is composed of numerous thin layers of
carbonate of lime so arranged that the edges of the suc-
cessive layers produce many fine striz very close together.
The beautiful iridescence of this inner shell-lining is caused
by the complicated diffraction and reflection (interference
effects) of the light by the fine striae and the translucent

ARTHROPODS AND MOLLUSCS 175

superposed thin plates of shell material. Pearls are simply
isolated deposits of shell material usually around some
particle of foreign substance which has found lodging in
the mantle-cavity. Sometimes small objects are pur-
posely introduced into the shell in order to stimulate the
formation of pearls. ‘The pearl-fishers go out in boats and

Fic. 86. Martesia xylophaga, a Pholad, burrowing in Panama mahogany.
(Photograph by C. H. Snow; permission of the American Society
of Civil Engineers.)

dive to the bottom, filling baskets with pearl-oysters. These
are piled up in a bin and left to die and decompose. When
the flesh is pretty thoroughly disintegrated, it is washed away
with water, great care being taken that none of the pearls
loose in the flesh are lost. When the washing is concluded
the shells themselves are examined for pearls which may
be attached to the interior of the valves. The principal
pearl-fishery is that on the coast of Ceylon; pearl-fishing
has been carried on here for over 2000 years.

The ship-worm (Teredo) is an interesting member of this
class of bivalve molluscs, because of its unusual habits, and
strangely modified body form. The teredo is long and
worm-like in general appearance, with a small bivalve shell
at one end and two elongated siphons at the other. The

176 THE ANIMALS AND MAN

young teredo is a free-swimming ciliated embryo like the
young of the other bivalve molluscs, but it soon settles on a
piece of submerged wood, usually the pile of a wharf, or the
bottom of a ship, and burrows into this wood.. As it grows
it enlarges and deepens its tube-like burrow, and lines it with
a calcareous deposit. The burrow may be a foot long or
longer, and when thousands of teredos attack a pile or the
bottom of a ship, the wood soon becomes riddled with holes.

Fic. 87. The giant yellow slug of California, Ariolimax californica. This
slug reaches a length of twelve inches. (From life.)

These boring molluscs do great damage to wharves and
ships. In Holland where they were first discovered they
caused such injuries to the piles and other submerged wood
which supported the dikes and sea-walls that they seriously
threatened the safety of the country.

Perhaps one-half of all the known species of molluscs are
snails and slugs (fig. 87). Snails are either aquatic or ter-
restial in habit, but in either case they (the true pulmonate
snails) breathe not by means of gills, as do most of the other
molluscs, but by means of a so-called “‘lung.”’ This lung is
a sac with an external opening on the right side of the body
and with its inner surface richly furnished with fine blood-
vessels. The exchange of gases between the blood and the
outer air takes place through the thin walls of the blood-
vessels. Most snails which live in the water, as the pond-
snails and the river-snails, have to come occasionally to the
surface to breathe. These fresh-water and land-molluscs

ARTHROPODS AND MOLLUSCS ERT.

which possess a lung-sac instead of gills constitute the order
Pulmonata. The pulmonate pond- and land-snails and
slugs are vegetable feeders, and where they occur in large
numbers do much injury to vegetation. While the common
pond-srrails have but one pair of feelers, at the base of which
are found the eyes, most of the land-snails and slugs have
two pairs of “‘horns,” the eyes being on the tips of the second
pair.

There are other snails common in ponds, also called, like
the pulmonate forms, pond-snails, which have gills and no
lung-sac. ‘These pond-snails belong to a different order of
molluscs, and live on the bottom of the pond, crawling
about in the soft mud and feeding on animal instead of
vegetable food.

The shells of the various kinds of snails vary much. In
many of the land-snails the spiral is not spire-shaped or
conical, but is flat. In some the whorls of the spiral run
from left to right (dextral) when the shell is looked at with
apex held toward one, while in others the whorls run from
right to left (sinistral).

Of the hosts of marine Gastropods we can notice only a
few kinds. ‘The nudibranchs are a group of beautiful forms
in which the shell is wholly wanting and the mantle is usually
absent. The gills are thus exposed and are usually in the
shape of delicate freely projecting tufts arranged in rows
along the back. ‘The body is often strikingly and variedly
colored. ‘These soft, naked ‘‘sea-slugs” live near the shore,
creeping about among the rocks and seaweeds. About a
thousand species of nudibranchs are known.

Among the shell-forming marine Gastropods there is
great variety in the size and shape and coloring of the shells.
Many are beautifully colored and patterned; others are
oddly and fantastically shaped. The cowries, or porcelain
shells, familiar in collections of ocean curiosities, have a
large body whorl and a very short flat spire, and the brightly

178 THE ANIMALS AND MAN

colored shell looks as if enamelled. Some of the coast tribes
of Africa once used, and perhaps still use to some extent,
cowries as money. ‘The limpets are among the most abun-
dant of the seashore molluscs, their low, broadly conical shells
being plentifully scattered over the rocks between tide-lines.
The ‘oyster-drills” are Gastropods with odd spiny shells

Fic. 88. The giant squid, Ommatostrephes californica. (From speci-
men with body, exclusive of tentacles, four feet long, thrown by waves
on the shore of the Bay of Monterey, Calif.)

which do much harm in oyster-beds by settling down on the
oysters, boring holes through the shells and eating the soft
parts within. The helmet-shells, from which shell cameos
are cut, are composed of layers of shell material of different
colors. Among the specially beautiful shells are the cone-
shells, the olive-shells, the ivory-shells, etc.

There are two principle groups of Cephalopods, namely
the Decapods and the Octopods. ‘The decapods, as their
name indicates, have ten feet or arms surrounding the
mouth, and the body is usually elongate and containing a
horny “‘pen’” or calcareous “bone.” This group includes
the cuttle-fishes or sepias, from which is obtained sepia ink
and the cuttle-fish bone used to feed canary birds. The ink
is a secretion which the cuttle-fish discharges when attacked,

ARTHROPODS AND MOLLUSCS 179

to create a cloud in the water and thus escape unperceived.
The squids commonly used as bait by fishermen also belong
to the decapods.

The octopods have a short sac-like body and neither an
external nor internal shell. To this group belong the famous
devil-fishes (octopus) whose strange and terrifying appear-
‘ance combined with their frequently great size, has furnished
the basis for many a weird tale of the sea. Devil-fishes hav-
ing tentacles more than thirty feet in length have been
found.

The pearly nautilus is a cephalopod of four gills instead of
two as with the octopods and decapods, and is the only
existing member of what was in the early times of earth’s
history a large group of animals. They make a many-
chambered, spiral shell with its inner surface lined with
beautiful pearly nacre.

CHAPTER XV

FIiGHLING INSECT: “PESTS

Experts estimate that insects rob us each year of $400,-
000,000 worth of crops and $100,000,000 worth of forest
trees and lumber. Besides this monetary loss insects also
disseminate disease among our domesticated animals and,
worst of all, among ourselves. It is no wonder then that
the United States takes a lively interest in fighting insects.

This fighting is done both by the Federal government
through its large and very effective Bureau of Entomology—
by far the largest and best such governmental bureau in
the world—and through the offices of state entomologists
and state agricultural colleges and experimental stations.
Besides, millions of farmers, fruit-growers and stock-raisers
are doing a good deal of insect-fighting on their own account.
The fighting includes first of all the acquiring of a thorough
knowledge of the kinds of insects doing injury and their
life-history and habits. Only with this knowledge can the
most effective and economical means be devised for checking
them. Hence much of the work of the governmental and
state bureaus of entomology is the careful scientific study
of insect life in general. It is a direct outcome of such
study, for example, that the present widespread and _ suc-
cessful use of insect parasites as natural remedies for insect
pests has been developed. ‘This method of insect fighting,
which is simply the encouragement and assistance of Nature,
promises soon to be the most important of all modes of
lessening the losses due to our insect enemies.

In 1868 some young lemon and orange trees were brought
to Menlo Park, California, from Australia. These little

180

FIGHTING INSECT PESTS 181

trees were unfortunately infested by a few small degenerate
sap-sucking insects called, from the curious white waxen
egg-masses which they produce, cottony cushion scale insects.
These insects evidently found California and its orange
orchards congenial in climate, rich in food and devoid of
enemies for them, because by 1880 the cottony cushion scales
were so abundant and wide-spread as to be a serious pest.
By another ten years they had become a menace to the whole

Fic. 89. The cottony cushion scale, Icerya purchasi, attacked by the
Australian lady-bird beetle, Novius cardinalis. (Upper figure slightly
enlarged, lower figure much enlarged; drawn from life.)

orange industry of the state.

In 1888 an entomologist was sent to Australia to hunt
for native natural enemies of the cottony cushion scale.
He found a very small red and black lady-bird beetle, called
Novius cardinalis, feeding on the cottony cushion scales,
and doing this so effectively that the scale insects were kept
within safe numbers in Australia. Almost all the lady-bird
beetles are “‘beneficial insects” in that their food consists
chiefly of other insects and mostly such injurious kinds as
plant lice and scale bugs.

The entomologist collected a few of the little black and
red lady-bird beetles and sent them to California where
they were enclosed under netting with orange branches
infested by cottony cushion scales. The beetles began

182 THE ANIMALS AND MAN

their beneficent work, increased in numbers and were later
distributed in scale-infested orange orchards. In a few
years they had practically relieved the California orange
growers of all anxiety concerning cottony cushion scales.
And now they are the standard and easily and cheaply
applied remedy for scale insects of this kind.

This is so far the most successful case of the introduction
and establishing in America of one insect species to attack
and keep in check another insect species. But numerous
other introductions have been made both of predaceous
insects (lady-bird beetles, etc.), and parasitic insects (kinds
that lay their eggs in or on other kinds so that the hatching
young feed on the living bodies of the hosts). Among the
most conspicuous examples of this modern way of fighting
insect pests is the work now being done, chiefly under
governmental control, in connection with the gypsy moth
plague in New England.

In 1869 an astronomer and amateur naturalist living in
Medford, Mass., was experimenting in cross breeding various
silk-producing moths trying to produce a hardier silk maker
than the Chinese mulberry silkworm. He caused to be
sent to him from Europe the eggs and larve of various
cocooning moths and among them those of the gypsy.
In some way eggs or young of this moth, which has long been
known as a pest of shade and forest trees in Europe, escaped
from the experimenter’s rooms and found congenial growing
and breeding places in the neighborhood. ‘The naturalist
gave public notice of the escape but not until ten or twelve
years after was the new settler noticed as abundant enough
to be a nuisance and a menace, and not until 1889 was its
spread sufficiently wide to attract general attention. In
1890 a town meeting appropriated $300 to exterminate the
pest. These $300 did not do much exterminating and from
that time until today it has been a constant struggle between
moth and the people of New England backed by the United

FIGHTING INSECT PESTS 183

States government. More than a million dollars have
been expended, a score of professional entomologists aided
by hundreds of paid helpers have been employed, and all
the means known to scientific insect fighting have been tried,
The most interesting feature of the great struggle is the im-
portation from Europe and Japan of various natural insect
enemies of the moth. Already more than fifty kinds have
been introduced and experimented with, and it is for the
discovery of some kind that will prove as efficacious against
the soft winged gypsy as the Australia lady-bird beetle
against the cottony cushion scales of California that the
entomologists and New Englanders are working and pray-
ing. The gypsy moth if not fought against would probably
ruin all the trees of New York and New England in a very
few years.

But all this fighting of insects by the use of other insects,
bug versus bug, as a Californian entomologist describes
it, is but a small and, so far, a very small part of the war
waged against insect pests in our country. ‘There are
indeed many entomologists who hold that the older ways
of fighting, the use of so-called “artificial” remedies, as
poisonous sprays, preventive and repellent bands and washes,
traps and means of burning and crushing, and last but by
no means least the high culture and strengthening of the
attacked plants are ways that will never be satisfactorily
replaced by the newer so-called “natural” remedies.

Among these artificial remedies the most conspicuous,
widespread and generally applicable are the poisonous
sprays. These are of two general categories, just as in-
jurious insects are of two general categories. Insects are
either of sucking mouth, taking liquid food, plant sap, or
animal juices, by thrusting a sharp beak through the outer
covering of leaf or twig or fruit or animal body and sucking
up the sap or blood, or they are of biting mouth, nipping
off and chewing bits of plant or animal tissue and swallowing

184 THE ANIMALS AND MAN

solid particles. Now according as an injurious insect feeds
by one or the other of these ways, the poisonous spray or
insecticide must be specially chosen. For those plant at-
tacking insects that have chewing mouth-parts and bite
off and swallow bits of leaf or fruit or twig—all beetles,
caterpillars, slugs, locusts, etc., are of this category—some

Fic. 90. Spraying an arsenical poison on apple trees against the codlin
moth. (Photograph by Dudley Moulton.)

arsenical spray should be used. Paris green or London
Purple thoroughly mixed with water, 1lb. to 200 gallons,
or a mixture of 4 ounces of arsenate of soda and 11 ounces
of acetate of lead in too gallons of water, are the best of
such sprays. They should be so put on as to cover the
attacked foliage thoroughly with a thin coating of poison.
Then when the beetles or caterpillars bite off and swallow
bits of leaf they will at the same time swallow enough poison
to kill themselves.

FIGHTING INSECT PESTS 185

If, however, the insect pest is one with sucking mouth-
parts, obtaining its liquid food underneath the covering
tissue of leaf, fruit or twigs—all plant-lice, scale insects,
squash bugs, stink bugs and sucking bugs generally are of
this category—the poisonous spray must be one that will
kill by contact. It must be what is called an external
irritant. The most available and effective of these external
irritants is kerosene. As, however, the raw oil is also very
irritating and dangerous to plant tissue as well as to insects
it must be made into an emulsion
before being sprayed on to the insect-
infested foliage. The emulsion may ;
be made as follows: Dissolve one- !- =
half pound of hard soap shaved finely [|
in one gallon of boiling water. Add Ya
this to two gallons of kerosene aud
churn the mixture with a force pump
for a few minutes until it becomes ee es ee
a soft butter-like mass. This stock scale insect underneath
emulsion should be mixed with water its waxen covering.
whenever it is desired to make up the “Uh enlarged.)
spray, in the proportion of one part of stock to ten parts of
water.

Other insecticides that kill by contact are mixtures of
whale oil soap and water in the proportion of about one
pound of whale oil to six gallons of water; also pyrethrum
powder and water in the proportion of one pound of powder
to thirty gallons of water.

For scale insects, which are so covered and protected by
their waxen shell as to be very difficult to kill by contact,
washes made of unslacked lime 50 lbs., sulphur 25 lbs., salt
18 lbs., and water sufficient to make too gallons; or resin
20 lbs., caustic soda (70% strength) 5 lbs., fish oil 3 lbs., and
water sufficient to make roo gallons, may be used.

Lime alone is a very good insecticide; the best way to

186 THE ANIMALS AND MAN

prepare it is to add just water enough to stone- or shell-lime
to dry-slack thoroughly; then sift and apply as a powder as
soon as possible.

A method of insect killing which is available for use
against either biting or sucking insects but which requires a
good deal of special preparation and apparatus is that of
fumigating with hydrocyanic gas. By covering the tree
with a tent and ther generating the gas under it by adding
-ne ounce of pure potassium cyanide
to one ounce of sulphuric acid in
three fluid ounces of water, all insect
life on the: tree will be killed. The
quantities of cyanide, acid, and water
above given suffice to make gas to fill
150 feet of tent space. Hydrocyanic
gas 1s deadly not only to insect but
also to every other form of animal life.

The vapor of bisulphide of car-
Fic. 92. San Jose scale bon is a very effective insecticide.

insect removed from The bisulphide of carbon can _ be

A a eee bought as a liquid in drug stores and

a little of it poured into an open
saucer which can be placed in a closed closet, or bin or
trunk or even ina tight room. It volatilizes rapidly and the
fumes are deadly. As the fumes are heavier than air the
saucer should be placed in the upper part of the closet or
bin. One dram of the liquid will suffice for each cubic
foot of space in the receptacle. The vapor is inflammable
and explosive and cannot be used where it can come into
contact with fire. This remedy is very convenient and
effective for clothes’ moths.

For some kinds of insects simple methods of killing by
attracting them to light or to poisoned food can be used.

Preventive remedies for insects such as the screening of
windows, the covering of special plants with netting, or the

FIGHTING INSECT PESTS 197

encircling of tree trunks with bands of some sticky substance
to prevent the crawling up of wingless insects have their
place in insect fighting.

There still remains one other class of the so-called arti-
ficial remedies to be mentioned. They are really, however
natural remedies. These are all those included under the
general term of clean farming and high cultivation. The
result of their use is to make the plant better fitted to with-
stand the attacks of their insect enemies. In nature almost
all plants have to sustain more or less severe insect attacks.
It is naturally the weakest plants that succumb first. Where
man has gathered together many plant individuals of one
kind and has by that very act invited all the kinds of insects
that normally feed on these kinds of plants to come and
feast, he is, we might say, morally bound to protect his plant
wards from the too serious appetites of their guests. At
least he will be prudent if he recognizes this obligation.

Insect pests of even more importance than those that
attack our crops and our forests, our clothes and our domes-
tic animals are those that bring suffering and death to our
own bodies by breeding and disseminating the germs of
human disease.

The role played by insects in breeding and distributing
these animal disease germs, as well as bacterial (plant) germs,
has already been pointed out in Chapter XII. To fight
successfully these disease spreading insects, which is the
most effective way of fighting the insect-spread infectious
diseases, much has to be known of the structure, life-history
and general habits of the particular insect kinds involved.
The two most important kinds in our country are mosqul-
toes, which breed and disseminate malaria and yellow fever,
and house flies, which spread typhoid and other bacterial
diseases. The fleas, which disseminate plague, are also of
great Importance.

The very best way to fight house-flies is to destroy their

188 THE ANIMALS AND MAN

favorite breeding-places, which are manure piles and privy
vaults. ‘The eggs are laid on fresh manure or excrement
and hatch in from eight to twelve hours into footless mag-
gots that reach their full growth in as few as eight days,
Then they change to pupe from which the adult flies issue
in from eight to eighteen days. The length of life in the

Fic. 93. Foot of house-fly showing claws, hairs, pulvilli and the minute
clinging hairs on the pulvilli. (Photograph by R. W. Doane.)

different stages, egg, larva, and pupa, varies with tempera-
ture and other conditions. All manure should be removed
from barnyards at least once a week and spread out to dry.
The flies cannot breed in dry manure. If the manure
cannot be removed and spread out it should be kept in a fly-
tight bin. Outdoor privy vaults and cesspools must be
attended to. Cesspools should be kept covered and all pit
privies replaced by dry-earth closets. Finally garbage
cans and rubbish heaps should be cared for. Of course,

FIGHTING INSECT PESTS 189

any room or house can be kept free from flies, or nearly so,
by screens; but neighborhood and community effort toward
abolishing the breeding places is by far the most effective
means of fighting the deadly housefly.

To fight mosquitoes the same advice applies; destroy the
breeding places. Mosquitoes breed in puddles and ponds;

Fic. 94. Eggs, larve and pupze of mosquitoes, Theobaldia incidens.
(Photograph by R. W. Doane.)

in open barrels and tins of water; in marshes and lily-ponds;
in fresh or slightly salt water anywhere that is not flowing.
Mosquitoes mostly do not fly far; if the pests are abundant
in or about a house look for a near-by breeding place. If
this is a small puddle or pond that cannot be readily drained
pour kerosene on its surface. The oil will spread out forming
a thin coating over the water that will prove fatal to winged
mosquitoes coming to lay their eggs, and to larve (wrigglers)
coming up to the surface to breathe, as well as to the pupe

190 THE ANIMALS AND MAN

that normally float on the surface and to the adults trying
to issue from the pupal shells. About one pint of kerosene
will effectively cover fifteen square feet of water. Old cans
or pails or casks in which rainwater collects should be re-
moved; garden water taps should not be allowed to leak;
water troughs should be kept running or be emptied every
few days.

If the mosquitoes come from a marsh or large pond com-
munity efforts at drainage are in order. Certain little fishes
called ‘‘millions” or “top minnows” (Fundulus species) are
ereat mosquito-wriggler eaters, and a pond well stocked
with these, or indeed almost any kind of top feeding fishes,
will not produce many mosquitoes.

There are no very satisfactory ways of killing or driving
away the winged flies.. Smudges and pyrethrum powder do
some good. I[ll-smelling oils lke pennyroyal smeared on
hands and face may be helpful, but they are very disagree-
able to most persons. ‘The real way in which to rid a region
or community of mosquitoes—which is equivalent to rid-
ding it of all danger from malarial fevers—is to abolish the
breeding places or keep them covered with oil through the
mosquito breeding season.

An excellent recent book. about injurious insects and the ways to
fight them is “Our Insect Friends and Foes,’’ by J. B. Smith.

CHAPTER, XVI

THE VERTEBRATES

The backboned animals or vertebrates, comprising the
fishes, salamanders, frogs and toads, lizards, crocodiles,
turtles and snakes, birds, and all the quadrupeds or mam-
mals, belong to the great branch Chordata which includes
also a few small unfamiliar ocean animals which do not
look at all like the backboned animals, but which agree
with them in possessing a peculiar structure called the
notochord. This notochord consists of a series or cord of
cells extending longitudinally through the body from head
to tail, above the alimentary canal and below the spinal
nerve-cord. In all the vertebrates excepting a few low
forms, the notochord although present in the young, is replac-
ed in the adult by a segmented bony or cartilaginous axis, the
spinal or vertebral column. But in the ascidians or sea-
squirts (called also tunicates) it persists throughout life.
In addition to this characteristic notochord, nearly all the
Chordata are marked by the presence, either in embryonic
or larval stages only, or else persisting throughout life, of a
number of slits or clefts in the walls of the pharynx which
serve for breathing, and which are called gill-slits.
Structure of the vertebrates.—As the backboned or
vertebrate animals make up almost the whole of the branch
Chordata, and as the few other chordates are animals the
special structures of which we shall not undertake to study
in this book, we may note here some of the other more
obvious structural characteristics of the true vertebrates.
The possession of a backbone or bony (sometimes cartilagi-

Igt

192 THE ANIMALS AND MAN

nous) spinal column is the characteristic by which we dis-
tinguish them from the invertebrate or backboneless animals.
Furthermore, all of the vertebrates possess an internal
skeleton which is in most cases composed of bone, and is
firm and strong. In some of the lower fishes, as the sharks
and sturgeons, the skeleton is made up of cartilage, tough
but not hard. ‘The vertebrate skeleton consists typically
of an axial portion comprising the spinal column and head,
and of two pairs of appendages or limbs, variously developed
as fins, wings, legs and arms. In some vertebrates these
limbs are represented by mere rudiments, and in the lowest
fish-like forms, the lancelets and lampreys, there is not
the slightest trace of limbs. A part of the central ner-
vous system, the spinal cord, runs longitudinally through
the body on the dorsal side of the alimentary canal; the
circulatory system is closed, the blood being always confined
in the heart and in vessels called arteries, veins, and capil-
laries, and the blood is red in color owing to the presence of
numerous red corpuscles or blood-cells. The nervous
system is highly developed, with a large brain in all the
typical forms, and with complex and usually highly efficient
special sense-organss. Respiration is carried on by means
of external gills, or by internal lungs which communciate
with the outside through the mouth and nostrils. To the
lungs and gills the blood is brought to be “‘purified,”’ 1.e., to
give up its carbon dioxide and to take up oxygen.
Classification.—The Chordata are variously divided by
zoologists into eight or ten classes, of which (in the eight-
class system) the five classes* Pisces (fishes), Batrachia
(batrachians), Reptilia (reptiles), Aves (birds), and Mam-
malia (mammals), belong to the true vertebrates. These
classes will be considered in the following chapters.

*The animals included by some zoologists in the single class Pisces, are
held by other zoologists to constitute three distinct classes, thus making a
subdivision of the branch into ten classes.

THE VERTEBRATES 193

The remaining three classes include a number of strange
marine forms which until recent years were considered as
worms, but which are now known to be the nearest living
allies of the earliest or primitive vertebrates. The rela-
tionship of these forms to vertebrates is manifest, not in
the appearance or structure of the adult stage, but only
during embryonic or
larval stages.

The ascidians.—The
sea-squirts, or Ascidi-
ans, common on the
seashore, compose one
class of these primi-
tive chordate animals.
They possess a sim-
ple, sac-like body (fig.
95), fastened to the
rocks by one end, the
other being provided
with two openings,
one for the ingress
and the other for the
exit of water, a strong
current of which flows

constantly through the Fic. 95. An ascidian, or sea-squirt, from

body. By means of the coast of California. (Natural size;
after Jordan and Kellogg.)

this current the ascid-
ian obtains food. Usually sea-squirts live together in
large colonies, and in some cases a number of individuals
enclose themselves in a common gelatinous mass, forming
what is called a compound ascidian.

The ascidian when born is a tiny, free-swimming, tadpole-
like creature with a slender finned tail. It swims about
freely for only a few hours, however, soon attaching itself to
a rock, and in its further development becoming degenerate.

194 THE ANIMALS AND MAN

It loses its tail and with it the short notochord possessed by
the larva; the eye and the auditory organ are lost, and the
nervous system and alimentary canal become much reduced
and simplified. Sea-squirts in their adult stage are very
simple degenerate animals, with low functional development,
yet their embryonic and larval conditions show a consider-
able degree of structural specialization, and the presence of
the notochord in these early stages reveals their affinity with
the backboned animals.

The. fishes.—We have already studied (Chapter II) an
example of the class of fishes. The sunfish is common in
streams and ponds all over the country, and its habits can
be well observed by patient students. It lives in quiet
corners of brooks and rivers, preferably under a log or at the
root of an old stump. It is a beautiful fish, shining “‘like a
coin fresh from the mint.” Its body is mottled golden,
orange, and blue, with metallic luster, darker above, pale or
yellowish below. Its fins are of the same color, The tip
of its opercle or gill-cover is prolonged like an ear, and jet
black in color, with a dash of bright scarlet along its lower
edge. Nearly all of the thirty species of sunfish found in the
United States have this black ear-like opercle, but some
have it long, some short, and in some it is trimmed with
yellow or blue instead of scarlet.

The sunfish lays its eggs in the spring in a rude nest
scooped out in the gravel over which the male stands guard
with its bright fins spread, looking as big and dangerous
as possible. When thus employed it takes the hook savagely,
perhaps regarding the worm as a dangerous enemy. ‘The
young fishes soon hatch, looking very much like their parents,
although more transparent and not so brightly colored.
They grow rapidly, feeding on insects and other small
creatures, and reach their growth in two or three years.
They do not wander far and never willingly migrate. Stu-
dents should verify this account on the different species. A

THE VERTEBRATES 195

more exact study of the nests of the different species
and the fishes’ defense of them would be a valuable
addition to our knowledge. The most striking traits of
this fish are its vivacity and courage. ‘The sexes are similar
in appearance and both defend the nest.

Closely related to the sunfish are the various kinds of
bass, the ‘“‘crappies,” the calico bass, the rock-bass, and
the large-mouthed and small-mouthed bass. All the mem-
bers of the sunfish and bass family are carnivorous fishes,
especially common in the Mississippi Valley.

Another family of many species, especially common in
the clear, swift, and strong Eastern rivers, is that of the
darters and perches. The darters are little, slender-bodied
forms, which lie motionless on the bottom, moving lke
a flash when disturbed and slipping under stones out of
sight of their enemies. Some are most brilliantly colored,
surpassing in this respect all other fresh-water
fishes.

Unlike the sunfishes and the darters are the catfishes.
The catfish gets its name from the long feelers about its
mouth; from these also come its other names of horned
pout, and bull-head. It has no scales, but its spines are
sharp and often barbed or jagged and capable of making
a severe wound.

Remotely allied to the catfishes are the suckers, minnows,
and chubs, with smooth scales, soft fins, and soft bodies,
and the flesh full of small bones. These little fish are very
numerous in species, some kinds swarming in all fresh
water in America, Europe, and Asia. They usually swim
in the open water, the prey of every carnivorous fish, mak-
ing up by their fecundity or ability to produce young in
great numbers and their insignificance for their lack of
defensive armature. In some species the male is adorned
in the spring with bright pigment—red, black, blue, or
milk-white, In some cases, too, it has bony warts or horns

196 THE ANIMALS AND MAN

on its head or body. Such forms are known to the boys
as horned dace.

Most interesting to the angler are the members of the
salmon and trout family (fig. 96), because they are gamy,
beautiful, excellent as food, and above all perhaps, because
they live in the swiftest and clearest waters in the most
charming forests. The salmon live in the ocean most of
their lives, but ascend the rivers from the sea to deposit

Fic. 96. The rainbow-trout, Salmo irideus.

their eggs. The king salmon of the Columbia goes up the
great river more than a thousand miles, taking the whole
summer for it, and never feeding while in fresh water. Be-
sides the different kinds of salmon, the black-spotted or true
trout, the charr or red-spotted trout of various species,
the whitefish, the grayling, and the famous ayu of Japan
belong to this family.

In the sea are multitudes of fish forms. The myriad
species of eels agree in having a long, flexible, snake-like
body, without ventral fins. Most of them live in the sea,
but the single genus of true eels which ascends the
rivers is exceedingly abundant and widely distributed.
Most eels are extremely voracious, but some of them have
mouths that would barely admit a pin-head. Cod-fishes are
creatures of little beauty but of great usefulness, swarming

THE VERTEBRATES 197

in arctic and subarctic seas. The herring, soft and weak
in body, are more numerous in individuals than any other
fishes. ‘The flounders, of many kinds, lie flat on the sea
bottom. ‘They have the head so twisted that the two eyes
occur both together on the uppermost side (fig. 97). The
members of the great mackerel tribe swim in the open sea,

Fic. 97. The winter flounder, Pseudopleuronectes americanus. (After
Goode.)

often in great schools. Largest and swiftest of these is
the swordfish, in which the whole upper jaw is grown to-
gether to form a long bony sword, a weapen of offense that
can pierce the wooden bottom of a boat.

Many of the ocean fishes are of strange form and ap-
pearance. The sea-horses (fig. 98) are odd fishes, cov-
ered with a bony shell, and with the head shaped like that
of a‘horse. They are little fishes, rarely a foot long, and
cling by their curved tails to floating seaweed. ‘The por-
cupine fishes and swell fishes have the power of filling the
stomach with air, which they gulp from the surface. They
can escape from their pursuers by floating as a round spiny
ball on the surface. ‘The flying fishes leap out of the water,
and sail for long distances through the air like grasshoppers.
They cannot flap their long pectoral fins, and do not truly

198 THE VERTEBRATES

fly, but strike the anal fin with great force against the water
in making a leap so that they move swiftly, and thus escape
their pursuers. In its structure a flying fish differs little

Fic. 98. A_ sea-horse, Hippocampus
kelloggi. (Natural size, 8 inches

long; after Jordan and Snyder.)

from a pike or other ordi-
nary fish.

The rays and skates are
peculiar ocean fishes, which
lie at the bottom of shal-
low-water shores. They
feed on crabs, molluscs,
and bottom-fishes. The
small common _ skates,
“toODaceo- bDOxXes »a00Ltt
twenty inches long, and the
larger “barn-door”’ skates,
are numerous along the
Atlantic coast from Vir-
ginia northward. Especi-
ally interesting members
of this group, because of
the peculiar character of
the injuries produced by
them, are the sting-ray and
torpedoes, or electric-rays.
The sting-rays have spines
near the base of the tail
which cause very painful
wounds. The _ torpedoes
have two large electrical
organs, one on each side

of the body, just behind the head, with which they
can give a strong electric shock. ‘The discharge from a
large individual is sufficient to temporarily disable a man,
and were these animals at all numerous they would prove
dangerous to bathers.’”’ Very different from the typical

THE VERTEBRATES 199

rays in external appearance are the sawfishes, which belong
to this group. The body is elongate and shark-like, and
has a long, saw-like snout, This saw, which in large indi-
viduals may reach a length of six feet and a breadth of
twelve inches, makes its owner formidable among the small
sardines and herring-like fishes on which it feeds. The
sawfishes live in tropical rivers, descending to the sea.

Food-fishes and fish-hatcheries.—Most fishes are suit-
able for food, though not all. Some are too small to be
worth catching or too bony to be worth eating. Some of
the larger ones, especially the sharks, are tough and rank.
A few are bitter and in the tropics a number of species feed
on poisonous coelenterates about the coral reefs, becoming
themselves poisonous in turn. But a fish is rarely poisonous
or unwholesome unless it takes poisonous food. Where
fishes of a kind specially used for food gather in great num-
bers at certain seasons of the year, fishing is carried on
extensively and with an elaborate equipment. Such fish-
eries, some of which have been long known, are scattered all
over the world. Along the shores of the Mediterranean Sea,
and on the coasts of Norway, France, the British Isles and
Japan are numerous great fishing-places. But ‘nowhere
are there found such large fisheries as those along the north-
ern Atlantic coasts of our own continent, extending from
Massachusetts to Labrador. Especially on the banks of
Newfoundland are codfish, herring, and mackerel caught.”
Among our fresh-water fisheries the great salmon fisheries
of the Penobscot and Columbia rivers and of the Karluk and
other rivers of Alaska are the best known. ‘The whitefish
of our Great Lakes is also one of the important food-fishes
of the world.

In many places fishes are raised in so-called hatcheries,
not usually for immediate consumption but for the purpose
of stocking ponds and streams either in the neighborhood
of the hatchery or in distant waters which the special species

200 THE ANIMALS AND MAN

cultivated has not been able naturally to reach. The eggs
of some fishes are large and non-adherent, two features
which greatly favor artificial impregnation and hatching.
In the hatcheries the eggs are put first into warm water,
where development begins; they are then removed into cool
water, which arrests development without injury, making
shipment possible. The eggs of salmon and trout in par-
ticular can be sent long distances to suitable streams or
ponds. ‘The eggs of the shad have been thus carried from
the East to the streams of California, and trout have been
distributed to many streams in our country which by them-
selves they could never have reached.

The salmon is a conspicuous example of those fishes which
can be artificially propagated. The eggs of the salmon are
large, firm, and separate from each other. If the female fish
be caught when the eggs are ripe and her body be pressed
over a pan of water the eggs will flow out into the water. By
a similar process the milt or male sperm-cells can be pro-
cured and poured over the eggs to fertilize them. The young
after hatching are kept for a few days or weeks in artificial
pools, till the yolk-sacs are absorbed and they can take care
of themselves, They are then turned into the stream, where
they drift tail foremost with the current and pass downward
to the sea. All trout may be treated in similar fashion, but
there are many food-fishes which cannot be handled in this
way. In some the eggs are small or soft, or viscid and ad-
hering in bunches. In others the life-habits make artificial
fertilization impossible. Such species are artificially reared
only by catching the young and taking them from one stream
to another. ‘To this type belong the black bass, the sunfish,
the catfish and other familiar forms.

Baskett’s ‘‘Story of the Fishes,’? McCarthy’s ‘Familiar Fish,” and

Jordan and Evermann’s “‘Food and Game Fishes of America”’ are good
books for elementary students of fishes.

The batrachians.—We have made the acquaintance of

THE VERTEBRATES 201

the most familiar batrachians in our study of the toad and
frog (Chapters III and IX). Other familiar members of
this class are the salamanders. All batrachians breathe by
means of gills for a longer or shorter time after birth. But
except in very few cases these gills are lost and lungs de-
veloped so that the adults cannot breathe under water. The
toads and frogs are closely related, and have about the same
life-history and habits, except that the fully-grown toads live
on land instead of in and about ponds. In structure toads
differ from frogs in having no teeth. There are only a few
toad species in North America, but one of these is very
abundant and widespread. It appears in two or three
varieties, the common toad of the Southern States differing
in several particulars from that of the Northern. The toad
is a familiar inhabitant of gardens, and does much good by
feeding on noxious insects. It is most active at twilight.
Its eggs are laid in a single line in the center of a long, slender,
gelatinous string or rope, which is nearly always tangled and
wound round some water-plant or stick near the shore on
the bottom of a pond. The eggs are jet black, and when
freshly laid are nearly spherical. At the time of the egg-
laying the toads croak or call, making a sort of whistling
sound, and at the same time pronouncing deep in the throat
“bu-rr-r-r-r.”” The toad does not open its mouth when
croaking, but expands a large sac or resonator in its throat.
The toad tadpoles are blacker than those of frogs or sala-
manders, and undergo their metamorphosis while of smaller
size than those of frogs. When they leave the water they
travel for long distances, hopping along so vigorously that in
a few days they may be as far as a mile from the pond where
they were hatched. They conceal themselves by day, but
will appear after a warm shower; this sudden appearance
of many small toads sometimes gives rise to the false notion
that they have fallen with the rain.

There are about a dozen species of frogs in the United

202 THE ANIMALS AND MAN

States. The largest of these, and indeed the largest of all
the frogs, is the well-known bullfrog, which reaches a length
(head to the posterior end of the body) of eight inches. It
is found in ponds and sluggish streams all over the eastern
United States and in the Mississippi Valley. It is greenish
in color, with the head usually bright pale-green. Its croak-
ing is very deep and sonorous. The pickerel-frog, which is

FIG. 99. The southwestern tree-frog, H yla arenicolor. (After Dickinson.)

bright brown on the back, with two rows of large, oblong,
square blotches of dark brown, is found in the mountains of
the eastern United States. The little, pale, reddish-brown
wood-frog, with arms and legs barred above, is common in
damp woods, and is “‘an almost silent frog.”

The true tree-frogs, or tree-toads, constitute a family
especially well represented in tropical America. ‘They have
little pad-like swellings on the tips of their toes, to enable
them to hold firmly to the branches of the trees in which they
live. Some, like the swamp tree-frog and the cricket-frog,
are not arboreal in habit, remaining almost always on the
ground. The common tree-frog of the Eastern States is
green, gray, or brown above, with irregular dark blotches,
and yellow below. It croaks or trills, especially at evening
or in damp weather. Pickering’s tree-frog makes the “‘first
note of spring’ in the Eastern States. This is the one most

THE VERTEBRATES 203

frequently heard in the autumn, too, but “‘its voice is less
vivacious than in the spring, and its lonely pipe in dry wood-
lands is always associated with goldenrods and asters and
falling leaves.”” The tree-frogs of North America lay their
eggs in the water on some fixed object like an aquatic plant,
in smaller packets than those of the true frogs, and not in
strings as do the toads.

“The Frog Book” by Mary Dickerson is a well-illustrated and com-
plete account of the frogs and toads of this country.

The salamanders (figs. too and tor) are batrachians, with
the body not short and tailless as in the frogs and toads,

Fic. 100. The Western brown eft, or salamander, Diemyctylus torosus.
(From life.)

but elongate and slender and tailed. Their life-history
is like that of the frogs, although some salamanders which
live on land (they are to be found under logs and stones
in the woods) produce their young alive. The little green
triton or eft of the Eastern States, or its larger brown-backed
congener (fig. 100) of the Pacific coast, is common in water,
while another eft, the little red-backed salamander, is com-
mon in the woods under logs and stones.

The reptiles—The class of reptiles includes the liz-
ards, snakes, tortoises, turtles, crocodiles, and alligators.
They are cold-blooded and breathe for their whole life
exclusively by means of lungs, the forms which live in water
coming to the surface to breathe. They are covered with
horny scales or plates which with the entire absence of

204 THE ANIMALS AND MAN

gills after hatching readily distinguish them from all the
batrachians. While most reptiles live on land, some in-
habit fresh water and some the ocean. As the young have
the same habitat and general habits as the adult, there is
no such metamorphosis in their life-history as is shown by
the batrachians. The reptiles are widespread geographi-
cally, occurring, however, in greatest abundance in tropical

®
& a

"a

€: Sma wha
” \'
. a Ne

Fic. 101. The tiger salamander. (After Jenkins and Kellogg.)

regions, and being wholly absent from the arctic zone.
They are not capable of such migrations as are accomplished
by birds and many mammals, but withstand severely hot
or cold seasons by passing into a state of suspended ani-
mation or seasonal sleep or torpor.

The chief variations in body-form among the reptiles
are manifest when a turtle, lizard, and snake are compared.
In the turtles the body is short, flattened, and heavy, and
provided always with four limbs, each terminating in a
five-toed foot; in the lizards the body is more elongate,
and with usually four legs, but sometimes with two only,
or even none at all; while in the snakes the long, slender,
cylindrical body is legless, or at most has mere rudiments
of the hinder limbs. With the reptiles, locomotion is as
often effected by the bending or serpentine movements
of the trunk as by the use of the legs. Among lizards and
snakes the body is-covered with horny epidermal scales or

THE VERTEBRATES 205

plates, while among the turtles and crocodiles there may be,
in addition to the epidermal plates, a real deposit of bone
in the skin whereby the effectiveness of the armor is increased.
The epidermal covering of snakes and lizards is periodi-
cally moulted, or, as we say, the skin is shed. The bright
colors and patterns of snakes and of many lizards are due
to the presence and arrangement of pigment cells in the

Fic. 102. The giant land-tortoise of the Galapagos Islands, Tesiude
sp. These tortoises attain a length of four feet. (Photograph from
life by Geo. H. Coleman, of a specimen brought to Stanford University
by Snodgrass and Heller.)

skin. With some reptiles, notably the chameleons, the
colors and markings can be quickly and radically changed
by an automatic change in the tension of the skin.

Specimens of some pond or land turtle common in the
vicinity of the school should be obtained. The red-bellied
and yellow-bellied terrapins, or the painted or mud-turtles
are common over most of the United States. They may be
raked up from creek bottoms or fished for with strong hook
and line, using meat as a bait. They will live through the

206 THE ANIMALS AND MAN

winter, if kept in a cool place, without food or special care
of any kind. Observe their swimming and diving, the re-
traction of head and limbs into the shell, the use of the third
eyelid (nictitating membrane), and the swallowing of the

Fic. 103. A lizard in the grass. (Photograph from life by Cherry Kear-
ton; permission of Cassell & Co.)

air. Note the ‘‘shell,” consisting of a dorsal plate, the cara-
pace and ventral plate, plastron, and the lateral uniting
parts, the bridge. Almost all the fresh-water and land
turtles are carnivorous, but few catch any very active prey.

Fic. 104. The blue-tailed skink, Eumeces skeltonianus. (From life.)

While some are strictly aquatic others are as strictly terres-
trial, never entering the water. The eggs of all are oblong
and are deposited in hollows, sometimes covered in the sand.
The newly hatched young are usually circular in shape,
and differ in color and pattern from the adults.

The group of lizards (fig. 103) is a very large one, about

THE VERTEBRATES 207

fifteen hundred species being known in the world, but it
is represented in the United States by comparatively few
kinds. Specimens of some species of the common swift
are obtainable almost anywhere in the United States. They
may be looked for in woods, along fences, and especially
on warm rocks. In certain regions the glass-snake or
joint-snake is common. This lizard, popularly thought
to be a snake, has no external limbs, and its tail is so brittle,
the vertebree composing it being very fragile, that part of
it may break off at the slightest blow. In time a new tail
is regenerated. It lives in the central and northern part

Fic. 105. The Gila monster, Heloderma horridum. (One fourth natural
size; photograph from life by J. O. Snyder.)

of the United States, and burrows in dry places. In the
western part of the country horned toads are common,
about ten different species being known. These are liz-
ards with shortened and depressed body and well-developed
legs. The body is covered with protective spiny protuber-
ances, and in individual color and pattern resembles closely
the soil, rocks, and cactuses among which the particular
horned toad lives. All the species of horned toads are
viviparous, seven or eight young being born alive at a time.

In New Mexico, Arizona, and northern Mexico the only
existing poisonous lizard, the Gila monster (fig. 105), is
found. This is a heavy, deep-black, orange-mottled lizard
about sixteen inches long. There is much variance of belief
among people regarding the Gila monster, but recent ex-
periments have proved the poisonous nature of the animal.
The poison, which is secreted by the glands in the lower

208 THE ANIMALS AND MAN

jaw, flows along the grooved teeth into the wound. A beau-
tiful and interesting little lizard found in the south is the
green chameleon. Its body is about three inches long,
with a slender tail of about five or six inches. The nor-
mal color of the chameleon is grass-green, but it may as-
sume almost instantly shades varying from a_ beautiful
emerald to a dark and iridescent bronze color.

About tooo living species of snakes are known. Usually

Fic. 106. The gopher-snake, Pituophis bellona. (Photograph from life,
by” J: O. Snyder.) .

they have the body regularly cylindrical, and without dis-
tinct division into body-regions. Legs are wanting, loco-
motion being effected by the help of the scales and ribs.
No snake can move forward on a perfectly smooth surface,
and no snake can leap. In some forms, such as the pythons,
external rudiments of the hind limbs are present, but do
not aid in locomotion. The mouth is large and distensible,
so that prey of considerably greater size than the normal
diameter of the snake’s body is frequently swallowed whole.
The sense of taste is very little if at all developed, as the food
is swallowed without mastication. The tongue, which is

THE VERTEBRATES 209

protrusible, and usually red or blue-black, serves as a special
organ of touch. Hearing is poor, the ears being very little
developed. ‘The sense of sight is also probably not at all
keen. Snakes rely chiefly on the sense of smell for finding
their prey and their mates. The colors of snakes are often
brilliant, and in many cases serve to produce an effective
protective resemblance by harmonizing with the usual
surroundings of the animal. The food of snakes consists

Fic. 107. A garter-snake, Thamnophis parietalis. (Photograph from
life by J. O. Snyder.)

almost exclusively of other animals, which are caught alive.
Some of the poisonous snakes kill their prey before swallow-
ing it, as do some of the constrictors. While most snaKes live
on the ground, some are semi-arboreal and others spend
part or all of their time in the water. Cold-region snakes
spend the winter in a state of suspended animation; in the
tropics, on the contrary, the hottest part of the year is spent
by some species in a similar “‘sleep.”

Among the commonest members of this group are the
garter-snakes (fig.107), always striped, and not more than
three feet long. The most widespread species is rather
dully colored, with three series of small dark spots along
each side. The common water-snake is brownish, with
back and sides each with a series of about eighty large,

210 THE ANIMALS AND MAN

square, dark blotches alternating with each other. It feeds
on fishes and frogs, and, although unpleasant and ill-tem-
pered, is harmless. One of the prettiest and most gentle of
snakes is the familiar little green-snake, common in the
East and South in moist meadows and in bushes near the
water. It feeds on insects, and can be easily kept alive in
confinement. A familiar larger snake is the black-snake,
or “blue-racer,”’ lustrous pitch-black, general color greenish
below, and with
white throat. It
is Olen round
in the neighbor-
hood of water,
and is particu-
larly partial to
the thickets of
alders, where it
cany hunt) Lor
toads, mice, and
birds, and, being
am je ce le met
climber, it is often seen among the branches of small
trees and bushes, hunting for young birds in the
nest’ * The* chain-snake.ef the . Southeast (and. king=
snake (fig..108). of the- Central States are beautiful,
lustrous, black-and-yellow-spotted snakes, which feed not
only on lizards, salamanders, small birds, and mice, but also
on other snakes. The king-snake should be protected in
regions infested by “‘rattlers.””. The spreading-adder, or
blowing-viper, a common snake in the Eastern States,
brownish or reddish, with dark dorsal and lateral blotches,
depresses and expands the head when angry, hissing and
threatening. Despite the popular belief in its poisonous
nature this ugly reptile is quite harmless. It specially in-
fests dry and sandy places.

Fic. 108. A king-snake, Lampropeltis boyli. (Pho-
tograph from life, by J. O. Snyder.)

THE VERTEBRATES 211

With the exception of the coral- or bead-snake, a rather
small, jet-black snake, with seventeen broad, yellow-bor-
dered crimson rings, found in the Southern States, the only
poisonous snakes of the United States are the rattle-snakes
and their immediate relatives, the copperhead and water-
moccasin. ‘These snakes
all have a large triangu-
lar head, and in the rat-
tlesnakes the posterior
tip of the body is provi-
ded with a “‘rattle,” com-
posed, Gl <a series: Or
partly overlapping, thin,
horny capsules, or cones,
of shape as shown in fig.
tog. These horny pieces
are simply the somewhat Fic. 109. The rattles of the rattle-snake:
modified, successively the lower figure shows a longitudinal
focnied epidermal Ree section of the rattle. (Natural size.)

P
ings of the tip of the body, which instead of being entirely
moulted as the rest of the skin is, are, because of their pecu-
liar shape, loosely attached to one another, and by the basal
one to the body of the snake. The number of rattles does
not correspond to the snake’s years for several reasons, partly
because more than one rattle can be added ina year, and es-
pecially because rattles are easily and often broken off. As
many as thirty rattles have been found on one snake. There
are two species of ground-rattlesnakes, or massasaugas, in
the United States, and ten species of the true rattlesnakes.
The center of distribution of the rattlesnakes is the dry
tablelands of the Southwest in New Mexico, Arizona, and
Texas. But there are few localities in the United States
outside the high mountains in which “‘rattlers” do not occur,
or did not occur before they were exterminated by man.
The copperhead is light chestnut in color, with inverted Y-

oie THE ANIMALS AND MAN

shaped darker blotches on the sides, and seldom exceeds
three feet in length. It occurs in the Eastern and Middle
United States, from Pennsylvania and Nebraska southward.
It is a vicious and dangerous snake, striking without warn-
ing. The water-moccasin is dark chestnut-brown, with
darker markings. The head is purplish-black above. It
is found along the Atlantic
@l <x and Gulf coasts from North
a sa ~ Carolina to Mexico, extending
aw \ also some distance up the
Mississippi Valley. It is dis-
tinctively a water-snake, being
found in damp, swampy places
or actually in water. It reach-
es a length of over four feet,
and is a very venomous snake,
striking on the slightest pro-
Fic. 110. Dissection of the head vocation. The common,
of arattle-snake; /, poison fangs; harmless water-snake is often
Pp, polson-sac. Z B
called water-moccasin in the
Southern States, being popularly confounded with this most
dangerous of our serpents. The poison of all of these snakes
is a rather yellowish, transparent, sticky fluid, secreted by
glands in the head, from which it flows through the hollow
maxillary fangs. ‘The character and position of the fangs are
shown in fig. 110. Remedial measures for the bite of
poisonous snakes are first, to stop, if possible, the flow of
blood from the wound to the heart by compressing the
veins between the wound and the heart; then (if the lips
are unbroken) to suck the poison from the wound; next
to introduce by hypodermic injection permanganate of pot-
ash, bichloride of mercury, or chromic acid into the wound;
and finally, perhaps, to take some strong stimulant, as brandy
or whiskey.
The crocodiles and alligators are reptiles familiar by

THE VERTEBRATES 213

name and appearance, though seen in nature only by the
inhabitants or visitors in tropical and semi-tropical lands.
In the United States there are two species of these great
reptiles: the American crocodile, living in the West Indies
and South America, and occasionally found in Florida;
and the American alligator, common in the morasses and
stagnant pools of the Southern States. The alligator differs
from the crocodiles in having a broader snout. It is rarely
more than twelve feet long. The best-known crocodile is
the Nile crocodile, which is not limited to the Nile, but is
found throughout Africa. In the Ganges of India is found
another member of this group of reptiles, called the gavial.
It is among the largest of the order, reaching a length of
twenty feet. The crocodiles, alligators, and gavials com-
prise not more than a score of species altogether, but because
of their wide distribution, great size, and carnivorous habits
they are among the most conspicuous of the larger living
animals. ‘They live mostly in the water, going on land to
sun themselves or to lay their eggs. They move very quickly
and swiftly in water, but are awkward on land. Fish,
aquatic mammals, and other animals which occasionally
visit the water are their prey. The gavial and Nile croco-
dile are both known to attack and devour human beings,
and these species annually cause a considerable loss of life.
But few such fatalities, however, are accredited to the Ameri-
can alligator.

CHAPTER XVII

THE VERTEBRATES (continued): BIRDS

Birds are readily and unmistakably distinguishable from
all other kinds of animals by their feathers. -They are
further distinguished from the reptiles on one hand by their
possession of a complete double circulation and by their
warm blood (normally of a temperature of from too—-112° F.),
and from the mammals on the other by the absence of milk-
glands. There are about 10,000 known species of living
birds; they occur in all countries, being most numerous
and varied in the tropics.

Body form and_ structure.—The general body form
and external appearance of a bird are too familiar to need
description. The covering of feathers, the modification
of the fore limbs into wings, and the toothless, beaked mouth
are characteristic and distinguishing external features.
The feathers, although covering the whole of the surface of
the body, are not uniformly distributed, but are grouped
in tracts called pteryle, separated by bare or downy spaces
called apteria. ‘They are of several kinds, the short soft
plumules or down-feathers, the large stiffer contour-feathers,
whose ends form the outermost covering of the body, the
quill-feathers of the wings and tail, and the fine bristles or
vibrisse about the eyes and nostrils called thread-feathers.
The fore limbs are modified to serve as wings, which are
well developed in almost all birds. However, the strange
Kiwi or Apteryx of New Zealand with hair-like feathers is

214

THE VERTEBRATES: BIRDS 215

almost wingless, and the penguins have the wings so reduced
as to be incapable of flight, but serving as flippers to aid in
swimming underneath the water. The ostriches and cas-

Fic. 111. Cardinal grosbeak, or red bird, Cardinalis cardinalis. (One-
half natural size; from life.)

sowaries also have only rudimentary wings and are not able
to fly. Legs are present and functional in all birds, vary-
ing in relative length, shape of feet, etc., to suit the special
perching, running, wading, or swimming habits of the
various kinds. Living birds are toothless, although certain

216 THE ANIMALS AND MAN

extinct forms, known through fossils, had large teeth set in
sockets on both jaws. ‘The place of teeth is taken, as far
as may be, by the bill or beak formed of the two jaws, pro-
jecting forward and tapering more or less abruptly to a point.
In most birds the jaws or mandibles are covered by a horny
sheath. In some water and shore forms the mandibular
covering is soft and leathery. The range in size of birds is
indicated by comparing a humming-bird with an ostrich.

Fic. 112. Puffins. (Drawn from a photograph from life.)

Many of the bones of birds are hollow and contain air.
The air-spaces in them connect with air-sacs in the body,
which connect in turn with the lungs. Thus a bird’s body
contains a large amount of air, a condition helpful of course
in flight. The breast-bone is usually provided with a marked
ridge or keel for the attachment of the large and powerful
muscles that move the wings, but in those birds like the
ostriches, which do not fly and have only rudimentary
wings, this keel is greatly reduced or wholly wanting. ‘The
fore limbs or wings are terminated by three “‘fingers” only;
the legs have usually four, although a few birds have only
three toes and the ostriches but two.

As birds have no teeth with which to masticate their
food, a special region of the alimentary canal, the gizzard,
is provided with strong muscles and a hard and rough inner
surface by means of which the food is crushed. Seed-

THE VERTEBRATES: BIRDS 257

eating birds have the gizzard especially well developed, and
some birds take small stones into the gizzard to assist in the
grinding. ‘The lungs of birds are more complex than those
of batrachians and reptiles, being divided into small spaces
by numerous membranous partitions. They are not lobed
as in mammals, and do not lie free in the body-cavity, but

Fic. 113. Russet-backed thrush, Turdus ustulatus. (Photograph from
life by Eliz. and Jos. Grinnell.)

are fixed to the inner dorsal region of the body. Connected
with the lungs are the air-sacs already referred to, which
are in turn connected with the air-spaces in the hollow
bones. By this arrangement the bird can fill with air not
only its lungs but all the special air-sacs and spaces, and thus
greatly lower its specific gravity. The vocal utterances of
birds are produced by the vocal cords of the syrinx or lower
larynx, situated at the lower end of the trachea just where
it divides into the two bronchial tubes, the tracheal rings

218 THE ANIMALS AND MAN

being here modified so as to produce a voice-box contain-
ing two vocal cords controlled by five or six pairs of muscles.
The air passing through the voice-box strikes against the
vocal cords, the tension of which can be varied by the muscles.
In mammals the voice-organ is at the upper or throat end
of the trachea.

The heart of birds is composed of four distinct cham-
bers, the septum between the two ventricles, incomplete
in the Reptilia, being complete in this group. There is
thus no mixing of arterial and venous blood in the heart.
The systemic blood-circulation being completely separated
from the pulmonic, the circulation is said to be double.
The circulation of birds is active and intense; they have
the hottest blood and the quickest pulse of all animals. In
them the brain is compact and large, and more highly de-
veloped than in batrachians and reptiles, but the cerebrum
has no convolutions as in the mammals. Of the special
senses the organs of touch and taste are apparently not
keen; those of smell, hearing, and sight are well developed.
The optic lobes of the brain are of great size, relatively,
compared with those of other vertebrate brains, and there
is no doubt that the sight of birds is keen and effective.
The power of accommodation or of quickly changing the
focus of the eye is highly perfected. ‘The structure of the
ear 1s comparatively simple, there being ordinarily no ex-
ternal ear, other than a simple opening. The organs of
the inner ear, however, are well developed, and birds un-
doubtedly have excellent hearing. The nostrils open upon
the beak, and the nasal chambers are not at all complex,
the smelling surface being not very extensive. It is probable
that the sense of smell is not, as a rule, especially keen.

Development and _ life-history.—All birds are hatched
from eggs, which undergo a longer or shorter period of in-
cubation outside the body of the mother, and which are, in
most cases, laid in a nest and incubated by the parents.

THE VERTEBRATES: - BIRDS 219

The eggs are fertilized within the body of the female, the
mating time of most birds being in the spring or early summer.
Some kinds, the English sparrow, for example, rear numerous
broods each year, but most species have only one or at most
two. The eggs vary greatly in size and color-markings,
and in number from one, as with many of the Arctic ocean

Fic. 114. The nest and eggs of the black phoebe, Sayornis nigricans.
(Photograph by J. O. Snyder.)
birds, to six or ten, as with most of the familiar song-birds,
or from ten to twenty, as with some of the pheasants and
grouse. The duration of incubation (outside the body)
varies from ten to thirty days among the more familiar birds,
to nearly fifty among the ostriches. ‘The temperature neces-
sary for incubation is about 40° C. (100° F.).. Among polyga-
mous birds (species in which a male mates with several
or many females) the males take no part in the incubation
and little or none in the care of the hatched young; among
most monogamous birds, however, the male helps to build
the nest, takes his turn at sitting on the eggs, and is active

220 THE ANIMALS AND MAN

in bringing food for the young, and in defending them from
enemies. The young, when ready to hatch, break the egeg-
shell with the “egg-tooth,’ a horny pointed projection on
the upper mandible, and emerge either blind and almost
naked, dependent upon the parents for food until able to
fly (altricial young), or with eyes open and with body cov-

Fic. 115. Western chipping sparrow, Sp7zella socialis avizonae. (Photo-
graph from life by Eliz. and Jos. Grinnell.)

ered with down, and able in a few hours to feed themselves
(precocial young).

Classification and identification.—The class of birds,
Aves, is divided into various orders, of which seventeen are
represented in North America. There are eight hundred
(approximately) different species of North American birds,
but in any one locality not more than about a third of these
species can be found, and of these only comparatively few
are common or numerous. So that to learn the common
birds of a single locality is not a large matter; it means

THE VERTEBRATES: BIRDS

getting acquainted with per-
haps fifty or sixty different
kinds. As birds can usually
be readily identified by their
size and shape, and the color
pattern of their plumage, this

class is especially well adapt- -

ed for the beginning study of
systematic zoology, which con-
cerns the identification and
classification of species.

There are many good “bird

books”’ to enable students to learn :
For Western §

the different kinds.
birds Florence Merriam Bailey’s
‘Handbook of Birds of the Western
United States”’
useful. For

of Eastern North America’’ may be
recommended.

Birds and the seasons.—
In trying to become acquaint-
ed with the birds of a locality

it must be borne in mind that >

the bird-fauna of any region
varies with the season.

through; these are called resi-
dents. Some spend only the
summer or breeding season
in the locality, coming up
from the South in spring and
flying back in autumn; these
are summer residents. Some

will be the most §
Eastern birds Frank &
Chapman’s “‘ Handbook of the Birds

Some

birds live in it all the year Sie

221

Fic. 116. Nest and eggs of the
ruby-throat humming-bird, 7vo-
chilus colubris, seen from above,
in an apple-tree. (Photograph
by E. G. Tabor, permission of
The Macmillan Co.)

222 THE ANIMALS AND MAN

spend only the winter in the locality, coming down from
the severer North at the beginning of winter, and going
back with the coming of spring; these are winter residents.
Some are to be found in the locality only in spring and
autumn, as they are migrating north and south between
their tropical winter quarters and their northern summer
or breeding home; these are migrants. And, finally, an
occasional representative of certain bird species, whose normal
range does not include the given locality at all, will appear
now and then, blown aside from its regular path of migra-
tion, or otherwise astray; these are visitants. As to the
relative importance, numerically, of these various categories
among the birds which may be found in a certain region,
and thus form its bird-fauna, we may illustrate by refer-
ence to a definite region. Of the 351 species of birds which
have been found in the State of Kansas (a region without
distinct natural boundaries, and fairly representative of any
Mississippi valley region of similar extent), 51 are all-year
residents, 125 are summer residents, 36 are winter residents,
104 are migrants, and 35 are rare visitants.

The all-year residents and the summer residents, com-
prising about one-half of the species to be found in a locality,
are the only ones which breed there, and which thus pre-
sent opportunity for observations on their nest-building
habits and care of the young. Numerous suggestive ques-
tions present themselves in connection with breeding in ad-
dition to the simpler ones already propounded in Chapter IX.
Why is it that some species nest early and some late? Can
the character of the food of the young have anything to do
with this? If so, how? Does the condition of the particular
trees, bushes or other favorite sites for nests help determine
the nesting time? Why should some birds raise but one
brood a year, and others two or even three? Does the fact
that a bird is an all-year resident or only a summer resident
have any influence in determining its nesting time and the

THE VERTEBRATES: BIRDS 223

number of broods it rears? Compare the habits of the
various breeding species of the locality, and find out if the
summer residents have any breeding habits in common as
distinguished from the all-year residents.

Observe the behav-
ior of the birds in
courtme time. Do
the males have “‘sing-
ing contests,’ as is
sometimes reported?
Do they fight with
each other? Do the
males or females show
any differences, at this
time, from their more
usual plumage? After
mating which bird
selects the nesting
site? Are old nesting
sites preferred to new
ones? If two broods
are reared 1s a new
nest built? What are
the principal causes
of mortality among
the eggs and young

during the breeding
season? What in- Fic. 117. Razorbill auk and egg. (Drawn

Bee el haa bits OF the from photograph made from life.)

parents have direct reference to these dangerous conditions ?
What means of protecting the nest are resorted to? What is
the behavior of the parents towards enemies of the young?
The field-study of the birds of a given locality will comprise
much observation bearing directly on their distribution or
special habitat. Certain birds will be found to be limited to

224 THE ANIMALS AND MAN

certain parts of even a small region; the swimmers will be
found in ponds and streams, and the long-legged shore-birds
on the pond- or stream-banks, or in the marshes and wet
meadows, although a few, like the upland-plover, curlews,
and godwits are common on the dry upland pastures. Dis-

Fic. 118. Young barn-owls. (Photograph from life by Geo. Towne;
permission of The Condor.)

tinguish the ground-birds from the birds of the shrubs
and hedge-rows, and these again from the strictly forest-
birds. Find the special haunts of swallows and kingfishers.
Which are the shy birds driven constantly deeper into the
wild places, or being exterminated by the advance of man?
Which birds do not retreat, but even find an advantage in
man’s seizure of the land, obtaining food from his fields
and gardens?

THE VERTEBRATES: BIRDS 225

Make a map on large scale of the locality of the school,
showing on it the topographic features of the region, such
as streams, ponds, marshes, hills, woods, springs, wild

~
=.

_—
AN

~~.
i

Ve —

Fic. 119. Nest of the buff-breasted fly-catcher, Empidonax fulvifrons
pygmaeus, on the cone of a pine-tree. (Photograph by R. D. Lusk;
permission of The Condor.)

pastures, etc., also roads and paths, and such landmarks as
schoolhouses, country churches, etc. On this map in-
dicate the local distribution of the birds, as determined by

226 THE ANIMALS AND MAN

the data gradually gathered; mark favorite nesting-places
of various species, roosting-places of crows and blackbirds,
feeding-places, and bathing- and drinking-places of certain
kinds, the exact spots of finding rare visitants, rare nests, etc.

As already mentioned, many of the birds of a locality are
“migrants,” that is, they breed farther north, but spend the
winter in more southern latitudes. These migrants pass
through the locality twice each year, going North in the
spring and South in the autumn. They are much more
likely to be observed during the spring migration than in
the fall, as the flight South is usually more hurried. The
observation of the migration of birds is very _interest-
ing, and much can be done by beginning students. Notes
should be made recording the first time in the spring
a migrating species is seen, the time when it is most abun-
dant, and the last time it is seen the same spring. Similar
records should be made showing the movements of the birds
in the fall. A series of such records kept by the school,
covering a few years, will show which are the earliest to
appear, which the later, and which the last. Such records
of appearance and disappearance should also be kept for
the summer residents, those birds that come from the South
in the spring, breed in the locality, and then depart for the
South again in the autumn. Notes on the kinds of days, as
stormy, clear, cold, warm, on which the migration seems to
be most active; on the greater prevalence of migratory
flights by day or by night; on the height from the earth at
which the migrants fly, etc., are all worth while.

For an excellent simple account of migration see Chapman’s “Bird-
Life,” Chapter IV. A book about migration, and one giving the
records for many species at many points in the Mississippi Valley, is
Cooke’s “Bird Migration in the Mississippi Valley.”’

It must also be kept in mind in using bird-keys and de-
scriptions to determine species that the descriptions and
keys refer to adult birds, and in ordinary plumage. -Among

THE VERTEBRATES: BIRDS 227

numerous birds the young of the year, old enough to fly and
as large as the adults, still differ considerably in plumage
from the latter; males differ from females, and, finally, both
males and females may change their plumage (hence color and
markings) with the season. The seasonal changes of plum-
age accomplished by moulting may be marked or hardly
noticeable. ‘‘All birds get new suits at least once a year,
changing in the fall. Some change in the spring also, either
partially or wholly, while others have as many as three
changes—perhaps, to a slight extent, a few more.
It is claimed by some that now all new colors are acquired by
moult, and by others that in some instances (young hawks)
an infusion or loss, as the case may be, of pigment takes
place as the feather forms, and continues so long as it grows.”
There is much lack and uncertainty of knowledge con-
cerning the moulting and change of plumage by birds, and
careful observations by bird-students should be made on
the subject.

The uses of colors and patterns in animals are discussed in Chapter
XXXII. Foraccounts of the plumage and color of birds see Chapter
III in Chapman’s “‘ Bird-Life,”’ and Chapters VIII and IX in Baskett’s
“Story of the Birds.”

Structure and habit.—In connection with learning the
different kinds of birds in a locality, observations should be
made, and notes of them recorded, on their habits, and on
their external structure and its relation to the habits of the
bird. The interesting adaptation of structure to special
use is particularly well shown in the varying character of
the bill and feet of birds. The various feeding habits and
uses of the feet of different birds are readily observed. The
characters of bills and feet are much used in the classifica-
tion of birds, so that any knowledge of them gained primarily
in the study of adaptations will have a secondary use in
classification work.

228 THE ANIMALS AND MAN

Note the foot of the robin, bluebird, catbird, wren, warb-
ler, and other passerine or perching birds. It has three
unwebbed toes in front and a long hind toe perfectly oppos-
able to the middle front one. This is the perching foot.

Fic. 120. Ostriches on ostrich-farm at Pasadena, California. (Photo-
graph from life.)
Note the so-called zygodactyl foot of the woodpecker, with
two toes projecting in front and partly yoked together, and
two similarly yoked projecting behind. Note the webbea
swimming-foot of the aquatic birds; note the different de-
grees of webbing, from the totipalmate, where all four toes
are completely webbed, palmate, where the three front toes
only are bound together but the web runs out to the claws,

THE VERTEBRATES: BIRDS 229

to the semi-palmate, where the web runs out only about
half-way. Note the lobate foot of the coots and phalaropes.
Note the long, slender, wading legs of the sandpipers, snipe,
and other shore-birds; the short, heavy, strong leg of the
divers; the small, weak leg of the swifts and humming-

Fic. 121. Western robin, Merula migratoria propinqua. (Photograph
from life by Eliz. and Jos. Grinnell.)

birds, almost always on the wing; the stout, heavily nailed
foot of the scratchers, as the hens, grouse, and turkeys; and
the strong, grasping talons, with their sharp, long, curving
nails, of the hawks and owls, and other birds of prey. In
all these cases the fitness of the structure of the foot to the
special habits of the bird is apparent.

Similarly the shape and structural character of the bill

should be noted, as related to its use, this being chiefly

230 THE ANIMALS AND MAN

concerned of course with the feeding habits. Note the
strong, hooked, and dentate bill of the birds of prey; they
tear their prey. Note the long, slender, sensitive bill of the
sandpipers; they probe the wet sand for worms. Note the
short, weak bill and wide mouth of the night-hawk and
whippoorwill, and of the swifts and swallows; they catch
insects in this wide mouth while on the wing. Note the flat,
lamellate bill of the ducks; they scoop up mud and water

Fic. 122. Young ostriches just from egg, at ostrich-farm at Pasadena,
California. (Photograph from life.)

and strain their food from it. Note the firm, chisel-like bill
(fig. 123) of the woodpeckers; they bore into hard wood for
insects. Note the peculiarly crossed mandibles of the cross-
bills; they tear open pine cones for seeds. Note the long,
sharp, slender bill of the humming-birds; they get insects
from the bottom of flower-cups. Note the bill and foot of
any bird you examine, and see if you can recognize their
special adaptation to the habits of the bird.

The most casual observation of birds reveals differences
in the flight of different kinds so characteristic and dis-

THESVERTEBRATES: - BIRDS 231

tinctive as to give much aid in determining the identity of
birds in nature. Note the flight of the woodpeckers; it
identifies them unmistakably in the air. Note the rapid

Fic. 123. The yellow-hammer, Colaptes auratus. (Photograph from
life by W. E. Carlin; permission of G. O. Shields.)

beating of the wings of quail and grouse; also of wild ducks;
the slow, heavy, flapping of the larger hawks and owls, and
of the crows; and the splendid soaring of the turkey-buzzard
and of the gulls. This soaring has been the subject of much
observation and study, but is still imperfectly understood.

232 THE ANIMALS AND MAN

The soaring bird evidently takes advantage of horizontal air-
currents, and some observers maintain that upward currents
also must be present. The speed of flight of some birds is
enormous, the passenger-pigeon having been estimated to

Fic. 124. Sickle-billed thrasher, Harporhynchus redivivus. (Photograph
from life by Eliz. and Jos. Grinnell.)

attain a speed of one hundred miles an hour. ‘The long
distances covered in a single continuous flight by certain
birds are also extraordinary, as is also the total distance
covered by some of the migrants. The differences in the
structural character of the wings should be noted in connec-

THE VERTEBRATES: BIRDS 233

tion with the observation of the differences in flight habit.
The tongues and tails of birds are two other structures

the modifications and special uses of which may be readily

observed and studied. Note the structure and special use

Fic. 125. Gulls soaring. (Photograph by O. H. von Bargen, on San
Francisco Bay; permission of Camera Craft.)

of the tongue and tail (fig. 123) of the woodpeckers; note
the tongue of the humming-bird; the tail of the grackles.
Feeding habits, economics, and protection of birds.—
The feeding habits of birds are not only interesting, but
their determination decides the economic relation of birds
to man, that is, whether a particular bird species is harmful

234 THE ANIMALS AND MAN

or beneficial to man. Casual observation shows that birds
eat worms, grains, seeds, fruits, insects. A single species
often is both fruit-eating and insect-eating. Do fruits or do
insects compose the chief food-supply of the species? To
determine this more than casual observation is necessary.

as a Leet

Fic. 126. Horned larks, Osocorzs alpesirvis, and snowflakes, Plecirophenax
nivalis. (Photograph by H.W. Menke; permission of The Macmillan
Co.)

The birds must be watched when feeding at different sea-
sons. The most effective way of determining the kind of
food which the bird takes is to examine the stomach of many
individuals taken at various times and localities. Much
work of this kind has been done, especially by investigators
connected with the Division of Biological Survey of the
United States Department of Agriculture, and pamphlets
giving the results of these investigations can be had from

THE VERTEBRATES: BIRDS 235
the Division. It has been distinctly shown that a great
majority of birds are chiefly beneficial to man by eating
noxious insects and the seeds of weeds. Most birds com-
monly reputed to be harmful, and for that reason shot by
farmers and fruit-growers, have been proved to do much
more good than harm. Some few birds have been proved
to be, on the whole, harmful. An investigation of the food
habits of the crow, a bird of ill-repute *mong farmers, based
on an examination of gog stomachs, ssc ws that about 29 per
cent of the food for the year consists of grain, of which corn
constitutes something more than 21 per cent, the greatest
quantity being eaten in the three winter months. All of
this must be either waste grain picked up in fields and roads,
or corn stolen from cribs and shocks. May, the month of
sprouting corn, shows a slight increase over the other spring
and summer months. On the other hand, the loss of grain
is offset by the destruction of insects. ‘These constitute
more than 23 per cent of the crow’s yearly diet, and the
larger part of them are noxious. The remainder of the
crow’s food consists of wild fruit, seeds, and various animal
substances which may on the whole be considered neutral.

The slaughter of birds for millinery purposes has become
so fearful and apparent in recent years that a strong move-
ment for their protection has been inaugurated. Rapacious
ege-collecting, legislation against birds wrongly thought to
be harmful to grains and fruit, and the selfish wholesale kill-
ing of birds by professional and amateur hunters, help in
the work of destruction. Apart from the brutality of such
slaughter, and the extermination of the most beautiful and
enjoyable of our animal companions, this destruction works
strongly against our material interests. Birds are the natural
enemies of insect pests, and the destroying of the birds
means the rapid increase and spread, and the enhanced
destructive power of the pests. It is asserted by investi-
gators that during the past fifteen years the number of our

236 THE ANIMALS AND MAN

common song-birds has been reduced to one-fourth. At
the present rate, says one author, extermination of many
species will occur during the lives of most of us. Already
the passenger-pigeon and Carolina paroquet, only a few
years ago abundant, are practically exterminated. Protect
the birds!

CHAPTER XVIII

THE VERTEBRATES (continued): MAMMALS

The mammals constitute the highest group of animals,
including man, the monkeys and apes, the quadrupeds, the
bird-like bats and fish-like seals and whales; in all about
2500 species. ‘They are found everywhere except on a few
small South Sea islands. Only a few species, however, have
a world-wide distribution. The name Mammalia is de-
rived from the mammary or milk glands with which the
females are provided and by the secretion of which the young
of this class, born free in all but a few of the lowest forms,
are nourished for some time after birth. In size mammals
range from the tiny pigmy-shrew and harvest mouse, which
can climb a stem of wheat, to the great sulphur-bottom
whale of the Pacific Ocean, which attains a length of a hun-
dred feet and a weight of many tons. Mammals differ from
fishes and batrachians and agree with reptiles and birds in
never having external gills; they differ from reptiles and
agree with birds in being warm-blooded and in having a
heart with two distinct ventricles and a complete double cir-
culation; finally, they differ from both reptiles and birds in
having the skin more or less clothed with hair, the lungs freely
suspended in a thoracic cavity separated from the abdominal
by a muscular partition, the diaphragm, and in the possession
by the females of mammary glands. In economic uses to
man mammals are the most important of all animals. They
furnish the greater portion of the animal food of many human
races, likewise a large amount of their clothing. Horses,

237

Fic. 127. A group of Rocky Mountain Sheep, Ovis canadensis. (Photo-
graph of specimens mounted by L. L. Dyche.)

THE VERTEBRATES: MAMMALS 239

asses, oxen, camels, reindeer, elephants, and llamas are
beasts of burden and draught; swine, sheep, cattle, and
goats furnish flesh, and the two latter milk for food; the
wool of sheep, the furs of the carnivores, and the leather of
cattle, horses, and others are used for clothing, while the
bones and horns of various mammals serve various purposes.

Body form and structure.—The mammalian body varies
creatly. Its variety of form and general organization is
explained by the facts that, although most of the species live
on the surface of the earth, some are burrowers in the ground,
some flyers in the air, and some swimmers in the water.
Mammals never have more than two pairs of limbs; in most
cases both pairs are well developed and adapted for terres-
trial progression. In the aerial bats the fore limbs are
modified into organs of flight; among the aquatic seals, sea-
lions, walruses, and whales both sets are modified to be
swimming flippersor paddles. In many of these aquatic forms
the hind limbsare greatly reduced or even completely wanting.

Most mammals are externally clothed with hair, which
is a peculiarly modified epidermal process. Each hair,
usually cylindrical, is composed of two parts, a central pith
containing air, and an outer more solid cortex; each hair
rises from a short papilla sunk at the bottom of a follicle
lying in the true skin. In some mammals the hairs assume
the form of spines or “quills,” as in the porcupine. The
hairy coat is virtually wanting in whales and is very sparse
in certain other forms, the elephant, for example, which has
its skin greatly thickened. ‘The claws of beasts of prey, the
hooves of the hoofed mammals, and the outer horny sheaths
of the hollow-horned ruminants are all epidermal structures.

The bones of mammals are firmer than those of other
vertebrates, containing a larger porportion of salts of lime.
Among the different forms the spinal column varies largely
in the number of vertebre, this variation being chiefly due
to differences in length of tail. Apart from the caudal ver-

240 THE ANIMALS AND MAN

tebre their usual number is about thirty. The mammalian
skull is very firm and rigid, all the bones composing it, ex-
cepting the lower jaw, the tiny auditory ossicles, and the
slender bones of the hyoid arch, being immovably articu-
lated together. The correspondence between the bones of
the two sets of limbs is very apparent. The number of
digits varies in different mammals, and also in the fore and
hind limbs of a single species. Among the Ungulates the
reduction in the number of digits is especially noticeable;
the forefoot of a pig has four digits, that of the cow two, and
that of the horse one. The two short “splint” bones in the
horse are remnants of lost digits. The teeth are important
structures in mammals, being used not only for tearing and
masticating food, but as weapons of offence and defence.
A tooth consists of an inner soft pulp (in old teeth the pulp
may become converted into bone-like material) surrounded
by hard white dentine or ivory, which is covered by a thin
layer of enamel, the hardest tissue known in the animal
body. A hard cement sometimes covers over as a thin layer
the outer surface of the root, and may also cover the enamel
of the crown. ‘The teeth in most forms are of three groups:
(a) the incisors, with sharp cutting edges and simple roots,
situated in the centre of the jaw; (b) the canines, often con-
ical and sharp-pointed, next to the incisors; (c) next the
molars, broad and flat-topped for grinding, and divided
into premolars and true molars. ‘There is great variety in
the character and arrangement of these structures In mam-
mals, their variations being much used in classification.
The number and arrangement of the teeth is expressed by
a dental formula, as, for example, in the case of man:
ae eee | 2 2 Bye
4 =. & See. 5m
Zhe 2 5 Eh a BE 2) ee iD hcema el
The mouth is bounded by fleshy lips. On the floor of
the mouth is the tongue, which bears the taste-buds or papil-

2s

THE VERTEBRATES: MAMMALS 241

le, the organs of taste. The cesophagus is always a simple
straight tube, but the stomach varies greatly, being usually
simple, but sometimes, as in the ruminants and whales,
divided into several distinct chambers. The intestine in
vegetarian mammals is very long, being in a cow twenty
times the length of the body. In the carnivores it is com-
paratively short—in a tiger, for example, but two or three
times the length of the body.

The blood of mammals is warm, having a temperature of
from 38°C. toe? C)(95"-F: to tog” F)2; Ibis red imcolor;
owing to the reddish-yellow, circular, non-nucleated blood-
corpuscles. The circulation is double, the heart being com-
posed of two distinct auricles and two distinct ventricles.
Air is taken in through the nostrils or mouth and carried
through the windpipe (trachea) and a pair of bronchi to the
lungs, where it gives up its oxygen to the blood, from which
it takes up carbon dioxide in turn. At the upper end of
the trachea is the larynx or voice-box, consisting of several
cartilages attaching by one end to the vocal cords and by the
other to muscles. By the alteration of the relative position
of these cartilages the cords can be tightened or relaxed,
brought together or moved apart, as required to modulate
the tone and volume of the voice.

The kidneys of mammals are more compact and definite
in form than those of other vertebrates. In all mammals
except the Monotremes they discharge their product through
the paired ureters into a bladder, whence the urine passes
from the body by a single median urethra. Mammary
glands, secreting the milk by which the young are nourished
during the first period of their existence after birth, are
present in both sexes in all mammals, though usually func-
tional in the female only.

The nervous system and the organs of special sense reach
their highest development in the mammals. In them the
brain is distinguished by its large size, and by the special

242 THE ANIMALS AND MAN

preponderance of the forebrain or cerebral hemispheres
over the mid- and hind-brain. Man’s brain is many times
larger than that of all other known mammals of equal bulk
of body, and nearly three times as large as that of the largest-
brained ape. In man and the higher mammals the surface
of the forebrain is thrown into many convolutions; among
the lowest the surface is smooth. Of the organs of special
sense, those of touch consist of free nerve-endings or minute
tactile corpuscles in the skin. The tactile sense is especially
acute in certain regions, as the lips and end of the snout in
animals like hogs, the fingers in man, and the under surface
of the tail in certain monkeys. All the other sense-organs
are situated on the head. ‘The organs of taste are certain
so-called taste-buds located in the mucous membrane cov-
ering certain papillae on the surface of the tongue. The
organ of smell, absent only in certain whales, consists of a
ramification of the olfactory nerves over a moist mucous
membrane in the nose. The ears of mammals are more
highly developed than those of other vertebrates both in
respect to the greater complexity of the inner part and the
size of the outer part. A large outer ear for collecting the
sound-waves is present in all but a few mammals. A tym-
panic membrane separates it from the middle ear in which
is a chain of three tiny bones leading from the tympanum
to the inner ear, composed of the three semi-circular canals
and the spiral cochlea. The eyes have the structure char-
acteristic of the vertebrate eye, consisting of a movable eye-
ball composed of parts through which the rays of light are
admitted, regulated, and concentrated upon the sensitive
expansion, retina, of the optic nerve lining the posterior
part of the ball. The eye is protected by two movable lids.
In almost all mammals below the Primates there is a
third lid, the nictitating membrane. In some burrowing
rodents and others the eye is quite vestigial and even con-
cealed beneath the skin, |

THE VERTEBRATES: MAMMALS 243

Development and life-history.—All mammals except the
Monotremes give birth to free young. The two genera of
Monotremes produce their young from eggs hatched out-
side the body; Tachyglossus lays one egg which it carries in
an external pouch, while Ornithorhynchus deposits two eggs
in its burrow. The embryo of other mammals develops in
the lower portion of the egg-tube, to the walls of which it is
intimately connected by a membrane called the placenta.
(In the kangaroos and opossums, Marsupialia, there is no
placenta.) Through this placenta blood-vessels extend from
the body of the mother to the embryo, the young developing
mammal thus deriving its nourishment directly from the
parent.

The duration of gestation (embryonic or prenatal develop-
ment in the mother’s body) varies from three weeks with the
mouse, eight weeks with the cat, nine months with the stag,
to twenty months with the elephant. Like the birds, the
young of some mammals, the carnivores for example, are
helpless at birth, while those of others, as the hoofed mam-
mals, are very soon able torun about. But all are nourished
for a longer or shorter time by the milk secreted by the
mammary gland of the mother.

Habits, instinct, and reason.—Despite the wonderful ex-
amples of instinct and intelligence shown by many insects
and by the other vertebrates, especially the birds, it is among
mammals that we find the highest development of these
qualities and of reason. In the wary and patient hunting
for prey by the carnivora, in the gregarious and altruistic
habits of the herding hoofed mammals, in the highly devel-
oped and affectionate care of the young shown by most mam-
mals, and in the loyal friendship and self-sacrifice of dogs
and horses in their relations to man, we see the culmination
among animals of the development of the functions of the
nervous system. In the characteristics of intelligence and
reason man of course stands immensely superior to all other

244 THE ANIMALS AND MAN

animals, but both intelligence and reason are too often shown
by many of the other mammals not to make us aware that
man’s mental powers differ only in degree, not in kind, from
those of other animals.

Pure instinct is hereditary, and purely instinctive actions
are common to all the individuals of a species. Those
actions which the individual could not learn by teaching,
imitation, or experience are instinctive. The accurate peck-
ing at food by chicks just hatched from an incubator is
purely instinctive. Purely instinctive also is the laying of
eggs by a butterfly on a certain species of plant which may
have to be sought for over wide acres, so that the caterpillars
when hatched shall find themselves on their own special food-
plant. Yet the butterfly never ate of this plant and will
never see its young. Such elaborate instincts as these have
been developed from the simplest manifestations of sensation
and nervous function, just as the complex structures of the
body have been developed from simple structures.

The feeding and domestic habits and the whole general
behavior of animals are extremely interesting subjects of
observation and study. And such observation intelligently
pursued will be of much value. The point to be kept ever
in mind is that all animal habits are connected with certain
conditions of life; that in every case there is an answer to the
question “why.” This answer may not be found; in many
cases it is extremely difficult to get at, but often it is simple
and obvious and can be found by the veriest beginner.

Classification.—The mammals of North America repre-
sent eight orders. Three additional mammalian orders,
namely, the Monotremata, including the extraordinary duck-
bills (Ornithorhynchus) and a species of Tachyglossus in
Australia and Tasmania; the Edentata, including the sloths,
armadillos, and ant-eaters found in tropical regions; and
the Sirenia, including the marine manatees and dugongs, are
not represented (except by a single manatee) in North

THE VERTEBRATES: MAMMALS 245

America. In the following paragraphs some of the more
familiar mammals representing each of the eight orders
represented in North America are referred to.

The opossums (Marsupialia).—The opossum (Didelphys
virginiana) is the only North American representative of
the order Marsupialia, the other members of which are
limited exclusively to Australia and certain neighboring
islands. The kangaroos are the best known of the foreign
marsupials. After birth the young are transferred to an
external pouch, the marsupium, on the ventral surface of
the mother, in which they are carried about and fed. The
opossum lives in trees, is about the size of a common cat,
and has a dirty-yellowish woolly fur. Its tailis long and scaly,
like a rat’s. Its food consists chiefly of insects, although
small reptiles, birds, and bird’s eggs are eaten. When ready
to bear young the opossum makes a nest of dried grass in the
hollow of a tree, and produces about thirteen very small (half
an inch long) helpless creatures. These are then placed by
the mother in her pouch. Here they remain until two
months or more after birth. Probably all the North Ameri-
can opossums found from New York to California and espe-
cially common in the Southern States belong to a single
species, but there is much variety among the individu-
als.

The rodents or gnawers (Glires).—The rabbits, porcu-
pines, gophers, chipmunks, beavers, squirrels, and rats and
mice compose the largest order among the mammals. ‘They
are called the rodents or gnawers (Glires) because of their
well-known gnawing powers and proclivities. ‘The special
arrangement and character of the teeth are characteristic of
this order. There are no canines, a toothless space being
left between the incisors and molars on each side. ‘There are
only two incisor teeth in each jaw (rarely four in the upper
jaw), and these teeth grow continuously and are kept sharp
and of uniform length by the gnawing on hard substances

246 THE ANIMALS AND MAN

and the constant rubbing on each other. ‘The food of rodents
is chiefly vegetable.

Of the hares and rabbits the cottontail (Lepus nuttallz)
and the common jack-rabbit (L. campestris) are the best
known. ‘The cottontail is found all over the United States,
but shows some variation in the different regions. ‘There are
several species of jack-rabbit, all limited to the plains and
mountain regions west of the Mississippi River. The food of
rabbits is strictly vegetable, consisting of succulent roots,
branches, or leaves. . Rabbits are very prolific and yearly
rear from three to six broods of from three to six young each.
There are two North American species of porcupines, an
Eastern one, Erethizon dorsatus, and a Western one, E.
epixanthus. The quills in both these species are short, being
only a few inches in length, and are barbed. In some
foreign porcupines they are a foot long. They are loosely
attached in the skin and may be readily pulled out, but they
cannot be shot out by the porcupine, as is popularly told.
The little guinea-pigs (Cavia), kept as pets, are South
American animals related to the porcupines.

The pocket gophers, of which there are several species
mostly inhabiting the central plains, are rodents found
only in North America. They all live underground,
making extensive galleries and feeding chiefly on bulbous
roots. The mice and rats constitute a large family of
which the house-mice and rats, the various field-mice, the
wood-rat (Neotoma pennsylvanica) and the muskrat (/7ber
zibethicus) are familiar representatives. ‘The common brown
rat (Mus decumanus) was introduced into this country
from Europe about 1775, and has now nearly wholly sup-
planted the black rat (MW. rattus), also a European species,
introduced about 1544. The beaver (Castor canadensis)
is the largest rodent. It seems to be doomed to extermin-
ation through the relentless hunting of it for its fur. The
woodchuck or ground-hog (Arctomys monax) is another

THE VERTEBRATES: MAMMALS 247

familiar rodent larger than most members of the order.
The chipmunks (fig. 128) and ground-squirrels are com-
monly known rodents found all over the country. They are
the terrestrial members of the squirrel family, the best known

Fic. 128. Chipmunk. (Permission of Camera Craft.)

arboreal members of which are the red squirrel (Sczurus
hudsonicus), the fox-squirrel (S. ludovicianus), and the gray
or black squirrel (S. carolinensis). The little flying squirrel
(Sciuro pterus volans) is abundant in the Eastern States.
The shrews and moles (Insectivora).—The shrews

248 THE ANIMALS AND MAN

and moles are all small carnivorous animals, which, be-
cause of their size, confine their attacks chiefly to insects.
The shrews are small and mouse-like; certain kinds of
them lead a semi-aquatic life. There are nearly a score
of species in North America. Of the moles, of which there

Fic. 129. The hoary bat, Lasiurus cinereus. (Photograph from life,
by J. O. Snyder.)

are but few species, the common mole (Scalops aquaticus)
is well known, while the star-nosed mole (Condylura cristata)
is recognizable by the peculiar rosette of about twenty carti-
laginous rays at the tip of its snout. Moles live underground
and have the fore feet wide and shovel-like for digging.
The European hedgehogs are members of this order.

The bats (Chiroptera).—The bats (fig. 129), order Chi-

THE VERTEBRATES: MAMMALS 249

roptera, differ from all other mammals in having the fore
limbs modified for flight by the elongation of the forearms
and especially of four of the fingers, all of which are con-
nected by a thin leathery membrane which includes also
the hind feet and usually the tail. Bats are chiefly noc-
turnal, hanging head downward by their hind claws in
caves, hollow trees, or dark rooms through the day. ‘They
feed chiefly on insects, although some foreign kinds live
on fruits. There are a dozen or more species of bats in
North America, the most abundant kinds in the Eastern
States being the little brown bat (Myotis subulatus), about
three inches long with small fox-like face, high slender
ears, and a uniform dull olive-brown color; and the red
bat (Lasiurus borealis), nearly four inches long, covered
with long, silky, reddish-brown fur, mostly white at tips
of the hairs.

The dolphins, porpoises, and whales (Cete).—The
dolphins, porpoises, and whales (Cete) compose an order
of more or less fish-like aquatic mammals, among which
are the largest of living animals. In all the posterior limbs
are wanting, and the fore limbs are developed as broad
flattened paddles without distinct fingers or nails. ‘The
tail ends in a broad horizontal fin or paddle. The Cete
are all predaceous, fish, pelagic crustaceans, and especially
squids and cuttlefishes forming their principal food. Most
of the species are gregarious, the individuals swimming
together in ‘‘schools.”” The dolphins and porpoises com-
pose a family (Delphinidz) including the smaller and many
of the most active and voracious of the Cete. The whales
compose two families, the sperm-whales (Physeteride) with
numerous teeth (in the lower jaw only) and the whalebone
whales (Balenidz) without teeth, their place being taken
in the upper jaw by an array of parallel plates with fringed
edges known as “whalebone.” The great sperm-whales
or cachalots (Physeter macrocephalus) found in southern

250 THE ANIMALS AND MAN

oceans reach a length (males) of eighty feet, of which the
head forms nearly one-third. Of the whalebone whales,
the sulphur-bottom (Balenoptera sulfurea) of the Pacific
Ocean, reaching a length of nearly one hundred feet, is
the largest, and hence the largest of all living animals.
The common large whale of the Eastern coast and North
Atlantic is the right whale (Balena glacialis); a near relative
is the great bowhead (B. mysticetus) of the Arctic seas, the
most valuable of all whales to man. Whales are hunted for
their whalebone and the oil yielded by their fat or blubber.
The story of whale-fishing is an extremely interesting one,
the great size and strength of the ‘““game”’ making the ‘‘fish-
ing” a hazardous business.

The hoofed mammals (Ungulata).—The order Ungu-
lata includes some of the most familiar mammal forms.
Most of the domestic animals, as the horse, cow, hog, sheep,
and goat, belong to this order, as well as the familiar deer,
antelope, and buffalo of our own land and the elephant,
rhinoceros, hippopotamus, giraffe, camel, zebra, etc., familiar
in zoological gardens and menageries. ‘The order is a
large one, its members being characterized by the presence
of from one to four hooves, which are the enlarged and
thickened claws of the toes. ‘The Ungulates are all herbiv-
orous, and have their molar teeth fitted for grinding, the
canines being absent or small. The order is divided into
the Perissodactyla or odd-toed forms, like the horse, zebra,
tapir, and rhinocerus, and the Artiodactyla or even-toed
forms, like the oxen, sheep, deer, camels, pigs, and hippo-
potami. The Artiodactyls comprise two groups, the Ru-
minants and Non-ruminants. All of the native Ungulata
of our Northern States belong to the Ruminants, so called
because of their habit of chewing a cud. A ruminant
first presses its food into a ball, swallows it into a particular
one of the divisions of its four-chambered stomach, and
later regurgitates it into the mouth, thoroughly masticates

THE VERTEBRATES: MAMMALS 251

it, and swallows it again, but into another stomach-chamber.

From this it passes through the other two into the intestine.
The deer family (Cervide) comprises the familiar Vir-

ginia or red deer (Odocoileus americanus) of the Eastern

ee

Fic. 130. Male elk, or wapiti, Cervus canadensis. (Photograph of a
specimen mounted by L. L. Dyche.)

and Central States and the white-tailed, black-tailed, and
mule deers of the West, the great-antlered elk or wapiti
(Cervus canadensis) (fig. 130), the great moose (Alce amert-
cana), largest of the deer family, and the American reindeer
or caribou (Rangifer caribou). All species of the Cervide
have solid horns, more or less branched, which are shed

252 THE ANIMALS AND MAN

annually. Only the males (except with the reindeer) have
horns. The antelope (Antilocapra americana) (fig. 131)
common on the Western plains also sheds its horns, which,

(Photograph of

Antilocapra americana.

Antelope, male, female, and young,

Jaden 9 Bal

however, are not solid and do not break off at the base as
in the deer, but are composed of an inner bony core and
an outer horny sheath, the outer sheath only being shed.
The family Bovide includes the once abundant buffalo or

specimens mounted by L. L. Dyche.)

THE VERTEBRATES: MAMMALS 253

bison (Bison bison) (frontispiece), the big-horn or Rocky
Mountain sheep (Ovis canadensis) (fig. 128), and the strange
pure-white Rocky Mountain goat (Oreamnos montanus).
The buffalo was once abundant on the Western plains,

Fic. 132. <A buffalo, Bison bison, killed for its skin and tongue on the
plains of Western Kansas, forty years ago. (Photograph by J. Lee
Knight.)

travelling in enormous herds. But so relentlessly has this
fine animal been hunted for its skin and flesh that it is now
practically exterminated (fig. 132). A small herd is still
to be found in Yellowstone Park, and a few individuals
live in parks and zoological gardens. In all of the Bovide
the horns are simple, hollow, and permanent, each enclosing
a bony core.

254 THE ANIMALS AND MAN

The carnivorous mammals (Fere).—The order Fere
includes all those mammals usually called the carnivora,
such as the lions, tigers, cats, wolves, dogs, bears, panthers,
foxes, weasels, seals, etc. All of them feed chiefly on animal
substance and are predatory, pursuing and killing their
prey. ‘They are mostly fur-covered and many are hunted
for their skin. They have never less than four toes, which
are provided with strong claws that are frequently more or
less retractile. The canine teeth are usually large, curved,
and pointed.

While most of the Ferz live on land, some are strictly
aquatic. The true seals, fur-seals, sea-lions, and walruses
comprise the aquatic forms, all being inhabitants of the
ocean. ‘The true seals, of which the common harbor seal
(Phoca vitulina) is our most familiar representative, have
the limbs so thoroughly modified for swimming that they
are useless on land. ‘The fur-seals, sea-lions, and walruses
use the hind legs to scramble about on the rocks or beaches
of the shore. The fur-seals (fig. 133) live gregariously
in great rookeries on the Pribilof or Fur Seal Islands, and
the Commander Islands in Bering Sea.

The bears are represented in North America by nine
species, of which the best known are the wide-spread
brown, or black bear (Ursus americanus) and the huge
grizzly bear (U. horribilis). ‘The great polar bear (Thal-
arctos maritumus) lives in arctic regions. The otters,
skunks, badgers, wolverines, sables, minks, and weasels
compose the family Mustelide, which includes most
of the valuable fur-bearing animals. Some of the mem-
bers of this family lead a semi-aquatic or even strictly
aquatic life and have webbed feet. The wolves, foxes,
and dogs belong to the family Canide. ‘The coyote (Canis
latrans), the gray wolf (C. mubilus), and the red fox (Vulpes
pennsylvanicus) are the most familiar representatives of
this family, in addition to the dog (C. familiaris), which is

Fic. 133. The Lukanin rookery of fur seals, Callorhinus atascanus, on St. Paul Island, Pribilof group, Bering Sea.
(Photograph from life, by the Fur Seal Commission.)

256 THE ANIMALS AND MAN

closely allied to the wolf. ‘Most carnivorous of the
carnivora, formed to devour, with every offensive weapon
specialized to its utmost, the Felidz, whether large or small,
are, relatively to their size, the fiercest, strongest, and most
terrible of beasts.”” The Felidz or cat family includes the
lions, tigers, hyenas, leopards, jaguars, panthers, wildcats,
and lynxes. In this country the most formidable of the
Felide is the American panther or puma (Felis concolor).
It reaches a length from nose to root of tail of over four feet.
Its tail is long. The wildcat (Lynx rufus) is much smaller
and has a short tail.

The man-like mammals (Primates).—The primates,
the highest order of mammals, include the lemurs, monkeys,
baboons, apes, and men. Man (Homo sapiens) is the only
native representative of this order in our country. All the
races and kinds of men known, although really showing
much variety in appearance and body structure, are com-
monly \included im one” species.) \Uhe ehier “structural
characteristics which distinguish man from the other members
of this order are the great development of his brain and the
non-opposability of his great toe. Despite the similarity
in general structure between him and the anthropoid apes
of the Old World, in particular the chimpanzee and orang-
outang, the disparity in size of brain is enormous.

The lowest Primates are the lemurs, found in Madagas-
car, in which island they include about one-half of all the
mammalian species found there. The brain is much less
developed in the lemurs than in any of the other mon-
keys. ‘The monkeys and apes may be divided into two
groups, the lower, platyrrhine monkeys, found in the New
World, and the higher, catarrhine forms, limited to the Old
World. The platyrrhine monkeys have wide noses in
which the nostrils are separated by a broad septum and
with the openings directed laterally. These monkeys are
mostly smaller and weaker than the Old World forms and

THE VERTEBRATES: MAMMALS 257

are always long-tailed, the tail being frequently prehen-
sile. They include the howling, squirrel, spider, and ca-
puchin monkeys common in the forests of tropical South
America. The catarrhine monkeys have the nose-septum
narrow and the openings of the nostrils directed forwards,

Fic. 134, “Bob,” a monkey of the genus Cercopithecus. (Photograph
from life by D. S. Jordan.)

and the tail is wanting in numerous members of the group.
They include the baboons, gorillas, orang-outangs, and
chimpanzees. These apes have a dentition approaching
that of man, and in all ways are the animals which most
nearly resemble man in physical character,

CHAPTER (XTX

DOMESTICATED ANIMALS

The animals that we call domestic while sometimes of
kinds and appearance very different from any wild animals
that we know are yet certainly all descended from kinds that
are or were originally wild. ‘There are wild pigs, wild goats,
wild doves, wild ducks, wild silkworms! ‘There are no
wild dogs nor probably any longer any true wild horses but
it is easy for us to see from what wild animals our tame dogs
and horses have been derived.

It is certain from the records of history, of ancient pic-
tures and carvings and still more ancient bones and relics,
that man has had domesticated animals for the last ten
thousand years. How long before that he made a practise
of taming and using and perhaps breeding his animal com-
panions of pre-historic times we may never know. In the
caves where are found the bones and rude implements of
early man, that primitive man of the Glacial epoch, there are
also found the bones of various animals, but these seem to be
the remains of kinds that were either his victims or his con-
querors in the raw struggle for existence of those ancient
times. However, when the pre-historic Egyptians emerged
from the Stone Age into the earliest light of history they
appear with cattle, sheep, donkeys and dogs already fully
domesticated.

The domestication of animals is the result of several
different factors. First, there may be the simple capture
and taming and using of individuals of a wild species.
Then comes the rearing in captivity of young of this species,

258

DOMESTICATED ANIMALS 250

and the easier taming of these home-reared individuals be-
cause of their earlier acquaintanceship with man.

But in this rearing in captivity a new element enters almost
at once. That is the choosing or selection of certain of
these young to be allowed to grow up, and again the choos-
ing among these when grown up of those to be the parents

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Fic. 135. Assyrian hunters with great dogs. From an Assyrian wal]
relief of 668 B.C., now in the British Museum. (After Keller.)

of more young. This selection may be almost unconsciously
done, or it may be made intentionally and carefully, so as to
preserve the most desirable individuals and have them give
birth to others like themselves.

Then there comes the crossing of special individuals or the
hybridizing with other races in the hope of adding or com-
bining in the offspring the desirable qualities of both kinds
of parents. It is this careful selecting and crossing that are

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Fic. 136. Various races of pigeons, all probably descended from the
European rock dove, Columba livia, shown in lower right hand corner.

(After Haeckeb.) 260

DOMESTICATED ANIMALS 261

usually meant when animal breeding is spoken of. And
our modern hosts of kinds or races of domesticated animals,
the scores of sorts of dogs and cats and cows and pigeons
and ducks have all been produced by “breeding.” The
acts of choosing and hybridizing and choosing again and
rearing from these chosen offspring and again from
each following generation until a form is arrived at very
different in appearance or habit from the original ancestor
are called also artificial selection. It was largely on a basis
of his observations of the methods and results of artificial
selection that Charles Darwin founded his great theory
of natural selection, which, is, simply, that Nature uncon-
sciously chooses or selects among animal and plant indi-
viduals and kinds through the survival and producing of
young by those types born with traits advantageous in the
struggle for existence, this struggle being inevitable on
account of the geometrical ration by which animals multiply.

The art of the animal breeder has reached in these later
days, the days since Darwin particularly, a very high stage
of development. It is becoming a science, because the
breeders are studying the laws of variation and _ heredity
and making their hybridizations on a basis of the scientific
knowledge of these laws.

There is in our country a large association of animal and
plant breeders known as the American Breeders’ Associa-
tion, the reports of whose meetings with the discussions and
prefaced papers presented at them are books of true science.
Such men as Luther Burbank have given the science of
breeding a popular fame and familiarity that was not known
a half century ago.

An important thing to note in connection with animal
breeding and artificial selection is that the selecting and
modifying is all made to change the animals along lines
wholly determined by man; lines that make the animals
more useful or pleasing or curious to us but not better fitted

262 THE ANIMALS AND MAN

to survive in Nature. In fact most of these artificially in-
duced changes tend to unfit the animal for success in life
unaided by man; they are mostly degenerative changes.
The loss of flight, the shortening of legs, the over-develop-
ment of fat, the production of crests and plumes and ruffs,
the loss of horns, the sluggishness and helplessness that
characterize the domesticated animals of different kinds, are
all characters and conditions of degeneration.

Fic. 137. Thibet wolf, Canis niger, one of the wild ancestors of dogs.
(After Sclater.)

As an outcome of this modern great interest and activity
in the methods and results of producing new races and types
of domesticated animals, the history of the origin of many
of the more wide-spread and useful of these animal races
has been unraveled, and the following paragraphs give in
briefest possible form some interesting facts about the origin
of our more familiar animal companions.

There seems to be no doubt that the dog is the oldest
domesticated animal as he is also the closest and the most
universal. From among the crudest of living human races
to the most civilized and cultivated, the dog is everywhere al-
ways man’s companion, serving him as faithful helper in

DOMESTICATED ANIMALS 263

the chase, in caring for his flocks and home, and as com-
panion of his table and fireside. The Bushmen of Australia,
the Esquimaux of the Arctic, the Indians of the prairie and
pampas, the cannibals of the scattered Pacific Islands as
well as the Caucasians of the world’s great capitals have
their dog companions. And as is inevitable under such
many and different conditions and civilization stages of hu-
man existence the kinds of dogs are many and very different.
How many dog races and types there now are I do not know;
hundreds, at least. There are many long books filled with
the descriptions and illustrations of these manifold varieties,
from the tiny, toy dogs of Paris, that a lady can carry in her
muff, to the great Danes and St. Bernards that stand three
feet high and weigh one hundred and fifty pounds.

The origin of all these dog races is not to be found in any
one wild species of doglike animal but in several. These
wild ancestors of the dogs are certain wolves and jackals of
various lands. Dogs are descended from at least seven
such wild species, namely the jackal (Canis aureus) of west-
ern Asia, the landga (Canis pallipes) of India, the jackal
wolf (Canis anthus) of northeast Africa, the walgie (Canis
simensis) of Ethiopia, the black Thibet wolf (Canis niger)
of Thibet, and the coyote (Canis latrans) and dun-gray wolf
(Canis occidentalis) of North America.

The house cats, on the contrary, as various and as widely
distributed as they are, seem to be all descended from a
single wild species. This is the dun wild cat (Felis mant-
culata) of northeast Africa. All of the present races of
house cats trace their lineage back to Egypt. That the
Egyptians were much given to the possession and care of
cats the numerous cat mummies of their graves show.
Cats were a sacred animal for them under the special pro-
tection of the Goddess Bast, a goddess introduced into
Egypt by Semitic influence.

The horses of modern times can be traced back to two

264 THE ANIMALS AND MAN

wild ancestors, namely Equus przewalskii of northern Asia,
from which all the Oriental, Mongolian, Arabian, North
African and East European races have sprung; and
Equus caballus fossilis, or the diluvial horse, of Europe, from
which the German, Norman, English and West European
horses generally have arisen. In America fossil horses have

Fic. 138. Arion, a_ record-holding American trotting horse. (After
Plumb.)

been found back through a series of geologic ages as far as
the beginning of the Tertiary age forming a connected series
from the small Eohippus of the Lower Eocene period, about
the size of a fox, and with four toes and splint of the first digit
on the front feet and three toes and splint of the fifth di-
git on each hind foot; through Protorohippus and Oro-
hippus of the Middle Eocene, about 14 inches high, with
four toes on front feet and three toes on hind feet, and no
splints; through Mesohippus of the Oligocene, about the

DOMESTICATED ANIMALS 26

st

size of a coyote, and with three toes on all its feet; through
Protohippus and certain other kinds of the Middle Miocene,
about as large as Shetland ponies and with three toes on all
feet but with the side toes not touching the ground; to
Equus, which first appeared in the Pleistocene with only
one developed toe and splints of the 2d and 4th on each foot.

Fic. 139. Restoration of the tour-toed horse; based on a mounted skeleton,
16 inches high, in the American Museum of Natural History. (After
a water-color by C. R. Knight.)

The color of the prehistoric horse is not known but it was
probably dun with more or less well-defined stripes like a
zebra. The bones of human beings have been found associ-
ated with those of prehistoric horses in South America and
in Europe. Remains of horses are associated in Europe
with human relics of the Bronze Age.

Donkeys have been derived from two wild species, the
Nubian Desert donkey, Equus teniopus, and the onager,
Equus onager of eastern Asia. Tame donkeys are figured
in the earliest of Egyptian and Assyrian drawings and
carvings.

266 THE ANIMALS AND MAN

The races of domesticated hogs are also descended from
two wild races, the European wild boar, Sus scrofa, and
another species, Sus vittatus, from eastern Asia. From this
latter the swine of China and those of the Romans and indeed
most of the European races have descended. The lake
dwellers of Switzerland had domesticated hogs, and pig

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Romanes. )

remains have been found with prehistoric relics in Denmark.
China has had domesticated swine for thousands of years.

The many races of cattle all trace back to two sources,
the wild Banteng, Bos sondaicus, of Java and South Asia,
from which are derived the zebus, the old Egyptian long-
horns, and many of the races of Europe, such as the Span-
ish, Albanian, Sardinian, Polish and brown Alpine cattle;
and the primitive wild ox of Europe, Bos primigenius, from
which have descended most of the English, North German,

DOMESTICATED ANIMALS 267

and Holland races. This wild species persisted in Germany
until the r2th century and in Poland up to the 18th century.
A few persons in America have tried to create a hybrid race
by crossing domestic cattle with the buffalo but probably
no permanent result has been reached. It is a pity that our
American bison could not have left us more of a heritage
than a shameful memory.

Fic. 141. The Banteng, Bos sondaicus, or wild ox of Java and South
Asia. (After Keller.)

The domesticated races of sheep seem to have had three
original wild sources, the Ovis musimon of South Europe,
the Ovis arkal of Western Asia and the Ovis tragelaphus of
North Africa. Most of our present European and American
races come from the second named of these wild kinds.
The earliest certain remains of tame sheep appear in the
Stone Age. In the Bronze Age sheep domestication was
well developed. The oldest of Assyrian drawings picture
domesticated sheep, among which the still persisting fat-
tailed race appears. The Egyptians had domesticated
sheep in pre-Pharaonian times.

Our goats also are descended from three wild races,
namely Capra aegagrus of Western Asia, Capra falconert

Fic. 142. Heads of various British breeds of domestic cattle, showing
variations in shape of head and condition of horns: 1. Highland Scot;
2, Irish Kerry; 3, Aberdeen Angus; 4, Hereford; 5, Jersey; 6, Long-
horned Midland. (After Romanes.)

DOMESTICATED ANIMALS 269

and Capra jemlaica of the Himalayas. The earliest pre-
historic indications of tame goats come from the times of
the Lake-dwellers. In the Bronze Age they were common.

Other mammals that are represented by domestic races are
the camel, the elephant, the water buffalo, the rabbit, the
ferret, the reindeer, the lama and alpaca, the guinea-pig,
the mouse, the rat, etc. But excepting with the rabbit the

Fic. 143. White Hall Sultan, a Shorthorn prize bull. (After Plumb.)

domesticated forms of these animals are only wild species
tamed and reared under man’s hand but not much modi-
fied by breeding. There are several well-marked races
of domesticated rabbits all of which probably trace their
lineage back to a wild species native to Spain and South-
ern France.

Of birds there are domesticated races of doves, chickens,
turkeys, ducks, geese, swans, pea-fowls, pheasants, canary
birds, ostriches, cormorants and others. Of these the doves
and chickens are represented by the most varieties. Brown,
an English authority on domesticated birds, lists more than

270 THE ANIMALS AND MAN

seventy races of chickens now living, thirteen races of ducks,
ten of geese and eight of turkeys. Of pigeons there must
be nearly as many domestic races as there are of chickens.
And yet all of them, with all their extraordinary variety of
crests, and ruffs, and tails and plumage pattern, and all
their various special manners such as tumbling, dancing,

Fic. 144. Typical American Merino ewe, a highly specialized breed of
sheep, with fine, close-set wool. (After Shaw.)

and the like, are descended from a single wild species, the

common rock dove, Columba livia, of Europe, Asia and

North Africa (fig. 136).

The domestic races of chickens are by some naturalists
also held to be descended from a single wild species, the
jungle fowl, Gallus bankivus, which ranges from Hindukoosh
to the Chinese island of Hainau and through most of the
Indonesian islands. But other naturalists believe that one
or two other wild species of fowl are concerned in the an-
cestry of our barnyard hen.

DOMESTICATED ANIMALS 271

The domestic ducks are derived from the wild duck Anas
boschas, and have evidently originated from this ancestor
independently both in China and in Europe. The domestic
geese seem to have an older origin than the ducks; in fact
geese are probably the oldest of domesticated birds. The
ancestor of our races is the wild species Anas cinereus. ‘The
Chinese races how-
ever, are descended
from Anas ¢ ygmot-
des, and the early
Egyptians seem to
have tamed and
used “the. eivile
goose, Chenalo pex
egy ptiaca.

The domesticated
peacocks are de-
scended from the
wild species of In-
dia, Pavo cristatus.
The, turkeys-trace
their ancestry to
the wild Meleagris

gallo pavo of North F's. 145. The wild sheep of the ‘Trans-Caspian
steppes, Ovis arkal. (After Keller.)

Aamerica: “lie
swans are really only tamed wild kinds. Common spe-
cies are the white swan of Europe, Cygnus olor, the black
swan of New Holland, Cygnus atratus, and the black-
necked swan of South America, Cygnus nigricollis. The
pheasants also are so far practically only partially tamed wild
species, whose eggs however, are usually hatched under
turkeys. Most of the kinds kept are from the Orient.
Canary birds are descended from the wild species, Frin-
gilla canariensis of the Canary Islands. But there has been
some crossing of them with other species of wild birds,

272 THE ANIMALS AND MAN

especially certain sparrow and finch kinds. ‘There are now
numerous domesticated races which vary structurally in
color-pattern as well as in voice. Many of the characters
resemble the ruffs, crests, and other plumage eccentricities
of pigeons. The principal place of canary bird breeding
at present is in the Harz Mountains of Germany.

Tamed cormorants are used by the Chinese and Japanese
as fishing birds, somewhat as falcons were used in days of

Fic. 146. Wild jungle fowls, Gallus bankiva, of India. | After Brown.)

old as hunting birds. Indeed in these same days cormorants
were used for sport. Charles I of England had a ‘‘master of
the cormorants.”’ Nowadays, however, cormorant fishing
is a practical means of gaining food. A ring is placed about
the neck of each bird so as to prevent it from swallowing
the fish it catches. Several different species of cormorants
are thus used.

The ostrich is the most recent addition to the ranks of
domesticated birds. The tamed species is derived directly
from the widely distributed African ostrich, Struthio camelus.

Besides mammals and birds two or three species of fish,
such as the carp and goldfish, may be called domesticated.

DOMESTICATED ANIMALS 273

This is certainly true of
the goldfish which is a
product of Chinese ani-
mal: breeding. Some
most bizarre forms have
been produced in the
thousand or more years in
which this fish has been a
subject of selection and
hybridization.

There are also finally
at least two species of
insects that have a right
to be called domesticated
animals, namely, the
honeybee and the mul-
berry silkworm. The

Fic. 148. White-crested black Polish cock.

honeybee, Apis mel-
lifica, has been long
used by man to obtain
honey from, but only
in modern times has
the species been the
subject of true “‘breed-
ing.”’ However, already
several distinct races
have been produced.
The bee is native to
Europe and Asia, and
“wild” honeybees in
America are only com-
munities established by
wandering swarms
from hives, or from
other “wild” communi-

274 THE ANIMALS AND MAN

ties which have descended from such escaped swarms.

The silkworm, Bombyx mori, has on the contrary been
an artificially bred animal for five thousand years, and
Scores of races,
with differently
= colored and shaped

Wd ABS
Fic. 149. Tiger-banded variety of the Bagdad COCOONS exist) ihe
silkworm race. (Natural size.) actual wild species
from which the domesticated races are descended is not
known, but it is most likely some one of the several wild
species of Northern India.. The cocoons of “certain. of
these wild Indian species are today still collected for the
sik and sold under the commercial name of ‘“Tussoor’’
silk. The ancient breeding and care of silkworms was
mostly done in China and Japan. ‘Today it is carried on
even more extensively in France and Italy.

CHAPTER XX

FOSSIL ANIMALS

Not all the animal kinds that have lived on this earth
still live on it. Indeed those that now exist, as many hun-
dred thousands or millions as they may be, are certainly only
a small part of all that have existed. The earth has had
a history of life as varied and nearly as old as the history
of its own liquid and solid self. As soon as it had cooled
and contracted from a great gaseous mass to a smaller com-
pacter liquid and solid one it began to bea possible abode of
life. And sometime after its temperature had got below the co-
agulation or killing point for protoplasm—which is the basic
substance of every living thing—life appeared. Whence it
came or how it came to be produced are great questions that
science has yet no answer for and may never have. The
speculations about it are various: such as that living germs
reached the earth from other planets in meteorites or as
“cosmic dust,’ or that it originated spontaneously under
the peculiar chemical and physical conditions of the earth’s
surface in those ancient dim days of the first hardening and
cooling. And there are even some biologists who think that
such spontaneous generation of life from non-living sub-
stances may be going on today. But no one of them has
been able to prove this. ‘All life from previous life’’ is
the dictum of most naturalists of today. And this poses the
problem of the origin of the first life as one far beyond
present scientific knowledge.

If, however science knows nothing about the origin of life
in the early days of the earth’s history it does know something

275

THE ANIMALS AND MAN

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FOSSIL ANIMALS 277

about what kinds of living creatures, both plants and ani-
mals lived in those and succeeding ages. It knows this by
virtue of the preservation of parts of some of these animals
and plants as fossils.

Animal fossils are the actual remains of bones or shells
or other (usually hard) parts of the body preserved intact in
soil or rock; or else, and more commonly, are parts of ani-
mals which have been turned into stone by slow replacement
of these parts by rock particles; or else, finally, are parts of
which stony casts have been made. Examples of these three
kinds of fossil are (1) extinct insects preserved in amber,
teeth of ancient sharks, tusks of mammoths, shells of various
molluscs; (2) petrified bones, corals, crinoids shells, etc.;
(3) casts of insect wings, etc.

Huxley said that “fossils are only animals and plants which
have been dead rather longer than those which died yester-
day.” This “rather longer’? may mean anywhere from a
few thousand to several million years. Geologists estimate
the age of the habitable earth—the time, that is, since life
could have existed on the surface—as being from fifteen mil-
lion to seventy million years. ‘This enormous time is divided
into certain periods of various lengths each period being
characterized by a certain set of geologic, geographic and
life conditions, and these conditions determining in some
measure the kinds of plants and animals living during the
period. The geologic history of the earth, which is a very
broken and partial one, is read by the geologists from the
kind and succession of rocks and fossils which form the
outer crust. Only in certain rocks, those that have been
slowly deposited in water as small (usually soil) particles
and have become compacted and hardened into layers or
strata, one above the other, do fossils occur. Hence only
water-inhabiting animal kinds, or those land kinds whose
dead bodies might get into lakes or oceans, are represented
by fossil remains. Also, sedimentary or stratified rocks

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280 THE ANIMALS AND MAN

form only a part of the earth’s crust. Rocks that are cooled
and solidified from a molten condition, such as volcanic
and other igneous kinds, and even stratified rocks that have
been highly heated, contain no fossils. Hence the record
or history of the life of the long geologic ages before our
present one is most incomplete. But it is one of extraor-
dinary interest and value in any study of biology.

Only a very few words can be said about the interesting
kinds of earlier creatures, now extinct, that inhabited our
earth in ancient times. In the very oldest fossil bearing
rocks are found only remains of the simpler kinds of animals
as the one-celled kinds, and the sponges, corals, jelly-fishes,
etc. In the next oldest strata there are still only simple
invertebrate animals but more kinds than in the older rocks.
The first vertebrates appear next and these are all fishes.
Amphibians are found only in more recent strata, reptiles
in still more recent and mammals and birds in still younger
strata. That is, it is plain from the record of the rocks that
the animal types have appeared in succession beginning with
the simpler kinds and advancing towards the most complex
or higher types by regular stages. ‘This fact is one of the
most important that has been learned about life, for it is
very strong evidence for the belief of most naturalists that
animal kinds are descended from each other, the complex
or higher ones from simpler or lower ones.

The table or diagram on the next page shows the order
of the appearance of various kinds of animals in geologic
time.

One must not believe that with the advent of new types
of animal life all of the old types became extinct. It is
not at all true. Although hundreds of thousands of animal
species have become extinct and are known to us only
through their fossil remains, or are not known at all, some

Eras or
Periods.

Cenozoic.
Era of
Mammals.

Mesozoic.
Era of
Reptiles.

Paleozoic.
Era of

Inverte-

brates.

Archean.

| Triassic

| Carboniferous (age of

FOSSIL ANIMALS

Ages or Systems.

Quaternary or Pleis-
tocene (age of manand

recent mammals). .
Tertiary: Pliocene,

Miocene, Eocene...

Cretaceous

Jurassic

ecerececeecse2ecece

281

Animals’ Especially Charac-
teristic of the Era or Age.

Man; mammals, mostly of spe-
cies still living.

Mammals abundant; belonging
to numerous extinct families
and orders.

Birdlike reptiles; flying reptiles;
toothed birds; first snakes;
bony fishes abound; sharks
again numerous.

First birds; giant reptiles; am-
monites; clams and_ snails
abundant.

First mammals (a marsupial);
sharks reduced to few forms;
bony fishes appear.

amphibians): ~.<<'... -
Devonian (age of
lishes in eee eee

Silurian (age of in-

vertebrates)

Ordovician or Lower
Silurian

- se eee eee

' Earliest of true reptiles. Amphi-

bians; lung fishes; fringe fins;
first crayfishes; insects abun-
dant; spiders; fresh-water
mussels.
First amphibians (froglike ani-
mals); sharks; ostracophores;
first land shells (snails); mol-
luscs abundant; first crabs.
First truly terrestrial or air-
breathing animals; first in-
sects; corals abundant; mailed
fishes.

First known fishes, ostracophores,
mailed and with cartilaginous
skeleton; brachiopods; _ trilo-
bites, molluscs, ete.

Invertebrates only.

AW.

|
|
|

Simple marine invertebrates.

282 THE ANIMALS AND MAN

species of all the great groups from simplest to higher are
living today. Most of these species are however modern
in their origin. The original or first species in all the great

Fic. 153. Skeleton of Hesperornis regalis, the Giant Toothed Bird of
the Kansas Cretaceous. (Inthe American Museum of Natural History;

after Sternberg.)

groups are gone; and some whole families and orders of
species are extinct. For example in the class of reptiles
there existed in the Mesozoic era many enormous kinds

FOSSIL ANIMALS 283

called Dinosaurs, Ichthyosaurs, Pterodactyls, etc., of which
no living representatives are left. Some of these reptiles
had wings (Pterodactyls) and seem more like great birds
than true reptiles. In the bird class, too, there were, in the
same era, various enormous kinds now extinct, some of which
had teeth. :

An interesting example of the geologic succession of
related animals and one often referred to in books about
extinct animals, is that of the horse series. In lower Eocene
rocks is found an animal called Eohippus, about the size
of a fox, with four hoofed toes and the rudiment of a fifth
on forefeet and three hoofed toes on hind feet. This is the
first of a series of similar but always differing and ever-
more horse-like forms that are found in the rock strata suc-
cessively younger and higher, representing Miocene, Pliocene
and Quaternary periods. The hoofed toes disappear one
by one, the size of the whole animal is ever larger, and the
teeth are more and more like horse’s teeth as we examine the
successively younger (more recent) members of the series,
until in the rocks of our present epoch we find the bones of
an animal which is essentially identical with the horse as we
know it today.

Similar ancestral series have been discovered for the
deer, for certain pond snails, for the ammonites, for many
other kinds of animals, indeed. ‘The first deer in the early
Miocene had no antlers. In the middle Miocene are found
small deer with small two-pronged antlers. In the upper
Miocene and lower Pliocene there are larger deer with
three-pronged, larger antlers. In the later Pliocene occur
four and five-pronged antlers, while in the Pleistocene are
remains of deer with branching antlers like those of the liv-
ing species.

The fossil fishes of the earlier geologic periods are all
of the simpler, more primitive families of which none or
but few representatives occur today. Of the 12,000 known

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FOSSIL ANIMALS 285

living species of fishes 11,500 belong to the great group
of Teleostomi or bony fishes, of which the first representatives
are found only in Triassic strata. But fossil fishes are known
from all the geologic periods from the Silurian on up. All
the fishes of these earlier millions of years were of more
primitive shark-like families. Many of these families
are now wholly extinct and of the others only a few per-
sisting species remain. Even those early families of the
true bony fishes of the Triassic and Jurassic rocks are mostly
now extinct. Most modern families date from Cretaceous
times.

The question may be asked: Are there any fossil men
known? The answer is yes. But man is very young,
geologically speaking. No indubitable human bones or
relics have been found in rocks earlier than those of the
present great epoch, the Quaternary. But this epoch is
certainly already many thousand years old. Man existed
in Glacial times. Remains of the mammoth, the cave-lion,
cave-bear, and other extinct animals have been found in
the same caves with human bones. So man has a certain
geologic history; one at least of 20,000 years; probably
much longer.

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PART. IV

HUMAN STRUCTURE AND
PHYSIOLOGY

(Chapters XXT to XXVIII, inclusive, by ISABEL MCCRACKEN)
CHAPTER XXI

INTRODUCTION

The study of physiology and its purpose.—We have
found in our study of animals that they are made up of
many parts or structures arranged in definite ways. To
see many of the parts it was necessary to dissect the animals
that we have studied most carefully, as the frog and craw-
fish. This study of the structure of animals is called the
study of anatomy. We must know something of the anat-
omy of the animal body to understand what it can do.

We have learned that each part has its special function
and that these various functions constitute the processes
which, added together, are life itself.

The study of the functions of the various structures of
the body is called the study of physiology.

Since the study of physiology is the study of the parts of
the living body in action, the study of human physiology
at first hand is very difficult. We can dissect the lower
animals easily, and find out at first hand what their parts
are and how they are put together, but elementary students
cannot dissect the human body. They must depend upon

287

288 THE ANIMALS AND MAN

the statements of physicians, surgeons, and trained physi-
ologists for most of their knowledge of human anatomy and
human physiology.

The health of the human body depends upon the right
performance of its proper function by each part of the body.
The laws of health or of hygiene are merely those rules
that have been proved by experience and experimentation
to be best adapted for maintaining the body in its best work-
ing condition.

Our chief purpose in studying human physiology is there-
fore to understand the working of the human body as a
self-regulated, working machine, that we may know how to
give it the protection and care necessary to preserve it as such.

Structural units of the living body and division of
labor.—In a lifeless mechanism like a watch, we find many
individual parts, and these parts so nicely adjusted one to
the other that they all work together successfully as a whole.
So it is in the living mechanism.

Our study of the amoeba (Chapter V) made us acquainted
with a living, feeding and moving animal whose body is
composed of a single cell. Our study of the structure of
the toad (Chapter III) showed us that the life-functions
are performed in this animal by certain large systems of
organs; that these organs are made up of groups of tissues
formed of masses of similar cells, each cell performing its
own special kind of work. The cell is therefore the struc-
_ tural and physiological unit of the body. Each cell does
its share of the work of that tissue of which it is a part,
and each tissue does its share of the work of the organ of
which it is a part. In the same way each organ works in
harmony with all the other parts in its system, and all the
systems work together to maintain life.

The living substance of the cell and metabolism.—In
Chapter V it was explained that while the cells of the body
may differ very much in appearance and function, they are

HUMAN PHYSIOLOGY: INTRODUCTION 289

alike in being chiefly made up of the one substance proto-
plasm. This is the living substance of the cell. The life
and activity of the body depend upon the life and activities
of the protoplasm of the many cells of the body that make
up the various organs. A diseased condition of body means
a diseased condition of the protoplasmic cells of the body.

Metabolism.—In their functional activity, the cells of
the body provide feat and do some kind of work. This
work is done by reason of the energy generated by the cell.
In providing energy the cell itself wears out or wastes away.
It has, however, the power of self-renewal or self-repair.
This double process of ‘waste and repair’ is known as
metabolism.

The air we breathe, the water we drink and the food we
eat supply the cells of the body with the three essentials
for their metabolism.

Protoplasm is a very complex substance built of simpler
substances. The foods we eat are first reduced to simple
substances. Each protoplasmic cell acts as a little chemical
laboratory in laying hold of these simple food substances,
and recombining their elements into its own complex sub-
stance. It then reverses the process and, with the aid of
oxygen, breaks up this complex substance into simple sub-
stances. These are then thrown out of the cell as waste
products.

The whole problem of the body, as a mechanism, is, there-
fore, to obtain air, water, and food and to carry these to the
cells; then to carry the waste away from the deep-seated
cells, and eliminate it from the body.

It is to this end that all the systems of the body work
together.

Systems of the human body and their functions.—In
the human body, as in the higher animals already studied.
there is a digestive system, consisting of the alimentary canal
and all of its parts. This system supplies the body with

290 THE ANIMALS AND MAN

food and prepares the food for the use of the tissues. A
circulatory system, consisting of heart, blood-vessels, capil-
laries, and lymphatics, transports the prepared food and
oxygen to the cells of the body. The muscular and skeletal
systems, consisting of the muscles and bones of the body and
their attachments, enable the body to do all the things re-
quiring motion. The respiratory system, consisting of the
air passages of the nose, throat or pharynx, larynx, the
bronchial tubes and minute air sacs forming the large respira-
tory surface, is employed in supplying the blood with oxygen
which is to be carried to the cells. An excretory system, con-
sisting of the kidneys and their ducts, and certain glands in the
skin known as sweat glands, take up the waste from the
blood and remove it from the body. The nervous system,
consisting of the brain, spinal column and innumerable
nerves, puts all the parts of the body into communication
so that they may work in harmony. The sense-organ sys-
tem, intimately connected with the nervous system and
functioning with it, comprises the organs for seeing, hearing,
smelling, tasting, feeling, etc. They put the inside of the
body into communication with the outside world.

All of these systems work together to maintain life, that
is, to maintain the metabolism of the cells. If any system
fails to fulfill its function the whole body suffers and disease
sets in. It is our business to provide the body with good
food, fresh air, pure water and daily exercise so that each
system may be kept in the best condition possible for its work.

The chemistry of the body.—The chemist tells us that,
in all the world, there are only about seventy simple or e/e-
mentary substances. All the gases, liquids and solids that
we know of, are formed by uniting these simple elements in
many ways. Thus the simple element oxygen united with
the simple element hydrogen forms the water we drink. A
mixture of pure oxygen, nitrogen, hydrogen and a few other
gases forms the air we breathe.

HUMAN PHYSIOLOGY: INTRODUCTION 291

The cells of the body are made up of certain chemical
substances, compounds of the simple elements, sulphur,
phosphorus, carbon, oxygen, hydrogen and nitrogen and a
few other substances (potassium, chlorine, calcium and
magnesium). Comparatively few elements, therefore, are
found in the animal tissues. These are, however, united in
many ways to form many different compounds.

Chemical compounds of the body.—The chemical
compounds found in the body are proteids, carbo-hydrates,
fats, acids, and salts.

Proteids contain carbon, oxygen, hydrogen, and nitrogen.
These are called the nitrogenous compounds.

Carbo-hydrates contain carbon, hydrogen and oxygen,
the former predominating.

Fats contain also chiefly oxygen, carbon and hydrogen,
the latter predominating. The carbo-hydrates and fats
are known as non-nitrogenous substances.

Since these are the chief substances that the body is built
up of, they must also be the chief substances in the foods we
eat.

OBSERVATION OF A FEW SIMPLE CHEMICAL
ELEMENTS

Oxygen, the properties of.—The most necessary ele-
ment in all the world is oxygen. Neither plant nor animal
can live without it. Fire cannot burn without it. It forms
about one-fifth of the atmosphere. It is a colorless, odor-
less and tasteless gas. Most of the other simple elements
will combine with it, especially at a high temperature.

Oxidation and combustion.—Oxidation is the union of
oxygen with any other substance. We say that a substance
is oxidized if it has taken up oxygen. Thus carbon, when
it takes up oxygen, is oxidized and becomes carbon-dioxide.
When oxidation is rapid or accompanied by light or great

292 THE ANIMALS AND MAN

heat it is called combustion. When a match is rubbed on
a surface, the heat produced by friction causes the phos-
phorus and other substances at the match tip to take up
oxygen rapidly, causing combustion. Phosphorus is thus
oxidized and the combustion that arises from its rapid
oxidation sets the match on fire and consumes it.

Rust is oxidized iron or iron-oxide.

It is the nature of organic substances (compounds con-
taining carbon) to unite easily with oxygen. That is, oxygen
has a great affinity for these compounds. It combines easily
with other elements.

To obtain oxygen.—The simplest way to obtain pure
oxygen is to heat some compound containing it. The heat
breaks up the compound and sets its elements free. The
oxygen thus escaping may be collected.

EXPERIMENT 1.—Place some oxide of mercury in a test tube and heat
it. It gradually disappears from view. The oxygen and the mercury of
the compound have separated. The oxygen has become an invisible
gas, the mercury has become vaporized. Drops of pure mercury will
soon condense on the sides of the glass.

If, while the experiment is in progress, a live coal on the end of a
stick, be inserted into the mouth of the test tube the coal will glow with
a greater brilliancy. This means that oxygen in its pure state unites
more freely with the carbon of the wood and makes a more brilliant
glow than did the oxygen of the air, mixed as it was with other gases.

Potassium chlorate gives up oxygen rapidly when heat is applied to
it, so rapidly indeed as to cause an explosion. If an equal quantity
of black oxide of manganese be mixed with potassium chlorate, the
oxygen is given off more slowly and without danger of explosion, and
may then be collected in jars as follows:

Arrange an apparatus as in fig. 155. First fill the jar with water
and invert it over the pan of water. Partly fill the test tube with the
mixture of potassium chlorate and black oxide of manganese (equal
parts). Fit the test tube with a tightly fitting cork and a bent glass
delivery rod. Before placing the delivery tube in the water move the
alcohol flame along the test tube so as to drive out the air and warm
the tube, that no moisture may form on the tube and break the glass.

Then heat the mixture gradually, beginning at the top and working

HUMAN PHYSIOLOGY: INTRODUCTION 293

toward the bottom. After a few seconds gas will come off. The de-
livery tube may then be placed under water beneath the opening of
the jar, and soon the bubbles of oxygen coming off will displace the
water in the jar.

Caution.—After collecting a jar of oxygen (or several jars) lift the
end of the delivery tube out of the water before removing the lamp,
otherwise the water will rush back into the delivery tube and crack it.

Insert the live coal of a splinter into the jar. It will burst into flame.

Fic. 155. Apparatus for collecting oxygen. (After Jenkins and Kellogg.)

Or heat the end of a piece of picture wire and insert the red-hot wire into
the oxygen. It will burn with a bright flame, thus showing again that
oxygen “‘supports combustion.”

Other experiments with oxygen may be found in books on elementary
chemistry.

Properties of Carbon.—Carbon is the chief solid element
in wood, muscle, fat, sugar, starch, etc., in fact in every
substance that is or has been living. For this reason, sub-
stances containing carbon are called organic substances. It
is found in coal, showing that coal was once a living sub-
stance. A special branch of chemistry, called ‘Organic
Chemistry,” is devoted to the study of the carbon compounds.

The black substance, or charcoal, left after the splinter
was burned is almost pure carbon. It is without taste or
odor. When carbon is cold it has little affinity for other
elements. When it is heated, however, it takes up oxygen,
or becomes oxidized, as we have seen in our oxygen experi-

294 THE ANIMALS AND MAN

ment. The gas formed by oxidized carbon is carbon dioxide.
It is colorless but may be readily detected on account of its
power to turn lime water milky.

Carbon dioxide is constantly formed in our bodies and
given off in the breath. If we breathe through a straw or
glass tube into a jar of lime water, the water in the Jar will
soon take on a milky appearance due to the union of the
carbon and lime. In the formation of carbon dioxide, as in
other oxidations (or formation of other oxides), heat is gen-
erated.

This principle is made use of in the cells of the body for
the generation of heat and energy.

Oxidation in the body.—The oxygen of the air is taken
into the lungs and passed into the blood. ‘The blood carries
it to the cells. The carbon of the living cell derived from
the food takes up oxygen, that is, becomes oxidized. Heat
is produced, and the energy, by means of which the work of
the body is done, is liberated.

Phosphorus.—Phosphorus in its pure state is a yellowish
waxy substance. With calcium and oxygen it forms a large
part of our bones. The affinity of pure phosphorus for
oxygen is so great that it must be kept under water or else
combustion will take place.

Sulphur.—Pure yellow sulphur is familiar to all of us.
When sulphur is oxidized it gives off suffocating fumes.
Muscle is largely a compound of sulphur and other elements.
The disagreeable odor given off by decaying flesh is caused
chiefly, by the sulphur fumes. In eating an egg with a
silver spoon the sulphur of the egg forms with the silver a
blackish compound.

FOODS AND NUTRITION

Food nutrients.—Those substances needed by the cells
for their metabolism and their growth are called food nu-
trients. The nutrient or food value of any substance there-

HUMAN PHYSIOLOGY: INTRODUCTION 295

fore depends upon its composition or the amounts and kinds
of nutrients present. It must contain one or more of the
following substances, proteids, carbohydrates, fats, water
and inorganic salts.

The following table shows approximately the average com-
position of some of those substances commonly used as food.

Composition of Foods.*

| Carbohydrate
(In roo =} Water Proteid | Fat | Digestible Inorganic
parts) H,0 Starch | Cellulose Salts
and Sugar

Meat 2232-1 9047 20.8 BAZ 3 Log
Eegse ssc: 7 Sd) | 20) ieee 1
Sheeses a= BO-00" 25-24, 17-20 23 3-4
Cow’s milk .| 87.5 ZA AU) Bee 4.8 a7
Wheat flour.| 13-3 | 10-2 aS 74.8 Pe
Wheat bread] 35.6 | 7-1 2 55.5 3 Da
RoverHOour yet 3.5°7 Brs5 21 69.7 a 1.4
Rye aa A203 O21 4 4Q-2 1.6 Tats
RUGeece<-: eS 720 9 giriae| 5 1.0
Gores). 5.3 27 9-9 | 4.6 68.4 -6 et
Macaroni. --.}| 10-1 g.0 2 79-0 2.5 5
Peas, beans, |

lentils =2.|52-n5, || 23-20) \n5 ol Ag —c4 oe: 23
Potatoes 2222) 75-5 2 2 20.6 4-7 ie
Carrots: 22.5 - 8721 ie 2 Oe By 9
Cabbages -.]} go. aa 5) 4-6 EA 12
Mushrooms -}73-91 4-8 _5| 3-12 I-2 1.2
Heute sae 84 5 | 10. I-5 5
Butter). 2 By 83. 4- |

- *Howell’s Physiology, p. 676 (with slight additions).

Uses of nutrients (proteids, carbohydrates, fats, salts,
and water).—The exact use of each kind of nutrient to the
body is a subject upon which there has been much careful
experimentation. Two things are positively known, and
they have already been stated. First, the nutrients furnish
the cells with materials for growth and metabolism, and

296 THE ANIMALS AND MAN

second, their oxidation in the cells results in the production
of energy, in the form of heat or motion; that is, they furnish
the body with building material and fuel.

The proteid compounds are best fitted for this purpose,
though each food nutrient has its value.

We may now consider each of the food nutrients sepa-
rately, and the place of each in our diet.

Proteids or nitrogenous compounds (albumins, etc.).—
While the exact composition of proteid is unknown the
substances forming it are known to be carbon, oxygen,
hydrogen, nitrogen, sulphur and other elements. Such
foods as white of egg, lean meat, milk curd and the gluten of
wheat, contain large amounts of proteid. ‘The proteid food
stuffs are the only food stuffs supplying nitrogen to the body.
This nitrogen is being constantly eliminated from the cells
and hence must be constantly restored ¢o the cells.

Proteids have been called flesh-producers or tissue-formers
because they possess all the elements for forming tissues and
cells, as muscles, nerves, etc.

Plants manufacture proteid from sugars and certain min-
eral salts, the former supplying the carbon, hydrogen, and
oxygen, the latter supplying nitrogen, sulphur, and other
elements. Plants are therefore the original source of supply
for proteid food. While carnivorous animals obtain their
proteid by eating the flesh of other animals, these have
obtained it from plants.

Tests For Proteid.

a. Xanthoproteic Test.—Boil the substance to be tested in strong
nitric acid (80%); a lemon yellow appears. Wash in water and add
enough ammonia to neutralize the acid. If the color changes to deep
orange proteid is present.

b. Millon’s Test.—Pour Millon’s reagent (solution of mercury in
nitric acid) over the substance to be tested and bring slowly to a
boiling point. If proteid is present the solution becomes rose red.

Proteid burns with the odor of burning leather.

Carbohydrates (starches, sugars, etc.).—Carbohydrates con-

HUMAN PHYSIOLOGY: INTRODUCTION 297

tain carbon, oxygen and hydrogen. The green parts of plants
are, with the aid of sunlight, the manufacturers of starch.
The materials used are carbon dioxide (CO,) obtained from
the air by the leaves, and water obtained by the roots.
Thus vegetables and fruits supply the carbohydrate foods.

Starch forms the chief carbohydrate food of the world.

Carbohydrates unaided could not, however, form living
cells because they lack the element nitrogen, therefore, they
could not take the place of proteids.

The carbohydrates, with the fats, have been called the
heat and energy producers because their compounds, in
becoming split up and oxidized, produce energy for the per-
formance of the body movements, and heat to maintain the
temperature of the body.

The carbohydrates and fats have also been called ‘“‘proteid
sparers’”’ because by keeping up the supply of heat and
energy of the body they spare the proteids from that kind of
work so that their main work may be that of tissue formation
and growth.

It would take relatively a very large amount of proteid to
furnish sufficient heat and energy. ‘Therefore, if we should
furnish the body with enough proteid for this we should
over-furnish it with tissue-building material. It is thus
economy to furnish carbohydrate foods for heat and energy
and proteid for tissue-building.

Test For Starch.—Break up and crush the substance to be
tested (a bit of potato or corn). Pour over it a few drops of iodine
solution. If there is a large amount of starch present it will turn black,
if but little starch is present it will turn blue.

Test For Grape or Cane Sugar.—Heat the substance to be tested,
slightly, in a test tube with a little water. Add to this twice its bulk
of Fehling’s solution* (may be obtained at the drugstore). Heat

*To prepare Fehling’s solution:

Solution 1.—Add to 35 grains of copper sulphate (blue vitriol) 500 cubic
centimeters of water and put aside until dissolved.

Solution 2.—Add to 160 grains of caustic soda and 173 grains of Rochelle
salts, 500 cubic centimeters of water. Mix equal parts of solutions 1 and 2,

2098 THE ANIMALS AND MAN

the mixture or allow it to remain over night ina warm room. If grape
sugar is present in any quantity, the contents of the tube will turn first
greenish, then yellow and finally brick red.

Fats (butter, oils, oil of nuts, etc.).—Like carbohydrates,
fats contain carbon, oxygen, and hydrogen but in different
proportions. ‘They are insoluble in and lighter than water.
They are easily oxidized as we know from the rapidity with
which they burn. Like carbohydrates, they are heat and
energy producers and proteid savers.

Tests for Fats.—Rub the substance to be tested upon a sheet of
white paper, or heat it in an oven upon paper. If oil is present, it will
show as a grease spot.

Water.— Water undergoes no chemical change in the body.
Its importance as a food is due to the fact that it forms a
large percentage of the composition of the body, nearly 59%
of the total weight. <A large amount of water is thrown off
daily as waste, through the skin and kidneys. This must
be restored daily to keep the body well. Our food provides
only about one-third of the water we need and we must
drink three or four pints each day to supply the deficiency.

Water promotes digestion, by aiding in softening and
dissolving the food and stimulating contractions of the
muscle. A large amount of muscle and a much larger
amount of blood is water.

Inorganic salts (chlorides, sulphates, carbonates, etc.).—
Inorganic salts are found in the cells and fluids of the body,
and particularly in the bones, of which they form an im-
portant part. They are non-oxidizable and hence have no
importance as sources of energy. They are supposed to
function in controlling the flow of water to and from the
tissues. This is by virtue of the principle of osmotic pres-
sure. These salts are supplied to the body largely through
vegetable food.

Diffusion and Osmosis.—When one liquid is poured
into another the resulting solution will be a blend of the two

HUMAN PHYSIOLOGY: INTRODUCTION 299

substances, if they are capable of mixing. That is, the
molecules of one liquid become thoroughly intermingled
with the molecules of the other, as when syrup is poured into
water. This is diffusion.

If two such liquids are separated by an animal membrane,
the molecules of each will pass through the membranes
so that in time the solutions on each side will be equally
diffused. This passage of the molecules of liquid through
an animal membrane is known as osmosis. The “attrac-
tion” exerted mutually by the liquids is called osmotic pres-
sure. Osmotic pressure varies with the density and tem-
perature of the solutions. Osmosis and osmotic pressure
are facts of great importance in animal physiology as we
shall see when we study the nutrition of the cells.

Procure from the butcher a small bladder; moisten it and fill it with
sugar solution. Insert a tube into the opening and tie the neck of the
bladder tightly around the tube. Immerse this in a dish of water and
note the result. The energy with which the water enters the solution of
greater density is due to osmotic pressure.

Relative value of common foods.—-Our meals consist
usually of a “mixed diet,” of fruit, nuts, cereal and eggs,
or perhaps bread, meat, and vegetables. Experience has
shown that a mixed diet is better suited to the appetite
and to the needs of the body than a single food material.
Eggs, milk and bread are nutritious because they contain
almost no waste. Meat is valuable for its high percentage
of proteid. Potatoes and other vegetables are valuable for
their high percentage of carbohydrates. Some foods are
valuable for their large percentage of water.

Daily diet.—Certain experiments have been made both in
Europe and America to determine a “‘standard diet’’—the
amount of food that should be consumed in order to
preserve the health. This amount varies of course with
the occupation,- the sex and the age of the individual
and with the climate.

300 THE ANIMALS AND MAN

Prof. Atwater of the U. S. Department of Agriculture gives
the following table as approximating the average amounts
of nutrients needed per day.

Conditions Proteid Carbo- Fat *Calories
Ibs. hydrate Ibs.
Man with light muscular work....... 222 2807, 222) 20802
Man with moderate work............ 228 2590) 220) a5 70e
Man with active muscular work...... =32 TeTOMMHE eo) VAOOOr

Principles involved in cooking food.—Cooking improves
the taste of food, by bringing out its natural flavors. It
renders food more wholesome by killing any noxious or poi-
sonous organisms that may have collected on it in the mar-
kets. It makes the food more digestible by softening the
fibers, and in vegetables by bursting the cell walls so that the
digestive juices can get at it.

Economy in the purchase of foods.—The Department
of Agriculture at Washington is giving much attention
to this subject and bulletins of the results of investigations
are published from time to time to furnish information
about it.

“The cheapest food is that which supplies the most
nutrient for the least money. ‘The most economical food is
that which is cheapest and at the same time best adapted
to the wants of the eater.” If we adopt these as rules for
the purchase of foods we must study tables of the relative
values of foods and consult the markets for relative prices.

Food accessories.—We commonly add certain things to
our foods to make them more palatable, to make them taste
better, such as pepper, mustard, vanilla, cinnamon, nutmeg,
vinegar, pickles, lemon juice, etc. “These are condiments, or
flavors, and contain none or but little of the food nutrients.

*A calory is the accepted unit for measuring heat. It is the amount of
heat necessary to raise the temperature of one kilogram of water one degree.

tFarmers’ Bulletin, 23, p. 20.

HUMAN PHYSIOLOGY: INTRODUCTION 301

They are therefore known as food accessories. They are not
absolutely necessary as part of the diet, but, used in limita-
tion, they stimulate the appetite and favor the flow of diges-
tive juices. They, therefore, have a place upon the table.
If used in excess, however, they destroy the normal appetite
for natural flavors and may over-stimulate the glands that
furnish the digestive juices.

Stimulants.—There are certain other substances that
primarily excite or stimulate the activity of certain parts
of the body, chiefly the nervous system, without providing
material for growth or repair, for heat or energy. These
are stimulants. They are chiefly tea, coffee, cocoa, chocolate
and alcoholic liquors. While in small amounts these may
be harmless, it is not easy to tell how small this amount
should be, and it differs with different dispositions.

Their chief injury to the body lies in the fact that, by
stimulating the nervous system, they deprive the body of
the sense of fatigue, or of the desire for sleep, and so also
of the benefits derived from rest and sleep.

Alcohol.—A true food is a substance which nourishes the
body, acts as a tissue builder or as a heat and energy producer.

It has been determined by experiment, that in very small
amounts given at stated and widely separated periods,
alcohol is oxidized in the body, and thus produces heat and
energy as do the fat and carbohydrate foods. These are
such doses as the physician sometimes gives when for some
reason he must find an equivalent for fats and carbohydrates.

In large amounts, alcohol has been found to act as a
drug, causing much harm to the tissues, poisoning them and
disarranging them seriously.

Like other stimulants, and acting more quickly and in-
juriously, it excites the nervous system in a peculiar manner.
Unlike other poisons, its use establishes a craving or appetite
for it which eventually weakens the will and is apt to lead
to intoxication.

302 THE ANIMALS AND MAN

In small amounts, then, alcohol may be considered as a
kind of food but should be administered, like other medicines,
under a physician’s order. In large amounts it is recognized
as a poison and dangerous. The direct action of alcohol
upon certain organs will be considered later.

Narcotics.—Narcotics are substances which blunt the
sensibilities and induce sleep. Tobacco, alcohol (in large
quantities), opium, morphine and cocaine, are the most
common. All narcotics are deadly poison when taken in
large quantities. Some of them, like tobacco and alcohol
may stimulate in small doses and narcotize in large doses.

Tobacco, like alcohol, affects the nervous system. It
leads to weakness of the heart and irregular pulse by inter-
fering with nerve regulation. ‘The poisonous ingredient
of tobacco is nicotine. It is this that makes boys sick and
sleepy when they first begin to use tobacco. The constant
use of tobacco impairs the digestion through its action on
the salivary secretions. It produces hoarseness and catarrh
through irritation of the mucous lining of the mouth.

CHAPTER XXII
DIGESTION AND ABSORPTION

Digestion.—We have learned that it is the function of
food to nourish the cells of the body. The cells can, how-
ever, absorb liquid food only, so the food requires further
treatment than mere cooking to render it of use to the cells.

It is the function of the alimentary canal and its assisting
or digestive glands to dissolve thoroughly the food, to separate
the nutritious from the non-nutritious, and to treat it with
such reagents that it can be taken up by the cells. This is
digestion.

The alimentary canal.—Digestion, as has been said,
takes place in the alimentary canal. Our study of the ali-
mentary canal of the frog, together with the use of the accom-
panying diagram (fig. 156), will aid us in understanding this
structure in the human body. It is a continuous tube from
the mouth to the anus. Part of the tube is twisted and
doubled back upon itself, as shown in the figure. Its
entire length, were it stretched out, is about thirty feet.
Its diameter varies at different points, being widest at the
stomach. There are outgrowths at different points called
glands that furnish the digestive juices for dissolving and
preparing the food. These glands pour their secretions
into the various parts of the alimentary canal where they
become thoroughly mixed with the food.

The alimentary canal is lined with a soft mucous membrane
like that within the mouth. Its secreting cells furnish
mucous for keeping the inner surface moist.

The mouth or buccal cavity.—If we close the lips and
feel around with the tongue we find the mouth bounded on

393

304 THE ANIMALS AND MAN

the front and sides by the /ips, the teeth, the gums and cheeks.
The tongue (fig. 157) lies on the floor of the mouth. The

Salivary
Glarids

Win dpipe eee Sees

Gullet

ay --- Gg Mel Mi APR) ie
ci IS oes
DA

war SSS s— eae
4 Pancreas

Duodenum -

lerge
nestir@ ------

Smal/ Inlestine

Verrmform Agpernax ---

Fic. 156. Diagram of the alimentary canal. (Modified from Landois.)
hard palate and soft palate form the roof of the mouth. The

pendant hanging from the soft palate is the uvula. During
deglutition or swallowing the wvula closes the inner passage

DIGESTION AND ABSORPTION 305

into the nasal cavity which lies above the palate (see fig. 157).
The teeth and tongue act mechanically upon the food,

masticating it or breaking it up.

The teeth.—The teeth are important structures since
they initiate the work of digestion. Those that grow in
during the first two years
aon of life are called milk
“\ teeth. They have small-
er roots than the _per-
manent teeth and ap-
pear while the jaws are
small. As the jaws
enlarge (during the sixth
and seventh years) the
second set or perma-
nent teeth grow in and
one by one replace the
milk teeth. The perma-
nent teeth need much
care and attention as
they must last through-
out life.

Fic. 157. Diagram of the buccal cavity Kinds of teeth ae
showing the manner of closing the There are eight feet mean
posterior nares during deglutition. the front of the mouth
(After Landois & Stirling.) (four on each jaw) called

incisors, to bite and cut the food. The sharp pointed teeth

on either side of the incisors are the canines. On either
side of the canines there are two large teeth with two-point-
ed surfaces. These are the bicuspids or premolars. On
either side of the premolars are three large molars. The
premolars and molars are grinders. The third molars fre-
quently do not appear until after the twentieth year, and
are commonly called the wisdom teeth.

Structure of the teeth (fig. 158).—The teeth, though as

306 THE ANIMALS AND MAN

hard as bone, are not bone but a hardened epithelium tissue.
The part above the gum is the crown and is but a part of
the whole tooth. Under the gum are the neck and roots.
The roots are inserted into sockets in the jaws. The in-
cisors and canines have but

Uf,

tiff

one root, the premolars have Cy
WM Yi

usually two roots and the mo- Cy
iitcA

lars have from two to five. oy Z
If a tooth is cut lengthwise a2
aA
Z

AN
UNIS
qe

\

\\

ai
\

ry no 8!
\t

ai
i

nut
i

as shown in the figure, there

is exposed a central chamber,»
or pulp chamber filled with ee
blood-vessels and nerves which a).
have entered the cavity c_£
through the roots. The pulp
chamber is surrounded by a pe_}
layer of dentine (D), an ivory- ali}
like substance which makes up rete INE aac
the bulk of the tooth. The NAW a
dentine is protected on the
crown by enamel (E), the
hardest substance in the body,
and on the roots by cement
(©) Whe enamel, protects
the teeth from mechanical Fic. 159.
injury and from the effect of

bi

wn

section of a
EB, enamel; Dp:

Vertical
tooth in jaw.

chemicals and_ bacteria.
Care of the teeth.—As the

teeth masticate or grind the

food and prepare it for the

dentine; P. M., peridontal mem-

brane;. Ps (C. pulp! cavity; “©
cement; B, bone of lower jaw;
V, vein; A, artery; N. nerve.

(After Stirling.)

action of the digestive juices, their condition has much to

do with the health.

Decay of teeth is caused by injury to the enamel.

This

is due mainly (1) to the action of bacteria or particles of
food that lodge between the teeth; (2) to tartar, a deposit

DIGESTION AND ABSORPTION 307

of lime salts that collects on the teeth especially near the
gums.

The teeth should be brushed with water after every meal
to remove every particle of food from the mouth. Once
or twice a week a good tooth powder like precipitate of
chalk should be used. This is not hard enough to injure
the enamel but removes the tarter. A dentist should examine
the teeth about once a year.

Salivary glands.—The salivary glands open into the
mouth. There are three pairs. These are named from
their location: parotid, lying in front of and below the ears;
submaxillary, lying beneath the lower jaw, and sublingual,
lying beneath the mucous membrane in the floor of the
mouth. The position and openings of these glands are
shown in fig. 156.

Chemical action of saliva.—The salivary glands secrete
a digestive juice called saliva. This is composed mainly
of water and a certain enzyme called ptyalin.

An enzyme is an organic substance which acts chemically
upon another substance so as to change its nature without
itself becoming changed.

Ptyalin changes starch, an insoluble food, to sugar, a
soluble food, that is, it digests starch.

The chewing process in the mouth thoroughly mixes the
saliva with the food so that the enzyme can reach the starch.
This is the first act of digestion. The mechanical action
of moistening the food and thus preparing it for swallowing
is quite as important as its chemical action. Food thus
moistened stimulates the sensation of taste.

Experiment to Show Digestion of Starch.—Chew a piece of par-
affin; this will start the flow of saliva in the mouth. Collect the saliva
in a test tube. Test its chemical reaction with litmus paper. If
it changes blue litmus to red it is alkaline. If it changes red litmus
to blue it is acid. Add a little vinegar to the saliva and test
again. Account for the different result. Partly fill a test tube
with saliva, another with water, a third with saliva to which vinegar

308 THE ANIMALS AND MAN

has been added. Test a bit of soda cracker for its starch reaction
(see p. 297). Place the soda cracker (a little boiled starch will do
as well) in each of the three test tubes and leave over night in a warm
room. In the morning test the contents of each tube for starch and
for sugar. In which has digestion taken place?

Deglutition.—Deglutition is the act of swallowing. Fig.
157 shows how it is begun. ‘The tongue is raised to the
roof of the mouth, and the uvula automatically closes the
nasal passage. The food is pushed into the pharynx by
means of the muscles at the base of the tongue.

The pharynx.—There are seven openings into the pharynx;
one each to the mouth, the windpipe or larynx, and the
oesophagus, a pair to the nasal passages, and a pair to the
Eustachian tubes leading to the middle ear. The opening
into the larynx (or glottis) is closed by the epiglottis during
deglutition.

The pharyngeal cavity is lined with mucous membrane.

The oesophagus.—The pharynx narrows intotheelongated
oesophagus. ‘This is also lined with mucous membrane and
has muscular walls which by peristaltic contraction pass the
food into the stomach. Pertstaltic contraction is a contrac-
tion that starts at one end of a series of muscles and moves
along the muscles in a wave. It may be imitated by press-
ing the fingers on a rubber tube and drawing them the
length of the tube.

The abdominal cavity.—This is the large cavity shown in
fig. 159 separated from the thorax or chest by the muscular
diaphragm (D). At the back are the spinal column and
lower ribs. Its base is formed by the large pelvic bones (P).
The sides and front are covered with muscles. The cavity
is lined with peritoneum, a membrane which is deflected
over the organs lying in this region, and which supports
them. ‘This membrane secretes a fluid (serous fluid) which
keeps it moist.

Form and structure of the stomach (figs. 156 and 159).—

DIGESTION AND ABSORPTION 309

The stomach is a pear-shaped organ lying just beneath the
diaphragm. The oesophagus opens into its larger or cardiac

Fic. 159. Diagram of thorax and abdomen showing location of heart,
viscera and lungs. C, clavicle; D, diaphragm; 10, first dorsal vertebra;
F, femurs H, humerus; Ht, heart; I, ilum; LE, liver; L. T., large
intestine; “L. L., left lung; P. pelvis; R. L., right lung; S. I., small
intestine; S, scapula; St., sternum. (After Deaver.)

end which is at the left side. The walls are muscular, and
distend as food enters. It is covered on the outside with

310 THE ANIMALS AND MAN

the peritoneal membrane and lined by a mucous membrane.
A submucous membrane les between the muscular coats
and the mucous coat or epithelium. The large blood
vessels of the stomach lie in the peritoneum and send capil-

laries into the submucous coat.

The mucous coat is smooth

when the walls of the stomach are distended, but wrinkled
when the stomach is empty and its walls collapsed.
The stomach narrows at its lower or pyloric end and opens

into thesmall intestine (fig. 156).

Glands.—The mucous lining
is covered with minute shallow
pits,” the+sopenings,.one the
gastric glands. The glands fur-
nish certain enzymes, pepsin
and rennin, all of which aid
in digestion. The pyloric glands
(fig. 160), which furnish pepsin
only, lie in the pyloric end of
the stomach: 9 “The? yundus
glands in the cardiac part of
the stomach, are formed of sev-
eral kinds of cells, and furnish
pepsin, rennin and hydrochloric
acid.

The gastric juice containing
these enzymes acts in an acid

si 1 Kl a
he Ge fe (04
WE Sh 4 ye ef
ee Be y

4, ie) HE 2 AN E aN
BEBE NNN)
Ea Ne NN ENS
A
ae ee :
Yee) ee Say

Fic. 160. Section of pyloric
glands from human stomach.
a, mouth of gland leading into
a long wide duct (6), into
which open the terminal divi-
sions; c, connective tissue of
mucosa. (After Piersoe.)

medium upon proteid food, while the ptyalin of the
salivary juice acts in an alkaline medium and upon carbo-

hydrates.

The presence of food or food accessories in the stomach
stimulates the flow of gastric juice.

Pepsin,—This-enzyme changes proteid into a soluble form
called peptone. It acts at a rather high temperature.

Rennin.—This enzyme acts upon milk, causing it to coagu-
late or separate into curds (the proteid part) and whey (mostly

DIGESTION AND ABSORPTION 311

water). This separation prepares it for the action of pepsin.

Hydrochloric acid.—This secretion establishes the acid
medium necessary for the action of pepsin and may dissolve
some of the mineral salts.

The cardiac or fundic end of the stomach (fig. 156) acts
as a reservoir for the food as it leaves the oesophagus. Here
the food may remain for sometime while the starchy matter
is further acted upon by
the salivary juice.

In the pre-pyloric and
pyloric end digestion of
proteid is begun by the
gastric juice. This is the
second stage in digestion.
It results in a milky mass
called chyme, which in
part is ready for absorp-
tion and in part needs

Exes fee §6further treatment. ‘This

| passes in small amounts
Fic. 161. Mucous membrane of the . ‘ :
small intestine of the dog. A, artery; into the small intestine.

B, vein; C, capillaries; D, lacteals; The small intestine and

E, glands of Lieberktihn; Ep., epi- the intestinal juices.—The

thelial tissue. (After Cadiat.) : : :

intestine is a very long
coiled tube held in place by a fold of the peritoneum
called the mesentery. The mesentery is fastened at the
back to the spinal column.

The coats of the small intestine are similar to those of the
stomach. The inner surface of the small intestine is covered
with minute papille or projections called villi (fig. 161).
These are filled with blood vessels and lymphatic vessels.
Between the villi are numerous minute pores. These are
openings of tiny glands that secrete intestinal juices. Other
digestive secretions found in the small intestine are the bile
and the pancreatic juice,

x

Baa Sty
\

—
i

312 THE ANIMALS AND MAN

The liver.—This is the largest gland in the body. It
lies (fig. 159 Li) beneath the diaphragm, its lobes partly over-
lapping the stomach. Its cells, called hepatic cells, secrete
bile. Its duct opens into the small intestine near the pyloric
end. Unused bile is stored in a small sac or gall bladder con-
nected by a duct with the bile duct near its distal end.

The pancreas (fig. 156).—This gland lies along the
curvature of the stomach. Its cells secrete pancreatic
juice. Its duct joins the bile duct near its opening into the
intestine, so that bile and pancreatic juice intermingle while
entering the intestines.

Digestion in the small intestine.—This is due to the
combined action of the three digestive fluids mentioned,
intestinal quice, pancreatic juice and bile.

The intestinal juice furnishes an enzyme that acts upon
starches and sugars and upon fats. ‘The pancreatic juice
furnishes three enzymes, trypsin, amylopsin, and steapsin.
Trypsin, like ptyalin, acts in an alkaline medium. Like
pepsin it acts upon proteid converting it into peptone.
Amylopsin (diastase), like ptyalin, acts upon starch, con-
verting it into sugar. Steapsin (lipase) acts upon fat. Fat
is chemically composed of fatty acid and glycerine. This
combination must be broken up before fat can be made di-
gestible. When once broken up, the fatty acids unite with
the alkali present and form a soap which is soluble. This
process is saponification. Fat must also be broken up into
tiny droplets. This is emulsification. ‘These two processes
are accomplished by intestinal juice and steapsin.

Bile is alkaline and hence serves to neutralize the acid
chyme and prepare it for the action of the intestinal and
pancreatic juices. It also aids in emulsifying and saponi-
fying fats.

Digestion may be artificially demonstrated as follows. Procure from

a druggist some dry pancreatic extract. Dissolve 15 grs. of this in
2 oz. of warm water. (1) Half fill a test tube with this artificial digest-

DIGESTION AND ABSORPTION 313

ive juice and place in it a small amount of cooked starch. (2) In a
second tube, place a small amount of white of egg or other proteid
with the artificial digestive juice. (3) Ina third, place a few drops of
olive oil and artificial digestive juice. Leave these preparations in a
water bath or oven at 98° F. for 12 hours and note results.

When the food is thoroughly dissolved it has reached the
last stage of digestion. It is now ready for absorption.

Absorption.—We have learned that the blood carries food
to the deep seated cells of the body. The transfer of the
digested food through the walls of the intestine to the blood
is called absorption.

The sole object of absorption is to get the digested food
into the blood. ‘This takes it through the walls of the villi.
Fig. 161 represents a series of villi cut through to show the
loose network of blood capillaries and lymphatic capillaries
(lacteals) within each one. Lymphatic vessels are like blood
vessels in some ways but they carry a milky fluid and not
red blood. The mucous membrane of the intestine is
bathed by the digested food. To reach the blood and
lacteals, this digested food must pass through the mucous
membrane of the villi and the thin walls of the capillaries
and lacteals.

This is accomplished by osmosis (see page 298). Only
soluble substances can mix by osmosis, hence it is that starch,
proteids and other foods must be dissolved or digested before
they are ready for absorption.

Where absorption takes place.—A minute quantity of
peptone (derived from proteids) may be absorbed in the
stomach, and a small amount may pass into the large in-
testine and become absorbed there, but most of it passes
through the walls of the villi of the small intestine into the
blood.

The sugar (derived from carbohydrates) is absorbed into
the blood through the villi also.

The fats (as emulsions or soaps) pass into the lacteals.

314 THE ANIMALS AND MAN

Water and salts pass into the blood mainly in the small
and large intestine.

Alcohol is absorbed very quickly through the walls of the
stomach. Its quick action upon the body is probably due
to this fact.

Action of the liver upon nutrients.—Absorbed food is
carried immediately by a large blood vessel (the portal vein)
to the liver. Here it undergoes further changes before it is
distributed to the cells of the body. Here glycogen or liver
starch is formed of any normal excess of sugar in the blood and
held as a reserve supply. Here, also, any poisonous com-
pounds, that may have been absorbed with the food and
that might injure the tissues, are removed.

The large intestine.—During its passage through the
small intestine most of the digested food is absorbed, as we
have learned. The undigested parts of the food, together
with such poisons as have been collected by the liver, pass into
the large intestine and out of the body through the rectum,
by peristalsis. Constipation is the clogging of the rectum
or large intestine. Constipation is dangerous because the
poisons from the liver become reabsorbed. ‘This results
in biliousness, headache and often very serious troubles.

Hygiene of eating and digestion.—The body requires
that some proteid, carbohydrate and fat and water shall
be absorbed each day. The digestive system is regulated
to care for a certain amount only. If too much is demanded
of the alimentary canal, digestion is impaired and dyspepsia
results. Digestion is a ‘‘chain of results;’”’ first the cooking,
then the masticating, and finally solution in the digestive
juices. All this takes care and time. A poorly cooked
meal or a hurried meal means a partially digested meal.
Lack of the right kind of food and of exercise engender con-
stipation. Indigestion and constipation are the signs by
which we know that something is going wrong and must
be remedied.

DIGESTION AND ABSORPTION 315

Effect of alcohol upon digestion.—While the use of
alcohol may have a serious effect upon the activities of the
body as a whole, through its influence on the nervous system,
according to Chittenden and others it has little direct effect
upon digestion. ‘Their experiments have shown that it
leaves the alimentary canal and enters the blood very soon
after it reaches the stomach. In quantity it deprives the
system of its normal healthy appetite.

CHAPTER. XXIII

THE BLOOD AND CIRCULATION

BLOOD

We have seen that digestion prepares the food for the
cells and that by means of absorption this food enters the
blood. ‘The blood is the common carrier between the ab-
sorptive surface of the small intestine and all the tissues of
the body. It circulates within a closed system of tubes or
blood-vessels, and substances that pass into or out of the
blood must pass through the walls of the blood-vessels.

Composition of the blood.—If the finger is pricked with
a clean needle and a drop of blood placed on a slide and
looked at under the microscope, the blood will be seen as
yellowish liquid, containing a great many tiny round disks
and a few particles of irregular shape. The yellowish liquid
is the plasma, the disks and other floating cells are corpuscles
(red and white).

Structure and function of the red corpuscles.—The
red corpuscles are biconcave disks without nuclei and con-
tain a red pigment, hemoglobin. It is the function of
hemoglobin to carry oxygen to the tissues and carbon dioxide
from the tissues.

Structure and function of white blood corpuscles.—
The white blood corpuscles are of many sizes and without
definite form. They are colorless and nucleated. Many
of them move about in the blood plasma like amcebe.
Some of the white blood corpuscles (phagocytes) take up
from the blood foreign organisms such as disease produc-

316

THE BLOOD AND CIRCULATION 317

ing bacteria. The formation of immunizing substances in
the blood is attributed to leucocytes. Other corpuscles aid
in the absorption of fats while others aid in forming a clot
when a blood-vessel is wounded.

Blood plasma.—-The plasma is the fluid part of the blood.
It supports the red and white corpuscles. It is composed of
much water, a substance called fibrin, certain salts, absorbed
nutrients in the form of serum albumin, and certain wastes
(urea and acids) from the tissue cells.

Blood clotting.—Blood exposed to the air forms a clot
by the mixture of some of the white blood corpuscles and fi-
brin of the plasma. If a bowl of blood is stirred vigorously
the fibrin may be separated from the serum and blood cor-
puscles. Blood clot or coagulation protects against the
loss of blood when a blood-vessel is wounded.

The amount of blood in the body and its distri-
bution.—A grown person is provided with about six quarts
of blood which equals about one-thirteenth the weight of
the body. This amount is constant under normal conditions,
because the amount of food and oxygen given up to the tissues
is balanced by the amount of waste received. The supply of
blood to the heart and lungs, the liver and the skeletal
muscles equals about seventy-five per centum of the whole
amount in the body. It is distributed to the tissues accord-
ing to their needs. An active gland or an active muscle
requires more than a resting gland or muscle. During di-
gestion and absorption a large supply goes to the stomach.

Effect of food, fresh air, exercise and rest upon the
blood.—The healthy condition of the blood depends upon
abundance of fresh air to supply it with oxygen; nutritious
food and plenty of water to maintain the proper composition
of the blood plasma and to supply iron for the red corpuscles;
a sufficient amount of exercise so that all. the arteries and
capillaries may be thrown into activity; and sleep and rest
* that the demands of the tissues may not be too great a drain

318 THE ANIMALS AND MAN

upon it. A short rest gives the blood time to carry away the
wastes from the tissues.

CIRCULATION

In order that the blood may find its way from the absorp-
tive cells of the intestine to every tissue of the body and
from these to the lungs, it must circulate in a continuous
flow. This it does by means of a closed system of vessels,
the blood-vessels, and a pumping organ, the heart. The
arteries carry blood away from the heart to the system and
the lungs. The veins carry blood to the heart from the sys-
tem and the lungs. Tiny anastomosing (many branched)
vessels called capillaries connect the arteries and veins.

Structure and position of the heart.—In fig. 159 the
heart may be seen lying in its natural position, a little to the
left of the thoracic cavity, just above the diaphragm and. be-
tween the two lobes of the lungs. The apex points down-
ward and to the left.

The heart is enclosed within a sac called the pericar-
dium. The walls of the heart are thick and muscular
and are supplied with blood-vessels and nerves.

Internal structure of the heart.—The heart is divided
by a muscular partition into right and left halves, having
no intercommunication. Each half is separated into an
upper and lower cavity, the auricle and ventricle. The
right auricle opens into the right ventricle and the left aur-
icle opens into the left ventricle. The blood flows from the
auricles into the ventricles and out into the arteries. Fig.
162 shows the left side of the heart opened so that the inside
may be seen. ‘The opening between the left auricle and the
left ventricle is guarded by a valve, the mitral valve, with
two flaps (6,6). These flaps are fastened by strong cords
to tiny muscular pillars on the walls of the ventriculus (5,5 ).
The cords prevent the flaps from being forced backward
into the auricle when the heart beats.

THE BLOOD AND CIRCULATION 319

The opening between right auricle and right ventricle is
guarded by the tricuspid valve. ‘This is similar in structure
to the mitral except
that there are three
flaps instead of two.

The position of
these valves in action
is shown in figs. 163
ang. TOA.

Blood-vessels direct-
ly connected with the
heart.—The large
veins open into the
aurteles. .On”* the
right side of the heart
opening into the right
auricle there are three
VES, the ~ superior

Fic. 162. Left auricle and
ventricle opened and a
part of anterior and left
wall removed. 1, two
right pulmonary veins
cut short; 1’,within cavity
of left auricle; 2, wall
between auricle and ven-
tricle:3;. 37,3" > cut. walls
of ventricle; 4, portion of
wall of ventricle with
muscular pillar to which

tendons of mitral valve are attached; 5, 5, muscular pillars on inner wall

of left ventricle; 5’, within cavity of left ventricle; 6, 6’ mitral valve; 7,

commencement of aorta (with semilunar valve below); 7’, aorta; 8, root

of pulmonary artery and its semilunar valve; 8’, continuation of the pul-
monary artery; 9, artery connecting pulmonary artery and aorta; 10, arteries
arising from summit of aortic arch. (After Allen Thomson.)

vena cava (descending from the parts of the body above
the heart) the inferior vena cava (ascending from the parts

320 THE ANIMALS AND MAN

of the body below the heart), and the coronary vein arising
in the walls of the heart.

On the left side of the heart opening into the left auricle
there are four large veins, the pulmonary veins. Two of
these arise in the left lung and two in the right lung. Two
of these are shown at (1) in fig. 162. The large arteries
arise im the ventricles. «The aorta (7) arises in the left
ventricle and carries the blood that is to be distributed to

Fic. 163. Right cavities of the heart; auriculo-ventricular valves open,
arterial valves closed. (After Dalton.)

the tissues of the body. Its branches go to the tissues

carrying blood laden with food and oxygen.

The pulmonary artery (8) arises in the right ventricle and
carries the blood that is to be distributed to the air chambers
of the lungs. Its branches go to the walls of the lungs filled
with blood laden with carbon dioxide which is there ex-
changed for oxygen. The openings from the ventricles
into the arteries are guarded by semilunar valves shown
in fig. 16z. Their position in action is shown in figs. 163

THE BLOOD AND CIRCULATION 321

and 164. Thus we see that the flow of blood from auricle
to ventricle, and from ventricle to artery, can take place
in one direction only. In case of diseased valves there may
be a backward flow or regurgitation.

How the heart works.—The auricles are constantly fill-
ing with blood from the great veins. Both auricles contract
at the same time, the auriculo-ventricular valves open and
the blood is driven into the ventricles. The ventricles con-

Fic. 164. Right cavities of the heart; auriculo-ventricular valves closed,
arterial valves open. (After Dalton.)

tract at once and send the blood out into the great arteries.
The heart beat is the alternate contraction (systole) and
relaxation or expansion (dzastole) of the walls of the heart.
In man this occurs about seventy-five times per minute
under normal conditions. A child’s pulse is more rapid.
Systemic circulation.—We have seen that the | aorta
carries food and oxygen to the tissues. It passes anteriorly
from the left ventricle, then arches and passes posteriorly

322 THE ANIMALS AND MAN

and dorsally, forming thus the arch of the aorta (fig. 162,7’).
The dorsal aorta passes downward through the diaphragm
near the spinal cord (fig. 167) to the lower part of the abdom-
inal cavity. Here it divides into two great arteries, one to
each of the lower limbs, the common iliac arteries.

Branches of the aorta.—T wo small arteries, the coronary
arteries, leave the aorta near its point of origin. ‘These sup-
ply blood to the walls of the heart. From the arch of the
aorta (fig. 162) three large arteries pass to the head, neck
and shoulders. From the thoracic aorta, a number of small
arteries pass to the muscles of the thorax, the pericardium
and the oesophagus.

Abdominal aorta and its branches.—A series of arteries
arise from the aorta in the abdomen.

1. Two phrenic arteries passing to the muscles of the
diaphragm.

2. Celiac axis—a short trunk that soon divides into
three important branches supplying the stomach, liver, gall
bladder, pancreas, and first part of the duodenum, and
the spleen.

3. The superior mesenteric artery with its many branches
supplying the small intestine (except the duodenum).

4. The renal arteries, passing to the kidneys.

5. The iferior mesenteric artery, supplying the large
intestine and rectum.

All of these arteries break up into capillaries in the tissues
they supply. Thus the aorta, through its branches, supplies
blood to every part of the body.

The capillaries.—At the extremities of the arteries the
blood-vessels branch into finer and finer branches until they
end in vessels of minute size. These are the capillaries.
They penetrate the tissues of the glands, muscles, skin, brain,
etc. Capillaries with the blood corpuscles trickling through
them may be seen in a frog’s foot under the microscope.

The tissue cells are surrounded by a watery fluid

THE BLOOD AND CIRCULATION 323

called lymph. The capillaries are also bathed by lymph.

Composition and uses of lymph.—Lymph is composed
partly of water and partly of food material derived from the
capillaries through their walls. Lymph gives up food and
water to the tissue cells and receives from them, through
their walls, certain waste products. Oxygen also passes
from the capillaries through the lymph to the cells, and carbon
dioxide passes from the cells through the lymph to the blood.

We see, therefore, that the important changes in the
blood take place in the capillaries and that the lymph sur-
rounding the cells functions as a medium of interchange
between the blood and the cells. This interchange is ac-
complished by the process of osmosis (see p. 298).

The veins.—As the arteries break up into capillaries, so
the capillaries unite, after leaving the tissues, to form veins.
The blood that flows to the tissues through the arteries is
laden with food and oxygen. We have seen that much of
this is exchanged in the capillaries for carbon dioxide and
waste products. Hence it is that the blood in the veins is
laden with these substances and needs to be purified before
it again becomes fit for use by the tissue cells.

The blood is partly purified in the kidney, partly in the
liver, and partly in the lungs. The blood from the intestines,
stomach, spleen and pancreas, passes by way of the portal
vein to the liver. In the intestines it has gathered the di-
gested food, as already described on page 313. ‘The portal
vein breaks up into capillaries in the liver and some of the
particularly deleterious waste products and poisonous sub-
stances that may have passed into the blood with the digested
food, are here removed. From the liver the hepatic vein car-
ries the blood into the vena cava ascending and thus back to
the right auricle of the heart. Veins from other parts of the
body, as the arms, legs, and muscles, return the blood from
the capillaries of these parts, directly to the vena cava de-
scending and so to the right auricle (fig. 165).

324 THE ANIMALS AND MAN

This completes the systemic circulation.

Pulmonary circulatioa.—We have learned that the sys-
temic arteries carry blood away from the left ventricle, and
that the veins return it to the right auricle. In this circula-
tion the blood gathers food by absorption from the intestines,
gives up food and oxygen to all the tissues and gets rid
of certain waste products in the kidneys and liver, but it
must also get rid of the large amount of carbon dioxide
collected from the tissue cells. It does this through the
pulmonary circulation.

The blood received into the right auricle from the system
(through the vena cavas) is forced into the right ventricle
through the tricuspid valve. It is then pumped out into the
pulmonary artery which carries it to the lungs, as already
stated. The pulmonary arteries break up into capillaries in
the tissues of the air sacs of the lungs (fig. 176). Carbon
dioxide in the blood is here exchanged for oxygen. ‘The
blood thus purified is collected by four large pulmonary
veins, (d1e://1754 125; 14s, 15, 40)) and sents backeto-thesiert
auricle of the heart. Figure 165 shows the course of this
blood-flow as just described.

We see, therefore, that all the blood leaves the heart by
way of arteries and returns to the heart by way of capillaries
and veins. We see that it all passes through one set of cap-
illaries and that the blood from some of the organs (stomach,
intestines, spleen and pancreas) passes through a second set
of capillaries in the liver before returning to the heart.

How is the circulation of blood maintained >—The
circulation of blood is effected as follows: The muscular
ventricles pump the blood into the arteries. The valves be-
tween the ventricles and arteries prevent the reflux of blood.
The fine capillaries, because of their immense number and
small size, exert a certain resistance so that all the blood thus
pumped out of the heart can not at once pass through them.
The walls of the arteries are elastic and hence expand to ac-

THE BLOOD AND CIRCULATION 325

commodate whatever blood fails
to pass through the capillaries
durme thes heart beat. ' ~The
elasticity of the walls of the
arteries exerts sufficient con-
stant pressure to force the blood
through the capillaries between
heart beats. In this way the
amount of blood passing
through the capillaries between
heart beats equals the whole
amount that leaves the ven-
tricle at each succeeding beat,
and a constant flow is kept up.

The blood rushes very rap-
idly through the arteries, slowly
but steadily through the capil-
laries, and moderately slowly
through the veins.

During diastole the chambers
of the heart enlarge and fill
up with blood from the veins.
During systole this blood is
forced into the arteries.

The pulse.—During systole,
a wave of muscular contraction
begins in the auricles and ends
in the ventricles. This sudden
and forcible contraction of the
heart causes a wave of contrac:
tion to run throughout the
whole length of the arterial

Fic. 165. Diagram of circulation. 1,
heart; 2, lungs; 3, head and upper
extremities; 4, spleen; 5, intestine; 6, kidney; 7, lower extremities; 8, liver.
(After Dalton.)

326 THE ANIMALS AND MAN

system. This is the pulse wave. It may be detected by the
tip of the finger where the artery lies near the surface, as in
the wrist, and the rate of the heart beat counted. This we
call ‘feeling the pulse.”’ It is used by physicians to deter-
mine the condition of the heart; for conditions affecting the
heart will change the rate of the pulse beat.

Sounds of the heart.—The heart in action makes two
sounds, one—a long sound (lub), caused by contraction,
and another—a short sound (dub), caused by the closing
of the valves. These strokes are repeated about seventy-
two times a minute, day and night.

Nervous control of the circulatory apparatus.—When
an organ is at work it needs a greater supply of blood than
when at rest. After a meal the stomach and intestines need
a large amount of blood. During exercise, the muscles
need a large supply.

The caliber of the arteries of any organ is increased or
decreased according to the needs of the organ. During
activity of the organ, the caliber of its arteries is increased,
and hence the organ receives an increased supply of blood.
During rest, the caliber of the arteries is reduced and hence
part of the blood supply is shut off.

This increase and decrease of the caliber of the blood-
vessels is effected by the nervous system. ‘There are aug-
menting (hastening) and inhibiting (checking) nerve fibers,
passing from central nervous ganglia to each blood-vessel.

Effects of exercise upon circulation.—During muscular
activity, or exercise, the muscles need a large supply of blood.
The arteries of the muscles dilate and the heart increases
the rapidity of its beat. This results in a rapid supply of
blood to the lungs, a quick exchange of carbon dioxide and
oxygen, and a large supply of oxygen to the muscle. In
the muscle rapid metabolism is in progress which, if not
overdone, invigorates the whole system. The heart may
be weakened by over exercise or by vigorous exercise at

THE BLOOD AND CIRCULATION 227)

long intervals only. The heart must be trained by well
regulated exercise to respond to all demands upon it.

Regulation of heart action.—If a heart is cut off from
the living body it goes right on beating for a while. This
shows that cardiac or heart muscle differs from any other,
since it does not require an impulse from the central ner-
vous system to keep up its movements.

Inhibitory and acceleration fibers.—The heart is, however,
supplied with two kinds of nerve fibers which regulate the
force and rate of the heart beat. The acceleration fibers
stimulate the heart to beat stronger and faster. The inhibi-
tory fibers slow the beat and lessen its strength. The
nerve centers where these fibers originate are believed to
be stimulated by the products of muscular activity resulting
from metabolism. Thus the activity of one organ regulates
the activity of another and the work of one is adjusted to
the demands of the other.

Treatment of cuts and bruises.—In cases of injury
where the skin is broken, special precaution must be taken
in dressing the wound to prevent bacteria or other
microbes from infecting the wound and thus gaining entrance
into the circulation. Lockjaw and blood poisoning are
diseases that result from such infection. The first thing
to do, therefore, is to wash the wound and the skin about
the wound with a clean cloth or bit of absorbent cotton and
soap, and apply a disinfectant such as weak corrosive subli-
mate (1 part to 100 parts water) or peroxide of hydrogen.
If a large artery is cut, the high pressure in the arteries
will cause the blood to flow out in spurts. In this case,
the artery must be bandaged between the wound and the
heart. To do this press the artery firmly with the finger
until the blood ceases to flow. Then have someone tie
a knot in a handkerchief or bandage and twist this loosely
about the limb with the knot applied over the artery. Place
a stick under the bandage, and twist it until the constriction

328 THE ANIMALS AND MAN

is sufficient to check the flow of blood. If a vein is cut the
blood will simply ooze out and may of itself form a clot
that will stop the wound; if not, the blood flow may be
stopped by applying a bandage over the wound, first disin-
fecting it and drawing the edges of the wound together.

In the ‘case of a bruise, the skin is not broken, but the
tissue or blood-vessels beneath the skin are crushed. This
may cause a swelling and a dark appearance by the collection
of blood and lymph at the spot. Gentle rubbing or a hot
or ice-water application will ease the pain and keep down
the swelling.

Effects of alcohol on circulation.—The use of alcohol
may seriously affect the distribution of blood in the body.
By weakening the inhibitory impulses, the blood-vessels of
the skin become permanently dilated or enlarged so that a
large amount of blood is found in the skin. This disarranges
the normal adjustment of blood in the tissues. Such a
disarrangement is more serious in cold than warm weather
because it results in much loss of heat to the body.

CHAPTER XXIV

THE SKELETON AND MUSCLES

Two very important tissues of the body are the bones and
muscles.

The skeleton (fig. 166A).—The bones, of which there are
some two hundred or more in the body, are arranged and
joined in such a way as to form the skeleton. ‘The skeleton
fulfills three purposes:

(x). It is made use of by the muscles to enable the body
parts and the whole body to move about and handle things.

(2). It forms a framework to protect the delicate organs
of other systems.

(3). It gives form and rigidity to the body.

In man, as in other vertebrate animals, the axial skeleton
is formed of the bones of the skull, vertebral column or
backbone, ribs, and sternum. ‘The bones of the skull
protect the brain. The vertebral column encloses the long
dorsal nerve cord. The long, flat, curved ribs, articulating
at the back with the vertebral column and in front with
the sternum, protect the heart and lungs in the thoracic
cavity (fig. 159). The large hip bones (pelvic bones, figs.
166,S and 159, P) form a sort of basket for the support
of the organs of the abdominal cavity.

The bones of the legs and arms form the appendicular
skeleton. The leg bones articulate with or join the pelvic
bones, pelvic girdle, and the arm bones articulate with the
shoulder bones, or pectoral girdle. A comparison of the skele-
ton of the toad (fig. 9) with that of man (fig. 166 A)
shows that while the different bones vary in relative size and
shape, the same regions are laid down in each.

379

Q

SS
DPS

———
CA

\ AN
iy p \\\

{i ) ; fi
WEG 2
AY”

1} Zz

{
Ri

Fic. 166 B. Side view
of spinal column.
C-1 to 7, cervical ver-
tebree; D-1 to 12, dor-
sal vertebre; L-1 to
5, lumbar vertebra;
S. 1. sacrum; Co. 1-4
coccyx. (After Mar-
tin.)

Fic. 166 A, Bony and cartilaginous skeleton. a, left parietal bone of cran-

ium; b, frontal bone; c, cervical vertebra; d, sternum; e, lumbar verte-
bre; f, ulna; g, radius; #, carpals; 7, meta-carpals; k, phalanges; /,
tibia; m, fibula; , tarsal bones; 0, metatarsals; p, phalanges; g, pa-
tella (knee-pan); 7, femur; s, pelvis; ¢, humerus; uw, clavicle. (After
Martin.)

THE SKELETON AND MUSCLES 331

The vertebral column (fig. 166).—The long backbone
in man is composed of separate ringlike pieces, called verte-
bre, placed one above the other. Each has several lateral pro-
jections for the attachment of muscles and for interlocking
adjacent vertebre.
Rineavenue beg= ane
held together by
strong ligaments,
passing from one ver-
tebra to another. The
first seven vertebre
are called cervical or
neck vertebre. The
next twelve are the
dorsal vertebre. To
each one of these is
attached a pair of
ribs, as shown in fig.
Lope, we last: ive

= are the lumbar ver-
Fic. 167. Lower half of thorax with dorsal tebre. The single

and lumbar vertebre. A, sixth dorsal large bone below the

vertebre; Ao, aorta; D, (lower) dia- % oe
nes lumbar vertebre is

phragm; D, (upper) aorta passing through

diaphragm; I, intercostal muscles; O, the sacrum and the

oesophagus; IV, opening in diaphragm for cyrved tip at the end
vena cava ascending; T T, tendons of .- Aa nthe
right and left crura attaching diaphragm ~ Fe sea
to 3rd, and 4th lumbar vertebre. (After Sacrum 1S really com-

Allen Thomson.) posed of five vertebrze
fused together, and the coccyx of four bones fused into one.
Each of the twenty-six vertebre differs a little in shape
from its neighbor, but all are nicely adjusted to one another.

Between the vertebrz are pads of elastic cartilage. ‘These
act as cushions and prevent jarring of the vertebral column.

The ribs.—The ribs, articulating with the twelve dorsal
vertebre, are held in place by sheaths of connecting muscles

332 THE ANIMALS AND MAN

(fig. 167). Each of the first seven ribs is attached to the
sternum or breast bone by a rod of cartilage. The carti-
laginous ends of the next three join with the cartilage of the
seventh, while the remaining two are the so-called floating
ribs, joined only to the vertebral column (figs. 166 A, and 159).

The skull (fig. 168).—The skull is formed by the union

- —— === —
\ a = y |
ee * 2 4 2
» A “i é
{
|

Fic. 168. <A side view of the skull. F, frontal bone; P, parietal; S,
sphenoid; T, temporal; N, nasal; M, malar; S M., superior maxilla;
I M., inferior maxilla; O, occipital. (After Martin.)

of the cranial and facial bones. They are so fitted to one
another that they completely enclose the brain. Some are
perforated to admit the passage of nerves and blood-vessels.
The sphenoids and ethnoid bones form the floor of the cra-
nium. The occipital bone (O) lies at the back of the skull.
The temporal bones (T) form the sides. Within the tem-
poral bones are embedded the channels of the inner ear.

THE SKELETON AND MUSCLES 333

The parietals (P) lie above the temporals and meet on the
top of the head. The frontal bone (/) covers the front
part of the brain and forms part of the bony socket that
protects the eye. The facial bones are those forming the
jaws, the sides of the nose and the roof of the mouth.

Support of the skull.—The first spinal vertebra, the adlas,
supports the skull. ‘This bone articulates movably with the
second vertebra called the axis, and permits of much move-
ment, as nodding, turning the head, etc.

Pelvic and pectoral girdles.—The large pelvic bone (fig.
166 A-s) forms the pelvic girdle and contains the socket of
the hip-joint (fig. 171), by means of which the legs are ar-
ticulated with the axial skeleton.

The collar bones (clavicles) (fig. 159 C) and shoulder
blades (scapulas) (fig. 159 S) form the pectoral girdle. The
collar bones, one on either side, may be felt just beneath the
neck. They articulate with the sternum in front and at
their outer extremities with the upper bone of the arm. The
two large shoulder blades at the back, the scapulas, are held
in place merely by muscles attached to the ribs. At their
outer ends they also articulate with the humerus. ‘The pec-
toral girdle articulates with the axial skeleton through the
clavicles only. This adjustment permits a wide range of
motion to the arms.

Structure of a long bone.—A bone in a prepared skeleton,
or one picked up in the field after it has been exposed to
the weather for a long time, shows only the mineral matter
of which it is composed. It has lost all of its organic or
living material. A fresh bone, procured from the butcher,
shows the features indicated in fig. 169. At each end is
an enlargement or head, with certain protuberances for the
attachment of muscles. The ends are capped with dense
white elastic tissue or cartilage (fig. 170d). These are the
surfaces that articulate with other bones. The central shaft
(fig. 169, x-z) is covered with a sheath of connective tissue,

334 THE ANIMALS AND MAN

Ee
3

{keg

Cp

pte

the periosteum, which is bone-
forming material. Surfaces
for articulation with other
bones are smooth and covered
with cartilage (Cpl, Tr and Cp).

A bone, sawed through the
middle, as shown in fig. 170,
exposes a dense layer of hard
bone (b) enclosing, at the
ends, a spongy mass of bone
tissue (c), the spaces of which

,are filled with red marrow.

Here red blood corpuscles are
formed. The shaft encloses
a space filled with yellow
marrow (a). This is rich in
fat and gelatin. This struc-
ture secures the maximum
of strength for a given amount
of bone material. In the ribs,
or other flat bones, the entire
outer wall is dense and hard,
while the entire central part
is made up of a spongy mass
of bone filled with red marrow.

Chemical composition of
bone.—Bone is formed from
materials taken into the body
with the food, chiefly lime,
salts (mineral matter) and
Fic. 169. Right humerus seen from

in front. Cp, rounded surface of

upper extremity; Tr, Cpl, round-
ed surfaces of lower extremity.

Tmj, Tm, El, Em, prominences for attachment of muscles; Aa (x--z)
central shaft. (After Martin.)

THE SKELETON AND MUSCLES 335

organic compounds. Place a small bone
in dilute hydrochloric acid and leave it
for several days. The acid will dissolve
out the mineral matter, leaving the soft
parts, the cartilage at the ends, the
periosteum and the organic matter of the
bone tissue. The bone so decalcified
does not lose its shape but can be twisted
and bent without breaking. Burn a bone
in the fire. The organic matter disap-
pears leaving the mineral matter only,
which is now white and brittle. The
animal matter, therefore, gives the bone
flexibility, while the mineral matter gives
it stiffness.

Bone is nourished by blood that passes
in blood-vessels through the periosteum
into a series of microscopic canals that
perforate the bone tissue.

Joints.—Movements between the limbs
are accomplished by joints or articulations.
There are four classes of joints, the ball
and socket, like that of the femur or leg
with the hip bone; the hinge joint, as at
the elbow or ankle; the gliding joint, as
the wrist and knee joints; and the pzvot
joint as exhibited by the articulation of
as and atlas: in the neck... Figure 171
shows a perfect example of a ball and
socket joint, the hip joint. On the left,
the femur is shown held in place by bands
of strong ligaments (H L) attaching it to
the pelvic bone, and so arranged as to
give perfect freedom of movement. On

Fic. 170. Humerus,

bisected
wise.
cavity;

length-
a, marrow-
b, hard
bone; ¢, spongy
bone; d, articular
cartilage. (After
Martin. )

the right, these bands have been cut away to show the

336 THE ANIMALS AND MAN

rounded head of the femur (/) fitting exactly into the
socket and attached to its base by the capsular lig-
aments.

The surface of the ball and of the socket are each covered
with a smooth elastic cartilage to prevent friction. Cover-
ing the inside of the ligaments there is a thin membrane,
the synovial membrane, which secretes a thick viscid fluid

Fic. 171. Articulation of pelvis and hip-joint seen from before. (The
anterior half of the capsular ligament of the left hip-joint has been
removed and the femur rotated outwards.) F, femur; H L, capsular
ligament of hip-joint; S, sacrum; L, vertebral ligament inserted on
sacrum; L I, ligaments inserted on vertebrae. (After Allen Thomson.)

called synovial fluid. This acts as a lubricating fluid for
joints.

In a hinge joint, as at the elbow, the bones are so connected
as to admit of motion in only two directions, like a door
upon. hinges.

Dislocation, fractures and sprains.—A dislocation occurs
when the bones of a joint are forced out of place. ‘The bones
must be replaced at once by a physician. In the meantime
the pain may be relieved by hot or ice cold applications.

THE SKELETON AND MUSCLES 337

Fractures.—A fracture is a break in a bone, and usually
injures the periosteum and other tissues connected with the
bone. In an accident of this kind the physician brings
the two ends of the bones together and binds them between
splints until new bone is formed and the fracture healed.

Sprains.—The tearing, or pulling out of place, of a liga-
ment and muscles in the region of a joint results in a sprain.
The physician must bandage a sprain tightly and the patient
must rest the injured parts for many weeks. Relief from
pain before the physician comes is afforded by hot applica-
tions and by arnica or other liniment.

Comparison and composition of skeleton of child
and adult.—In very early life many of the bones are formed
of cartilage. Later the real bone tissue is formed that sup-
plants the cartilage except in the region of the joints. In
youth, when bone tissue is first formed it is comparatively
soft and flexible, the living or organic part far exceeding
the mineral matter. It is for this reason that bones are less
easily broken and more quickly repaired in youth than in
age. It is for this reason also that young people must
exercise much care in standing, walking and sitting correct-
ly, for in youth the skeleton is sometimes permanently de-
formed by incorrect usage.

THE MUSCLES

Arrangement and structure.—The muscles in the human
body, as in all animals, are the active organs of motion and
locomotion. Each muscle constitutes a separate organ,
composed of a mass of fibers collected in bundles and im-
bedded in connective tissue. The biceps muscle is a mass
of muscle fibers on the front part of the upper arm. When
the arm is hanging by the side at rest the muscle feels soft.
It is then relaxed and at its greatest length. When the arm
is bent at the elbow, the muscle is harder, shorter and bulges

338 THE ANIMALS AND MAN

slightly. It is now contracted. Fig. 173 shows this muscle
in both relaxed and contracted position. A muscle like the

SMERAY FEA RA:

‘ HAN

ee ERR Te eats

Fic. 172. Superficial muscles of trunk, shoulder and back viewed from
behind. A, external occipital protuberance; 1-1, trapezius muscles;
V’ oval tendon between right and left trapezius; 1” insertion of trapezius;
B, summit of shoulder (acronium); 2-2’, lateral muscle and insertion; 3,
sterno-mastoid; 4, deltoid; 5, infraspinatus; 6, teres minor; 7, teres
major; 8, rhomboideus major; 9, part of external oblique muscle of
abdomen. (After Allen Thomson.)

biceps is attached to two bones by strong white elastic cords
or tendons. One of the attachments serves as a fixed point

THE SKELETON AND MUSCLES 339

or point of origin of the muscle; the other as the point of
insertion. As the muscle shortens, the bone upon which
the muscle is inserted moves. In the biceps, the shoulder
blade is the point of origin, the radius of the forearm, the
point of insertion. Fig. 174 shows other muscles of the
forearm, inserted by tendons. In some parts of the body,
as in the back, the muscles lie in sheets, one upon the other,
and are attached at different places on the bones so as to
render many movements possible (fig. 172).

Certain sets of muscles are used for holding the body
ELECEs) OUNEES, 1Ane
used in moving the

ZR
whole body, as in ZN
walking, running or Ii 4
leaping; others for oe

moving parts of the
body as the arms,
the jaws, the eyelids,

eyes, etc. ir
These muscles are
entirely enclosed in \ DSS

a sheath of connec- —

tive tissue called Fic. 173. Biceps muscle and bones of arm,
perimysium. This illustrating flexion of elbow joint when

muscle contracts. (After Martin.
becomes extended ( )

at the ends as tendons. From the inner side of this sheath
partitions pass inward, separating the groups of reddish
muscle fibers into larger and smaller bundles, and binding all
together into a distinct muscle. ‘These partitions, or septa,
also afford support to the numerous blood-vessels and nerves
with which each muscle is supplied. Muscles of this type
have been called voluntary muscles because they are for
the most part under the control of the will. Such muscles
are also called striated muscles from their cross-striated ap-
pearance shown under the microscope.

340 THE ANIMALS AND MAN

There are certain other muscles that form expanded

membranes for enclosing cavities.

Fic. 174. Deep view of muscles and ten-
dons of right shoulder. A, brachialis
anticus; B, tendon of insertion of bi-
ceps (biceps removed); C,coracoid pro-
cess) On scapaila, (Cli clavicle: WH.
humerus; Sc, scapula with attached
subscapularis muscle. T-T, triceps.
(After Allen Thomson.)

These have no definite
point of insertion. Such
a sheet of muscle by its
contractions and relaxa-
tions exerts a pressure
that affects the move-
ments of the contents
of the cavity. Examples
of this we have already
found in the case of the
muscles of the heart and
arteries. Such also are
the muscles of yetive
oesophagus, stomach and
intestines. Muscles of
this type have been called
involuntary muscles be-
cause they are regula-
ted by the nervous sys-
tem without any control
of the will. Under the
microscope these mus-
cles present no appear-
ance of striations and so
have been called non-stri-
ated muscles.

Blood and nerve sup-
ply.—Since every muscle
of the body must be well
supplied with nutriment
and oxygen for its meta-

bolism and for the work it performs, all muscles of the
body are richly supplied with blood capillaries. These pene-
trate the connective tissues that separate the muscle fibers.

THE SKELETON AND MUSCLES 341

To each muscle also a nerve passes, distributing its nerve
fibers through the connective tissues to the muscle cells.
Without its nerve-supply, any muscle would be useless,
for the nerve centers must initiate and control every motion.

Hygiene of muscles; necessity for exercise.—Muscular
activity is absolutely essential to healthy living, and should
therefore be as much a daily habit as eating or sleeping.
Take a vigorous walk for a mile or two and note the result.
The day may be cold, but the body is soon aglow with
warmth, the heart beats more vigorously, the breathing is
deep and invigorating. What is taking place in the body?
The muscles are undergoing chemical change. Carbon
dioxide and other wastes are being thrown into the blood,
and large quantities of heat are being liberated so that the
temperature of the body rises considerably. ‘This calls
for a rapid supply of blood to the muscle cells, that there may
be a sufficient supply of food and oxygen. ‘The heart
responds by a quickened beat, driving the blood to the needy
tissues. The heat regulating apparatus is brought into
play. The small arteries of the skin dilate, and perspiration,
laden with water and waste, is secreted by the glands of the
skin. ‘The blood-vessels of the internal organs constrict,
reducing the blood flow to these organs. The respiratory
movements become deeper and more frequent, and, probably
most beneficial of all, the lymph circulation in the tissues
is improved. The lymph having no propelling organ like
the blood, is dependent upon the bodily movements, par-
ticularly the muscular movements, for its flow.

Muscular activity not only aids in the proper circulation
of food and oxygen, but in keeping the muscles at a proper
tension. An unused muscle becomes soft and flabby, and
tires easily when demands are made upon it. Those forms
of exercise are most valuable that call into play the greatest
number of muscles. Walking is perhaps the best exercise
because it exercises most of the body muscles and the

342 THE ANIMALS AND MAN

muscles of the lungs and heart, and so ‘“‘tones’’ up the whole
system. Exercise, to be of most value, should be regular.
It should not be taken immediately after a meal, because
then blood would be withdrawn from the digestive system
at a time when it is particularly needed there. ~

Fatigue and rest.—A feeling of weariness or muscular
fatigue follows prolonged exercise at irregular intervals, or
exercise of muscles occasionally used. If the heart has not
been trained by constant exercise to keep up a vigorous
movement of the blood, or if the heart is overworked, the
waste matter (carbon dioxide and urea) produced by muscular
activity accumulates in the tissues and the feeling of fatigue
follows. Thus the waste products, as such, fulfill an im-
portant function as indicators that rest is needed. A rest
of a few minutes, even, gives the blood time to carry off
the waste; and the feeling of fatigue ceases.

CHAPTER XXV

RESPIRATION AND EXCRETION
RESPIRATION

Cell breathing.—Cell breathing, the exchange of carbon
dioxide for oxygen, or the process of oxidizing the living cell,
is the essential act of respiration.

The amceba takes its oxygen from the water which sur-
rounds it, and discharges its carbon dioxide into the water.
Cells of the body take their oxygen from and discharge car-
bon dioxide into the lymph which surrounds them. From
the lymph carbon dioxide passes into the blood. The blood
carries it to the lungs. The respiratory or breathing appa-
ratus is a mechanism for supplying the blood with its needed
oxygen and for removing from the blood its load of carbon
dioxide. ‘The apparatus may be considered to consist of
the Jungs and the air passages leading into them.

Position and structure of the lungs.—The lungs (figs. 175
and 159 R. L., L. L.) fill the greater part of the thoracic
cavity. This cavity is lined by the pleural membrane which
folds neatly back over all the organs in the cavity. The lungs
are therefore suspended within this sac of pleural membrane.
The portion of the membrane covering the lungs is separated
from the portion lining the thoracic cavity by a liquid which
reduces friction between the two walls. The lungs are shaped
to fit around the heart which also les in this cavity. The
thoracic cavity is completely divided into two parts by a
partition of connective tissue, within which lie the trachea,
the oesophagus and large blood-vessels. One lung lies on

343

344 THE ANIMALS AND MAN

either side of the partition. The trachea (fig. 175, 3) divides
within the membranes into two branches or bronchi (fig.
175, 4) which pass through the membrane into the lungs.
The bronchi divide, in the lungs, into smaller and smaller

Fic. 175. Bronchi and lungs, posterior view, showing position of heart.
1, 1, summit of lungs; 2, 2, base of lungs; 3, trachea; 4, right bronchus;
5, branch to upper lobe of lung; 6, branch to lower lobe; 7, left bronchus;
8, branch to upper lobe; 9, branch to lower lobe; 10, left branch of
pulmonary artery; 11, right branch; 12, left auricle of heart; 13,
left superior pulmonary vein; 14, left inferior pulmonary vein; 15,
right superior pulmonary vein; 16, right inferior pulmonary vein; 17,
inferior vena cava; 18, left auricle of heart; 19, right ventricle. (After
Sappey.)

branches, each culminating in a minute vessel or bronchiole
(fig. 176) which ends in a small air sac or alveolus. ‘The
lungs are in reality masses of these tiny air sacs surrounded
by connective tissue. It is through the thin walls of the

RESPIRATION AND EXCRETION 345

alveoli that the interchange of carbon dioxide and oxygen,
which results in freshening the blood, is made.

Air, during respiration, enters through the nostrils into
the pharynx (figs. 156, 157). From the pharynx it passes
through the glottis into the larynx and trachea. The larynx
is the voice-box. The glottis is the opening of the voice-box,
closed at times by a flap called the epiglottis.

The respiratory and the
digestive paths cross in the
pharynx. During respira-
tion, the epiglottis 1s open
giving free passage for air
into the trachea. During
feeding it closes over the
glottis (fig. 157) so as to
admit the passage of food

a

al

Ke
nga

i
o

into the oesophagus only. fed oe x Er al

The heart lies in sucha 6") |S" Kotor &
position (fig. 175) as to be 4 SE ot i Oa :
able to send the blood ¢ ¥ a ap Sh Ay Na
through the pulmonary ar- “2 ba! Ye 7G
teries directly into the lung /4-

BSI The connective Drie. 176. <A bronchiole. B, entrance;
sue lying between the alveoli 4 p, alveolar passage: A ¢, air cells; I,
contains a mass of pulmo- infundibulum, or pouch into which
nary capillaries, and each ‘he ar cells open.

one of the infinite number of red blood corpuscles is exposed
separately to the air in the air cells. By this means the
hemoglobin of the blood corpuscles is kept saturated with
oxygen.

The mechanics of breathing movements.—Breathing
consists of inspiration, or taking the air through the air
passages into the air sacs of the lungs, and expiration, or
forcing air from the air sacs of the lungs out through the air
passages and nostrils.

346 THE ANIMALS AND MAN

To accomplish an inspiration, the thoracic or pleural cavity
must be enlarged. The pleural cavity is completely en-
closed, being bounded on the front by the sternum, on the
sides by the ribs with their intercostal muscles, and- on the
back by the backbone. The diaphragm forms the floor of
the cavity. This is a dome-shaped sheet of muscle (figs.
159, D and 167, D) convex upward. In ordinary breathing,
the muscles between the ribs, called intercostal muscles (fig.
167, I), the muscles between the backbone and ribs, called
elevators of the ribs, and the muscles of the diaphragm are all
brought into play. Contraction of these muscles elevates the
ribs and lowers the diaphragm, thus enlarging the cavity. The
air rushes in through the air passages and enters the lungs,
expanding the elastic lung tissue until it fills the enlarged
thoracic cavity. Immediately following inspiration the
diaphragm assumes its normal position, the intercostal and
elevator muscles relax, and thus the size of the pleural cavity
is reduced. The pressure of the walls of the thorax upon
the. lungs ~forces. ithe air; out and expiration. ‘takes
place.

The walls of the thorax move rhythmically normally sixteen
or eighteen times a minute. This rate is increased during
Exercise.

Composition of inspired and expired air.—The es-
sential components of air, from a physiological standpoint,
are oxygen, nitrogen and carbon dioxide. ‘There are a few
other elements, but they have not been shown to have any
physiological significance. There are also accidental con-
stituents of the air varying with the locality.

The following table, given by Howell, represents the
composition of ordinary inspired and expired air.

Carbon
Nitrogen Oxygen dioxide Water

TMISPIne A bee eh eye te ete eee ase 79 20.96 0.04
TURDITS Cra acne eet ok Beare ae 79 T6202, 4238 60

RESPIRATION AND EXCRETION 347

The air loses 4.94 parts of oxygen in the lungs, and
gains 4.34 parts carbon dioxide and .6 parts of water.
Notice that the amount of gases inspired equals the whole
amount of gases and water expired. ‘This indicates the
character and amount of exchange that has taken place in
the blood during its pulmonary circulation. ‘The blood is
thus aerated in the lungs. The presence of carbon dioxide
in expired air may be demonstrated by breathing through
a straw into lime water. Carbonate of lime will be
formed, giving the liquid a milky appearance. ‘The pres-
ence of water, as vapor, is easily demonstrated by breathing
upon glass.

Quantity of air breathed.—The lung capacity after the
deepest inspiration is, in a grown person, about 330 cubic
inches of air. About 30 cubic inches are inspired and ex-
pired during each ordinary act of breathing. This is known
as tidal air. During the deepest possible inspiration about
230 cubic inches of air enter the lungs. This represents the
vital capacity of the lungs. There is therefore at all times at
least 100 cubic inches of air in the lungs. This is the restdual
air which is kept aerated by diffusion from the tidal air.
Thus there is a constant supply of air in the lungs. This
allows continuous exchange between the blood and lungs,
while the exchange between the outer air and the lungs is
intermittent.

Hygienic habits of breathing.—Breathing should be
habitually deep in order to use all the parts of the lungs and
to have as large an amount of tidal air as possible passing
in and out of the lungs.

Occasionally the lungs should be tested to their fullest
capacity by the deepest possible inspirations. ‘This not
only effects as perfect ventilation as possible, but exercises
the respiratory muscles to their utmost extent, and exercise
of these develops the capacity of the lungs.

Effects of exercise upon breathing.—During exercise

348 THE ANIMALS AND MAN

there is an increased rapidity of tissue respiration. During
exercise also, the heart responds with a quickened beat and
the blood is carried more rapidly to the lungs. All this
quickens the movements of the respiratory apparatus so
that ventilation of the lungs may be more immediate and
complete.

This shows that the circulatory apparatus and the res-
piratory apparatus must work together. Deep breathing
would be of no avail were the heart not ready to respond by
a vigorous beat. When we run too hard, we get “out of
breath.”” This really means that the heart has become
fatigued, that it has been pushed beyond its normal capacity.

Exercise must therefore not be excessive, but it must
be vigorous and regular so as to keep the heart in training
for the demands upon it.

Effects of tight clothing on respiration.—Anything that
binds the walls of the thorax restricts the movements of the
respiratory muscles, the muscles of the ribs and diaphragm.
The result is that certain lobes of the lungs fail to enlarge
and hence remain unventilated. It is said that more than
sixty per cent of the beginnings of lung troubles are found in
the unused portions of the lungs.

Suffocation and artificial respiration.—Suffocation re-
sults from depriving the lungs of oxygen. ‘This may be
brought about by poisonous gases in the air, by obstruction
of the windpipe, or by drowning. Death may be prevented
in cases of suffocation if artificial respiration is resorted to
immediately. In artificial respiration the chest is expanded
and contracted artificially so as to induce an inflow of air
into the lungs. Three methods have been suggested.
In the first method the subject is placed face downwards
and pressure is exerted upon the back, then the body is
rolled from this to a lateral position. ‘The second method
is to place the patient upon his back; then raise the arms
above the head and body, and bring them down against the

RESPIRATION AND EXCRETION 349

sides of the chest so as to compress the chest. A third
method is to lay the subject face downward, placing a thick
folded garment beneath the chest. ‘The operator then puts
himself athwart or at the side of the subject, facing his head
and places his hands on each side of the lower part of the
back. He then slowly throws the weight of his body for-
ward to bear upon his own arms, and thus presses upon the
thorax of the subject and forces air out of the lungs. This
being effected, he gradually relaxes the pressure by bring-
ing his own body up again to a more erect position, but
without moving the hands. These movements are repeated
regularly, twelve to fifteen times per minute until normal
respiration begins or its possibility is abandoned. It may
require a half hour or more before independent breathing
movements start.”

Ventilation.—Ventilation is the circulation of the air
of rooms or buildings by means of which fresh air is brought
into the room and impure air removed. It may be accom-
plished by opening windows or by a mechanical ‘“‘system”’
such as is often used in public buildings. An open fire place
is a good ventilator. Ventilation must be rapid enough to
remove vitiated air but not so rapid as to cause a draft.

Where many people occupy the same room some system of
ventilation must be maintained or the supply of oxygen
would soon be exhausted. If we always lived in the open
air, as our ancestors did, there would be no need for arti-
ficial ventilation.

Foreign substances in the air.—In the air there is a
large amount of floating dust, as we can see by observing the
path of a ray of sunlight in the room. The cilia and hairs
that line the air passages normally prevent this dust from
entering the bronchial tubes. When rooms are carefully
and frequently cleaned and dusted with a damp cloth the
amount of dust in the air in an ordinary room is at a mininum
and is not injurious. If the room is carelessly swept and

350 THE ANIMALS AND MAN

dusted, the amount of dust in the air may be positively in-
jurious. The dust may, in addition, contain germs of dis-
eases. ‘This is especially true in the sick room. ‘Therefore
the sick room should have special care and no one should
enter except the nurse or caretaker.

EXCRETION

Besides the carbon dioxide that is thrown into the blood by
the tissues, during their activity, certain nitrogenous com-
pounds (the wastes) are also eliminated by the cells. As
there is a special apparatus for removing the carbon dioxide
from the blood so there are special organs for removing
the nitrogenous wastes. These are the organs of excretion.

They consist of the skin and kidneys. ‘The manner of
removal of nitrogenous waste from the blood is quite as
interesting as the manner of removal of carbon dioxide.

THE KIDNEYS

Structure of the kidneys.—The human kidneys are
located in the dorsal (lumbar) region next to the backbone
and immediately beneath the diaphragm. ‘There is one
kidney on each side. A duct, or ureter, passes from each
kidney to the urinary bladder. If a kidney is cut through
crosswise (fig. 177) the ureter (u) is seen to widen into a
cavity (p), the pelvis of the kidney. From the pelvis,
branches, called calices, extend into the kidney substance.
Of the solid part of the kidney there are two layers, the
cortex (c) and the medulla (m). The medulla is divided into
pyramids (pyramids of Malpighi) whose small ends (0) are
directed into the pelvis.

The renal artery (R. A.) enters the kidney at the /ilus, or
depression on the inner side of the kidney below the ureter,
and the branches of the renal vein (R. V.) leave it above the
Weer:

The pyramids in the medulla are composed of hundreds of
microscopic tubules (T). ‘These open by minute pores at

RESPIRATION AND EXCRETION 351

the points of the pyramids into the calices of the pelvis.
They extend back through the medulla and convolute
or wind about in the cortex. Here they form multitudes
of tiny capsules which surround a network of capillaries.
The branches of the renal artery pass into the connective tis-
sue of the cortex, giving off a few branches to the pyramids.

Fic. 177. Longitudinal section through the kidney, (pelvis and a number
of renal’ calices). U, ureter; C, cortex; M, medulla; P, pelvis;
T, tubules; B, blood vessel (arterial branch); R. V., branch of renal
vein; R. A, branch of renal artery. O, O, pyramids. (Tyson after
Henley.)
Then a branch enters each tiny capsule where it breaks up
into a little ball of capillaries called a glomerulus. From the
glomerulus a tiny vein passes to the tubules and there again
breaks up into capillaries. ‘This network of capillaries finally
becomes the branches of the renal vein. These leave the
kidney to carry the blood back again to the heart by way
of the vena cava ascending.

352 THE ANIMALS AND MAN

The cells which line the capsules and part of the tubules
are secreting cells (somewhat similar to those of the salivary
glands and of the pancreas). These cells secrete water, in-
organic salts and organic wastes (urea, etc.) from the blood.
Thus the blood gets rid of its load of waste products. These
accumulate in the tubules drop by drop, and finally exude
into the calices and into the pelvis of the kidney and are then
carried away to the bladder.

The amount of urine formed depends chiefly upon the
quantity of blood sent to the liver and upon the healthful
action of the kidneys. ‘The wastes of the tissues, constant-
ly accumulating in the blood, are as constantly being re-
moved by the kidneys.

Cool temperature, the drinking of large quantities of
water and the use of proteid food favor the healthy action of
the kidneys.

THE SKIN

The skin is a complex organ of the body that performs
several functions:

t. It protects the underlying structures as a covering.

2. It regulates the temperature of the body.

3. It receives the stimuli from without, by means of
which the body is guided in its behavior.

4. It serves as an excretory organ.

Structure of the skin.—The skin consists of two layers
(fig. 178), the epidermis (a), an outer or superficial layer,
and the dermis (d), a deep layer or true skin.

The epidermis is composed of epithelial cells. The
outer layer consists of flattened or dead cells that are con-
stantly peeling off. This is sometimes called the cuticle.
The inner cells of the epidermis are live growing cells,
constantly dividing and forming new cells to take the place
of those lost from the surface. The inner cells of the epi-
dermis contain pigment granules which give the skin its

RESPIRATION. AND EXCRETION 353

color. On the palms of the hands and soles of the feet
the cuticle becomes quite horny in structure.

The dermis or true skin is-largely composed of connective
tissue with a mass of blood-vessels, nerves, sweat glands and

Fic. 178. Section perpendicularly through skin. a, epidermis; 5, pig-
mentary layer of epidermis; c, papillary layer of dermis; d, dermis or
true skin; e, fatty tissue; f, g,h, sweat glands and duct; 7, k, hair
with its follicle and papilla; /, sebaceous gland. (After Brubaker.)

hair follicles. This part of the skin is very sensitive owing

to the numerous tactile corpuscles which are the end-organs

of the nerves (fig. 183).

Nails.—The nails are modified epidermal cells. The
growing part of the nail is embedded beneath the skin at
the base of the nail. The nail protects the ends of the
fingers and renders them more useful.

354 THE ANIMALS AND MAN

Hair.—Hair is similar to the nails in formation, that is
it is epidermal in origin. A section of a hair shows it to be
a long hollow shaft embedded at its base in a socket of
dermis called a hair follicle (fig. 178, k). The socket is lined
with an epithelial layer. The growing part of the hair is
the papilla at its base. ‘This is supplied with blood-vessels
and sensitive nerves. ‘These nerves are stimulated when a
hair is pulled. Connected with each hair follicle is a tiny
oil-secreting gland called a sebaceous gland (fig. 178, 1).
Its duct opens into the follicle and the secretion from the
gland is poured out on the surface about the base of the
hair, thus keeping the skin from becoming hard and dry,
and, on the head, rendering the hair glossy.

The care of the hair means the care of the skin where
the hair grows. The scalp must be kept clean and rubbed
that a good circulation may be maintained, and the hair
must be well brushed.

The scales of fishes and snakes, the hoofs and horns of
cattle, and the feathers of birds are, like nails and hair,
modifications of the epidermis and outgrowths from it.

Sweat glands.—The sweat glands of the skin are among
the most important glands of the body, and with the kidneys,
function as excretory organs.

These glands (fig. 178, f, g, h,) open in the tiny pits that
may be seen covering the surface of the skin. The base of
the gland lies coiled up in a little compact knot, deep in the
dermis or true skin (g, h,). Here it is surrounded by lymph
and numerous blood capillaries and is supplied with nerve
fibers. These glands are microscopic but very numerous,
probably 2500 or more to the square inch, so that their
combined secretion amounts to a great deal.

The skin as an excretory organ.—The principal waste
given off by the skin is water in the form of perspiration.
The amount varies under different conditions. Usually
it evaporates immediately so as to become invisible. During

RESPIRATION AND EXCRETION 355

warm weather when there is a large amount of blood in the
skin, water is collected in large drops upon the skin-surface.
As a result of muscular activity, and sometimes during
illness, other wastes are eliminated by the sweat glands,
particularly when the kidneys fail to function properly.
Hence it is that the skin is an important organ of excretion
and an important help to the kidneys.

Regulation of the temperature of the body.—The skin
has a still more important function to perform for the body,
and this is the regulation of its temperature.

The body must be maintained at a somewhat constant
temperature (varying from 97.5° to 99.5° F.) to fulfill its
functions normally and healthfully. During cell activity
much heat is generated. In a warm climate the body
receives heat also from the surrounding atmosphere. But
the temperature of the body can remain constant only when
the amount of heat produced within the body and received
from without is equal to the amount it gives out. Should
the amount produced and the amount received increase
above that given off, the temperature would rise abnormally.

The body gives off heat through the aid of the skin in
two ways. First, by radiation. The blood as it flows
through the organs where metabolism is going on, as the
muscles or kidneys, becomes heated. As it flows to other
organs less active it transfers part of its heat to surrounding
tissues by conduction. Or the heat may be radiated from
the surface of the skin, as heat is radiated from a stove.
This takes place when the atmosphere is cooler than the
body. The greater the difference in the temperature of
the atmosphere and that of the body the greater the amount
of heat lost and the more rapidly the body cools.

When, however, the surrounding atmosphere is warmer
than the body how is the body to be cooled? The changing
of a substance from a liquid to a gaseous state always requires
heat. Place a drop of ether on the finger and notice the

356 THE ANIMALS AND MAN

effect as it evaporates. ‘The feeling of cold is due to the
heat used up by its rapid evaporation. Or, moisten the
back of the hand and then blow upon the moistened surface.
Then blow upon the dry surface of the other hand. In
the latter case, the hand feels the warm breath. In the
former case the hand feels cool because the heat is used up
in evaporating the water. Thus, when perspiration forms,
it evaporates through the use of a large amount of heat.
This heat is furnished by the blood and thus the blood is
cooled. This is the natural means of cooling the body in
a warm atmosphere.

Importance of cleanliness.—Since the skin is an ex-
creting organ of some importance and a heat regulator of
much importance the tiny pores of the sweat glands must
be kept open and the skin must be kept clean. When
perspiration collects upon the surface of the skin, the liquid
part quickly evaporates or is absorbed by the underwear.

The solid substances remain upon the surface of the
skin. The cast-off epidermal cells collect there, as well as
the many foreign substances with which the skin may come
in contact. Even the dust in the air adheres to the oily
secretion of the sebaceous glands. Any of these substances
would soon clog the tiny pores of the sweat glands and of
the sebaceous glands were they not removed by frequent
bathing. Vigorous exercise before bathing adds to the
benefits of the bath by opening up the pores and covering
the skin with its natural secretions.

Treatment of burn.—In the case of burns or scalds the
outer epidermal skin, the natural protector of the dermis,
is separated from it and broken, so that the dermis becomes
exposed to the air. This is exceeding painful. A burn
should therefore be covered at once with a paste of baking
soda or thick oil. This will keep out the air and reduce
the inflammation. A mixture of lime water and linseed
oil is also a good remedy for scalds.

CHAPTER XXVI

NERVOUS: SYS EEM

General function of the nervous system.—The di-
gestive system takes care of the food we eat; it crushes it,
mixes it with digestive juices and gets it ready for the use
of the body tissues. The respiratory system furnishes the
blood with oxygen for the tissues. ‘The circulatory system
carries the food and oxygen to the tissues. The excretory
system eliminates waste from the body. The muscles by
reason of their property of contractility, enable the body to
accomplish all of its movements, whether voluntary or in-
voluntary.

The life of the cells of all the tissues, depends upon the
harmonious working together of all the systems. The activi-
ties of the body must therefore be co-ordinated. This is
brought about by the nervous system. Fibers from the cen-
tral nervous system pass to every organ and tissue of the
body. The distribution of nerves is so extensive that, as Dr.
Hardesty says, if all other tissues of the body could be “dis-
solved away there would still be left, in gossamer, its form and
proportions—a phantom of the body composed entirely of
nerves.”

The nervous system, therefore, controls and harmonizes
the functions of all the other organs of the body.

Structure of the nervous system.—In the human body,
the brain and spinal cord lie essentially as they do in the
frog and other vertebrate animals studied. The brain (fg.
179, F T O) is enclosed by the bony plates of the skull. It is
continued downward, as the spinal cord, through the spinal

Sei

Fie. 179 A. Central or-
gans of the nervous sys-
tem.) jb) 7. ©.) irontal,

temporal and _ occipital
lobes of the cerebrum; C,
cerebellum; P, pons varo-
lii; mo, medulla oblon-
gata; ms-ms, upper and
lower limits of the spinal
cord; CVIII, 8th cervi-
cal nerve; DXII, 12th
dorsal nerve. (Quain
after Bourgery.)

ANIMALS AND MAN

cavities of the vertebrae. Both brain
and spinal cord are further protected
by three membranes of connective tis-
sue. Of these the dura mater is the
tough outer coat. ‘The pia mater is
the delicate inner membrane. This
is closely applied to the surface of
the brain and spinal cord following
all the fissures. It is vascular, that is,
it contains the blood-vessels which
supply the cells of nervous tissue with
blood and oxygen and remove waste.
Between the dura mater and the pia
mater is an inner coat, the arachnoid
membrane. This membrane contains
large spaces filled with a fluid (the
cerebro-spinal fluid). ‘This, like the
serous fluids surrounding the heart and
lungs, is a protective fluid.

Structure of the brain (fig. 179 A
and fig. 179 B).—Like the brain of the
cat (see page 67) the human brain
consists primarily of three parts, the
fore brain, mid brain, and hind brain.
The fore brain or cerebrum is large and
conspicuous. It comprises nine-tenths
of the brain’s bulk and almost
completely covers the other parts.
This disproportion in size gives some
indication of its very great importance
as compared with that of the other
parts. The cerebrum is characterized
by many convolutions. Seen from
above its right and left halves (hemi-
spheres) are separated from each other

NERVOUS SYSTEM 359

by a deep fissure. They are connected below by a broad
nerve mass, the corpus callosum.

From the under surface of the brain, the other parts can
be made out. The fissure continues back to the mid brain.

Fic. 179 B. Ventral view of brain, showing origin of cranial nerves. I,
olfactory; II, optic; III, ocular motor; IV, patheticus; V, trigeminal;
VI, abducent; VII, facial; VIII, auditory; IX, glossopharyngeal;
X, pneumogastrie; XI, spinal accessory; XII, hypoglossal; ncl, ist
spinal nerve. (After Martin.)

The two long olfactory lobes project forward from in front

of the mid brain. The optic nerves arise from it. Posterior

to the mid brain lies the hind brain, consisting of the large

wrinkled lobes of the cerebellum (fig. 179 A, c), lying appar-

360 THE ANIMALS AND MAN

ently one on either side of the medulla oblongata. The two
lobes of the cerebellum are connected by a mass of nerve
fibers called the pons varolii (fig. 179 A). The medulla ob-
longata (fig. 179 A, mo) is continued ventrally into the spinal
cord.

Fic. 180. General plan of branches of trigeminal or fifth nerve. 1,
small root of 5th nerve; 2, large root; 3, placed on bone above opthal-
mic nerve, (with frontal, lachrymal and nasal branches); 4, superior
maxillary division; 5, inferior maxillary division; 6, chordi tympani;
7, facial; A, lachrymal gland; B, lower jaw; C, sub-lingual gland; D,
submaxillary gland. (After a sketch by Charles Bell.)

The cranial nerves.—The twelve cranial nerves arise

from the under side of the brain (fig. 179 B, I to XII).

(1) The olfactory nerves arise from the anterior end of
the olfactory lobes. ‘These pass to the nasal passages and
are the nerves of smell,

NERVOUS SYSTEM | 361

(2) The optic nerves pass to the eyes. They are the nerves
of sight.

(3) The oculo-motor nerves pass to certain muscles of the
eyes. They are the nerves that partly control the move-
ments of the eye-balls.

(4) The patheticus nerves go also to muscles of the eye.

(5) The trigeminal nerve goes to different regions of the
face and the salivary glands. Figure 180 shows the general
plan of branching of the trigeminal nerve.

(6) The abducent nerves, like the third and fourth, pass
also to certain muscles of the eye.

(7) The facial nerves go to the muscles of the head and face.

(8) The auditory nerves go to the ear. It is the nerve
of hearing. Its distribution is shown in figure 187.

(9) The glosso-pharyngeal nerves pass to the tongue
and other parts of the mouth and throat.

(10) The vagus or pneumogastric nerves go to the
oesophagus, larynx, lungs, stomach, heart and intestines.

(11) The spinal accessory nerves go to the neck and
shoulders.

(12) The hypoglossal nerves go to the muscles of the
tongue.

Each nerve consists of a mass of fibers surrounded by a
sheath of connective tissue. Each fiber is a fine thread-like
process continuous somewhere with a nerve cell. ‘That is, it
is a branch of a nerve cell. Each of the hundreds and thou-
sands of nerve fibers within a single nerve functions in-
dependently of all the others.

Internal structure of the brain.—If the brain is sliced
through or sectioned, the solid part will be seen to be com-
posed of two kinds of matter, white and gray. The gray
matter follows the outer surface of the brain and the folds,
and is known as the cortex of the brain. The white mat-
ter forms the core of the brain. The cell bodies of the
brain lie in the cortex. The fibers, passing from a cell

362 THE ANIMALS AND MAN

body in one part to a cell body in another part, or from a
cell body in the cortex of the brain down to the cranial
nerves or into the spinal cord, lie in or form most of the
white matter of the brain.

The spinal cord.—The spinal cord is an extension of the
medulla oblongata. It extends from the medulla (at the
foramen magnum or opening through the skull) through
the vertebral cavities to the lumbar vertebre (fig. 66 B).
It is shghtly enlarged in the neck region and again in the
lumbar region. It is protected by three coats, like the brain.
The cord is partly divided into halves by two deep fissures
(fig. 181). In the cervical and lumbar regions the cord

Fic. 181. Diagram of a simple reflex arc. 1, sensory surface; 2, afferent
nerve; 3, motor cell in gray matter of cord; 4, efferent nerve; 5, mus-
cle. (After Morat and Dayton.)

gives off a series of spinal nerves. These occur in pairs.

Each one arises from the cord by two roots, an anterior

and posterior (fig. 181). These roots unite to form the

single nerve on either side.

The posterior root of a spinal nerve is the sensory root,
the anterior one is the motor root. The posterior root
bears a ganglion, an enlargement of nerve tissue within which
is found a collection of sensory nerve cells. Fig. 181 shows
the relation of the gray and white matter within the spinal
cord. It shows also the path of impulses from the sensory
nerve ending in the skin (1) to the cell bodies in the gan-
glion and spinal cord, and from them to the muscle (5).

NERVOUS SYSTEM 362

Structure of a neurone or nerve cell.—A neurone,
commonly called a nerve cell, consists of a cell body and its

processes. ‘There are
usually several short
processes called den-
drites and one long
process or axon with
a central fiber or axis
cylinder. Dendrites
are usually branched
like the limbs of a
tree. The axon be-
comes the nerve fiber
of, the nerves. Im-
pulses pass to and
from the cell body
along the axis cylinder
Ol ethe: axons “Lhe
dendrites of each cell
body surround or
come into close con-
tact with the dendrites
of other cell bodies
so that communica-
tion is believed to be
established between
them; that is, an 1m-
pulse may travel from
one cell to another
through its dendrites.

External stimuli
have their origin in
agmerve Vending, in

Fic. 182. Diagram showing relation of
centers of language and their principal
associations. A, auditory center; V, visual
center; M, motor speech center; E, motor
writing center; O. O., intellectual center.
(After Grasset.)

some part of the body, as in the retina of the eye. Visual
stimuli are carried along the axis cylinders of the nerves to the

364 THE ANIMALS AND MAN

cortex of the brain where the center of sight, or visual center,
is located. The cells in the visual center transmit the im-
pulse to its dendrites. These dendrites are in contact with
dendrites from the auditory centers, the intellectual center,
the speech centers, etc. Any of these dendrites or all of
them may be stimulated. The stimulation might thus
result in speech, or in motion with the hands or feet, or it
might produce a thought (fig. 182).

The manner in which nervous impulses originate is
unknown, but it is believed to be due to the character of
the metabolism of the nerve cells.

Classification of nerve fibers.—A nerve fiber is either
sensory (afferent) or motor (efferent) or commisural. Sen-
sory fibers carry impulses from the cell endings in the tissues
to the cell bodies within the central nervous system. Motor
fibers carry impulses away from the cell body within the
central nervous system to the cell endings in the tissues.
Thus in fig. 181 the motor root contains a mass of
efferent fibers, while the sensory root contains a mass
of afferent fibers. A stimulus at 1 produces a motion at 5.
Commisural fibers connect cells within the central nervous
system.

A reflex action.—Such an action as that pictured in
fig. r8r is known as a reflex action, because it takes place
without the exercise of the will. In this case no impulse
passes up through the spinal cord to the brain calling into
play the intellectual centers, or consciousness. ‘The spinal
cord is the center of most, though not of all, reflex action.
Most reflexes are more complex than the one illustrated,
for a sensory impulse may stimulate several motor nerves
of the cord and a complicated set of actions may result.

Excitation and inhibition of reflexes.—Certain nerve
fibres carry impulses that excite action, while others carry
impulses that inhibit or keep from action the muscles or
glands to which they are distributed. We do not know

NERVOUS SYSTEM 365

whether there are separate sets of fibers for each of these
functions, but we know that in some way there are excitory
and inhibitory influences. ‘The function of the nervous
system to excite or to inhibit is very important with reference
not only to the control of the organs of the body but with
reference to its own interaction. Co-ordination could not
take place without it.

Hygiene of the nervous system.—Since the nervous
system is connected with every part of the body, and controls
and co-ordinates the work of every organ of the body, the
demands upon it are very great. The skeletal muscles
may rest during the activity of the digestive system. Or
the organs of the digestive system may rest while we play
our games or prepare our lessons. But the nervous system
must remain in activity or we will lose the game or fail in
our lesson. The nervous system therefore needs special
care so that in the hurry and rush of life it will not be so
overcrowded by work and worry that it will fail to respond
in a healthful way.

Things that cause nerve strain.—Unwholesome condi-
tions of living, such as overeating, eating at all hours, living
in poorly ventilated rooms, neglect of exercise and lack of
sufficient sleep, smoking and the use of alcohol; these are
the things that materially affect the health of the nervous
system.

It is often said of the business man, “he has nervous
prostration from overwork;”’ or of a student, “he is broken
down through overstudy.” Could we know the real facts
we should probably see in each case that the man or the boy
had neglected exercise, or taken the minimum amount of
sleep, or was suffering from the result of both these
mistakes.

While muscular exercise is refreshing and change of
occupation sometimes prevents undue demands on certain
sets of nerve elements, nevertheless every exertion costs the

366 THE ANIMALS AND MAN

nervous system something, and nothing can take the place
of the complete relaxation that comes through sleep. Every
child should sleep at least ten hours, and ordinarily every
adult at least eight hours each night. ‘Thus only can the
brain cells rest and recuperate for the next day’s activities.

Necessity of food and fresh air.—From what we have
learned of the function of nerve cells and of metabolism
of cells in general, we know that an active nerve cell is
constantly using up energy, and is constantly wasting away
and being rebuilt. This necessitates a constant supply
of nutriment and oxygen. The blood furnishes these to
the nerve tissues just as to all other tissues, hence when
we are eating proper food and breathing in the fresh air
we are satisfying the needs of the nerve tissues as well as
those of other parts of the body.

Effect of alcohol on the nervous system.—In its normal
healthy condition, the nervous system is an efficient regulator
of the bodily activities. It inhibits or excites the various
organs of the body according to their needs. We can
readily understand that any substance, which, when taken
into the body, interferes with the nervous system as a regula-
tor of the body, is a deleterious substance. This is what
alcohol does. Chiefly, it paralyses the inhibitory centers
so as to weaken or dissipate the control of the nervous
system. It causes an abnormal distribution of blood by
its action upon certain nerve centers. Dr. D. S. Jordan in
the ‘‘Popular Science Monthly,”’ Feb. 1898, sums up the
effect of alcohol and other stimulants upon the nervous
system in these words:

“The healthy mind stands in clear and normal relations
to Nature. It feels pain as pain. It feels action as pleasure.
The drug which conceals pain or gives false pleasure when
pleasure does not exist forces a lie upon the nervous system.
The drug which disposes to reverie rather than to work,
which makes us feel well when we are not well, destroys

NERVOUS SYSTEM 367

the sanity of life. All stimulants, narcotics, and tonics
which affect the nervous system in whatever way, reduce
the truthfulness of sensation, thought and action. The
man who would see clearly, think truthfully and act ef-
fectively must avoid them.”

CHAPTER XXVII

SPECIAL SENSES

Classification of special sense organs.—We have dis-
cussed in the previous chapter the mechanism which controls
sensory and motor impulses. ‘The peripheral end of each
sensory (afferent) nerve fiber is always a specialized structure
of some kind and is called a sense organ or end organ. Each
kind of sense organ is adapted to respond to a certain kind
of stimulus only. The impulse thus originated travels back
to the brain or spinal cord through the afferent fiber and the
brain then becomes conscious of a sensation, or a reflex
action results.

In former times it was customary to refer to the five
senses of man as sight, hearing, touch, taste, and smell.
The sense of touch has been shown by physiologists to con-
sist of four distinct qualities, pressure, heat, cold and pain.
For each quality there is a specialized end organ with its
particular fiber passing back to the brain. ‘These four sense
organs are grouped together as cutaneous sense organs be-
cause their end organs are found in the skin. Certain spots
in the skin respond only to pressure, others to heat, others
to cold. ‘The pain spots are most numerous and the warmth
spots least numerous. These spots may be demonstrated
by touching the back of the hand here and there with a
metallic point. You will notice, if the point be colder than
the hand, that certain spots feel pressure only, others pain,
and others cold. These different sensations are due to the
microscopic nerve endings, or end organs, that lie in the

368

SPECIAL SENSES 369

epidermal tissue of the skin (fig. 183). It is believed that
those end organs that give the sense of pain lie nearer the
surface, while those for the sense of warmth lie more deeply
in the skin.

The pressure spots are very close together at the tips of
the fingers and on the tongue, a condition which makes these
places very sensitive to touch. Most parts of the body are
covered with fine hairs. Physiologists have shown that
pressure points lie over the hair follicles, and that the pressure
nerve fibrils end in a ring surrounding the hair follicle. Any
movement of the hair, therefore, stimulates the nerve fibril.

Fic. 183. Papille of skin in palm of hand (epidermis removed). E,
end organ of nerve; N, nerve; B, blood-vessels; V, capillaries. (After

Sappey.)

Sense of taste.—The sense of taste is carried to the
brain through nerve fibers that have their end organs in
the mouth-cavity, particularly on the tip, the borders and the
back of the tongue.

The circumvallate papille shown in fig. 184 are the
largest taste papilla, but are few in number. In all of the
taste papilla there are found certain minute organs formed
of a mass of delicate cells each ending in a microscopic hair
which projects at the surface of the organ. These organs
are called taste buds and are the true sense cells, the hair-
like process being the part that is stimulated by substances

370 THE ANIMALS AND MAN

in solution. ‘There are four primary taste sensations, namely
sweet, bitter, salty and acid, and these are distributed to
different parts of the tongue. All other tastes are com-
binations of these. A taste sensation is aroused by sub-
stances in solution only.

Sense of odor.—The end organs of the sense of odor, or
the olfactory sensation, lie in the upper part of the nose,
just above the hard palate. They
are formed of groups of epithelial
cells each bearing on its free end
a little tuft of hairs. At the other
end, the cell as. continueds mito 7a
nerve fiber which passes back to the
olfactory bulb of the brain. During
inspiration air currents bring vapors
or gases into the nasal passages.
These are dissolved in the moisture
of the mucous membrane lining the
nasal passage and can then stimu-
late the hair-like processes of the
sensory cells. Substances that are
swallowed may send their vapors
into the nasal passage through the
Fic. 184. Upper surface of opening of this passage into the
the tongue, Ty eicumyal- “pharynx, and thus ome sometimes
late papilla; 2, fungi-form
papille. (After Brubaker.) COnfuses the sense of taste and the

sense of odor. The stimulation
caused by the flavors of fruits, for instance, while really
affecting the olfactory organs seems to affect the taste organs.

Sense of sight. Structure of the eyes.—The eyes are
complex structures nearly spherical in form and set deeply
into the sockets of the cranium. Procure the eye of a sheep
or calf of the butcher, and study its parts.

The eyeball is protected in front by movable folds of
skin called eyelids. The hairs along their edges serve to

SPECIAL SENSES 371

keep out dust and slightly to shade the eye. The lids are
lined with a mucous membrane which furnishes moisture.
This acts as a lubricant so that the eyelids close over the eyes
without friction. This meinbrane is also deflected over
the surface of the eye. On the upper outer side of the eye is
situated a gland, the lachrymal gland. This secretes a
salty fluid which also serves to keep the eye moist and clean
of dust. At the inner angle of the eye, next the nose, a tiny
duct ordinarily carries into the nasal passage any excess
of this secretion. If the membrane covering the eye is
irritated or strong emotion is aroused there is such a copi-
ous flow of this secretion that the tear duct fails to carry
it off and it overflows the edges of the eyelids as tears.

The orbit of the eye is lined with a fatty layer which forms
a sort of cushion for the eyeball. The optic nerve (fig. 185,0)
enters the eyeball from behind, through an opening in the
socket. This nerve is composed of fibers which pass to
the visual centers of the brain.

The eyeball is held firmly in place and moved from side
to side or up and down by six strong muscles. ‘These muscles
are controlled by motor nerves from the third, fourth and
sixth cranial nerves. The muscles of the eyeballs contract
and relax in pairs so that the eyes move together.

The eyeball consists of three concentric coats surround-
ing and enclosing certain transparent substances through
which the light passes to the inner coat of the eye. On this
inner coat the sensory surface is found.

The outer coat is the sclerotic coat (fig. 185,S), commonly
known as the white of the eye. It is formed of very tough
dense connective tissue, and serves as the main protecting
coat. In the front part of the eye, the sclerotic is trans-
parent and bulges slightly outward. This part is known
as the cornea (fig. 185, C). Within the sclerotic coat and
closely applied to it is the choroid coat (Ch). ‘This is a con-
nective tissue layer through which ramify the blood-vessels of

372 THE ANIMALS AND MAN

the eye. It also contains large quantities of black pigment,
so that no light can enter the eyeball except through the
corea. In the front, of the eye, where it meets the cor-
nea, the choroid coat leaves the sclerotic and _ projects
toward the long axis of the eye, as a circular muscular
curtain with an opening in the middle. This is the zris (1),
and is the part of the eye that we see as hazel, gray, or blue.
The pupil is the opening in the iris.
Where the choroid
5 SS coat leaves the sclerotic
coat it is firmly joined
to it by small but strong
and important muscle
processes called ciliary
processes (Cp). which,
with the suspensory lig-
ament (SL) hold the lens
in place.
Within the choroid
coat is “the )third sand

, innermost coat, called
Fic. 185. Horizontal section of the eye- Sao T!
ball. S, sclerotie coat; ch, choroid coat; the retina (R). 1€

R, retina; O, optic nerve; Cp, ciliary retina 1S composed of

processes; Cm, ciliary muscles; idens: sensory nerve endings

€ .cormea; = siriss, S54) suspensony. ae
ligament. (After Brubaker.) that are sensitive to
light. The fibers from
these nerve cells pass backward to the brain through the
optic nerve (QO).

Behind the iris lies the crystalline lens (fig. 185, L). Its
front surface is slightly flattened. The space between
the lens and the cornea is filled with a clear transparent
liquid, the aqueous humor. ‘The cavity of the eyeball back
of the lens is also filled with a transparent semi-solid or
jelly-like substance called the vztreous humor.

Functions of the eye.—In general structure, the human

SPECIAL SENSES 373

eye is like a camera. The cornea and lens of the eye cor-
respond to the lens of the camera, and the retina corresponds
to the sensitive plate.

The pupil of the iris determines the amount of light that
shall enter the eye.

How a lens forms an image.—A ray of light passing
from a rarer to a denser medium is bent or refracted from
a straight line. ‘Therefore rays of light when they enter a
convex lens as shown in fig. 186, are bent so that they all
converge at point A behind the lens, that is, they come toa
focus at this point. Thus rays of light from the arrow
AB cplacssam &
through the lens
form a picture on
the Telia “at 0—a.-

Accommodation
of the eye to different ee
distances.—A photo- |."
grapher changes the 7”
relative position of Fic. 186. Refraction of rays of light and for-

mation of an image on the retina. A-B, ob-
ject; b-a, image on retina. (After Brubaker.)

A

the camera lens and
the sensitive plate by
focusing for near or far objects. He increases the distance
between the lens and the sensitive plate, which is at the
back of the camera, for near objects, and decreases it for
distant objects. When a camera is focused for a near ob-
ject it will give only a very indistinct picture of a far object.
And so with the eye. Hold up a pencil in front of the eye
between the eye and the door. Upon looking at the pencil
you see it clearly but see the door beyond indistinctly. Look-
ing beyond the pencil to the door, the door is seen clearly
and the pencil indistinctly. The eye in looking first at
a near and then at a far object changes its focus. The walls
of the eye, unlike the walls of the camera, are immovable,
but there is a very neat arrangement for changing the

374 THE ANIMALS AND MAN

focus by changing the thickness of the lens. That is, the
eye accommodates itself, by a self-regulating mechanism,
to near and far objects.

The choroid coat exerts a constant pull upon the lens
through the suspensory ligaments (fig. 185, SL). This pull
slightly flattens the lens, that is, makes it less convex, so that
it will focus far objects upon the retina. But when the
ciliary muscles (fig. 185, Cm) contract they pull the choroid
coat forward so that it fails to exert a pull upon the lens.
The lens then, of its own elasticity, becomes more convex
and will then focus near objects upon the retina. ‘The invol-
untary movements of these muscles therefore enable the eye
automatically to accommodate itself to near and far objects.

Sensation of sight.—The sensation of sight is, however,
not located in the retina, but in a certain part of the cortex
of the cerebral hemispheres. The cells affected by the
light are in the retina. Nerve fibers from these cells pass
back, as shown in figure 182, through the optic nerve to the
nerve-centers of sight in the brain.

The essential parts therefore, of the sight-apparatus
are the retina, the optic nerve and nerve centers in the
brain. All the other parts are accessory parts to render the
function of these more perfect.

Hygiene or care of the eyes.—Because the eyes are
such extremely delicate structures they must be treated with
as much care as the most delicate piece of machinery.

Anything that affects the general health affects the eyes
very quickly. Therefore what has been said about good
food, fresh air and exercise being necessary for other parts
of the body applies to the care of the eyes as well.

Reading in a bright light, as with sunshine upon the
book, or in a dim light, as at dusk, weakens the muscles that
operate the lenses and the eyeballs. A flickering light is
exceedingly bad as it over-exerts the muscles of accommo-
dation,

SPECIAL SENSES 375

If the eye has a defect of structure, as when the eyeball
is too short or too long, the picture is blurred because the
image is not formed exactly upon the retina. We say we
cannot see clearly. When the image is formed in front of
the retina, the defect is called near-sightedness or myopia.
When the image comes to a focus back of the retina, the
defect is called hypermetropia. In case of either of these

Fic. 187. Semidiagrammatic section through the right ear. M, pinna;
G, meatus; T, tympanic membrane; P, tympanic cavity or middle
ear; R, Eustachian tube; r, fenestra rotunda; o, fenestra ovalis; V,
vestibule; B, a semicircular canal; S, cochlea; A, auditory nerve;
K, 1, 2, 3, 4, 5, cartilages; Vt, passage of cochlea opening into vesti-
bule; Pt, passage of cochlea opening into tympanic cavity; a1, 1, },
ampullz of the semi-circular canals; c, organof Corti. (After Martin.)

troubles glasses should be worn to overcome the defects,
otherwise the strain upon the eye, in its effort to focus sharply,
will be so great as to affect the nervous system seriously and
cause headaches.

Astigmatism is another common defect of the eye due to
irregular curvature of either the surface of the cornea or

376 THE ANIMALS AND MAN

that of the lens. This must also be corrected by glasses.
Only a good oculist, by careful examination of the eyes, can
tell the kinds of glasses that are needed for the various
defects.

Auditory sensations (sound and hearing).—The ear is
an organ specially adapted to receive vibrations of air and
to transmit them to the auditory nerve. It is made up of
three principal parts called the outer, middle and inner
ears.

The outer ear.—The part that we commonly call the
ear is known as the pinna (fg. 187, M). It forms a sort of
funnel or trumpet for catching the sound-waves, and leads
into a funnel-shaped canal, the meatus (G). The sebaceous
glands of this canal produce the wax of the ear. ‘This serves
to keep the ear drum or tympanic membrane (T) moist and
to render it flexible.

The middle ear or tympanic cavity (P) is lined with mu-
cous membrane and filled with air. The air is admitted to it
through the Eustachian tube (R) which opens into the pharynx.
The tympanic membrane forms the outer covering of this
cavity. This membrane is thrown into vibrations by the
sound waves that have passed through the meatus.

On the inner surface of the cavity of the middle ear are
two openings which, like the one on the outer surface are
covered with membranes, the fenestra rotunda (r) and the
fenestra ovalis (0). There is a chain of three small bones
strung across the cavity from the tympanic membrane to
the fenestra ovalis. ‘These bones are named from their
peculiar shapes, the hammer (malleus), the anvil (incus),
and the stirrup (stapes). One end of the malleus rests on
the inner side of the tympanic membrane, the other end
rests upon the incus. The incus lies between the malleus
and the stapes and the stapes connects the inner end of the
incus with the fenestra ovalis. Vibrations of the tympanic
membrane, due to air pressure on its outer surface, are

SPECIAL SENSES 377

transmitted to the inner ear at the fenestra ovalis through
these small bones. The air received into the middle ear
through the Eustachian tube serves to equalize the pressure
upon the tympanic membranes. When this tube is clogged
up with mucous, as when one has a cold, deafness re-
sults.

The inner ear consists of an irregular cavity hollowed out
of the temporal bone, known as the bony labyrinth. It
consists of three parts, the vestibule (V), the semicircular
canals (B) and the cochlea (S). The vestibule communicates
with the tympanic cavity by the fenestra ovalis (closed by
the stapes). It opens into the semicircular canal and into
the cochlea. These parts are all lined by a membrane, called
the membranous labyrinth. This membrane secretes a fluid,
the endolymph, which fills semicircular canals, vestibule and
cochlea.

One of the canals lies in a horizontal plane (when the
body is upright) while the other two lie in a vertical plane
but at right angles to one another. The membrane lining
the three canals contains a series of nerve endings. Nerve
fibers from the auditory nerve (fig. 187, A) are distributed to
these endings. Our sensations of position in space, or
equilibrium, are gained through the nerve endings of the
semicircular canals.

The cochlea is a complicated organ with a very delicate
set of sensory cells, known collectively as the organ of Corti
(fig. 187, c). These cells are the very delicate nerve
endings of fibers from another part of the auditory nerve,
as shown in the figure. The nerve endings in the organ
of Corti are stimulated by the vibrations in the endolymph
which bathes them. The endolymph receives vibrations
through the small chain of bones.

Care of the ears.—The inner ear is well protected and
can scarcely be injured by external causes. Colds or sore
throat frequently cause stoppages of the Eustachian tube

378 THE ANIMALS AND MAN

that may result in inflammation of the ear or deafness.
Such cases should be treated by a physician. The ear
should be guarded against sudden loud sounds lest they
break the tympanic membrane.

If it becomes necessary to remove an extra secretion
of wax from the meatus, it should be done by washing the
ear with warm water. Inno case should a sharp instrument
be used, lest the tympanic membrane be injured.

CHAPTER, XXVilI
MICROORGANISMS AND SANITATION

Microorganisms are the lowest forms of life. They are
invisible to the naked eye. They are often called germs or
microbes, and some of them are of the utmost importance
because of their relation to human welfare.

The plant microdrganisms which especially concern us
are known as bacteria. Animal microorganisms are known
as Protozoa.

Bacilli (rod-like), cocci (ball-like), and spirilla (spiral)
are all forms of bacteria. They multiply in number very
rapidly. In a few hours certain kinds increase from a few
individuals to 200,000,000,000.. This enormous rate of in-
crease makes them very powerful organisms in effect though
very small and weak individually. They may be found
almost anywhere. They abound in stale milk, in impure
water, and in decaying substances, in which they are indeed
the actual cause of decay.

Certain kinds of bacteria may be easily observed. Set
aside a glass of milk for a few days until it sours. Then
put a drop of the milk upon a glass slide under a cover glass
and look at it under the microscope. The little swarming
bodies, each consisting of a single cell, or speck of proto-
plasm, are bacteria. The souring of the milk is caused by
the action of the bacteria upon the sugar of the milk. Another
species may be observed by putting some dry grass in a dish
of water and leaving it for a few days. A scum forms on the
surface. Examine a bit of this scum under the microscope.
The myriads of tiny rod-like structures swarming about,

379

380 THE ANIMALS AND MAN

among which larger animalcule are darting, are bacteria.

Of the many kinds of bacteria some are useless to man,
some are of benefit, while many are positively dangerous.
Those found in the scum are probably harmless and may
even be beneficial as scavengers.

Bacteria feeding upon substances such as meat, fish,
milk, etc., decompose or rot them.

The importance of bacteria in the economy of our lives is
so great that it has given rise to a study called ‘‘bacteriology.”’

Beneficial bacteria.—When the farmer plows his field,
he turns under the soil the dry grasses from the top surface.
These are then attacked by certain bacteria which decom-
pose them and set free the chemical compounds of which they
are composed. These substances, mostly originally derived
from the soil, are thus again returned to the soil to enrich it
for the use of growing plants. The manufacture of cheese
and butter would be impossible without the aid of certain
bacteria.

Harmful bacteria.—For many years now, owing chiefly to
the work of Pasteur and Koch, it has been known that several
diseases that inflict mankind are caused by the parasitic
growth of certain microdrganisms in the human _ body.
These harmful microorganisms break down or poison the
blood or other body tissues and thus greatly derange the
normal functions. The derangement results in disease
and even death. It is of importance, therefore, for every-
one to know how to prevent the spread of such diseases
that result from the attacks of bacteria. ‘These are the
infectious and contagious diseases such as_ tuberculosis,
typhoid fever and diphtheria. Malaria and certain other
diseases are known to be caused by Protozoan microbes.
The cure of patients having these or other diseases
lies for the most part in the hand of the physician,
but the prevention of the diseases lies chiefly in the hands
of the individual and the community. The best rule for the

MICROORGANISMS AND SANITATION 381

individual to observe is so to regulate his diet, his exercise,
his rest, and his bathing that he may build up a healthy body
that will of itself be resistant to disease. He should also take
great care to avoid exposure to infection.

Bacteria or other microbes often gain entrance into the
system through impure milk, impure meat, impure water or
other impure food. One of the objects in cooking food is
to sterilize it thoroughly. Sterilization is the killing of all
bacterial life by the application of heat. Bacteria also gain
entrance into the system, sometimes, through wounds. For
this reason a wound, large or small, should be carefully dis-
infected as described on page 327, and should be bound
with disinfected or sterilized bandages. Strong acids, alka-
lies or other substances that will kill microbes are called
disinfectants.

Quarantine.—When a person is ill of an infectious or
contagious disease, it is necessary as a matter of safety to
other people to place him by himself, allowing no one to
enter the room but the nurse and doctor. Thus he is quar-
antined. When ships come into harbor from a foreign
port, they are placed in quarantine until the health officers
have examined the passengers so as to be sure there are no
persons on board with contagious diseases.

Disinfection.—After a patient has been ill of an infectious
or contagious disease, and before the quarantine has been
removed, the room he has occupied, with everything in it,
must be made germ-free. This is known as disinfection.
The burning of sulphur is an ordinary method of disinfection.
The fumes of the burning sulphur kill any harmful bac-
teria that may be in the air, in the clothing, or on the walls.
There are other disinfectants that are furnished or suggested
by Boards of Health.

Immunity.—During an epidemic, that is, when a con-
tagious disease as smallpox or diphtheria seems to be spread-
ing through a community, it becomes necessary to take ex-

352 THE ANIMALS AND MAN

treme precautions against it. Gradually physicians and
bacteriologists are discovering means of making people
immune or thoroughly resistant to diseases. The first step
in these discoveries is the thorough investigation of the
disease and the nature of its cause. The next step is to
find out what substance will, if inoculated or injected into
the blood, serve as an effective preventive of the disease.

Immunity from smallpox was discovered over a hundred
years ago in the use of the comparatively harmless vaccine
or virus of cowpox. ‘This was a great discovery and its use
has prevented the spread of many epidemics of smallpox.
The discovery of the use of antitoxin for the cure and pre-
vention of diphtheria has also been of great benefit to man-
kind. As science advances, other such means of producing
artificial immunity from disease will be discovered until infec-
tious disease will come to be largely under the control of man.

Public hygiene and sanitation.—In a large community,
there are always a great many careless and ignorant people.
It therefore becomes necessary to appoint boards and officers
to look after the public health. It is the duty of a board of
health, through its officers, to examine all the conditions af-
fecting the health of the people at large. It must examine
public supplies such as milk, water, ice, meats, etc. It must
examine the dairies that furnish milk to the community,
see that the cows are healthy, the buildings clean, and that
the milk pails and pans are thoroughly sterilized, etc. It
must look after the water supply, to be sure that there is no
opportunity for its contamination with impurities. It must
inspect the markets to see that no tainted meats or other
dangerous foods are offered for sale. It must see that the city
is well drained and that the sewers of houses are properly
connected with the city drainage system. In short, a health
board must take charge of everything that affects the health
of the people, and hence its duties are many and of the
utmost importance.

MICROORGANISMS AND SANITATION 383

In most cities there is a special “street cleaning” depart-
ment which attempts to have all rubbish and garbage re-
moved from the streets before it begins to decay so that
there may be nothing lying about of obnoxious or disease-
breeding character.

In many ways the city authorities can regulate conditions
so that fresh air, pure water and pure food are assured to
the community, but it is the duty of each citizen to have an
intelligent knowledge of the laws of hygiene and sanitation,
not only that he himself may run no risks but that he may
not be the cause of any risks to his neighbor or to the
community.

CHAPTER XXIX
ANCIENT AND MODERN MAN

The written history of man goes back about five thousand
years. The recorded history of the Greeks and Romans
dates from about ten centuries or less before Christ although
it is certain that the actual history of the Grecian people
is’) dar older, Whe vearliest. writings) of the) Chinese and
Egyptians and Arabians carry us back to a period three or
perhaps four thousand years earlier than the Christian era.
But it is also certainly true that the civilization of these
peoples extends far into prehistoric times. ‘Traces of the
ancient Ethiopian civilization of 10,000 years ago are claimed
to have been found.

Where history leaves off archeology takes up the work of
deciphering man’s earlier civilization and manners, and
where there are no more sculptured stones and pictured
walls discoverable, the student of geology and paleontology
and the student of anatomy unite to interpret the story
told by exhumed bones and relics of man and his earliest
animal companions.

Bones of undoubted human origin have been found in
long-buried caves with those of the mammoth, the cave-bear
and other extinct animals of Glacial times. There is no
doubt that man lived on this earth at least as far back as
the beginning of this present geologic epoch, the Quaternary
(or Pleistocene) and it is probable, though not proved to
anything like the unanimous satisfaction of anthropologists,
that he existed in late Tertiary times.

At any rate the human species, upright, large-brained,
with wit enough to chip flints into rough weapons, and to

384

ANCIENT AND MODERN MAN 385

make fire, and probably capable of speech, lived on this
earth one hundred thousand years ago. Some geologists
make this distance backward in time a shorter one by half;
most make it twice as long. At least it was back to the days
of great wild animals now extinct, and when other animals
and plants that now live only in the Arctic regions lived in
middle Europe.

During the Quaternary epoch four successive large animal
species have lived in and disappeared from France, namely,
the cave-bear, the mammoth, the reindeer and the aurochs.

Fic. 188. Specimen of Indian picture-writing. (After Lubbock.)

Man has lived contemporaneously with them all. He used
their flesh for food and has left representations of them in
rude carvings and drawings. All through these times he
used stone implements chipped and shaped by his hands.
These relics exist by thousands in all the great museums
of the world. And, besides, as we shall see in a moment,
the early Quaternary man has left his own bones to prove
even more positively his existence.

From a geologic epoch earlier than Quaternary there
are in existence certain suggestively shaped pieces of flint,
called eoliths, concerning which a great strife rages among

386 THE ANIMALS AND MAN

the scientific men. Some say they show the indubitable
crude work of earliest man; others say that their shape
and chipped character are due to the fortuitous action of
the elements. If these eoliths are of human shaping, the
dawn of man’s history goes very much farther back than
we now know it to go.

The English anthropologist, Abbott, has lately drawn a
word picture, on the basis of his discoveries near Hastings,
of a scene from the life of prehistoric man:

Fic. 189. Vertebra of young reindeer with flint arrowhead imbedded in
the bone. From the Cave of Perigord, France. (After Lartel and
Christy.)

“In a corner formed by the cliff face and a projecting
fissure wall squatted one of the old fellows chipping away
at a flint, a heap of which lay by his side. In his hand was a
hard-worn quartzite hammer-stone, one of the most cherished
objects of his life. Near him crouched his wife, and possibly
offspring, collecting the flakes he struck off, and sorting
them into little heaps according to the purposes for which
they were suitable. Near him was another old fellow,
working away at one of those beautiful bi-concavo-convex
ridged-back, finely-worked, round-based, spear tips; he
had finished the prize all but one blow, which would have

ANCIENT AND MODERN MAN 387

removed the implement from the flint block in a finished
condition, when he, too, stops of a sudden. Near to him
are several others splitting bones either for their marrow
or for material for implements, etc. One old fellow has
broken a leg bone of one of the trophies just secured in the
chase; beside him are two pointed flint wedges. He has
already inserted one into the narrow cavity, and the bone*
is splitting in several places but the skeletal element is firm
and healthy, and grips the wedge tightly, and splitting re-
quires force applied several times.

Fic. 190. Drawing of mammoth on piece of mammoth tusk. From
the Cave of the Madeleine in southwest France. The drawing was
made by prehistoric man of the early Post-Glacial times. (One-
third natural size of the drawing.)

“A little farther away there is a fire on the hearth which
has baked the underlying loam into a red brick for several
feet in extent. Over this is roasting a boar’s head, till the jaw-
bones are becoming so exposed that before the great episode
of the evening is finished they will all be reduced to charcoal.
Near at hand there are also several of the community en-
gaged in taking off the damaged flint points broken in the
chase, and replacing these truncated butt ends with new
flint tops; consigning these broken portions to the accumu-
lating midden or refuse heap. ‘The number of these flint
butt ends that have accumulated tell us that these flint

*Now in the British Museum,

388 THE ANIMALS AND MAN

tools, whether on sticks or sinews as fish hooks, or bound
to hafts or reeds, suffered greatly in use, and required periodi-
cal replacing. At this moment an esteemed implement
has come into the hands of one of the old fellows. It is
broken asunder across its center, and out of some respect
for it he is putting a new point to it, working off those delicate
minute flakes in the manner characteristic of the race. He
has run his bone flaker up one side, and left an edge such
as no other system of flint working can produce. He has
just begun the other, and apparently in a minute or two

Fic. 191. Drawing of a feeding reindeer, on a piece of reindeer horn.
From the Cave of Thayngen, Switzerland. (After Mark.)

bi-symmetry will again be obtained with a sharp piercing
point as a result, but he stops just as suddenly! Near him,
upon the hot ashes of a fire, stands the coarse earthen pot,
the prototype of our modern tar kettle—the earliest saucepan
we know; its bottom and sides are incrusted with a thick
layer of soot, telling of the withstanding of the ordeal of
fire accompanying many an evening meal, while close by
is a pile of calcined flints beneath burning wood, cooking
a clay-invested rabbit. Near by are several flat-bottomed
vessels, the prototypes of our first saucers or basins, although
the soot upon their bottoms tells the tale of their having

ANCIENT AND MODERN MAN 389

been put upon the blazing fire. Everyone is busy; everyone
appears intent upon what he is doing, when an alarm is
raised, and everyone in the settlement has stopped what he
is doing. Itis the enemy! Down goes the core upon which
the first man is engaged; even his cherished quartzite
hammer is dropped in the alarm. Down goes the marrow-
bone, with the flint wedge firmly gripped, and down is
thrown the implement finished all but for one blow. The
pot is left upon the hearth, the heap of hot stones, and
everyone flees for dear life, which, in all probability is barely
saved! From the discovery of human bones it is probable
that all did not escape, and g.

those who did were afraid to —
come back again for a long
period; and between this time
and renewed operations the Fy¢. 192. Drawing of a naked
Zephyrs and good old Aeolus man, with short spear, hunting

hed caesar plow: wild horses. From the Cave of
P the Madeleine, France; carved

sand over it all, and thus on the handle of a primitive bone
preserved the picture of the ornament. (After Lartet and
times for thousands of years, P™S*Y.)

to delight the soul of the prehistoric archeologist at the
close of the nineteenth century, A. D.”

The oldest actual human bones are those found in various
places in Belgium, France, Germany, Croatia and elsewhere
in Europe in geological formations far more recent than
those of the eoliths. They all come from Pleistocene
(Quaternary) formations. Our prehistoric ancestors, repre-
sented by these grim relics, have been called the Neanderthal
man, the Spy man, the Krapina man, the man of Correze,
etc., depending on the location of their final resting-place.
And all of them agree in revealing certain characteristics
which show that they were men of a lower order of develop-
ment than men of historic times. In all, the brain cavity
was much smaller than ours, the forehead was low and re-

390 THE ANIMALS AND MAN

treating, the jaw prominent but with little chin, and in some
the leg bones seem to be a little bent as if the erect posture
were not so perfectly acquired as now. In fact anthropolo-
gists are pretty well agreed to call this early prehistoric man
the primitive or fossil man, Homo primigenius, to distinguish
him from historic man, Homo sapiens.

The general course of human development from the dawn
of man up to the present is indicated by the names that have

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See

Er,
ik Se

Fic. 193. Remains of the Neanderthal man, in the Provincial Museum
of Bonn. (From Weltall w. Menschheit).

been given to successive periods in this long history.

The first period is called Paleolithic or Old Stone Age,
when man was contemporary with the cave-bear and mam-
moth, rhinoceros, reindeer and hyena in Europe and with
other ancient animals in Asia and Africa and perhaps Brazil.
No indubitable remains of paleolithic man have yet been
_ discovered in North America. The Calaveras skull of
California nor the Lansing man of Kansas nor any other
of the few American remains which when first found were
attributed to the man of prediluvial times have been able

ANCIENT AND MODERN MAN 301

to prove their claim to such remote antiquity. The mound
builders and Aztecs were human beings of times far younger
than those of the first men.

The Old Stone age seems to have been a very long one
and is sometimes divided into the Mammoth Age, and the
Reindeer Age.

The next general period was the Neolithic or Newer Stone
Age when man’s weapons and implements were of polished
stone and he set up large stones as monuments and used
caves and grottoes for burial as well as for dwelling-places.

Fic. 194. Skull cap of Pithecanthropus erectus, the fossil man-like ape
of Java. (Shown from above and in profile; from Weltall u. Mensch-
heit.)

This was not a long period but different races of man seem

to have arisen in it and there were great wars and migrations.

Next came the Metal Age, usually subdivided into the

Ages of Copper, of Bronze, and of Iron, according to the

kind of metal chiefly used for implements. Thousands of

relics of these ages exist in the museums, and evidences of
much differentiation and dispersal of races, with varying
manners of life, are plain.

From these ages, still prehistoric, man slowly emerges
into the light of decipherable history. The great variety

392 THE ANIMALS AND MAN

and abundance of his tools and specially constructed dwell-
ing and burial places; the carved sculptures and pictures
and inscriptions on his monuments and walls; the remains
of his food and clothing exhumed from graves, all taken
together constitute material enough for the archeologist to
begin writing the story of human civilization. It includes
the history of the shell-fish eaters of Denmark whose kitchen
middens or shell heaps were a thousand feet long, two hun-
dred feet wide and three feet thick; of the ancient lake
dwellers of Switzer-
land and Italy and
Austria and France;
of the Sardinian build-
ers of great monu-
ments called Nuraghi;
of the broch builders
of Scotland and the
dolmen makers of
Brittany and _ other
parts of the world;
and of still other an-
cient races known to

Fries /1955 Skull of ancient) man=trom the ok by special relics
Cave of Spy, Belgium. (After Fraipont’s OF Constructions. It
photograph of the original in the Museum js all a fascinating
of Liege; from Weltall u. Menschheit.) story Saavel sale youth

should fail to read some good telling of it, such as Joly’s
‘Man Before Metals.”

As man lives on the earth today he looks upon himself,
and rightly, as a kind of organism very far removed from all
other kinds and as one of great unity of character. But he
recognizes within this large and distinctive unity a consider-
able diversity in stature, color, hair-shape, degree of mental
development, language and manner of life generally repre-
sented by men of various tribes and races. It is said by

ANCIENT AND MODERN MAN 393

philologists that more than tooo different languages are
spoken on the earth today. The distinct man races are
not so many as that of course, but these many different
languages suggest in some measure how various living man is.

The differences in men are mostly correlated pretty closely
with geographical distri-
bution and are readily
discovered to be also and
more importantly cor-
related with genealogy.
On these differences are
based the separation of
the man species into
many races of closer or
wider relationship and
hence similarity of ap-
pearance and_ behavior.

The »taces-or- man
arose far back in _pre-
historic night. Some of
these races have disap-
peared but new ones
and more have taken
their places. There are Fic. 196. Lower jaw bones of 1, pre-

See Ca ed historic man, found in the Cave of
existing ay the Naulette, Belguim; 2, a Melanesian

havea! hte but little savage of the New Hebrides Islands;
above that of the men 3, a modern Parisian. Note the mark-

Gi rue Stone Age. The eee development of chin.
Fuegians of Patagonia

and the savages of Australia use stone and bone implements
of crudest character. The New Caledonians use polished
stone and rough iron implements. The Weddas of Ceylon,
the Akkas and Bushmen of Central Africa and the Papuas
of Melanesia live in a stage of barbarism, and even have a
physical makeup, much like that of prehistoric man. They

394 THE ANIMALS AND MAN

are indeed a sort of living link connecting Homo sapiens
with Homo primigenius.

Different anthropologists and ethnologists classify and
catalogue the existing human races differently but they are in
pretty fair agreement about the principal categories. Four
basic great groups are generally recognized, namely, the
Ethiopic, the Mongolic, the Caucasic and the American.
The Pacific island-inhabiting peoples of Melanesia, Malaysia,

Fic. 197. At right, a carved flint from Denmark, of the Old Stone Age;
at left, a polished stone axe head from Ireland, of the New Stone Age.

Polynesia and Australia may also be grouped together as
a fifth or Insular and Littoral race. Each of these races
is probably independently traceable back to Pleistocene
man. Within each one of these great groups are several
sub-groups or branches, as the Northern, Central and
Southern branches of the American race; and in each branch
are one or more stocks as the Arctic, Atlantic, and Pacific
stocks of the Northern American; and finally each stock
may include several groups or peoples, as the Tinneh, Al-
gonquin, Iroquois and other peoples of the Atlantic stock.

ANCIENT AND MODERN MAN 395

The differences among these races, branches, stocks, etc.,
are originally largely the outcome of different environments.
By the early migrations of prehistoric man the different
parts of the great continents and the principal islands were
successively reached and inhabited. But all these regions
differ more or less from each other in their temperature,
humidity, amount of sunshine or cloudiness, freedom from
or prevalence of storms and rigorous conditions of life,
abundance and kind of vegetation, presence or ee of
rivers, lakes and ocean, etc., etc. .
These physical differences of
environment have certainly chief-
ly determined the stature, color,
brain development, hair charac-
ter, size of teeth, prominence of
jaws, muscular conditions and
other structural characters on
which race distinctions are made.

These structural conditions
are, of course, intimately allied
to physiological and mental and
moral conditions and habits. Fi. 198. Head of the “Hot-

: : : tentot Venus ” from a mould
Indeed, this alliance or relation taken after death, now in the
is partly that of cause and effect. Paris Museum of Natural
Ethnologists recognize physiolog- History. (After Quatrefages.)
ical and mental and moral differences among peoples just
as they do structural differences and use these differences to
help trace out racial and stock relationships. Likeness and
unlikeness of language have been of great service in the study
of relationships. But for the actual distinguishing and
classification of different peoples physical characteristics
are used first of all and given most weight.

The characters chiefly relied on to distinguish races and
stocks are shape of skull, shape of nose, eyes, jaws and whole
face, width of pelvis, color of skin, and character of hair.

396 THE ANIMALS AND MAN

For example, all the various peoples and stocks and branches
of the American race agree in having coffee-colored skin,
straight or wavy hair and medium nose. ‘This race has
great unity of type although it ranges over two continents
from the Arctic to the Antarctic regions. The most developed
early peoples of the race lived in Mexico and Peru; the
lowest lived and still live in Patagonia.

All the white peoples belong to the Caucasic or Caucasian
race. The name is not a good one because it suggests an
origin in the Caucasus, which
it did not have. ‘The Ameri-
can ethnologist Brinton
maintains that it undoubted-
ly arose in Southern Europe
and Northern Africa. In-
deed these two regions were
probably one in early Qua-
ternary times. And he be-
lieves that the present types
of the race have come from
this region rather than, as
more popularly thought, from
Fic. 199. Head of Orion, Negrito- Asia. However, the princi-

Papuan of Tidore. Cast now in pal historic nations of Eu-

the Paris Museum of Natural His- rope are descended from

tory. (After Quatrefages.) :

Aryan stock, which most
ethnologists believed to have migrated into Europe from Asia.
But Brinton denies even this, holding that the Aryan an-
cestors of the European races originated in Europe itself.
The white race of America is, of course, the off-shoot by
direct immigration and descent of the historic European
races.

The Mongolic or Asian race includes a great many peoples
represented by an enormous number of individuals all
characterized by their yellowish skin color, straight coarse

ANCIENT AND MODERN MAN

397
black hair, flat-bridged nose, small and more or less ob-

lique-lidded eyes. It includes two large branches, one
called the Sinitic, comprising the Chinese, Tibetans, and

Fic. 200. An Akka pygmy from Equatorial! Africa.
Indo-Chinese (Birmese, Siamese, Annamese, Tonkinese,
etc.);. the other called the Siberic branch, including the
Japanese, Koreans, Manchus, Kamschatkans, Tartars,
Finns, Magyars, etc. This race possesses one of the oldest

398 THE ANIMALS AND MAN

civilizations of the world and all of the great world religions
except Christianity.

Lowest of the great races is the Ethiopic or Negro, whose
members are black-skinned, black-eyed, wooly-haired, full-
jawed and generally long-skulled. The race is mostly
confined to regions of great heat and humidity, its center
being the hot, low, broad valley of the great river Niger.
There are three principal branches of the race, the Negrillo,
the true Negro and the Negroid. ‘To the Negrillo branch be-
long what are probably the lowest of living human peoples,
the Akkas and other pygmies of Equatorial Africa and the
Bushmen of Southern Africa. These peoples have no
settled abodes, build no towns, cultivate nothing. They
live by hunting and fishing and exchange of the trophies
of the chase with neighboring agricultural people. They
use the bow and arrow and many are cannibals.

The Negrillos are only approached in their primitive
condition by the Papuans of New Guinea, some of whose
tribes do not even know the bow and arrow. The Fuegians
of Patagonia have also an extremely low culture, although
physically they are well developed. But the African Ne-
grillos have a physical make-up but little in advance of the
prehistoric men of the Stone Age. Their brain cavity is
about 1250 c.c. compared with the 1600 c.c. of the European;
their facial angle is less, their maxillary angle less; and,
in fact, in all those measurements and characters which go
to separate man from the other mammals the Akkas and
Bushmen of Africa, with perhaps the native Australians,
are distinctly lowest and most animal like. Also these
peoples, are, on the whole, in the lowest stage of culture
of any of the human kind. But low as this culture may be
it is yet something wholly unapproached or resembled in
the life of the lower animals. Man’s relationship to the
animals is revealed only in his anatomy and physiology;
not in his habits of life, his social and religious relations.

PART V

ANIMALS IN RELATION TO EACH
OtmErR. TO. PLANTS, AND FO
TEE, OUPSIDE WeRED

CHAPTER XXX

THE STRUGGLE TO EIVE; ADAPTA—
ZION AND* DISTRIBUBION

The multiplication of animals.—The English sparrow,
now a common bird over our whole country, rears five or
six broods every year, each brood containing six to ten young.
That is, each pair of healthy English sparrows produces
from thirty to sixty new sparrows each year. Now if all
these young come safely to maturity and each sparrow
maintains the same rate of increase, and every sparrow lives
to its normal age, how long will it take to cover the face of
the land with these pugnacious, noisy, little birds? As a
matter of fact a professor of mathematics has solved this
problem, and finds that at the normal rate of increase,
and if no sparrows were to die save naturally of old age,
it would take about twenty-five years to give one sparrow
to every square inch in the United States.

But English sparrows are not the only birds in the country,
and although the robins, bluebirds, woodpeckers, and the
scores of other kinds do not lay so many eggs nor lay so
many times a year, yet each pair does produce more than

399

400 THE ANIMALS AND MAN

two eggs yearly, that is, each pair yearly multiplies, not
simply replaces itself. Most birds, however, are slow multi-
pliers. But what of the hosts of insects where each female
lays from a few dozen to many hundred or even thousand
eggs each year; and the fishes, almost none of which lays
less than several thousand a year? A few years of unin-
terrupted normal increase among sunfishes would fill every
stream and pond solidly full of them. Even certain of the
tiniest animals, microscopic animalcules which live in the
ocean, if left to multiply at their usual rate with no losses
except by natural death, would, it has been estimated,
completely fill the ocean in about a week!

Of course no such appalling increase in the number of
living animals occurs, although we may fairly consider
that each kind of animal is constantly trying to usurp far
more food and space in the world than it now has. But
there are about as many squirrels in the forest one year as
another, about as many butterflies in the field, about as many
frogs in the pond. Sometimes a particular kind of ani-
mal gets into a new part of the world and suddenly mul-
tiplies with great rapidity. A few rabbits were introduced
into Australia (where there were none) in 1860, and in fifteen
years had become so abundant as to be a great pest. The
government pays large sums in bounties every year to rab-
bit-hunters.

The struggle to live.—All animals tend to increase in
geometrical ratio, that is, the production of new individuals
is by multiplication, not by simple addition. But food and
space on the earth have definite limits, and so there is con-
stantly going on a great struggle for existence. In the case
of any individual the struggle is threefold: (1) with the
other animals of his own kind or species for food and room;
(2) with other kinds of animals which want the same food
and space, or which may want him for food; and finally,
(3) with the conditions of life, such as cold and heat, and

THE STRUGGLE TO LIVE 401

drouth and flood. No living being can escape from this
struggle. Each strives to feed itself, to save its own life,
to produce and protect its young. But in spite of all their
efforts only a few individuals out of the hundreds and thou-
sands born live to maturity. The great majority are killed
in the egg stage, or during adolescence.

Selection by nature.—What individuals survive of the
many which are born? Presumably those best fitted for
life; those which are a little stronger, a little swifter, a little
hardier, a little less readily perceived by their enemies than
the others. We know from our observation of a brood of
young kittens or puppies that there are differences in new-
born individuals of the same kind, and even among those
born from the same mother. ‘Thus it is with all animals.
No two individuals even in the same brood are exactly
alike at birth. And the very few members of each brood
which do survive are almost always the hardier, stronger,
and swifter. They are the winners in the struggle for
existence. And this survival of the fittest, as it is called,
is practically a weeding out or selecting process of Nature.
She selects the fittest to live and to perpetuate their kind.
Their young in turn must undergo the struggle and the
selecting process, and again the fittest live. And so on
until the adjustment or harmonizing of the bodies and
habits of animals with the conditions of their life, their
environment, comes to be extremely fine and nearly perfect.

Special means to get food.—With such a constant
struggle, such a race for food, it is not strange that we find
different animals having various kinds of special arrange-
ment for getting it. Those which live on plants can get
it in two ways, either by biting off the green leaves and stems
and crushing them in the mouth, or by thrusting a sucking
beak into the plant tissue and drawing out the sap. So
the different plant-feeding animals have the mouth specially
arranged for one or the other of these ways. Cattle and

402

Fic. 201.
moth;

the moth seen in profile) the proboscis ers have sucking-tubes

is shown coiled up on the under side of
the head, the normal position when not

in use. (One half natural size). (fig. 201); and a famous

Sucking proboscis of a sphinx
in small figure (the head of other deep-cupped flow-

THE ANIMALS AND MAN

horses and sheep have teeth for biting
off and crushing dry or green plant
food, while many insects, like the
plant-lice and various flower-bugs,
have a tiny, sharp, hollow beak, which
they thrust into a green leaf or stem,
and through which they suck up the
sap. Similarly with those animals
which feed on animal matter. Lions,
tigers, dogs, and cats have strong
teeth for tearing and broad teeth for
crushing the flesh of other animals,
while the mosquito, flea, and other
insects which live principally on ani-
mal blood have a piercing and suck-
ing beak.

But animals must first obtain their
food. Giraffes get theirs from high
}trees and they have wonderfully
long necks to enable
them! to: reach “up; “te
moths and __ butterflies
which feed on nectar
from flowers have long,
slender sucking-tubes
with which to reach
down to the base of a
flower-cup. The com-
mon hawk-moths or
humming-bird moths that
hover over petunias and

three or four inches long

THE STRUGGLE TO LIVE 403

member of this family in Madagascar has its sucking-
tube fourteen inches long, which enables it to reach to the
bottom of a great trumpet-shaped flower. Lions and tigers,
wolves, and the like which feed upon other live animals
must have specially developed legs and muscles for swift
running, or springing, or swimming. The otter can swim
and dive better than most fishes, and with his greater clever-
ness has little difficulty in
capturing the swiftest of them.
The eagle has great talons for
grasping its prey, and a strong
hooked beak for tearing it.
The pelican has a large pouch
or sac on its lower Jaw which
it uses as a scoop-net for catch-
ing fish. The spoon-bill duck
takes up mouthfuls of mud
and water which it strains out
through a close fringe of small
thin plates at the sides. The
preying mantis (fig. 202) has
great spiny fore legs for seiz-
ing its prey, the unwary house-
flies, on the window-panes,
while the dragon-fly has a large
mouth which it can open very wide, and can engulf in this
fatal trap many tiny midges as it flies swiftly through their
dancing swarms.

Special means for protection.—Some animals have
poison-fangs, like the rattlesnake and the ugly lizard of
the desert called Gila monster, and others stings, like the
scorpion, to kill their prey. These weapons are of course
also used in self-defense. The same is true also of numerous
other special means of food-getting, such as the power to
run swiftly, to leap, and swim. But there are in addition

Fic. 202. A preying mantis.
(Natural size.)

404 THE ANIMALS AND MAN

many special means of defense and protection which have

nothing to do with food-getting.

Fic. 203. Bag-worm; the larva of
a moth that builds a_ protecting
case out of silk and bits of stick,
in which the whole body except
horny head thorax and legs, is con-
cealed. (Natural size.)

The males of most mem-
bers of the deer family
—the moose, elk, and red
deer for example—have
antlers strong and sharp-
pointed, which they can
use effectively in fighting
wolves and other enemies
as) well) as) cach” other
At the same» time: they,
have legs finely developed
for swift running, and to
run away is often better
protection than to fight.
The porcupine has long,
sharp quills which make
a bad mouthful for any
animal that attempts to
nip the prickly ball; the
armadillo of tropical coun-
tries has its body covered
with horny shields, and
when it draws in its head
and curls up tightly it is
as well protected as a
turtle in its box-like armor.
Numerous fishes have
other means of protection
besides their ability to
swim swiftly; the catfishes
stiffen a long spine in each
pectoral fin, which makes

a bad wound; the so-called poison-fishes of the ocean
have spines provided with poison glands; the _ sting-

THE SERUGGLE TO LIVE 405

rays, common on the coast, have a strong, jagged
spine in the tail, armed with broad saw-like teeth, which
inflicts a bad, ragged cut. The torpedoes or electric rays
found on the sandy shores of all warm seas have on each
side of the head a large honeycomb-like structure which
gives a strong electric shock whenever the live fish is touched.
Among the reptiles of our country the poisonous bite of
the rattlesnake, copperhead, and water-moccasin is a familiar
example of a very effective special means of defense.

Certain special habits of animals, too, help much to pro-
tect them, and to save their lives. The migration of birds
takes many from a bleak, foodless winter to the luxuriant
tropical forests, where there is plenty of food and the weather
is mild. ‘The hibernation or ‘“‘winter sleep” of bears, snakes,
and lizards carries them safely through a season when food
is scarce or wanting altogether. And some animals come
from their holes and hiding-places to hunt food only at
night, when most of their enemies are asleep.

Finally (as we shall learn particularly in a later chapter),
many animals are colored and marked in such manner that
they match or fit in so well with the soil or leaves or stones
on which they rest as to be indistinguishable. And this
scheme of harmonious coloration is one of the most success-
ful and wide-spread of all the special protective devices.

Examples to be looked for by the pupils.—Only a
few of the special means for food-getting and protection
are mentioned in this chapter, and those animals which
may be most readily observed by the pupils have purposely
not been referred to. When we come upon such a peculiar
device as the long neck of the giraffe or the fishing-pouch of
the pelican our attention is specially attracted, and we are
likely to consider such cases unusual and exceptional. But
they are not exceptional, they are simply unusual and un-
familiar and specially conspicuous. All animals, including
all those we know best, have special means of food-getting

406 THE ANIMALS AND MAN

and protection, and many of them, particularly the insects
and birds, have just as unusual and just as wonderful and
interesting devices as any mentioned in the preceding para-
graphs. Let each pupil observe carefully and thoughtfully
the animals familiar and accessible to him, remembering
that smallness does not at all mean lack of wonderful and
interesting structures and habits. Let each make a list
from personal observation of the special devices and habits
for getting food and for protection possessed by the animals
he knows.

The distribution of animals.—We are used to seeing
certain kinds of animals, such as rabbits, robins, field-mice,
and garter-snakes in the particular region in which we live,
and never seeing others, such as lions, elephants, birds-of-
paradise, and boa-constrictors. We know, indeed, that
these latter kinds do not live in our region nor even on our
continent. But we are too likely to take such things for
granted, and not inquire why it is that only certain particular
kinds live in North America and certain others in Africa,
while others still may be found all over the world.

As a matter of fact there are few things about animals
more interesting to observe than their distribution over
the world. Unfortunately in this matter we must depend
for many of our facts upon the statements of other people;
we can observe at first hand only a few of them. We can
see for ourselves what kinds of animals live in our neighbor-
hood, and that certain other kinds with which we are some-
what familiar from menageries or books do not. We can
see that some animals, fishes for example, live always in
water; and that some water animals live always in ponds,
while others prefer the brooks. Many other water animals,
on the contrary, can live only in the ocean, and of these
some always keep near the bottom, where it is dark and
cold, while many live on or near the surface. Again, some
of the surface forms keep always near the shore, while others

THE STRUGGLE TO LIVE 407

never or rarely come in sight of land. But most of the
familiar animals about us cannot live in water at all. They
either burrow in the ground like moles and gophers, or
live in trees like squirrels, or fly in the air like birds and
butterflies. |

Barriers.—Of land animals some can live only in tropical
and sub-tropical regions, as the monkeys and most of the
parrots, some live only in the snowy regions near the poles,
as the polar bear and great walrus, while many prefer neither

Fic. 204. The Parnassian butterfly, Parnassius smintheus, which lives
in the Rocky Mountains and Sierra Nevada at an altitude of 5000 feet
and above. (Natural size).

of these extremes but live in the temperate zones. Although
the word “prefer” has been used, it is usually true that
animals which live in arctic regions are not able to live
elsewhere; they seem to be adapted solely for an arctic
climate, so that the line around the earth south of which
there is frost and freezing weather during a part of the year
only is a sort of barrier beyond which they cannot safely
venture. And, turning to the animals of the tropics, we
find that most of them cannot endure any frost or freezing

408 THE ANIMALS AND MAN

at all, the southernmost line of frost being to them a barrier
north of which they cannot live. ‘These barriers are raised
by temperature. Similarly there are barriers made by
differences in rainfall. The animals of the Eastern United
States, accustomed to a large amount of moisture and to
luxuriant vegetation, could not live on the arid, burning,
sterile desert; but the lizards and desert rats and coyotes
live there successfully.

But barriers more marked and more tangible are those
such as oceans which surround continents and islands and
thus limit the land animals of these regions to their respective
districts. Similarly the land which surrounds a lake or
pond limits the fishes in it to that particular lake or pond,
although they would live quite as well in some other. And
it is true that many animals could live elsewhere than in the
place to which they are now restricted if they could only
get there. Indeed they could live in any other region where
the climate and general conditions are like their present
home. So we say that the distribution of animals over the
world is largely determined by barriers—barriers of tem-
perature, of moisture, of water, of land, of high mountains,
of deserts, of anything that the animal cannot cross.

How animals spread.—The ways in which animals
spread are mostly easily understood. Birds can fly to new
regions; quadrupeds can travel on foot for long distances;
fishes can swim from one part of a river or lake or ocean
to another. But although two rivers may empty into the
ocean close together fishes cannot often easily get from one
into the other. For most fresh-water fishes cannot live
in salt water, so that even a small stretch of ocean is an
effective barrier to them. Salmon, some eels, and a few
other fishes, however, live part of the time in the ocean and
part in streams. Many animals are transported long
distances involuntarily. Rats and mice invading a ship
from wharves at Liverpool sometimes get carried across

THE STRUGGLE TO LIVE 409

the Atlantic Ocean to America. In fact the common black
rats and brown rats of the houses and barns over this whole
country are not native rats at all, but are descendants of
European rats unintentionally brought across the ocean in
ships. The same is true of many of the insect pests which
trouble us; for example, the Hessian fly, which does great
damage to wheat, the cockroaches of our houses and the
carpet beetles or buffalo bugs which attack rugs and carpets.
Sometimes a boring insect lying snugly in a log gets carried
down a river, out into the ocean, and by means of ocean
currents far away to some island where it may crawl out
and lay eggs and so establish itself in a new country. Some-
times animals are intentionally imported by man from
foreign countries. The introduction of the English sparrow
into this country and the rabbits into Australia are examples
of unfortunate experiments along this line.

Map showing the distribution of animals.—Zoolo-
gists have been studying the distribution of animals so long
that they have been able to map out the range of many of
the well-known kinds. On a map of the world they in-
dicate, by shading, all those regions in which lions exist;
all those in which elephants live, and all those in which
humming-birds are found. Now this kind of map-making
reveals many things of interest and throws much light on
the relations of animals to climate, to geography, and to
each other.

Such zoological map-making may be restricted to a limited
locality, and is the best way for beginning students to study
distribution. On a large sheet of strong paper a map of
the region, say one or two miles square, about the school-
house, should be made, with all the streams, ponds, swamps,
pastures, woods, etc. Then search carefully for the haunts
of certain kinds of animals which are known to occur in
the mapped region, and mark them on the map. It will
soon be found that the different kinds of animals are more or

410 THE ANIMALS AND MAN

less limited to certain parts of the region. Attempt may
next be made to find out why. Are there barriers? If
so, of what nature? ‘They cannot well be barriers of temper-
ature or climate, unless a mountain is included in the region,
but may be concerned with food, suitable hiding-places,
proximity to man, necessity of water for breeding in, etc.
This is a study, all of which must be made in the field,
and where much ingenuity in observing and reasoning
must be used.

For a reference-book on the subject of animal distribution see Heil-
prin’s “Distribution of Animals,”’ or Beddard’s ‘‘Zoo-geography.”’

CHAPTER XXXI

ANIMAL PARASITES AND DEGEN-
ERATION

An animal parasite is an animal which lives and feeds
for all or part of its life on or in the body of another which
is called the host. Fleas, dogticks, and lice are familiar
parasites; they are not very pleasant to think about perhaps,
but their mode of life is interesting because it presents one
way of getting a living which has been adopted by many
different kinds of animals, and which always results in a
more or less marked change in their structure. This change
usually involves the loss or imperfect development of some
part of the body.

Degeneration of parasites.—Fleas and lice are insects,
but, unlike most of their kind, they have no wings. Being
carried about by the host they do not need to fly. One
of the most striking examples of loss of parts due to a para-
sitic habit is shown by an animal called Sacculina (fig. 205),
which belongs to the crab and crayfish ,class. The young
Sacculina, hatched from eggs laid in ocean tide-pools, has
legs and eyes and a mouth and feelers, and can swim
actively about. It looks much like a young crab or prawn.
But after a short period of free active life it finds a full-
grown crab and attaches itself to its body. There grow out
from the Sacculina and penetrate the body of the crab
slender root-like processes by means of which the parasite
sucks up the juices of its host. Soon it moults and loses
its legs, eyes, and feelers; it is now simply a pulsating tumor-

411

412 THE ANIMALS AND MAN

like sac fastened to the crab by means of the feeding root-
lets. Loss by degeneration of the body-parts is carried
very far in this case.

Numerous other parasites live, like Sacculina, attached
firmly to their host, and do not move about. They are

Fic. 205. Sacculina, a parasitic crustacean; A, attached to a crab, the
root-like processes of the parasite penetrating the body of the host;
B, the active larval condition; C, the adult removed from its host.
(Enlarged; after Haeckel.)

carried by the host. Such parasites are usually without
wings, legs, or other locomotory organs. Because they

ANIMAL PARASITES AND DEGENERATION 413

have given up locomotion they have no need of organs of
orientation, those special sense organs like eyes and ears
and feelers which serve to guide and direct the moving
animal; and most non-locomotory parasites will be found
to have no eyes, nor any of the organs of special sense which
are accessory to locomotion, and which serve for the de-
tection of food or enemies. Because these important organs,
which depend for their successful activity on a highly or-
ganized nervous system, are lacking, the nervous system
of parasites is usually very simple and undeveloped. Again,
because the parasite usually has for its sustenance the al-
ready digested highly nutritious food elaborated by its host,
most parasites have a very simple alimentary canal, or even
no alimentary canal at all. Finally, as the fixed parasite
leads a wholly sedentary and inactive life, the breaking down
and rebuilding of tissue in its body go on very slowly and in
minimum degree, and there is no need of highly developed
respiratory and circulatory organs, so that most fixed para-
sites have these systems of organs in simple condition.
Altogether the body of a fixed, permanent parasite is so
simplified and so wanting in all those special structures
which characterize the higher, active, complex animals,
that it often presents a very different appearance from those
animals with which we know it to be nearly related.

Internal parasites.—Inside the body of most animals
live various parasites belonging to the great branch of worms.
The tapeworm and the deadly trichina (fig. 206; for ac-
count see p. 147) are conspicuous examples of these. The
tapeworm (fig. 207) has the form of a narrow ribbon, per-
haps several yards long, attached at one end to the wall of
the intestine, while the remainder hangs freely in the interior.
Its body is composed of segments or serially arranged parts,
of which there are about 850 altogether. It has no
mouth or stomach. It feeds simply by absorbing into its
body, through the skin, the nutritious food already partly

414 THE ANIMALS AND MAN

digested in the intestine of its host. It has no eyes or other
special sense-organs, nor any organ of locomotion. Thus
its body is very degenerate. The life-history of the
tapeworm is interesting, because it lives in two hosts
during its life. The eggs of this parasite pass from
the intestine with the excreta, and to develop must

Fic. 206. Tyrichina spiralis, encysted in muscle of a pig. (Greatly en-
larged.)

be taken into the body of some other animal. In the
case of one of several species infesting man this second host
is the pig. In the alimentary canal of the pig the young
tapeworm develops, to bore its way later through the walls
of the canal and become imbedded in the muscles. There it

ANIMAL PARASITES AND DEGENERATION 415

lies until the diseased flesh containing it is eaten (without
being perfectly cooked), and thus it finds its way into the
alimentary canal and thence into the intestine of
man. It now continues to develop until it becomes
full grown.

Many animals are infested by minute parasites belonging
to the Protozoa or one-celled animals. The class Sporozoa
of the Protozoa is composed almost exclusively of parasitic
species living in the blood, liver, alimentary canal, and

(0m
Tit os

Ki
i

Fic. 207. Tape worm; the head, magnified, at left; the whole worm
may be several yards long. (After Lenckart.)

other organs and tissue of animals. Over seven hundred
and fifty kinds of these Sporozoan parasites have been de-
scribed. Some of them, as has already been told in Chap-
ter XII are parasites of the human body causing terrible
infectious diseases among us.

Parasitic insects.—Among the insects many live as para-
sites during their immature or larval life, but as adults

416 THE ANIMALS AND MAN

are free and independent creatures. From the chrysalid
of a butterfly or moth there will often come not a butterfly
but numerous tiny four-winged gnats, called ichneumon
flies. This is what happened. When the butterfly cater-
pillar was crawling about a female ichneumon darted down
on it, and with her sharp ovipositor either laid several eggs
beneath its skin or glued them to its outer surface. These
eggs hatched in two or three days as tiny white ichneumon
grubs, which immediately burrowed deep into the cater-
pillar and lay there feeding on the blood and tissues of its

Fic. 208. Larva of a sphinx moth, with cocoons of a parasitic ichneumon
fly. (Natural size.)

body. But the caterpillar went on eating and finally changed
into a chrysalid, with the ichneumon grubs still inside. Soon
the grubs, having eaten up most of the body of the developing
butterfly and thus killed it, changed into tiny pupe, and
later into fully developed ichneumon flies which gnawed
their way out through the horny case of the dead chrysalid.

One of the most interesting ichneumon flies is Thalessa,
which has a remarkably long, slender, flexible ovipositor.
Another insect, known as the pigeon horn-tail (fig. 209),
upon which Thalessa preys, deposits its eggs by means of
a strong, piercing ovipositor, half an inch deep, in the trunks
of growing trees. The young or larval horn-tail hatches

ANIMAL PARASITES AND DEGENERATION 417

as a soft-bodied white grub, which bores more deeply into
the tree, filling up the burrow behind it with small chips.
When a female Thalessa finds a tree infested by the horn-
tail she selects a_ place
which she judges is oppo-
site one of its burrows,
and elevating her long ovi-
positor in a loop over her
back, with its tip on the
bark of the tree, she makes
a derrick out of her body
and proceeds with great
skill and precision to drill
a hole (fig. 210). Having
reached the horn-tail’s
Fic. 209. The pigeon horn-tail, Tre- }yrrow she deposits an
mex. (Natural size.) ah & 7 :
egg in it. When the larva

hatches it creeps along the bur-
row until it reaches and fastens
itself upon the larval horn-tail
which it destroys by sucking its
blood. When full grown it
changes to a pupa within the
burrow of its host, and finally
the adult Thalessa gnaws a hole
out through the bark if it does
not find the one already made
by the horn-tail.

Almost all birds are infest- yy¢. 210. Thalessa drilling in-
ed with small, flattened, wing- to the burrow of Tremex.
less, parasitic insects which (Natural size; after Com-
‘ stock.)
live among the feathers, and
feed by biting off small bits of barbs. Chickens and pigeons
are specially infested by these biting bird-lice (called biting
to distinguish them from the common true lice of other ani-

418 THE ANIMALS AND MAN

mals, which have a piercing beak and suck blood) (fig. 211).
Specimens of these parasites should be obtained and ex-
amined under a microscope to note the absence of wings
and compound eyes, and the peculiarly shaped body well
fitted for swift running among the feathers. Note bits
of feathers in the stomach showing through the body-wall.

Parasites of the human body.—Our

own body is infested, or may be, by many
different parasites. More than fifty species
~ of worms have been recorded as human
parasites. The tapeworms and _trichine,
already referred to, may enter our body
when we eat under-cooked meat, especi-
ally pork, which has not been properly
inspected. Flukeworms of various species
may live in the liver, lungs, intestine and
even in the brain. A small round worm
of the genus Uncinaria, called hookworm,
which seriously affects the blood, has been
found to be a very common parasite, being
Fic. 211. A biting especially abundant in the South. Various
bird louse, Nir- Filarie or blood worms cause frightful
ae praesians, diseases among the natives of tropic lands.
rom the _ tern, aie ure ; 3
Sterna. maxima, Elephantiasis, in which ste patients leo? or
(About 1-12 of arm may become so enlarged as to weigh
an inch long; as much as all the rest of his body, is one
photo-micrograph : , :
by Geo. E. Mitch. Of these filaria-caused diseases from which
ell.) a third of all the Samoans suffer.

Even more serious in their results than the diseases and
troubles caused us by parasitic worms are those produced
by Protozoan parasites. Associated with these diseases
caused by animal parasites are those caused by the parasitic
growth in our bodies of bacteria and bacilli, which are one-
celled plants.

There are many other examples of parasitic life to be

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420 THE ANIMALS AND MAN

found among common and familiar animals. Careful
watch for them should be kept by the pupils in their field
work and in their rearing of insects and other animals in
the schoolroom.

For an account of many parasites see Van Beneden’s “‘ Animal Para-
sites and Messmates.”’

CHAPTER XXXIT

MUTUAL AID AND COMMUNAL
LIFE

It is an altogether too common idea that in Nature all is
one fierce and unrelenting warfare for place and food and
life itself. While the ‘‘struggle to live’ usually means to
the layman student of Nature an unrelieved competition
and often personal combat on the part of any one animal
species or individual, to the experienced naturalist it is a
large and general term which includes a great many kinds
of shifts for a living, some of which may depend on a total
cessation of individual competition and the adoption of
the principle of mutual aid. Many individuals of one
kind of animal may live together in a single elaborately or-
ganized community, as with the honeybee and the ants,
where each individual works for all in a measure never yet
realized among men. Or individuals of different species
of animals may live together in more or less developed con-
ditions of mutual tolerance and even helpfulness. Gre-
garious, commensal, social and communal forms of life
are all abundantly represented among the lower animals.
So that the phrase “‘struggle to live’? must be understood
to include altruistic as well as competitive and warring
means. It must be understood to signify simply “‘means
fo live.”

Commensalism.—The living together in peace and often
to mutual advantage of individuals of different kinds of
animals is called commensalism, or messmatism,

421

422 THE ANIMALS AND MAN

Among the coral reefs in the South Seas there lives an
enormous kind of sea anemone or polyp. Individuals
of this great polyp measure two feet across the disk when
fully expanded. In the interior, the stomach cavity, which
communicates freely with the outside by means of the large
mouth opening at the free end of the polyp, there may often
be found a small fish (Amphiprion percula). That this
fish is purposely in the gastral cavity of the polyp is proved
by the fact that when it is dislodged it invariably returns
to its singular lodging place. , The fish is brightly colored,
being of a brilliant vermilion hue with three broad white
cross bands. ‘The discoverer of this peculiar habit suggests
that there are mutual benefits to fish and polyp from this
habit. ‘The fish being conspicuous, is liable to attacks
which it escapes by a rapid retreat into the sea anemone.
Its enemies in hot pursuit blunder against the outspread
tentacles of the anemone and are at once narcotized by the
‘thread cells’ shot out in innumerable showers from the
tentacles, and afterwards drawn into the stomach of the
anemone and digested.”

Small fish of the genus Nomeus may often be found accom-
panying the beautiful Portuguese man-of-war (Physalia)
as it sails slowly about on the ocean’s surface. These little
fish lurk underneath the float and among the various hanging
thread-like parts of the Physalia, which are provided with
stinging cells. The fish are protected from their enemies
by their proximity to these stinging threads. Similarly,
several kinds of meduse are known to harbor or to be
accompanied by the young, or small adult fishes of the
genera Caranx and Psenes.

Hermit crabs live in the shells of molluscs, most of the
body of the crab being concealed within the shell, only the
head and grasping and walking legs protruding. In some
species of hermit crabs there is always to be found on the
shell near the opening a hydroid polyp. “This hydroid

MUTUAL AID AND COMMUNAL LIFE 423

is carried from place to place by the crab, and in this way is
much aided in obtaining food. On the other hand, the crab
is protected from its enemies by the well-armed and danger-
ous tentacles of its companion. On the tentacles there are
many thousand long slender stinging threads, and the fish
that would eat the hermit-crab must first deal with the
stinging anemone.” If the hydroid be torn away from the
shell the crab will wander about seeking another polyp.
When he finds one, he struggles to loosen it from the rock

Fic. 213. Hermit crab within a shell on which is growing a hydroid polyp
colony. (After Weismann.)

to which it is attached, and does not rest until he has torn
it loose and placed it on his shell.

In the nests of the various species of ants and termites
many different kinds of other insects have been found.
Some of these are harmful to their hosts, in that they feed
on the food stores gathered by the industrious and provi-
dent ant, but others appear to feed only on refuse or useless
substances in the nest. Some appear to be of help to their
hosts by cleaning the nests and by secreting certain fluids
much liked by the ants. Over one thousand species of
these myrmecophilous (ant-loving) and termitophilous (ter-

424 THE ANIMALS AND MAN

mite-loving) insects have been recorded by collectors as
living habitually in the nests of ants and termites. Many
of them (they are mostly small beetles and flies) have lost
their wings and have had their bodies otherwise considerably
modified, often in such wise that they come greatly to
resemble in external appearance
the ants with which they live.
The relations between ants
and aphids (plant lice) are
often referred to in popular nat-
ural histories and books about
insects as examples of symbiosis Fic. 214. Termitogaster texana,
f be t Unf a rove-beetle (Staphylinidae)
of unusual interest. niortu- which lives in the nests of the
nately, however, not enough _ termite, Eutermes Cinereus, in
careful study has been given Texas. (Natural size 11-2
mm; after Bowes.)
to many of these apparently
true examples of symbiosis to enable us to
be certain of the truth of the alleged care
and guarding of the ant-cows, as Linnzus
called these aphids, by their milkers, the
ants. ‘That ants do swarm about the aphids
to lap up the “honey dew” excreted by
- them is wholly true, and the very presence
Fic. 215. Aenig- of the sharp-jawed and pugnacious ants
matis blattoides, eerste ae Fares) ai Pelee
a Phorid fly, MuUSt keep away many enemies of the de-
which lives in fenseless plant lice, toothsome morsels for
the nest of the the lady-bird beetles, flower-fly larve and
ant, Formica fus- °
_ Other predatory insects.
ca, in Denmark. , é ;
(Thirteen times In the case of the interesting relations
natural size; between the corn root aphid, Aphis maidis-
after Meinert.) st te eiLige Nee Wits : 5
radii, of the Mississippi Valley States,
and the little brown ant, JLasius brunneus, however,
we have the careful observations of Professor Forbes to rely
on. In the Mississippi Valley, this aphid deposits in autumn
its eggs In the ground in corn fields, often in the galleries

MUTUAL AID AND COMMUNAL LIFE 425

of the little brown ant. The following spring before the
corn is planted, these eggs hatch. Now, the little brown
ant is especially fond of the honey dew secreted by the corn
root lice. So when the latter hatch in the spring, before
there are corn roots for them to feed on, the ants carefully
place them on the roots of certain kinds of grass and knot-
weed (Setaria, Polygonum) and there protect them until
the corn germinates. They are then removed to the roots
of the corn. It is probable that the ants even collect the
eggs of the aphids in the autumn and carry them into their
nests for protection and care.

The studies of Wheeler and others have revealed some
interesting cases of the living together of different species
of ants. In some cases one of the ant species may be living
almost wholly at the expense of the other species, as does
the little yellow thief-ant, Solenopsis molesta. Although
this ant sometimes lives in independent nests, more often it
is to be found living in association with some large ant
species—it consorts with many different hosts—feeding
almost exclusively on the live larve and pupe of the host.
The thief-ant is so small and obscurely colored that it seems
to live in the nests of its host practically unperceived. The
Solenopsis nest may be found by the side of the host nest,
around it, or partly in it, the tiny Solenopsis galleries ramify-
ing through the nest mass of the host, and often opening
boldly into these large galleries. Through their narrower
passages, too narrow to be traversed by the hosts, the tiny
thief-ants thread their way through the host nest in their
burglarious excursions.

But there are numerous cases of a less one-sided advantage
in the association of different species. As an example, the
conditions exhibited by the red-brown ant, Myrmica brevi-
nodes and the smaller Le ptothorax emersoni (conditions made
known by Wheeler’s careful observations) may be briefly
described. The little Leptothorax ants live in the Myrmica

426 THE ANIMALS AND MAN

nests, building one or more chambers with entrances from
the Myrmica galleries, so narrow that the large Myrmicas
cannot get through them. When needing food the Lepto-
thorax workers come into the Myrmica galleries and chambers
and, climbing on the backs of the Myrmica workers, proceed
to lick the face and the back of the head of each host. A
Myrmica thus treated, says Wheeler, ‘‘paused, as if spell-
bound by this shampooing and occasionally folded its
antenne as if in sensuous enjoyment. The Leptothorax
after licking the Myrmica’s pate, moved its head round to
the side and began to lick the cheeks, mandibles, and labium
of the Myrmica. Such ardent osculation was not bestowed
in vain, for a minute drop of liquid—evidently some of the
recently imbibed sugar-water—appeared on the Myrmica’s
lower lip and was promptly lapped up by the Leptothorax.
The latter then dismounted, ran to another Myrmaica,
climbed on its back, and repeated the very same performance.
Again it took toll and passed on to still another Myrmaica.
On looking about in the nest I observed that nearly all the
Leptothorax workers were similarly employed.”

Wheeler believes that the Leptothorax get food only in
this way. They feed their queen and larve by regurgita-
tions. The Myrmicas seem not to resent at all the presence
of their Leptothorax guests, and indeed may derive some
benefit from the constant cleansing licking of their bodies by
the shampooers. But the Leptothorax workers are careful to
keep their queen and young in a separate chamber, not
accessible to their hosts. This is probably the part of
wisdom, as the thoughtless habit of eating any conveniently
accessible pup of another species is wide-spread among
ants.

Social and communal life.—The simplest form of true
social life exists among those animals in which many in-
dividuals of one species keep together, forming a great band
or herd. Such animals are said to be gregarious in habit,

MUTUAL AID AND COMMUNAL LIFE 427

and this gregariousness is undoubtedly advantageous to
the individuals of the band. The great herds of reindeer
in the North, and of the bison or buffalo which once ranged
over the Western American plains are examples of a gre-
gariousness in which mutual protection from enemies, as
wolves, seems to be the principal advantage gained. The
bands of wolves which hunted the buffalo show the advantage
of mutual help in aggression as well as in protection. Prairie-
dogs live in great villages or communities which spread over
many acres. By shrill cries they tell each other of the ap-
proach of enemies, and they seem to visit each other and to
enjoy each other’s society a great deal, although that they
are thus afforded much actual active help is not apparent.
The beavers furnish a well-known and very interesting
example of mutual help; they exhibit a communal life,
although a simple one. They live in villages or communities,
all helping to build the dam across the stream which is
necessary to form the marsh or pool in which the nests or
houses are built.

An interesting series of gradations from a strictly solitary
through a gregarious to an elaborately specialized communal
life is shown by the bees. Although the bumblebee and
the honeybee are so much more familiar to us than other
bee kinds that the communal life exemplified by them may
have come to seem the usual kind of bee life, yet as a matter
of fact, there are many more kinds of solitary bees than of so-
cial ones. The general character of the domestic economy of
the solitary bees is well shown by the interesting little green
carpenter bee, Ceratina dupla. Each female of this species
bores out the pith from five or six inches of an elder branch
or raspberry cane, and divides this space into a few cells
by means of transverse partitions. In each cell she lays an
egg, and puts with it enough food—flower pollen—to last
the grub or larva through its life. She then waits in an
upper cell of the nest until the young bees issue from their

428

THE ANIMALS AND MAN

cells, when she leads them off, and each begins active life
on its own account. The mining bees Andrena, which
make little burrows in a clay bank, live in large colonies—

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Fic. 216. Nest-
tunnel of a
Carpe miter
bee. (Natural
size. )

that is, they make their nest burrows close
together in the same clay bank, but each
female makes her own burrow, lays her own
eggs in it, furnishes it with food--a kind of
paste of nectar and pollen—and takes no
further care of her young. Nor has she at
any time any special interest in her neighbors.
But with the smaller mining bees, belonging
to the genus Halictus, several females unite
in making a common burrow, after which
each female makes side passages of her own,
extending from the main or public entrance
burrow. As a well-known entomologist has
said, Andrena builds villages composed of
individual homes, while Halictus makes cities
composed of apartment houses (fig. 217). The
bumblebee, however, establishes a real commu-
nity with a truly communal life, although a very
simple one. The few bumblebees which we
see in winter time are queens; all other bum-
blebees die in the autumn. In the spring a
queen selects some deserted nest of a field
mouse, or a hole in the ground, gathers
pollen which she molds into a rather large
irregular mass and puts into the hole, and
lays a few eggs on the pollen mass. The
young grubs or larve which soon hatch feed
on the pollen, grow, pupate, and issue as

workers—winged bees a little smaller than the queen.
These bring more pollen, enlarge the nest (fig. 218), and

make irregular cells in the pollen mass, in each of which

the queen lays an egg. She gathers no more pollen, does

MUTUAL AID AND COMMUNAL LIFE 429

no more work except that of egg-laying. From these new
eggs are produced more workers, and so on until the com-
munity may come to he pretty large. Later in the summer
males and females are produced and mate. With the
approach of winter all the workers and males die, leaving
only the fertilized females, the queens, to live through the
winter and found new communities in the spring.
Honeybees live together, as we know, in large communities.
We are accustomed to think of honeybees as the inhabitants
of beehives, but there were bees before there were hives.
The “bee tree” is famil-
iar to many of us. The
bees, in Nature, make
their home in the hollow
of some dead tree trunk
and carry on there all
the industries which
characterize the busy
communities in the hives.
These industries and
indeed the whole life of fye. 217. Diagrams of nest-burrows of
a honeybee community short-tongued mining-bees. B, nest of
are so interesting and Andrena; A, compound nest of
e : ; Halictus.
informing and withal so
readily studied in any schoolroom that I give in the fol-
lowing pages some detailed directions and suggestions for
a careful school study of the life of this fascinating insect.
The life of a honeybee.—In studying the life of the
honeybees one must observe them in the hive as well as
in the field. It is therefore highly desirable to have an
“observation” hive (fig. 219), ie., one made with glass
sides and glass top, covered with outer wooden sides which
are swung on hinges like doors, and with the usual removable
wooden roof. Ordinarily the wooden sides and top are
closed, thus leaving the hive in darkness. However, when

430 THE ANIMALS AND MAN

it is desired to observe the bees at work within, the wooden

sides are swung open;

the glass still encloses the busy

community, but affords an opportunity to see the actual

performance of such
interesting duties as wax-
making, comb-building,
food-storing, egg-laying,
nursing, etc. © “An “obser-
vation hive may be ob-
tained from a dealer in
beehives or be made out
of an ordinary hive by
any carpenter or ingeni-
ous boy. It should be
ser up, im =the Spring:
It canbe: kept un the
schoolyard, or even better,
in the schoolroom itself.
Substitute for a pane of
glass in a window a thin
wooden pane in which is
cut a narrow horizontal
opening, the Size: ol. the
regular hive opening.
If the latter is too broad
it may be covered over
at the ends. Set the ob-
servation hive on a table
or box against the window
so that its opening corre-
sponds with that in the

window. Or better, place

rl
AN
ZZ

EPIL,
WD

Fic. 218. Nest of bumble-bee, Bom-
bus sp., Showing opening at surface
of the ground and brood-cells in
cavity underneath. (Adapted from
McCook.)

it about six or eight inches from

the window and build an enclosed broad shallow tunnel,
covered above with glass, connecting the two openings.
Over the glass top of the tunnel lay a sheet of dark card-

MUTUAL AID AND COMMUNAL LIFE 431

board, which can be simply lifted off whenever it is desired
to see what is going on at the entrance. Here can be
seen the ‘ventilating,’ the alertness of the sentinels and
cuards, the killing of drones, the constant arrival of pollen-
laden food-gatherers, etc.

But observations may well begin in the field. Note the
gathering of flower pollen (fig. 220). Where does the bee
put the pollen as it collects it? Why doesn’t the pollen
fall off? Kill a bee in a killing-bottle and examine care-

NANT

Fic. 219. An “observation” beehive with glass top and sides. (Drawn
from hive in the author’s laboratory.)

fully one of its hind legs. Make a drawing showing the
pollen basket. At the flowers some of the bees do not
collect pollen but nectar. Examine the complex “tongue”
of a dead bee. By means of this tongue nectar is sucked
or lapped up and swallowed into a crop, where it is not
digested but retained until the bee returns to the hive.
By observing the bees there and examining the comb-cells
find out what is done with the pollen and nectar collected
by the food-gatherers.

432 THE ANIMALS AND MAN

Try to observe the making of wax and the building of
comb in the hive (fig. 221). The process is as follows:
after having fed bountifully on honey and pollen from the
food cells a number of bees gather together at the top of the
hive and there hang in a mass, usually buzzing the wings
violently. After a while small drops of liquid wax ooze
out on the under side of the body. ‘There are several pairs
of small scale-like folds of the skin, called wax plates, on
the under side of the hinder or abdominal body-rings.
On these plates the wax spreads out and hardens into tiny

Fic. 220. Honeybees gathering pollen and nectar.

thin sheets. After some of it has been made by a bee it
leaves its wax-making companions and goes to the place
where a new comb is to be builded or is building. Here
it nips off its wax by means of its hind legs, which are fur-
nished with a scissors-like arrangement, and with its broad,
trowel-like jaws moulds it on the forming cells. Examine
the ‘‘wax-shears” on the hindmost legs of a dead bee and
also the trowel-like jaws. Make drawings. Watch care-
fully the growth of the new comb. Of what shape are the
new cells? Are they all of the same size? Is the bottom

MUTUAL AID AND COMMUNAL LIFE 433

of each cell flat? How are those of the two opposite layers
of which the comb is composed related to each other ?

Note several bees standing in the covered entrance to
the hive and steadily and rapidly vibrating their wings.
They are “ventilating’”—that is, making currents of air
so that fresh air will constantly flow into the hive and foul
air out. Ventilating bees may also be seen scattered through
the hive.. A movement of air through the comb is necessary
for the honey-making as well as for ventilation. The nec-

1‘ =

o

i

Fic. 221. Honeybees building comb. (After Benton.)

tar as it is gathered from flowers and poured out into cells
from the crops of the food-gathering bees is too watery to
be good honey, and must be partly evaporated. The venti-
lation assists largely in its evaporation. Touching the hand
to the glass sides note that the interior of the hive is warmer
on a cold day than the outer air. This is because the bees,
when necessary, buzz violently to make themselves unusually
warm and thus raise the temperature of the hive. When
young bees are being reared the hive must always be kept

434 THE ANIMALS AND MAN

warm. Note the bees clustering thickly over the brood-
cells, i. e., the cells containing young.

Can you note any difference in the appearance of the
various individuals? Are there some which do not work?
Are all the cells filled with honey or pollen? If not, what
is put into the other cells? The correct answer to these
questions brings us to the consideration of the bees’ develop-
ment or life-history, and the make-up of the community.
Some of the facts in the following brief account can be readily
observed by the pupils, but some cannot. As many of the
following statements
as possible should be
confirmed by obser-
vation.

A honeybee com-
munity is made up of
three kinds of indi-
vic walisas Gio 9222).
namely, a single queen
or mother which lays
the eggs from which
Fic 222. The honeybee. Apis mellifica; A, all the other bees are

ae B, drone; C, worker. (From speci- produced, ee econ

dred drones or males,
one of which becomes the royal consort, fertilizing the
eggs, and from ten to forty thousand or more workers,
which do all the work of the community, gathering food,
making wax, building comb, ventilating the hive and car-
ing for the young bees. The drones are larger, more
robust, and more hairy than the workers, while the queen
is longer, with a slender tapering abdomen. Certain combs
are chosen as brood-combs (fig. 223), and beginning in the
center of these and working outward the queen lays a tiny
white elongate egg in the bottom of each cell. These eggs

foto)
hatch in three days, and the young bees or larve appear

MUTUAL AID AND COMMUNAL LIFE 435

as white, soft, footless, helpless, grubs. They are fed by
certain worker bees called nurses (workers which have not
yet learned to go out and gather pollen and honey), at first
on a highly nutritious substance called bee-jelly, which the
nurses make in their stomachs and regurgitate. After two
or three days of bee-jelly diet they are given pollen and
honey. A few days later a small mass of this new food
is put into each cell, which is then “‘capped” or covered
with wax. The larve after eating what is stored in their

Fic. 223. Worker brood and queen-cells of honeybee; beginning at the
upper right end of cells and going to the left is a series of egg, young
larvae, old larvae, pupa, and adult ready to issue; the large curving
cells below are queen-cells. (After Benton.)

cell change into pupz and lie quiescent for thirteen days
when they become fully developed bees. They now gnaw
the caps away and come out into the hive ready to work.
Such is the life-history of the worker bee. It has been
demonstrated that the eggs which produce workers and
those which produce queens do not differ, but that if the
workers desire to have a queen they tear down two or three
cells around some one cell, enlarging it into a vase-shaped
cavity (fig. 223). The larva that hatches in this large cell
is fed for its whole larval life with rich bee-jelly. From its

436 THE ANIMALS AND MAN

pupa issues not a worker but a new queen. The eggs
which produce drones or males differ from those which
produce queens and workers in being unfertilized, the queen
having the power to lay either fertilized or unfertilized eggs.
When a new queen appears, or when several appear at once,
there is great excitement in the community. If there are
several they are believed to fight among themselves until
only one survives. It is said that a queen never uses its
sting except against another queen. The old queen now
leaves the hive accompanied by many of the workers. She
and her followers fly away together, finally alighting on
some tree branch and hanging there in a dense mass. This
is the familiar act of ‘“‘swarming.”’ Scouts leave the swarm
to find a new home, to which they finally conduct the others.
Thus is founded a new colony.

There are many more interesting things to be learned
of the life in a honeybee community; how it protects itself
from the dangers of starvation, when food is scarce or winter
comes on, by killing the useless drones and the immature
bees in egg and larval stages; how the instinct of home-
finding has been so highly developed that the worker may
go miles away for honey and nectar, flying with unerring
accuracy back to the hive; of the extraordinarily nice
structural modifications which adapt the bee so perfectly
for its complex and varied affairs; and of the tireless per-
sistence of the workers until they fall exhausted and dying
in the performance of their duties. The community, it
is important to note, is a persistent or continuous one.
The workers do not live long, the spring broods usually
not over two or three months, and the fall broods not more
than six or eight months; but new bees are hatching while
the old ones are dying, and the community as a whole always
persists. The queen may live several years, perhaps as
many as five. She lays about one million eggs a year.

The honeybees offer a splendid example of mutual aid

MUTUAL AID AND COMMUNAL LIFE 437

instead of bitter war among individuals of a species. To
be sure there is competition among different honeybee
communities for food, but among the thousands of indi-
viduals composing a single colony every one works for the
benefit of the whole great family; the workers devote their
whole life unceasingly for others.

CHAPTER XXXII

COLORS AND MARKINGS OF ANIMALS, AND
THEO SSeS

The colors and markings of animals are among the most
conspicuous of their external characters, and constantly

Fic, 224. Owl butterfly, Caligo, under side. (Two thirds natural size.)

incite us to ask how they are produced and why they are

of such great variety. As no more familiar or interesting

examples of color patterns can be found than those on the
438

COLORS AND MARKINGS OF ANIMALS 439

wings of butterflies and moths, we can very advantageously
use these beautiful insects in beginning the study of animal
colors.

The scales and colors of butterflies’ wings.—Catch a
few butterflies of different kinds and kill in the killing-bottle.
With the finger rub lightly one of the wings and note that a
fine dust-like substance comes off on the finger-tip, and
that at the same time the pattern and color disappear. By
gentle steady rubbing with thumb and finger just opposite
each other on the upper and lower sides of the wings, a
clear, transparent spot may be made. It is evident that
the color and pattern of the wing depends upon its covering
of fine particles.

Fic. 225. Single scales from moths and butterflies; a, from Tolype velleda;
b, from Castnia sp., c, from Micropteryx aruncella. (Greatly magni-
fied.)

Rub some of this color-dust from the finger-tip on a
glass slide and examine under the microscope. Note that
the fine particles are all scale-like in shape and character,
each being composed of a tiny short stem and a broader
flattened blade which may have the margin of its broad
free end even or dentate, that is, showing little teeth or
fingers (fig. 225). These tiny scales are hollow, and inside
they may contain only air, in which case they are transparent
or whitish under the microscope, or they may hold small
granules of pigment, a colored substance which makes
them brown or yellowish or reddish or blackish,

440 THE ANIMALS AND MAN

Some butterflies have blue or green or purple colors,
iridescent and changeable, on their wings. The common
little ‘“blues”’ have the upper side of the whole wing metallic
blue. Examine under the microscope some scales from
one of these blue wings, or from a blue or greenish iridescent
spot on any butterfly’s wing. They will be seen to be not
blue or green (as long as light is allowed to come from the
mirror of the micro-
scope up through
them) but either color-
less or of a pale yel-
lowish_ or brownish
shade i butsait aauae
light from below is
: cut off by placing a
, hand over the micro-
scope mirror they will
show an_ iridescent
blue or green.

Examine under the
microscope a bit of
wing from which most
Fic. 226. A small, partly denuded part, of the scales have

much magnified, of a wing of the small been rubbed (figs.
blue butterfly, Lycaena sp., showing the o
scales and the pits in the wing-mem- 226 and 227). Note
brane, in which the tiny stems of the scales rows of tiny pits or
are inserted. (Photo-micrograph by G. O.
Mitchell.)

pockets in which the |
stems of the scales
fit. The scales are fastened, though not very firmly,
to the wing membrane by their stems, and are ar-
ranged in fairly even rows. In each row they are so thick
that they overlap each others’ sides, and the rows are so
close together that the tips of the scales of one row overlap
the bases of those of the one in front. This arrangement
is much like that of shingles on a roof, and each wing is

COLORS AND MARKINGS OF ANIMALS 441

thus shingled above and below (fig. 228) by thousands of
tiny scales which produce all its colors and markings. These
colors are made in two ways; either the scales are actually
brownish or reddish or yellowish or black themselves be-
cause they contain pigment granules inside, or else they
reflect white light in such a way that it is broken up, as by a
prism, into colors, only some of which reach our eyes. ‘The
metallic and iridescent kinds, the greens, blues, coppers,
purples, etc., all of which change somewhat as we change
fe |position ‘OL -our-.eyes;
are produced in the second
way. The duller and the
fixed colors, such as _ the
reds, yellows, browns, etc.,
are produced by scales con-
taining pigments of the same
shade.

Colors of other animals.
—The colors of other ani-
mals are also produced in
one or both of these two

Brea 22 7:

Bit of rubbed wing of a

ways; that is, either by col-
ored pigment, or by reflec-
tions from structures which

butterfly, Grapta sp., greatly mag-
nified, to show the rows of scale
insertion pits on both upper and

act as the prism does. lower sides of the wing.

Only a few other animals have scales, and almost no
others have scales just like those of the butterfly, but they
have other kinds of structures on the outside of the skin,
such as feathers or hairs, which contain pigment, or break
up white light into colors.

Observe the coloring on a blackbird; note the fine iri-
descent blue and purple or bronze-green reflections. These
are made by the feathers reflecting broken-up white light.
Such iridescent colors produced by structure, and hence
called structural colors, are especially proncunced and

442 THE ANIMALS AND MAN

beautiful on humming-birds. On the other hand the red
brown of the robin’s breast and the yellow of the meadow
lark’s are produced by feathers containing reddish and
yellowish pigment granules.

The colors of most quadrupeds, which are covered with
hair, are dull and almost entirely due to pigment in the
hair. Those of live fishes, often brilliant and iridescent
in the water, fade and sometimes wholly disappear when
the fish is dead and dry. Colors such as these are struc-
tural, the scales being mostly transparent.

Observe as many animals as possible and try to find
out how their colors and markings are produced, what
the external structures are which make them, and whether
they are made by pigment or by prismatic reflection.

eee ieee

ew wee i et

Fic. 228. Diagram to show the shingling arrangement of the scales over
the surface of a butterfly’s wing; the short black bars indicate scales
in cross-section, and the broad central bar, the wing in cross-section.

Uses of color.—Although we have been long accus-
tomed to see the beautiful and varied markings of birds
and butterflies, have we asked ourselves of what use these
colors and patterns are to the animals possessing them ?
We cannot think that they exist just to please us. We
have found that in animals’ bodies the parts are all made
so as to be just as useful as possible, each part having some
special thing to do to help the animals live successfully. The
same is true of the colors and patterns which are such con-
spicuous features of their external appearance.

Try to catch a locust. The insect will be plainly seen
as it flies or leaps through the air, but how when it alights
on the ground? If you do not watch carefully to see it
alight, you will have great difficulty in finding it now. It
is almost indistinguishable among the pebbles, bits of twigs,

COLORS AND MARKINGS OF ANIMALS 443

and soil of the surface. It resembles its surroundings
in coloration and undoubtedly is thus often saved from
pursuing enemies. A bird sees a locust flying. The lo-
cust alights and rests quietly on the ground; if distinguished
the bird seizes it and it loses its life; if not distinguished
the locust is saved, and saved by its color. So color is of
use to the locust.

Fic. 229. The so called deaths’-head sphinx moth; this moth is looked
on with superstitious dread by many people. (Natural size.)

But how about the birds themselves—the crouching,
immovable, dust-colored quail which waits until the hawk,
not perceiving it, flies away; and the rabbit, colored like
the dead grass and ground about it, which lies rigid until
you are fairly upon it, although it sees your every movement ?
Swift of foot as the rabbit is, it relies more for safety on its
protective color than on its fleetness. Among the green
leaves of trees live the katydids; they are all green. On the

444 THE ANIMALS AND MAN

great everlasting snow-fields of the arctic regions live foxes and
hares and ptarmigan, all white as the snow itself, although
their near cousins the foxes, hares, and ptarmigans of warmer

regions, where the snow
falls but occasionally, and
the earth’s surface is usually
brown and dark, are red-
dish or gray or brown. In
the desert the lizards and
snakes and insects are mot-
tled gray and sand-colored,
while in the evergreen foli-
age of trees In warm re-
gions live green tree-frogs
and tree-snakes and insects.

Special protective resem-
blance.—But some animals
show more than just a
general resemblance to, or
harmony with, the color
tone of their surroundings;

they show a striking resem- |

blance to some particular
part of their surroundings.
An insect common all over
the country, but only rare-
ly distinguished and recog-
gnized, is the walking-stick
insect (fig. 230). Its body
is. long, and: slender, ats
legs very long and held
stiffly and angularly, and
it has no wings. Its body
and legs are colored either
dulle ;ereen™ alli over, tor

Fic. 230. The twig insect or walking-
stick, Diapheromera femorata,
(Natural size.)

COLORS AND MARKINGS OF ANIMALS 445

Fic. 231. The dead-leaf butterfly, Kallima sp., a remarkable case of
special protective resemblance.

446 THE ANIMALS AND MAN

blackish brown. And when not walking slowly about
it always rests quietly on a twig or branch, from
which the eye with difficulty separates it. In the tropics
the so-called green-leaf insect, Phyllium, resembles in great
detail a broad green leaf. Its body is broad and leaf-shaped,
its color bright green with delicate lines to imitate the midrib
and veins of a leaf, and it even has pale irregular yellow’
spots which imitate mouldy and yellow places on a real
leaf. But most remarkable of all is the famous dead-leaf
insect, Kallima (fig. 231), not uncommon in tropical Africa,
South America, and the Australasian islands. ‘The upper
surfaces of the wings of this butterfly are brownish gray
with a broad purplish bar on each wing, making a rather
conspicuous pattern;
but the under sides
are so colored and
are marked with
such faithfulness of

detail that. when Fie, 932. Larva of the monarch butterfly,
Kallima alights and conspicuously marked with black and whitish-
yellow wings, and distasteful to birds. (Nat-
ural: size.)

folds its wings to-
gether va bo Ve its
back, as butterflies do, it resembles exactly a large, brown,
dead leaf, still attached to the twig by a short pedicel or
stem (imitated by a “tail” on the hind wings). The mock
leaf is veined by means of lines of darker scales exactly as
leaves are veined.

In this country are certain butterflies, the Graptas, some-
times called dead-leaf butterflies, which resemble in color
and shape, and in the ragged edges of the wing, dead and
torn autumn leaves, but the resemblance is not carried out
in such detail as with Kallima.

Warning colors.—But not all insects or other animals
are colored like their surroundings. Often indeed color and
pattern are such as to make an animal very noticeable.

COLORS AND MARKINGS OF ANIMALS 447

The common large red-brown monarch, or milkweed butter-
fly (fig. 233), is a conspicuous object whether in flight or
alighted on some flower or branch. But the birds do not
attack it; and for the reason that it contains, as has been
proved, an ill-tasting fluid which makes it a very disagree-
able mouthful for them. Now it is apparently so brightly

Fic. 233. The monarch butterfly, Anosia plexippus (above), distasteful
to birds, and the viceroy, Basilarchia archippus (below), which mimics
it. (Natural size.)

colored that the birds generally recognize it before actually
nipping it, and thus it often escapes with its life—for to
be nipped is death to a butterfly. Other conspicuously
marked butterflies and insects and some other forms, in
particular a famous little blue and red frog of Nicaragua,
are thought to be so marked for a similar reason. They are
easily recognized as animals having a bad taste and so are

448 THE ANIMALS AND MAN

generally let alone. Accordingly naturalists believe that
conspicuous color and markings often advertise some disa-
ereeable quality or some special means of defense in the
animal bearing them and thus ward off its enemies.

Fic. 234. Various moths and wasps, the moths having the appearance
of wasps, probably through mimicry, for the sake of the protection
afforded by their being mistaken for the stinging insects. (Natural
size; photograph by the author.)

Mimicry.—Certain other insects derive strange advan-
tage from the inedibleness of the warningly colored bad-
tasting kinds. There is, for example, another kind of
butterfly called the viceroy (fig. 233), which looks so much
like the monarch (although not nearly related to it), that

COLORS AND MARKINGS OF ANIMALS 449

it requires careful examination to distinguish the two kinds.
But the viceroy is not inedible. And yet it, too, escapes
very largely the attacks of birds because they mistake it
for the other. By mimicking in color and pattern the ap-
pearance of the inedible monarch it gains a great advantage.
Numerous other examples of protective mimicry are known
among butterflies, especially tropical ones.

Other uses of color and markings not yet under-
stood.—Protective resemblance and mimicry and warning
coloration do not account for the color-markings of all ani-
mals, although it is probably true that the most wide-spread
use of color in the animal kingdom is for protective resem-
blance. For example, the conspicuous white spot on the
rabbit’s tail is thought by some naturalists to be a means
whereby it can be recognized by others of its kind at long
distances. Some naturalists believe that the bright colors
and conspicuous markings of the male birds are for the
purpose of pleasing and attracting the females at mating
time. And still other uses have been ascribed to color-
markings in various animals. But with all these different
explanations there are still many cases for which we can
give no satisfactory explanation based on usefulness. ‘There
is much yet to be learned about color and pattern in animals.

Poulton’s the ‘‘Colors of Animals” is an interesting book on this
subject; see also Newbigin’s ‘Color in Nature,” and Beddard’s
‘Animal Coloration.”’

CHAPTER XXXIV

INSECTS AND FLOWERS

The nectar of flowers is a favorite food with many insects;
all the moths and butterflies, all the bees, and many kinds
of flies are nectar-drinkers. Flower-pollen, too, is food for
other hosts of insects, as well as for many of those which
take nectar. Ihe hundreds of bee kinds are the most
familiar and conspicuous of the pollen-eaters, but many
little beetles and some other obscure small insects feed
largely on the rich pollen-grains. But the flowers do not
provide nectar and pollen to these hosts of insect guests
without demanding and receiving a payment which fully
requites their apparent hospitality. And several particular
things about this payment are of especial interest to us.
These are, first, the unusual character of the payment re-
ceived; second, the great value of it to the plants; and
finally, the strange shifts and devices which the plants
exhibit for making the payment certain. This payment
is the cross-pollinating of the flowers by their insect visitors.
(Cross-pollination is simply the bringing of pollen from the
stamens of one flower to the pistils of another flower of the
same plant species.)

In 1793 a German naturalist named Christian Conrad
Sprengel published a book called ‘““The Discovered Secret
of Nature in the Structure and Fertilization of Flowers.”
This discovered secret was that insects were instrumental
in pollinating flowers and that the colors and shapes of
flowers helped to attract insects and compel them to do this
pollinating. But it was reserved for the great Darwin to

790

INSECTS AND FLOWERS 451

describe in wonderful detail this mutually advantageous
interrelation between flowers and insects and to explain
its chief causal factors. These are, first, the real advantage
to the plant of cross-pollination, and, second, the action of
natural selection in modifying both flowers and insects for
the sake, or by the reason, of this advantage.

Fertilization among plants is like fertilization among

Fic. 235. Diagram of section of pistil and ovary of a flower, showing the
descent of the pollen tube and its entrance into the ovule. . g., pollen-
grain; p. ¢., pollen-tube; e. s., embryo sac; e. c., egg-cell; s. ”., sperm
nucleus. Left-hand figure (1) shows the pollen-tube grown down,
around and up into the ovary with the sperm-nucleus just entering the
ovule; right-hand figure (2) shows the fusion of the sperm-nucleus.
(After Stevens.)

animals; a germ- (sperm-) cell from one individual (male or
hermaphrodite) fuses with a germ- (egg-) cell from another
(female or hermaphrodite) individual or from the same
(hermaphrodite) individual. The sperm-cells are contained
in pollen produced in the anthers of stamens; the egg-cells
lie in the ovaries at the base of the pistils, these pistils having
an exposed pollen-catching surface (stigma) at their free
tip. Before actual fertilization can occur pollination must

452 THE ANIMALS AND MAN

take place; pollination being the bringing and applying
of ripe pollen-grains to the ripe surface of the stigma. How
fertilization then takes place is succinctly explained by
fig. 235 and its caption, which are copied from Stevens
(‘Introduction to Botany,’ Boston, 1902).

The advantage of cross-pollination, as first experimentally
proved by Darwin and since then confirmed by other ex-
perimenters and by hosts of plant breeders, lies in the fact
that the seeds from cross-pollinated plants usually produce
stronger plants than are produced by the seeds of self-
pollinated plants. To effect cross-pollination plants have
developed two kinds of means; first, means to attract insects
and humming-birds, and to insure cross-pollination as the
result of their visits; second, means to prevent self-pollina-
tion. Also insects that visit flowers have developed certain
peculiarities of structure and habit which correspond to the
special character of the flowers chiefly visited by them.
These reciprocal modifications of flowers and insects have
gone so far in some cases that certain plants and certain
kinds of insects cannot exist apart from each other. Many
flowers are not fertile when fertilized by their own pollen
and these may have no other possible means of getting
pollen from other plants except by insect visits.

The principal means which have been developed to avoid
self-fertilization are the following: first, having flowers
either only staminate or pistillate; these different flowers
may occur on the same plant individual or only on separate
individuals; second, having both pistils and stamens on
each flower but with the pollen not ripe at the same time as
the stigma; third, having the stamens and pistils in the same
flower of different length or having them so situated that
the pollen will be unlikely to fall on the stigmas.

The principal means for insuring cross-pollination are:
first, the secretion of nectar to feed insects; second, the
development of odor, color, pattern and shape to guide

INSECTS AND FLOWERS 453

them to the flower and when there to the nectar and pollen
in such a way as to insure their brushing against either
the stamens or stigmas; third, modifications of shape so as
to prevent the stealing of nectar and pollen by non-helpful
insects; and fourth, blossoming at those times in the year
when the particularly helpful insects are most numerous,
and the opening of flowers at such times, in daylight, twi-
light or at night, as exactly to accord with the food seeking
times of the insects. ‘The great variety in the shape, color
and patterns of flowers suggests the great variety that actually
exists in the ways in which flowers attract and at the same
time profit by the insects.

The nectar, which is what most insects come to the flowers
to get, is a sweetish liquid secreted by special tissues called
nectaries. These may occur on any part of the flower,
but they are most frequently found at the bases of the stamens,
petals, and ovaries, and rarely on the calyx. In the plum
and peach they form a thick inner lining of the cup-shaped
receptacle. In nasturtiums the nectar is secreted in a
long spur from the calyx.

Some flowers of simple construction expose their nectar
freely to all sorts of insects, but others conceal it in various
ways so that it is accessible only to insects of certain kinds.
A frequent device is to have some parts of the corolla close
the way to the nectar so that small insects which would not
assist in cross-pollination are excluded, and only those
which are strong enough to push aside the barrier or have
proboscides of proper construction to thrust past it can
obtain nectar and accomplish the transference of the pollen.

The pollen, which is sought for only by bees and a few
little beetles, is a normal product of the flower and it is
only necessary that there be enough of it to supply the
insects and yet supply the plant’s own use for fertilization.
The oldest and most primitive means developed among
plants to effect cross-pollination, a means still used by all

454 THE ANIMALS AND MAN

the conifers, the grasses and many other plants mostly
without sepals and petals, is the production of vast quantities
of light loose pollen grains to be distributed by the winds.
“Sulphur rains” that come sometimes at the pollen ripening
time of pinetrees are simply showers of wind-blown yellow
pollen from the forests. With nectar and pollen ready
for use the plant has yet to advertise its sweets to the insects,
and for this brilliant colors and attractive odors are relied on.
An odor attractive to insects is not always pleasing to us, for
the Araceze, some Trilliums and others have a carrion-like
odor ‘‘combined with dull colors often marked with livid
blotches or veins like dead animal bodies, and these flowers
attract flesh-flies and carrion-beetles which are the pollinat-
ing agents.” The simpler insect-visited flowers, such as
those of the apple, cherry, wild rose, ranunculus, etc., are
mostly wide open and accessible to a large variety of insect
visitors. ‘They are all abundant pollen providers and some
secrete nectar which is easily got at. But to get either
nectar or pollen the insects have to scramble over and among
the many crowded stamens of the center, dusting themselves
well during the process with pollen, which is carried on to
the next flower visited and there probably rubbed off on to
the stigma. ‘To such simple flowers, and to others like
them, as the Umbelliferee and the numerous Composite,
many kinds of insects may come. For example, Robertson
found 275 different insect species visiting an Umbellifer
in three months in Illinois, and 146 kinds visiting a golden
rod in 11 days.

With the flowers of tubular corolla the nectar can be got
at only by insects especially provided with long tongues,
such as bees and some flies, moths and_ butterflies.
The deeper kinds of flowers are mostly visited by insects
with especially long proboscides. The common _ jimson-
weed, Datura stramonium, is, as Stevens says, an excellent
example of this. ‘““The corolla is about five centimeters

INSECTS AND FLOWERS 455

long, and the cavity of the tube is closed at about the middle
of its length by the insertion of filaments there. When the
flower opens in the evening it emits a strong musky odor,
and a large drop of nectar is already present in the bottom
of the tube; so that large sphinx moths, leaving the places
of seclusion occupied by them during the day, are attracted
by the strong odor and white color of the flowers.

“Flying swiftly from flower to flower, the moth thrusts
its long proboscis to the bottom of the tube and secures the
nectar; and while it is tarrying briefly at each flower, keeping
itself poised by the swift vibration of its wings, it is pretty
certain to touch with its proboscis both anthers and stigmas,
which stand close together at about the same height near
the mouth of the corolla. Both cross- and self-pollination
might be brought about in this way, but as Darwin has
shown, the foreign pollen would probably possess the greater
potency, and cross-fertilization would be apt to result.
The harmonious relation between length of the insect pro-
boscis and depth of the flower corolla is strikingly shown
by all the sphinx moths and the flowers they visit.

Another kind of arrangement of flower structure which
tends to preserve the nectar for certain special kinds of
insects is well illustrated by the salvias, snap-dragon, and
other similar flowers. In these the corolla is irregular and
the stamens and pistils are so arranged that insect visitors
are compelled to visit the nectary in one particular manner,
a manner such as to insure their touching the anthers or
stigma or both. In the snap-dragon the opening of the
flower-cup is normally closed, but when a bee alights on the
broad keel or platform (composed of two petals grown
together) its weight so depresses this platform as to open
the way into the flower-cup, which closes at once when the
bee goes in and drinks the nectar. Scrambling and twisting
about in the narrow chamber it thus thoroughly dusts itself
with pollen, or thoroughly dusts the stigma with pollen

456 THE ANIMALS AND MAN

acquired from a previous visit to another flower. Mis-
cellaneous small insects alighting on the keel are not heavy
enough to depress it, and thus are prevented from entering
and stealing the nectar. In the salvias (sages) the corolla
is similarly tubular below and two-lipped above, the lower
lip serving as an alighting-platform for the insect visitors
(usually bees), while the arched upper lip covers and pro-
tects the stamens and pistil.

In the scarlet sage (Salvia sp.)
cross-pollination is accomplished by
humming birds, which, hovering in
front of the narrow mouth of the
flower-cup, thrust deeply into it their
long bills in the search for small
insects which may have entered for
nectar. Other flowers regularly visit-
ed and cross-pollinated by humming
birds are the scarlet currant, various
painted cups (Castilleias), the scarlet
mimulus, the wild columbine, the
trumpet-creeper, the spotted touch-
Fic. 236. Honeybee at me-not, the cardinal-flowers, cannas,

dee ore tee ce and fuchsias. Red seems to be the

chamber of the flower attractive color for humming birds.

last visited. (Natural A wonderful arrangement to insure

size; alter Stevens.) Cross-pollination by insects is that
shown by the milkweeds of the genus Asclepias. Stevens
has described this so well (‘Introduction to Botany,”
p. Ig1 et seq.) that I simply quote here most of his account.

‘“‘As shown in fig. 236, the sepals and petals are reflexed;
the stamens are joined throughout their length, and are
united to a thick and flat structure at their apices, known
as the stigmatic disk, which is also united with the top of
the two pistils. The pistils are entirely enclosed by the
stamens and the stigmatic disk. Five spreading, hollow

INSECTS AND FLOWERS 457

receptacles for the nectar grow out and upward from the
bases of the stamen.

“Each pollen-sac contains a compact mass of pollen-grains
which never become separated from one another, and so con-
stitute what is termed a pollinium. ‘The two contiguous pol-
linia of adjacent anthers are united by horny rods which con-
verge upward and join with a horny dark body known as the
corpusculum, which is hollow and has a slit along its outer
face. This slit is relatively broad at the bottom, and tapers
toward the top, thus forming a clip in which the feet of the
insects get caught. Between each pair of anthers there is
a deep recess closed by two vertical lips which stand wider
open at the bottom than at the top, and the recess also nar-
rows at the top. The opening between the lips at the top
stands exactly beneath the slit in the corpusculum.

“The surface of the flower is slippery, so that when a
bee, for instance, visits it, a good foothold is not obtained
until the bee slips its foot into the recess between the anthers,
termed the stigmatic chamber. Having obtained a foot-
hold, the bee thrusts its sucking-apparatus into the hollow
nectar-receptacle and obtains the nectar which has invited
it to the flower. When the bee, however, seeks to go to an-
other flower, its foot slips upward and becomes caught in
the slit in the corpusculum. A struggle now ensues which
usually results in the bee pulling the two pollen-masses, united
to the corpusculum, through the narrow slits at the tops
of the pollen-sac; and thus laden, it seeks another flower,
and there slips its foot, together with the pollen-masses, into
the stigmatic chamber.

“Now when the bee attempts to leave the flower, the pol-
len-masses become tightly wedged at the narrow apex of the
chamber, and a hard pull is required to break them loose
from the foot. Finally, as the foot is being drawn from the
stigmatic chamber it catches into the corpusculum directly
above and pulls out a second pair of pollen-masses. Thus

458 THE ANIMALS AND MAN

the bee goes from flower to flower and from plant to plant,
repeatedly pulling pollen-masses from their sacs and de-
positing them in the stigmatic chamber. Fig. 236 is from a
photograph of a honey-bee gathering nectar from Aselepias-
flowers. One of the hind legs is still in the stigmatic cham-
ber of the flower, which the bee has just deserted.”

Hive-bees, although common
visitors to Asclepias, are really
hardly strong enough to insure
pulling loose from the flowers,
and many of them besides num-
erous flies and small butterflies,
get caught and die in the flower-
heads. Robertson has _ noted
nine species of insects thus killed
by Asclepios cornuti. Bumble-
bees and large wasps and large
butterflies are the most certain
milkweed pollinators.

Still another markedly differ-
ent kind of specialization to
Fic. 237. Flower of Aristolo- effect cross-pollination by insects

chia clematitis in longitudinal js that shown by many Araceze

schon: «2 below feralization snd Aristolochiaccass lhe flow=
by little fly; B, after fertiliza- _ :

tion; p, pollen-masses; s, stig- ©T (fig. 237) in these plants

ma; 6, bristly hairs; wb, with- consists of a long tubular peri-

ue hairs, (After H. anth (spathe) with a constriction
near the base, the narrow open-

ing into the cavity below being nearly closed by stiff down=
ward-pointing hairs, so as to make a sort of floral eel-trap.
It really is an insect-trap; small flies crawl down the long
tube and through the narrow opening in search of nectar;
but when ready to return find themselves imprisoned by
the downward-pointing hairs. After a while the stigmas,
which mature before the anthers and have likely been polli-

INSECTS AND FLOWERS 459

nated (with pollen brought from other flowers) by the enter-
ing insects, wither, a drop of nectar is secreted for the
benefit of the captured insects, and the anthers mature,
exposing their ripe pollen-grains. The hairs in the throat
of the flower gradually shrivel up and release the insects
which are now well showered with pollen falling on them
from the anthers above. Visiting another Arum-flower,
they hardly fail to rub off some of this pollen on the mature
stigmas. Sometimes more than a hundred small flies will
be found imprisoned in a single Arum.

Classic examples of apparently the wildest vagaries in
flower structure are those presented by the orchids. But
Darwin’s fine work revealed the method in all this floral mad-
ness. Orchids are pollinated almost exclusively by insects,
and the extravagant shapes and color-patterns are all means
for accomplishing cross-pollination. Any one interested at
all in the interrelation between flowers and insects should
read Darwin’s account of the orchids and their insect visitors,
in his book “On the Fertilization of Orchids by
Insects.?’

The above few examples of the interrelations between
flowers and insects are not exceptional cases. Indeed, this
state of affairs is the rule throughout the families of flower-
ing plants. The absence of it is the exception. Cross-
pollination by insects is far more abundant than self-pollin-
ation.

It is of distinct interest to note that no plants of colored
flower-parts existed (in geologic time) before the time of
winged insects. The insects which we know today as the
pollen- and nectar-feeders, hence flower visitors, began to
be abundant in the world coincidentally with or a little in
advance of the flowering plants. Mutually helpful and
mutually adapting themselves to each other, the flies, bees,
moths, and butterflies, on the animal side and all those plants
with flowers of varied shapes, color, and patterns, on the

460 THE ANIMALS AND MAN

vegetable side, have developed so successfully during the
course of the history of the earth that in present times flower-
visiting insects and insect-attracting flowers have come to
be the most specialized and notable members of each of
their great groups of organisms.

APPENDIX I
PUPIL AND SCHOOLROOM EQUIPMENT

Note-books and drawings.—Each pupil should have
a note-book of about 8 x Io inches, opening at the end,
in which both drawings and notes can be made. The paper
should be unruled and of good quality (not too soft). Each
pupil should make the drawings called for in connection
with the study of the various animals considered in this
book. These drawings should be in outline, and put in
by pencil; the lines may be inked over if preferred. Each
drawing and all the animal parts represented in it should
be fully named. Notes should be made of any observations
which cannot be represented in the drawings, for example,
on the behavior of living animals. All notes referring to
matters of life-history should be dated.

Scattered through this book will be found numerous
suggestions for student field-work, for the observation of the
life-history and habits and conditions of animals in nature.
The initiation and direction of such work is left to the teacher.
But its importance, both because of its instructiveness and
its interest, is great. Pupils should not only be incited to
make individual observations whenever and wherever they
can, but the teacher should make little field-excursions
with the class, or with parts of it, at various times, to ponds
or streams or woods, and “‘show things” to all. The life-
history and feeding-habits of insects, the web-making of
spiders, the flight, songs, nesting and care of young of birds,
the haunts of fishes, the development of frogs, toads, and
salamanders, the home-building and feeding-habits of
squirrels, mice, and other familiar mammals are all (as has
been called attention to at proper places in the book) specially
fit subjects for field-observation.

461

462 THE ANIMALS AND MAN

Each pupil should keep a field note-book, recording
from day to day, under exact date, any observations he may
make. Let the most trivial things be noted; when referred
to later in connection with other notes they may not seem
so trivial. The field note-book should be smaller than the
laboratory note- and drawing-book, small enough to be
carried in the pocket. Notes should be made on the spot
of observation; do not wait to get home. Sketches, even
rough ones, may be advantageously put into the book.
Students with photographic cameras can do some very
interesting and valuable field-work in making photographs
of animals, their nests and favorite haunts. Such photo-
graphic work is very effectively used now in the illustration
of books about animals and plants (see the reproductions
of photographs in this book). If the class is making a
collection the collecting notes or data made in the field-
books of the different pupil collectors should all be trans-
ferred to a common “Notes on Collections” book kept by
the whole class.

Equipment of schoolroom.—The equipment of the
classroom or laboratory will, of necessity, depend upon the
opportunities afforded the teacher by the school officers to
provide such facilities as instruments, books, and charts.
If dissections are to be seriously and properly made, how-
ever, some equipment is indispensable. Flat-topped tables,
not over 30 inches high, a few compound microscopes (one
is much better than none), as many simple lenses, or, far
better, simple dissecting-microscopes, as there are students,
dissecting-dishes, a pair of bone-clippers, one injecting-
syringe, a bunch of bristles, water, a few simple reagents
and some inexpensive glassware, as slides, cover-glasses,
watch-crystals, and fruit- or battery-jars for live cages and
aquaria, make up a sufficient equipment for good work.
Much can be done with less, and perhaps a little more with
some additional facilities.

The dissecting-pans should be of galvanized iron or tin,
oblong, about 6x8 inches by 2 inches deep, with slightly
flaring sides. If an iron wire be run around the margin,

PUPIL AND SCHOOLROOM EQUIPMENT 463

and the margin bent back over it, it will strengthen the
dish, and make a broader and smoother edge for the hands
to rest on. Diagonally across the dish, about one-fourth
inch from the bottom, should run a thick wire. A layer
of paraffin one-half inch thick should cover the bottom.
It should be poured in melted, when the diagonal wire
will be imbedded in it and will hold it in place. Acids
must not be put into the pan.

The reagents necessary are alcohol of 95 per cent and
85 per cent, and formalin of 4 per cent (the formaldehyde
sold by druggists is 40 per cent and should be diluted ten
times with water), these for preserving material for dis-
section; chloroform for killing specimens; glycerin for
making temporary microscopic mounts, and 20 per cent
nitric acid for preparing specimens for study of the nervous
system. In addition there will be needed the few other
materials mentioned in the following paragraphs as neces-
sary in the preparation of injecting-fluids, the staining of
fresh tissue and preserving by special methods.

A list of reference books desirable in the laboratory is
appended as a separate paragraph (see p. 466).

Collecting and preparing material for use in _ the
laboratory.—As directions have been given here and there
through the book for the collecting and _ preparing
of the various kinds of animals chosen as_ subjects
of the laboratory exercises, it will only be necessary
to give here directions for making certain special mixtures
and for the special preparation of specimens by injection,
etc. Specimens to be used for dissection should be kept in
alcohol 85 per cent or in formalin of 4 per cent. Alcohol is
better for the earthworm, but for the other examples formalin
is either better or as good, and as it is much cheaper it may
well be chosen for the general preservative.

Methyl green, a stain used for coloring fresh tissues.
Dissolve the methyl green powder in water, using about
as much powder as the water will take up. Add a few
drops of acetic acid.

Injecting-masses.—Injections are best made with prep-

464 THE ANIMALS AND MAN

arations of French gelatine, but white glue will answer
most purposes. For fine injection use a combination of
the following: 1 part of a solution of gelatine, 1 part to
4 parts of water; 1 part of a saturated solution of lead
acetate in water, and 1 part of a saturated solution of potas-
sium bichromate in water. A mixture of these when hot
gives a beautiful yellow injection-mass which, filtered, will
pass through the finest capillaries. For different colorings
use dry paints, which come in ultramarine blue, vermilion,
and green. The gelatine should be thoroughly soaked
before the coloring-matter is added. A mistake is generally
made in using the injection-mass too thick. One part by
weight of gelatine to six or even more parts of water is a
good proportion. The gelatine as well as glue-masses
should be made in a water-bath, which consists of one dish
placed within another outer one containing warm water.
The mass should be injected warm, not hot, after which the
injected specimen is to be placed in cold water until the
injecting-mass has set. Glue (the ordinary white kind)
can be used for most injections just as the gelatine was
used, but should not be so much diluted. All injection-
masses should be filtered through a cloth before using.
Preparing skeletons—In general, skeletons are best
cleaned by boiling. After most of the flesh has been cut
away the skeleton should be boiled in a soap solution
until the remaining parts of the muscles are thoroughly
softened. The soap solution is made of 2,000 c.c. of water,
preferably distilled, 12 grams of saltpetre, and 75 grams of
hard soap (white). Heat these until dissolved, then add
150 c.c. of strong ammonia. This stock solution is mixed
with four or five parts of water, when the mixture is ready
for use. The bones after boiling are rinsed in cold water,
brushed and picked clean, then left to dry on a clean surface.
Preserving anatomical preparations.—Many specimens
worth keeping will be found, and for them a solution known
as Fischer’s formula is suggested as good, especially for
brains. Fischer’s formula is made up as follows: 2,000 c.c.
of water, 50 c.c of formalin, too grams of sodium chloride,

PUPIL AND SCHOOLROOM EQUIPMENT 465

and 15 grams of zinc chloride. These are mixed together
until thoroughly dissolved. Open preparations well before
placing them in the liquid and use about twenty times the
volume of the object to be preserved.

To keep fresh dissections.—For materials which are
dissected fresh and must be kept over for several days in
a fresh condition add a few drops of carbolic acid to the
water which covers them. Carbolized water (2 per cent
in water) will preserve a great many tissues for a long time.
Hearts will remain for years in a supple condition in this
solution.

Obtaining marine animals, microscopic preparations,
etc.—For schools not on the seashore the marine animals
such as starfishes, etc., which are to be dissected or examined
as examples of the branches to which they belong must be
obtained as preserved specimens from dealers in such supplies.
Among such dealers on the Atlantic coast are the Marine
Biological Laboratory, Woods Holl, Mass.; F. W. Walm-
sley, Academy of Natural Sciences, Philadelphia, Pa.; and
and . 5. Brimley, Raleich > N2€-on the: Pacitic coast:
the Supply Department, Hopkins Seaside Laboratory, Stan-
ford University, California. Ward’s Natural Science Estab-
lishment, Rochester, N. Y.; and the Kny-Scheerer Co;,
New York City, supply almost any biological specimens
asked for. These establishments furnish ready made
dissections and sets illustrating life-history and meta-
morphosis. ‘The few permanent microscopic preparations
which are mentioned in the book as desirable to have
can be made by the teacher if he has had any training
in microscopical technic. If not, they may be bought
cheaply of such dealers in natural history supplies as the
Bausch & Lomb Optical Co., Rochester, N. Y.; the Kny-
scheerer Co., 17 Park Place, New York City; Queen &
Co., toro Chestnut Street, Philadelphia, Pa., and numerous
others. From these dealers also can be bought all of the
laboratory supplies, such as lenses, slides, cover-glasses,
dissecting-scalpels, scissors and needles, etc., mentioned in
this book.

466 THE ANIMALS AND MAN

Reference books.—Throughout the preceding chapters
exact references have been made to various books, as many
of which as possible should be in the school-library. Some
of these references have been made with special regard to
the teacher, but most with special regard to the pupil. Most
of the books referred to, together with some others, are
included in the following list. For the convenience of the
prospective buyer, the names of the publishers and prices
of the books are appended. In buying books, it is of course
not necessary to order from the various publishers. A
list of the books desired may be handed to any book-dealer,
who will order them and who should in all cases be able
to get them for at least no more than publisher’s list prices.

Agassiz, E. C. Editor. Louis Agassiz, Life and Correspondence. 1890,
Houghton, Mifflin & Co. $2.50.

Bailey, F. M. Handbook of Birds of Western U. S. 1902, Houghton,
Mifflin & Co. $3.50.

Baskett, Jj. N. Story of the Fishes. 1899, D. Appleton & Co. $0.75.

The Story of the Birds. 1899, D. Appleton & Co. $0.65.

Beddard, Frank. Animal Coloration. 1892, Macmillan Co. $3.50.

Zoogeography. 1895, Macmillan Co. $1.60.

Beebe, C. W. The Bird: Its Form and Function. 1909, Henry Holt
& Co. $3.50.

Bendire, Chas. Directions for Collecting, Preparing, and Preserving Birds’
Eggs and Nests. Distributed by U. S. National Museum.

Bird Lore, an Illustrated Journal about Birds Appleton Co. $1.00 a year.

Calkins, G. N. The Protozoa. 1901, Macmillan & Co. $3.00.

Chapman, Frank. Handbook of the Birds of Eastern North America.
1899. D. Appleton & Co. $3.00.

—— Bird Life. 1900, D. Appleton & Co. $2.00.

Comstock, A. B. How to Keep Bees. 1905, Doubleday, Page & Co.
$1.00.

Comstock, J. H. Manual for the Study of Insects. 1897, Comstock Pub-

lishing Co. $3.75.

Insect Life. 1901, D. Appleton & Co. $1.50.

—— and Kellogg, V. L. Elements of Insect Anatomy. 1901, Comstock
Publishing Co. $1.00.

Comstock, J. H. and A. B. How to Know the Butterflies. 1904, D.
Appleton & Co. $2.25.

Cooke, W. W. Bird Migration in the Mississippi Valley. Distributed by
the Division of Biological Survey, U. S. Dept. Agric.

Cowan, T. W. Natural History of the Honey-bee. 1890, London: Houls-
ton. 1s. 6d.

PUPIL AND SCHOOLROOM EQUIPMENT 467

Coues, Elliott. Key to North American Birds. 1890, Estes and Lauriat.
$7.50.

Darwin, Chas. Complete works.

Dickerson, M. C. Moths and Butterflies. 1901, Ginn & Co. $1.50.

Frog Book. 1906, Doubleday, Page & Co. $4.00.

Ditmars, R. L. Reptile Book. 1907, Doubleday, Page & Co. $4.00.

Doane, R. W. Insects and Disease. 1910, Henry Holt & Co. $1.50.

Eggeling and Ehrenberg. The Fresh-water Aquarium and Its Inhabi-
tants. 1909, Henry Holt & Co. $2.09.

Eliot, I. M. and Soule, C. G. Caterpillars and their Moths. 1902, The
Century Co. $2.00.

Emerton, J. E. Common Spiders of U. S. 1902, Ginn & Co. $1.50.

Gage, S. H. Life History of the Toad. Teacher’s Leaflets No. 9, April,
1898, prepared by College of Agriculture, Cornell University, Ithaca, N.Y.

Heilprin, A. The Distribution of Animals. 1886, D. Appleton & Co.
$2.00.

Hodge, C. F. The Common Toad. Nature Study Leaflet, Biology Series
No. 1, 1898, published by C. H. Hodge, Worcester, Mass.

Holland, W. J. The Butterfly Book. 1899, Doubleday, Page & Co. $3.00.

Moth Book. 1903, Doubleday. Page & Co. $4.00.

Hornaday, W. T. Taxidermy and Zoological Collecting. 1897, Chas.
Scribner’s Sons. $2.50 net.

Howard, L. O. Mosquitoes. 1901, Doubleday, Page & Co. $1.50.

Howell, W. H. Dissection of the Dog. 1889, Henry Holt &Co. $1.00.

Huxley, T. H. The Crayfish: an introduction to the Study of Zoology.
D. Appleton & Co. $1.75.

Joly, N. Man before Metals. 1883, D. Appleton & Co. $1.75.

Jordan, D. S. Manual of Vertebrates, 10th ed. Doubleday, Page &
Co. $2.00.

Jordan and Evermann. American Food and Game Fishes. 1905,
Doubleday, Page & Co. $4.00.

Jordan, D. S. and Kellogg, V. L. Animal Life. 1900, D. Appleton

& Co. $1.20.
Kellogg, V. L. American Insects, 2nd ed. revised, 1908, H. Holt & Co.
$5.00.

Insect Stories, 1908, H. Holt & Co. $1.50.

Kellogg, J. L. Shellfish Industries. 1910, Henry Holt & Co. $1.75.

Kropotkin, P. Mutual Aid. 1902, Doubleday, Page & Co. $2.00.

Lubbock, John. Ants, Bees, and Wasps. 1882, D. Appleton & Co.
$2.00.

MacCarthy, E. Familiar Fish. 1900. D. Appleton & Co. $1.50.

McCook, Henry. American Spiders and their Spinning Work, 3 vols.
1889-1893, H. C. McCook, Phila., Pa. $30.00.

—— Nature’s Craftsmen. 1907, Harper Bros. $2.00.

— Ant Communities. 1909, Harper Bros. $2.00.

Maeterlinck, M. Life of the Bee. 1902, Dodd, Mead & Co. $1.40.

Marshall, H. M., and Hurst, C. H. Practical Biology, 5th ed. G. P.

Putnam’s Sons. $3.50.

468 THE ANIMALS AND MAN

Miall, L. C. The Natural History of Aquatic Insects. 1895, Macmillan
Co. $1.75.

Mitchell, E. G. Mosquito Life. 1907, G. P. Putnam’s Sons. $2.00.

Newbigin, M. I. Color in Nature. 1898, John Murray (London).
7 sh.@. d:

Parker, T. J. A Course of Instruction in Zootomy. 1884, Macmillan
Co. $2.25.

— Lessons in Elementary Biology. 1897, Macmillan Co. $2.65.

—and Haswell, W. A. ‘Textbook of Zoology, 2 vols. 1897, Macmillan
Co. $9.00.

Peckham, George W. and E. J. Wasps, Social and Solitary. 1905,
Houghton, Mifflin & Co.

Poulton, E. B. The Colors of Animals. 1890, D. Appleton & Co. $1.75.

Reighard, J. E., and Jennings, H.S. The Anatomy of the Cat. 1901,
Henry Holt & Co. $4.00.

Ridgway, R. Directions for Collecting Birds. Distributed by U. S.
National Museum.

Riverside Natural History, 6 vols. Houghton, Mifflin & Co. $30.00.

Rogers, J. E. Shell Book. 1908, Doubleday, Page & Co. $4.00.

Romanes, Geo. Darwin and After Darwin, I. 1895-97, Open Court Pub-
lishing Co.

Scudder, S. H. The Life of a Butterfly. 1893, Henry Holt &Co. $1.00.

—— Everyday Butterflies. 1899, Houghton, Mifflin & Co. $2.00.

Smith, J. B. Our Insect Friends and Enemies. 1909, J. B. Lippincott

& Co. $1.50.

Stone and Cram. American Animals. 1905, Doubleday, Page & Co.
$3.00.

Van Beneden, E. Animal Parasites and Messmates. 1876, D. Appleton
& Co. $1.50.

Wallace, A. R. The Geographical Distribution of Animals. 1876, Harper
& Bros.

Island Life. 1881, Harper & Bros. $4.00.
Wheeler, W. M. Ants. 1910, Macmillan Co. $5.00.

APPENDIX II

REARING ANIMALS AND MAKING COLLEC-
TIONS

Much good work in observing the behavior and life-
history of some kinds of animals can be done by keeping
them alive in the schoolroom under conditions simulating
those to which they are exposed in nature. The growth
and development of frogs and toads from egg to adult, as
well as their feeding habits and general behavior, can all
be observed in the schoolroom, as explained in Chapter
IX. Harmless snakes are easily kept in glass-covered
boxes; snails and slugs are contented dwellers indoors;
certain fish live well in small aquaria, and many other
familiar forms can be kept alive under observation for a
longer or shorter time. But from the ease with which
they are obtained and cared for, the inexpensiveness of
their live-cages, and the interesting character of their life-
history and general habits, insects are, of all animals, the
ones which specially commend themselves for the school-
room menagerie. In Chapters VIII and XIV are numerous
suggestions regarding the obtaining and care of certain
kinds of insects which may be reared and studied to ad-
vantage in the schoolroom. In the following paragraphs
are given directions for making the necessary live-cages
and aquaria for these insects.

Live-cages and aquaria.—Prof. J. H. Comstock has
so well described the making of simple and inexpensive
cages and aquaria in his book, “Insect Life,” that, with
his permission, his account is quoted here.

Live-cages.—“‘A good home-made cage can be built by
fitting a pane of glass into one side of an empty soap-box. A
board, three or four inches wide, should be fastened below

469

470 THE ANIMALS AND MAN

the glass so as to admit of a layer of soil being placed in the
lower part of the cage, and the glass can be made to slide,
so as to serve as a door (fig. 238). The glass should fit
closely when shut, to prevent the escape of the insects.

“In rearing caterpillars and other leaf-eating larve,
branches of the food-plant should be stuck into bottles or
cans which are filled with sand saturated with water. By
keeping the sand wet the plants can be kept fresh longer than
in water alone, and the danger of the larve being drowned
is avoided by the use of sand.

“Many larve when full-grown enter the ground to pass the
pupal state; on this account a layer of loose soil should be
kept. im; the: bottom omta
breeding-cage. This soil
should not be allowed to
become dry, neither should
it be soaked with water.
If the soil is too dry the
pup will not mature, or
if they do so the wings will
not “expand fully; 1 the
soil is too damp the pup
are liable to be drowned or
to be killed by mold.

“itis often mecessary. to
keep pupze over winter, for
a large proportion of insects pass the winter in the pupal
state. Hibernating pup may be left in the breeding-cages
or removed and packed in moss in small boxes. Great
care should be taken to keep moist the soil in the breeding-
cages, or the moss if that be used. The cages or boxes
containing the pupz should be stored in a cool cellar, or in
an unheated room, or in a large box placed out of doors
where the sun cannot strike it. Low temperature is not so
much to be feared as great and frequent changes of tem-
perature.

“Hibernating pupe can be kept in a warm room if
care be taken to keep them moist, but under such treat-

Fic. 238. Soap-box breeding-cage for
insects.

REARING AND COLLECTING ANIMALS 471

ment the mature insects are apt to emerge in mid-winter.

‘“‘An excellent breeding-cage is represented by fig. 239. It
is made by combining a flower-pot and a lantern-globe.
When practicable, the food-plant of the insects to be bred
is planted in the flower-pot; in other cases a bottle or tin can
filled with wet sand is sunk into the soil in the flower-pot, and
the stems of the plant are stuck into this wet sand. The top
of the lantern-globe is covered with Swiss muslin. These
breeding-cages are inexpensive,
and especially so when the pots
and globes are bought in con-
siderable quantities. A modifi-
cation of this style of breeding-
cage that is used by the writer
differs only in that large glass
cylinders take the place of the
lantern-globes. These cylinders
were made especially for us by a
manufacturer of glass, and cost
from six to eight dollars per doz-
en, according to size, when made
in lots of fifty.

“When the transformation of
small insects or of a small num-
ber of larger ones are to be
studied, a convenient cage can Fic. 239. Lamp-chimney and
be made by combining a large flower-pot breeding-cage for
lamp-chimney” with ~ a. small ‘sec
flower-pot.

“The root-cage-—For the study of insects that infest the
roots of plants, the writer has devised a special form of breed-
ing-cage known as the root-cage. In its simplest form this
cage consists of a frame holding two plates of glass in a verti-
cal position and only a short distance apart. The space
between the plates of glass is filled with soil in which seeds
are planted or small plants set. The width of the space be-
tween the plates of glass depends on the width of two strips
of wood placed between them, one at each end, and should

472 THE ANIMALS AND MAN

be only wide enough to allow the insects under observation
to move freely through the soil. If it is too wide the insects
will be able to conceal themselves. Immediately outside
of each glass there is a piece of blackened zinc which slips
into grooves in the ends of the cage, and which can be easily
removed when it is desired to observe the insects in the soil.

‘“Aquaria.—For the breeding of aquatic insects aquaria
are needed. As the ordinary rectangular aquaria are ex-
pensive and are liable to leak we use glass vessels instead.

“Small aquaria
can be made of jelly-
tumblers, glass fin-
ger-bowls, and glass
fruit-cans, and larger
aquaria can be ob-
tained of dealers.
A good _ substitute
for these is what is
known as a battery-
jar (ig: 240), “Phere
are several sizes of
these, which can be
obtained of most
dealers in scientific
apparatus.

So. “prepare fan
aquarium, place in
the jar a layer of
sand; plant some
water-plants in this sand, cover the sand with a layer
of gravel or small stones, and then add the required
amount of water carefully, so as not to disturb the plants
or to roil the water unduly. The growing plants will keep
the water in good condition for aquatic animal life, and render
changing of the water unnecessary, if the animals in it live
naturally in quiet water. Among the more available plants
for use in aquaria are the following:

‘“Waterweed, EHlodea canadensis.

Fic. 240. Battery-jar aquarium.

REARING AND COLLECTING ANIMALS 473

“Bladderwort, Utricularia (several species).
“Water-starwort, Callitriche (several species).
“Watercress, Nasturtium officinale.

“Stoneworts, Chara and Nitella (several species of each).

“Frog-spittle or water-silk, Sprrogyra.

“A small quantity of duckweed, Lemna, placed on the
surface of the water adds to the beauty of an aquarium.

“When it is necessary to add water to an aquarium on
account of loss by evaporation, rain water should be used to
prevent an undue accumulation of the mineral-water held
in solution in other water.”

Making collections.—Much is to be learned about ani-
mals by “collecting” them. But the collecting should be
done chiefly with the idea of learning about the animals rather
than with the notion of getting as many specimens as possible.
To collect, it is necessary to find the animals alive; one learns
thus their haunts, their local distribution, and something
of their habits, while by continued work one comes to know
how many and what different kinds or species of each group
being collected occur in the region collected over. Collect-
ing requires the sacrifice of life, however, and this will always
be kept well in mind by the humane teacher and pupil.
Where one set of specimens will do, no more should be col-
lected. The author believes that high-school work in this
line should be almost exclusively limited to the building up
of a common school collection. Let a single set of speci-
mens be brought together by the combined efforts of all the
members of the class, and let it be well housed and cared for
permanently. Each succeeding class will add to it; it may
come in time to be a really representative exhibition of the
local fauna.

The high-school collection should include not only adult
specimens of the various kinds of animals, forming a system-
atic collection, as it is called, but also all kinds of specimens
which illustrate the structure and habits of the animals
in question and which will constitute a so-called biological
collection. Specimens of the eggs and all immature stages;
dissections preserved in alcohol or formalin showing the ex-

474 THE ANIMALS AND MAN

ternal and internal anatomy; nests, cocoons, and all speci-
mens showing the work and industries of the various animals;
in short, any specimen of the animal itself in embryonic or
postembryonic condition, or any parts of the animal, or any-
thing illustrating what the animal does or how it lives, all
these should be collected as assiduously as the adult indi-
viduals. Each specimen in the collection should be labelled
with the name of the animal, the date, and locality, and the
name of the collector, with any
particular information which will
make it more instructive. If
such special data are too volu-
minous for a label, they should
be written in a general note-book
called ‘‘Notes on Collections”’
(kept in the schoolroom with
the collection), the specimen
and corresponding data being
given a common number so that
their association may be recog-
nized. In the following para-
graphs are given brief directions
for catching, pinning up, and
caring for insects, for making
skins of birds. and mammals,
Fic. 241. Insect killing-bottle; and for the alcoholic preserva-

cyanide of potassium at bot- tion of other kinds of animals.

bom covered Gye th plasters 08 ig secist-= Morse aie bmmeincects

ae there are needed a net, a killing-
bottle, a few small vials of alcohol, and a few small
boxes to carry home live specimens, cocoons, galls, etc. For
preparing and preserving the insects there are needed insect-
pins, cork- or pith-lined drawers or boxes, and small wide-
mouthed bottles of alcohol.

The net, about 2 feet deep, tapering and rounded at its
lower end, is made of cheesecloth or bobinet (not mosquito-
netting, which is too frail), attached to a ring, one foot in
diameter, of No. 3 galvanized iron wire, which in turn is

REARING AND COLLECTING ANIMALS 475

fitted into a light wooden or cane handle about three and a
half feet long.

The killing-bottle (fig. 241) is prepared by putting a few
small lumps (about a teaspoonful) of cyanide of potassium
into the bottom of a wide-mouthed bottle holding about four
ounces, and covering this cyanide with wet plaster of Paris.
When the plaster sets it will hold the cyanide in place, and
allow the fumes given off by its gradual volatilization to fill
the bottle. Insects dropped into it will be killed in from
two or three to ten minutes. Keep a little tissue paper in
the bottle to soak up moisture and to prevent the specimens
from rubbing. Also keep the bottle well corked. Label
it “Poison,” and do not breathe the fumes (hydrocyanic gas).
Insects may be left in it over night without injury to them.

Butterflies or dragon-flies too large to drop into the kill-
ing-bottle may be killed by dropping a little chloroform or
benzine on a piece of cotton, to be placed in a tight box with
them. Larve (caterpillars, grubs, etc.) and pupe (chrysa-
lids) should be dropped into the vials of alcohol.

In collecting, visit flowers, sweep the net back and forth
over the small flowers and grasses of meadows and pastures,
look under stones, break up old logs and stumps, poke about
decaying matter, jar and shake small trees and shrubs, and
visit ponds and streams. Many insects can be collected in
summer at night about electric lights, or a lamp by an open
window.

When the insects are brought home or to the schoolroom
they must be “‘pinned up.” Buy insect-pins, long, slender,
small-headed, sharp-pointed pins, of a dealer in naturalists’
supplies (see p. 464). These pins cost ten cents a hundred.
Order Klaeger pins, No. 3, or Carlsbaeder pins, No. 5.
These are the most useful sizes. For larger pins order Klae-
ger No. 5 (Carlsbaeder No. 8); for smaller order Klaeger
Noa. 1 (Carlsbaeder No. 2). Pin each insect straight down
through the thorax (fig. 242) (except beetles, which pin through
the right wing-cover near the middle of the body). On each
pin below the insect place a small label with date and locality
of capture. Insects too small to be pinned may be gummed

476 THE ANIMALS AND MAN

on to small slips of cardboard, which should be then pinned
up. Keep the insects in drawers or boxes lined on the bot-
tom with a thin layer of cork, or pith of some kind. (Corn-
pith can be used; also in the West, the pith of the flowering
stalk of the century plant.) The cheapest insect-boxes and
very good ones, too, are cigar-boxes. But unless well looked
after they let in tiny live insects which feed on the dead speci-
mens. For a permanent collection, therefore, it will be
necessary to have made some tight boxes or drawers. Glass-
topped ones are best, so that the specimens may be examined
without opening them. A ‘“moth-ball” (naphthaline)
fastened in one corner of the box will help keep out the ma-
rauding insects.
Butterflies, dragon-
flies, and other larger
and beautiful winged
insects; suould spe
___ “spread,” tlnsant ise
F should be allowed to
dry with wings expand-
eds) Lode this spread-
ing- or setting-boards
(figs. 243 and 244) are
MECeSSahy . soca
board consists of two strips of wood fastened a short dis-
tance apart so as to leave between them a groove for the
body of the insect, and upon which the wings are held in
position until the insect is dry. A narrow strip of pith or
cork should be fastened to the lower side of the two strips
of wood, closing the groove below. Into this cork is thrust
the pin, on which the insect is mounted. Another strip of
wood is fastened to the lower sides of the cleats to which
the two strips are nailed. This serves as a bottom and
protects the points of the pins which project through the
piece of cork. The wings are held down, after having been
outspread with the hinder margins of the fore wings about
at right angles to the body, by strips of paper pinned down
over them.

Fic. 242. Insect properly pinned up.

REARING AND COLLECTING ANIMALS

477

“Soft specimens” such as insect larve, myriapods, and
spiders, should be. preserved in bottles of alcohol (85 per

cent).
and other dry specimens can
boxes.

Birds.—In collecting birds,
shooting is chiefly to be relied
on. Use dust-shot (the small-
est shot made) in small loads.
For shooting small birds it is
extremely desirable to have an
auxiliary barrel of much small-
er bore than the usual shotgun
which can be fitted into one
of the regular gun-barrels. In
such an auxiliary barrel use
32-calibre shells loaded with
dust-shot instead of bullets.
Plug up the throat and vent
of shot birds with cotton, and
thrust each bird head down-
ward into a cornucopia of pa-
per 2 Chis Gwilleikeep fhe
feathers unsoiled and smooth.

Birds should be skinned
soon after bringing home,
after they have become relax-
ed, but before evidences of
decomposition are manifest.
The tools and materials nec-
essary to make skins are scal-
pel, strong sharp-pointed scis-
sors, bone-cutters, forceps,
corn-meal, a mixture of two
parts white arsenic and one

Nests, galls, stems, and leaves partly eaten by insects,

be kept in small pasteboard

xy \

Uenlatobe!
LN
SSN
Wa? FE WN

Ww

A UILTUMLA EL MLL LULU MEALS TILLY DL INTELL

Fic. 243. Setting-board with but-
terflies properly “spread”. (After
Comstock.)

part powdered alum, cotton, and metric-system measure.

Before skinning, the bird should be measured.

With a

metric-system measure carefully take the alar extent, i. e.,

478 THE ANIMALS AND MAN

spread from tip to tip of outstretched wings; length of
wing, i. e., length of wrist-joint to tip; length of bill in
straight line from base (on dorsal aspect) to tip; length of
tarsus, and length of middle toe and claw.

To skin the bird, cut from anus to point of breast-bone
through the skin only. Work skin away on each side to legs;
push each leg up, cut off at knee-joint, skin down to next
joint, remove all flesh from bone, and pull leg back into place;
loosen skin at base of tail, cut through vertebral column at
last joint, being careful not to cut through bases of tail-
feathers; work skin forward, turning it inside out, loosening
it carefully “ail
around, without
stretching, to wings;
cut off wings at el-
bow-joint, skin
down to next joint
and remove flesh
from wing-bones;

em ——————————————

Ly y/o: sé push skin forward

to base of skull,
Fic. 244. Setting-board in cross-section to show and if skull is not
construction. (After Comstock.)

too large (it is in
ducks, woodpeckers, and some other birds), on over it to
ears and eyes; be very careful in loosening the membrane
of ears and in cutting nictitating membrane of eyes; do
not cut into eyeball; remove eyeballs without breaking;
cut off base of skull, and scoop out brain; remove flesh
from skull, and ‘‘poison” the skin by dusting it thoroughly
with the powdered arsenic and alum mixture. Turn skin
right side out, and clean off fresh blood-stains by soaking
them up with corn-meal; wash off dried blood with water,
and dry with corn-meal. Corn-meal may be used during
skinning to soak up blood and grease.

There remains to stuff the skin. Fill orbits of eyes with
cotton (this can be advantageously done before skin is re-
versed); thrust into neck a moderately compact, elastic,
smooth roll of cotton about thickness of the natural neck;

REARING AND COLLECTING ANIMALS 479

make a loose oval ball of size and general shape of bird’s body
and put into body-cavity with anterior end under the posterior
end of neck-roll; pull two edges of abdominal incision to-
gether over the cotton, fasten, if necessary, with a single
stitch of thread, smooth feathers, fold wings in natural
position, wrap skin, not tightly, in thin sheet of cotton (op-
portunity for delicate handling here) and put away in a drawer
or box to dry. Before putting away tie label to leg, giving
date and locality of capture, sex and measurements of bird,
and name of collector. Before bird is put into permanent
collection it should be labelled with its common and scientific
name.

The mounting of birds in lifelike shape and attitude is hard
to do successfully; and a collection of mounted birds demands
much more room and more expensive cabinets than one of
skins. For instructions for the mounting of birds see Davie’s
“Methods in the Art of Taxidermy,” pp. 39-57; or Horna-
day’s ‘““Taxidermy and Zoological Collecting.”” For a more
detailed account of making bird-skins, see also these books,
or Ridgway’s ‘Directions for Collecting Birds.”

In collecting birds’ nests cut off the branch or branches
on which the nest is placed a few inches above and below
the nest, leaving it in its natural position. Ground-nests
should have the section of the sod on which they are placed
taken up and preserved with them. If the inner lining of
the nest consists of feathers or fur put in a “moth-ball”
(naphthaline).

To preserve birds’ eggs they should be emptied through
a single small hole on one side by blowing. Prick a
hole with a needle and enlarge with an _ egg-drill
(obtain of dealers in naturalists’ supplies, see p. 464). Blow
with a simple bent blowpipe with point smaller than the
hole. After removing contents clean by blowing in a little
water, and blowing it out again. After cleaning, place the
egg, hole downward, on a layer of corn-meal to dry. Label
each egg by writing on it near the hole a number. Use a
soft pencil for writing. This number should refer to a
record (book) under similar number, or to an “‘egg-blank,”’

480 THE ANIMALS AND MAN

containing the following data: name of bird, number of
eggs in set, date and locality, name of collector, and any
special information about the eggs or nest which the collector
may think advisable. The eggs may be kept in drawers
or boxes lined with cotton, and divided into little compart-
ments.

For detailed directions for collecting and preserving birds’
eggs and nests, see Bendire’s “Directions for Collecting,
Preparing, and Preserving Birds’ Eggs and Nests,’ or Davie’s
“Methods in the Art of Taxidermy,” pp. 74-78.

*Mammals.—Any mammal intended for a scientific speci-
men should be measured in the flesh, before skinning, and
as soon after death as practicable, when the muscles are
still flexible. (This is particularly true of larger species,
such as foxes, wildcats, etc.) The measurements are taken
in millimetres, a rule or steel tape being used. (1) Total
length: stretch the animal on its back along the rule or tape
and measure from the tip of the nose (head extended as far
as possible) to the tip of the fleshy part of tail (not to end of
hairs). (2) Tail: bend tail at right angles from body back-
ward and place end of ruler in the angle, holding the tail
taut against the ruler. Measure only to tip of flesh (make
this measurement with a pair of dividers). (3) Hind foot:
place sole of foot flat on ruler and measure from heel to tip
of longest toe-nail (in certain small mammals it is necessary
to use dividers for accuracy). The measurements should
be entered on the label, along with such necessary data as
sex, locality, date, and collector’s name.

Skin a mammal as soon after death as possible. Lay
mammal on back and with scissors or scalpel open the
skin along belly from about midway between fore and hind
legs to vent, taking care not to cut muscles of abdomen.
Skin down on either side of the body by working the skin
from flesh with fingers till hind legs appear. Use corn-
meal to stanch blood or moisture. With left hand grasp

*The following directions for making skins of mammals were written
for this book by Professor W. K. Fisher of Stanford University, an experi-
enced collector.

REARING AND COLLECTING ANIMALS 481

a leg and work the knee from without into the opening just
made; cut the bone at the knee, skin leg to heel and clean
meat off the bone (leaving it attached of course to foot).
In animals larger than squirrels skin down to tips of toes.
Do the same with other leg. Skin around base of tail till
the skin is free all around so that a grip can be secured on
body; then with thumb and forefinger hold the skin tight
at base of tail and slowly pull out the tail. In small mammals
this can be done readily, but in foxes it is often necessary
to split the skin up along the under side and dissect it off
the tail-bones. After the tail is free skin down the body,
using the fingers (except in large mammals) till the fore
legs are reached; treat the fore legs in the same manner
as hind legs, thrusting elbow out of the skin much as a
person would do in taking off a coat; cut bone at elbow;
clean fore-arm bone. Skin over neck to base of ears. With
scalpel cut through ears close to skull. With scalpel dissect
off skin over the head (taking care not to injure eyelids)
down to tip of nose, severing its cartilage and hence freeing
skin from body. Sew mouth by passing needle through
under lip and then across through two sides of the upper
lip; draw taut and tie thread. Poison skin thoroughly.
Turn skin right side out. Next sever the skull carefully
from body, just where the last neck-vertebra joins the back
of the skull. It is necessary to keep the skull, because
characters of bone and teeth are much used in classification.
Remove superfluous meat from the skull and take out brain
with a little spoon made of a piece of wire with loop at end.
Tag the skull with a number corresponding to that on skin,
and hang up to dry. A finished specimen skull is made by
boiling it a short time and picking the meat off with forceps,
further cleaning it with an old tooth-brush, when it is placed
in the sun to bleach. Care must be taken always not to
injure bones or dislodge teeth.

Mammals are stuffed with cotton or tow; the latter is
used in species from a gray squirrel up. Large mammals
stuffed with cotton do not dry readily, and often spoil.
Being much thicker-skinned than birds, mammals require

482 THE ANIMALS AND MAN

more care in drying and ordinarily require a much longer
period. Soft hay may be substituted for tow; never use
feathers or hair. Roll a longish wad of cotton about the
size of body and insert with forceps, taking care to form
the head nearly as in life. Split the back end of the cotton
and stuff each hind leg with the two branches thus formed.
Roll a piece of cotton around end of forceps and stuff fore
legs. Place a stout straight piece of wire in the tail, wrapping
it slightly to give the tail the plump appearance of life.
(If the cotton cannot be reeled on to the wire evenly, leave
it off entirely.) Make the wire long enough to extend half
way up belly. Sew up slit in belly. Lay mammal on belly
and pin out on a board by legs, with the fore legs close beside
head, and hind legs parallel behind, soles downward. Be
sure the label is tied securely on right hind leg.

For directions for preparing and mounting skeletons of
birds, mammals, and other vertebrates, see the books of
Davie and Hornaday already referred to.

Fishes, batrachians, reptiles, and other animals.—The
most convenient and usual way of preserving the other
vertebrates (not birds or mammals) is to put the whole
body into 85 per cent alcohol or 4 per cent formalin. Batra-
chians should be kept in alcohol not exceeding 60 per cent
strength. Several incisions should always be made in the
body, at least one of which should penetrate the abdominal
cavity. Anatomical preparations are similarly preserved.
By keeping the specimens in glass jars they may be examined
without removal. Fishes should not be kept in formalin
more than a few months, as they absorb water, swell, and
grow fragile.

Of the invertebrates all, except the insects, are preserved
in alcohol or formalin. The shells of molluscs can be pre-
served dry, of course, in drawers or boxes divided into
small compartments.

END

INDEX

References to illustrations are indicated by an asterisk (*).

A

Abdomen and viscera in human
body, *309

Absorption in human body, 313;
object, 313; where it takes place,
313; of Sugar, 313; of fats, 313;
of water, 314; of salts, 314; of
alcohol, 314

Aenigmatis blattoides, *424

Agalendiz, 168

Age, old stone, 390; paleolithic, 390;
newer stone, 391; neolithic, 391;
metal, 391

Ages, geologic table of, 281

Air, composition of inspired and
expired, 346; quantity breathed,
347; tidal, 347; residual, 347

Akka pygmy, *397

Alcohol, absorption by human body,
313; effect upon digestion, 315;
effect on. circulation, 328; effect
on nervous system, 366

Alimentary canal of human body,
structure, 303; 303;
diagram, *304

Alligators, 212

Alveolus, 344

Ameeba, structure and_ behavior,
38; changing shape, *39

Amylopsin, 312

Anatomy, definition, 1

Anopheles
mosquito, *128

function,

maculipennis, malarial

483

Anosia plexippus, *447

Antelocapra americana, *252

Antelope, *252

Antenna of carrion beetle, bearing
smelling pits, *72

Ants, fly guest of, *424; social para-
sites of, 425

Aorta in human body, 320, 321;
branches, 322

Apes, 256

Apis mellifica, queen, drone and
worker, *433

Aquaria, how to prepare, 469

Aquarium, battery jar, *472

Arachnida, 149, 162

Arachnoid
body, 358

Argiope, 169

Aristolochia clematitis, *458

Arm of man, diagram to show how
the bones and muscles act, *53

Arrow head of ancient man, *386

Artery in human body, aorta, 320;
pulmonary, 320; phrenic, 322;

membrane, in human

coeliac axis, 322; superior mes-
enteric, 322; renal, 320, 322; infer-
ior mesenteric, 322; coronary, 322

Arthropoda, 149

Artiodactyla, 250

Ascidian, *193

Asclepias flowers, honeybee at, *456

Association centers in human brain,
*363

484 INDEX

Asterias, starfish, dissection, *141
Astigmatism, 375

Atlas, in human body, 333
Attide, *168

Auditory sensations of man, 376
Auk, razor-billed, *223

Auricle of human heart, 318
Axis, In human body, 333

Axis cylinder, 363

Axon, 363

B

Bacilli, 379

Back swimmer, *159; 160

Bacteria, 379; beneficial, 380; harm-
ful, 380; causing decay of teeth,
306

Bagworm, *404

Balanus, *152

Banteng, *267

Barnacles, *152;: California, #172

Barriers, in animal distribution, 407

Basilarchia archip pus, showing mim-
icry, *448

Bat, hoary, *248

Batrachians, 200; how to preserve,
482

Bear, 254

Beaver, 246

Bees, carpenter, nest of, *428; soli-
tary, 427; social, 428;
mining, *429

Beetle, Australian lady bird, *181;
carrion, antenna, *72; guest of

*424; 159;
water scavenger, 159; predaceous
diving, *159

Bile, in small intestine, 311, 312;

nests of

termite, whirligig,

reaction of, 312
Birds, body form and structure, 214;
development and life history, 218;

classification and_ identification,

220;
and nesting, 223; external parts
named, *16; life history, 102;
103; nest building, 103;
rearing of young, 103; giant
toothed, skeleton, *282;
how to collect, skin and_ stuff,
477; 269;

structure and habits, 227; food

migration, 221; breeding

nests,
fossil

domesticated kinds,
habits, economics and protection,
233

Birth, 83

Bison bison, *253

Bladder, urinary, 350

Blood in human body, function, 316;
composition of, 316; corpuscles,
316; plasma, 316, 317; structure,
316; clotting, 316; amount, 317;
distribution, 317; effect of food,
fresh air and rest on, 317; changes
in capillaries, 323;
323; vessels, 318; vessels con-
nected with heart, 319;
tion in live fish, 11

Boar, wild, *266

Bombus, *430

Bone in human body, structure, 333;

purification,

circula-

chemical composition, 334; nour-

ishment, 335; frontal, 333; collar,

333; sphenoid, 332; ethnoid, 332;

occipital, 332; temporal, 332;
parietal, 332

Books, references, 466

Bos sondaicus, *267

Bovidee, 253

Brachynotus nudus, crab, *152

Breathing, of man, mechanics, 345;
hygiene, 347; effects of exercise
on, 347

Brain of cat, *67; structure of hu-
man, 358;
human, 361;

internal structure of
ventral view of hu-

INDEX 485

man, *359; of vertebrates, *66

Branch, defined, 115

Branches, of animals, list, 116

Bronchi, in human body, 344

Bronchiole, in human body, dia-
gram, *344; 345

Brontosaurus, *276

Buffalo, *253

Bull, shorthorn, prize. *269

Bumble bees, social life, 428; nest,
*430

Burns, treatment, 356

Butterfly, owl, *438; dead _ leaf,
*445; scales of, *439; part of
wing showing scales, *440; *441;
diagram showing scales of wing,
*442; larve oi Monarch, *446:
Monarch, *447; Viceroy showing
mimicry, *448; Parnassius, *407;
violet-tipped, larve, *94; pupa,
*96; swallow tail, *163; how to
spread wings, *477; *478

Cc

Cage for breeding insects, *470;
*471

Calf, taste papilla, *71

Caligo, *438

Callorhinus atascanus, *255

Callorhinus ursinus, killed by para-
sites, *419

Calory, 300

Canary birds, domesticated races,
271

Cancer productus, *152

Canide, 254

Canis niger, *262

Capillaries, in human body, 322, 324

Carbo-hydrates, composition, 291,
296; as food nutrient, 295; as
proteid sparer, 297

Carbon, as a cell element, 291; in

proteid, 291, 296; in carbo-hy-
drate, 291; in fat, 291; in prop-
erties, 293

Carbon dioxide, 291; formation,
294; exchange in lungs of man,
324

Cartilage, 331

Cat, domesticated races, 263; skele-
ton, *52; muscles of fore leg, *53;
brain, *67

Caterpillars, structure and habits of,
92

Catfish, 195

Cattle, domesticated races, 266;
heads of British breeds, *268;

Cell, characterized, 46;
289; chemical composition of,
291; breathing, 343; chemistry,
291; as a unit of life, 288; living
substance of, 288

Centipede, *156; skein, *155; *156

Centrurus, *164

Cephalopoda, 171

Cercopithecus, *257

Cerebellum, of man, 359

Cerebro-spinal fluid, of man, 358

Cerebrum, of man, 358

Cervide, 251

Cervus canadensis, *251

Cete, 249

Charcoal, 293

Chemistry of the cell, 291

Chickens, domesticated races, 269

Chipmunk, *247

Chiroptera, 248

Circulation, in human body, 318;
systemic, 319; pulmonary, 324;
how maintained, 324;

function,

effect of
alcohol on, 328; effects of exercise
on, 326; diagram, *325

Circulatory system, of man, 290; of
young dragon fly, *62: of fish, *63

486 INDEX

Clams, 171

Class, defined, 114

Classes of animals, list, 116

Classification, 192; of animals, 107;
example, 110; table, 116

Clavicle, in human body, 333

Cleanliness, importance, 356

Coagulation, 317

Cocci, 379

Coccyx, in human body, 331

Cock, Polish, *273

Cockerel, _ silver-laced
*273

Coelenterata, 139

Colaptes auratus, *231

Collections, high school, 473; how
to make, 469, 473

Colors of animals, 438; uses of, 442;
how produced, 441; warning, 446

Columba livia, domesticated varie-
ties, *260

Combustion, 291

Commensalism, 421

Communal life, 426

Condiments, 300

Constipation, 314

Copper head, 211

Corals, 136

Corisa, *161

Cormorants, domesticated, 272

Corpus callosum, 359

Coyote, 254

Crab, 151, *152; hermit, with polyp
on shell, *423

Crayfish, 149; anatomy, 28; ven-
tral aspect and appendages, *29;
internal structure, *33

Crotodiles, 212

Cross-pollination, 452; by insects,
452

Crustacea, 149

Cuticle, of human body, 352

wyandotte,

Cuttlefish, 178
Cyclas, 171

D

Damp-bug, *154

Decapoda, 178

Deer) 251; extinct, 285

Deglutition, 308

Dendrites, 363

Dentine, 306

Dermacentor americanus, *166

Dermis, of human body, 352

Development of animals, 81

Devil fish, 179

Diaphragm, in human body, 309,
346

Diastase, 312

Diastole, 325

Dictynide, 168

Didelphys virginiana, 245

Diemycty!lus torosus, 203

Diet, standard, 299

Diffusion, 298

Digestive system, of man, 289

Digestion, in human body, defined,
3033< first: step in, 307;~ of starch;
307;- in’ stomachs Sit;
intestine, 312; experiment in arti-
ficial, 312; effect of alcohol on,
315

Dinosaur, extinct three-toed, *284

Diphtheria, 380

Disease, human, caused by one-
celled animals, 124

Disinfection, 381

Dislocation, 336

Distribution of animals, 406, 409

Dog, 254; ancient Assyrian, *259;
domesticated races, 263, 271; ner-
vous system, *67

Dolichorhynchus osborni, fossii skel-
eton, *279

in small

INDEX 487

Dolphins, 249

Domestication of animals, 258
Donkeys, 265

Doves, domesticated races. 269
Dragon fly, circulatory system, *62
Drawings, student, 462

Dura mater, 358

Dyticus, larva, *160

E

Ear, function and organs, 72; of
man, external part, *72; struc-
Ene W 7 Oo io care, Ob Sv 15. OL
locust, *73

Earthworm, dissection, *144

Echinodermata, 140

Eft, western brown, *203

Bik +25)

Em pidonax
*225

fulvifrons pygmeus,

Emulsification, 312

Enzyme, defined, 307;
juice, of man, 310; in intestinal
fluid, 312

Epeiride, 168

Epialtus productus, *152

Epidermis, of human body, 352

Epiglottis, of human body, 308, 345

Eumecus skeltonianus, *206

Eustachian tube, in man, 376

Excretion, in man, 350

Excretory system, of human body,
290

Exercise, effect upon heart, 326

Expiration, 346

Eyes, of man, structure, 370; func-
tions, 370; formation of image
in, 373; accommodation, 373;
hygiene, 374; section, *372; of
moth, part of section showing ele-
ments, *77; of jelly fish, *75; of
vertebrate, *76; of horse fly, *76,

in gastric

compound, 77; of various ani-

mals, 75
F

Family, defined, 114

Fatigue, 342

Fats, composition, 291, 298; as food
nutrient, 295; characteristics, 298;
tests for, 298

Fehling’s solution, 297

Felide, 256

Fere, 254

Fertilization of plants, 451

Fever, Texas cattle, caused by pro-
tozoan parasite, 130;
caused by protozoan parasite, 130

Fibrin, 317

Fish, 194; as food, 199; hatcheries,
199;
domesticated races, 272; how to
preserve, 482

Flounder, *197

Flowers and insects, 450

Fly, guest of ant, *424

Fly catcher, buff breasted, *225

Food, how animals obtain and digest,
59; necessity to animals, 54; spe-
cial means of getting, 401

Food nutrients, 294; oxidation, 294;
function, 295; accessories, 300;

Foods, chief substances in, 291;
composition, 296; relative value,

yellow,

circulatory system of, *63;

289; principles involved in cook-
ing, 299;
300

Fossils, how formed, 277; animals,
2715

Fowl, wild jungle, *272

Foxes, 254

Fracture, 337

Frog, 201; eggs and hatching of, 97;
life history, 97; tree, *202

economy in purchase,

488 INDEX

G
Gall bladder, in human body, 312
Galley-worm, *155, 156
Gallus bankiva, *272
Gastric fluid, of human body, 310
Gastropoda, 171
Gavial, 213
Geese, domesticated races, 271
Gila monster, *207
Glands, 310; gastric, 310; pyloric,
310; fundus; 310; 354;
lachrymal, 371; section of py-
loric, *310; sebaceous, 354
Glires, 245
Glomerulus, in human body, 351
Glottis, in human body, 308
Glycerine, 312
Goats, domesticated races,
Rocky Mountain, 253
Goniomena vertens, *138
Gophers, 246
Grantia, a simple sponge, *133

sweat,

207:

Grape sugar, test for, 297

Grapta, part of wing showing scales,
*441

Guinea pigs, 246

Gulls, *233

H

Hemamode, malarial, *126; *127;

Hemoglobin, 316; function, 316

Hair, 354

Hairworm, 146

Harporhynchus redivivus, *232

Hatching, 83

Hearing, 368

Heart, of man, structure and posi-
tion of, 318; internal structure of,
318; valves of, 318; action of,
321; beat of, 321; sounds of, 326;
effect of exercise on, 326; dia-
gram showing valves, *319; *320;
opened, *321

Heat, generation in body, 294

Heloderma horridum, *207

Hesperorinus regalis, fossil skeleton,
*282

Hippocampus kelloggi, *198

Hog, domesticated races, 266

Homo, primigenius, 390, 394; sa-
piens, 390, 394

Honeybee, queen, drone, worker,
*434; brood cells, *435; life, 429;
observation hive, *431; gathering
pollen and nectar, *432; building
comb, *433; at Asclepias flowers,
*456

Horse, domesticated races, 264;
American trotting, *264; four-
toed, *265; extinct, fossil, 283

Horsefly, eye, cornea, *76

Hottentot Venus, head, *395

House-flies, fighting, 187; foot, *188

Humerus, *334; section of, *335

Humming bird, nest, *103;
throat, nest and eggs, *221

Hydra, structure and habits, 134;
£135

Hydrochloric acid, in human body,
310; action of, 310

Hydrogen, as a cell element, 291;
in proteid, 291, 296; in carbo-
hydrate, 291; in fat, 291

Hygiene, laws, 288; of eating and
digestion, 314; of muscles, 341;
of the nervous system, 365; of
the eyes, 374; public, 382

F[ygrotrechus, *158

Fyla arenicolor, *202

Hypermetropia, 375

Ji

ruby

[cerya purchasi, *181
Immunity, 381
Indians, picture writing of, *385

INDEX BS os

Insecta, 149

Insects, 157; and flowers, 450;
fighting, 180; guests of ants, 424;
domesticated kinds, 273; cross*
section of thorax to show muscles
and exo-skeleton, *51; cross-pol-
linating flowers, 452; remedies
for injurious, 183; how to kill and

how to pin up,

*414; killing

preserve, 474;
*476; parasitic,
bottle, *474

Insecticides, 184

Insectivora, 247

Inspiration, 346

Intestine, in human body, structure
of small, 311; coats of small, 311;
villi of small, 311; glands of small,
311; digestion in small, 311; mu-
ous membrane of small, *311;
large, 314

Invertebrates, 132

Iron oxide, 292

Isopod, *154

J

Jelly fish, 136, 138; eye, *75

Joints, defined, 335; ball and socket,
335; hinge, 335; gliding, 335;
pivot, 335

Jordan, D. C., on effect of alcohol,
366

Julus, *155; 156

K

Kallima, *445

Kidneys, in human body, structure
and function, 350; section, *351

Koch, Robert, 380

L

Laboratory, material for use in, 463
Lacteals, in human body, 313

489

Lark, horned, *234

Larynx, of man, 308, 345

Lasiurus cinereus, *248

Leech, 145

Lemurs, 256

Leucocytes, in human body, 317

Life history, defined, 83; of mos-
quito, 85

Ligaments, in human body, capsu-
lar, 336

Lipase, 312

Liver, of man, position, 312; secre-
tion, 312; action, 314

Lizard, *206; thunder, extinct, *276

Lobster, 151

Locust, ear, *73; external
named, *4; on wild oats, *2

Louse, biting bird, *418

Lumbricus,
*144

Lungs and bronchi, of man, *344

Lungs, position and structure, in
man, 344

Lycena, part of wing showing scales,
*440)

Lycoside, 167, *168

Lymph, in human body, 323; com-
position and uses, 323

Lymphatics, in human body, 313

M

parts

earthworm dissection,

Malaria, 380; caused by protozoa,
125; mosquito which spreads,
*128; parasite, life history, *126;
*127

Mammals, 237; body form and
structure, 239; development and
life history, 243; instinct and
reason, 243; classification, 244;
carnivorous, 254; how to skin,
480; man-like, 256; various do-
mesticated, 269

490 INDEX

Mammoth, drawing by ancient man,
*387

Man, jawbones of ancient and mod-
ern, 256; *393; internal part of
ear, *72; tactile corpuscle of the
skin, *70; parasites of, 418; an-
cient and modern, 384; age of, on
earth, 384; 386;
Neanderthal, remains, *390; Spy,
remains, *392; races, . +393;
Ethiopic race, 394, 398; Mon-
golic race, 394, 396; Caucasic,
394, 396; American, 394, 396;

ol, #386;

*3,89;

ancient life,

ancient, arrow head
drawing of, by himself,
bones, 389; works, 392

Mantis, preying, *403

Margaropus annulatus, Texas fever
tick, *130

Marrow, 334

Marsupialia, 245

Martisia xylophaga, *175

Material for laboratory, how to ob-

tain, 465

May fly, 161; young, *162

Medulla oblongata, of man, 360

Medusa, *138

Melanoplus sp., ear, *73

Meleagrina margaritifera, 174

Merula migratoria propinqua, *229

Mesentery, in human body, position,
311

Metabolism, definition, 289;
essentials for, 289

Mice, 246

Microorganisms, 379

Millipede, *155

Millon’s test, 296

Mimicry, 448

Mites, 164; cheese, *165

Moles, 248

Mollusca, 169

three

Mollusk, burrowing, *174, *175
Monkeys, 256; *257

fighting, 189; eggs,
larvee and pupe, *189; eggs and
hatching, 85; larve, 86; all life
stages, *87; life history, 85; pupa

Mosquitoes,

89; external structure, 90; distri-
bution, 91; sucking beak of fe-
male, *91; malarial, *128

Moth, gypsy, 182; eye, part of sec-
tion showing elements, *77; Ache-
mon sphinx, *93; codlin, spray-
ing against, *184; Sphinx, para-
sitized larva, *416; Sphinx, suck-
ing proboscis, *402;
wasps, *448

Motions of animals, kinds and how
performed, 50

Mouth, 303

Mouth cavity, of man, diagram, *305

Multiplication of animals, 79

mimicking

Muscle, in human body, arrange-
ment and structure, 337; biceps,
337; *338; contraction, 337; re-
laxation, 337; voluntary, 339;
striated, 339; nonstriated, 340;
involuntary, 340; blood supply,
340; nerve supply, 340; hygiene,
341; of trunk, shoulder and back,
*338; of shoulder, *340

Muscular system, 290

Mussels, California, *172

Mustelide, 254

Mya arenaria, 172

Myopia, 375
Myriapoda, 149, 155

N
Nails, 353

Narcotics, 302
Nautilus, pearly, 179
Necessity of food and fresh air, 366

INDEX

Negrito-Papuan, head, *396

Nest of humming bird, *103; of
oriole, *104

Nerves of dog, *66; in human body,

cranial, 360; optic, 359; com-
misural, 364; efferent, 364;
motor, 364; sensory, 364; fifth
cranial, branches, *360

Nerve fibers, classification, 364;

strain, 365

Nervous system, 65; types, *68;
in human body, 290; hygiene, 365;
effect of alcohol on, 366; central
organs, *358

Neurone, structure, 363

Nicotine, 302

Nirmus prestans, *418

Nitrogen, in proteid, 296; elimina-
tion from cells, 295

Note books, student, 462

Novius cardinalis, *181

Nudibranch, 177

O

Octopoda, 179

Octopus, 179

Oesophagus, of man, 308; _peristal-
tic contraction, 308

Olfactory lobes, in man, 359

Ommatostrephes californica, *178

Onychophora, 149

Opossums, 245

~ Oriole, nest, *104

Osmosis, 298; experiment showing,
299; in small intestine, 313; in
capillaries, 323

Osmotic pressure, 299

Ostrea virginiana, *173

Ostriches, *228; *230; domesticat-
ed, 272

Otocoris alpestris, *234

Ovis arkal, *271

491

Owl, barn, *224

Oxidation, definition, 291;
body, 294

Oxygen, as a cell element, 291; in
proteid, 291, 296; in carbohy-
drate, 291; in fat, 291; proper-
ties, 291; affinity, 292; method of
obtaining pure, 292; apparatus
for collecting, *293; necessity to
animals, 55

Oyster. *173; pearl, 174; crabs, 153

P

in the

Pagurus samuelis, *152

Palate, of man, 304; soft, 304

Pancreas, of man, 312; secretion of,
S12

Panther, 256

Papilo rutulus, *163

Parameecium, structure
havior, 41; *40

Parasite, malarial, life history, *126;
*127; of Sphinx moth larva, *416;
degeneration, 411; internal, 413;
of man, 418

Parnassius smintheus, *407

Pasteur, Louis, 380

Peacocks, domesticated races, 271

Pectoral girdle, of man, 329, 333

Pelecypoda, 171

Pelvic girdle, of man, 329, 333

Pelvis, of man, *336

Pepsin, 310; action of, 310, 312

Peptone, 312 :

Pericardium, in human body, 318

Perimysium, 339

Periosteum, 334

Peripatus eiseni, *149

Perissodactyla, 250

Peritoneal membrane,
body, 310

Peritoneum, in human body, 308

and_be-

in human

492 INDEX

Perspiration, 354

Pests, fighting insect, 180

Phagocytes, 316

Pharynx, of man, 308

Philampelus achemon, *93

Phoebe, black, nest and eggs, *219

Pholas, *174

Phosphorus, as a cell element, 291;
properties, 294

Physiology, definition, 1; animal,

49; human, defined, 287; pur-
pose of study, 288

Pia mater, 358

Picture writing, Indian, *385

Pigeons, races of, *260; 270

Pill-bug, 154

Pinnotheres, 153

Pithecanthropus erectus, remains,
+391

Pituophis bellona, *208

Plants, as proteid manufacturers,
296; as source of proteids, 296;
as starch manufacturers, 297

Plants, fertilization of, 451

Plasmodium, malarial, *126; *127

Plectrophenax nivalis, *234

Plesiosaur, fossil skeleton, *279

Pollicipes polynemus, *152

Pollination of flowers, *450

Polygonia interrogationis, larvee, *94;
pupa, *96

Pons varolii, in man, 360

Porcupines, 246

Porpoise, 249

Primates, 256

Protection, special means, 403

Proteids, composition, 291-297; as
nitrogenous compounds, 291; as
food nutrient, 295; as flesh-pro-
ducers, 296; as_ tissue-formers,
295; tests for, 296

Protoplasm, described, 48

Protozoa, 118; form of body, 118;
marine, 120; causing human dis-
ease, 124

Pseudo pleuronectes americanus, *197

Ptyalin, 307

Pulse, 325; 326

Puma, 256

Pupation of caterpillars, 95

Pigmy, *397

Piroplasma, germ of Texas cattle
fever, 130

Q

Quarantine, 381
Quohog, 171

R

Rabbits, 246

Rats, 246

Reflex action, 364; inhibition, 364;
simple arc, diagram, *362

Reindeer, drawing by ancient man,
*388

Remedies for injurious insects, 133

Rennin, 310; action of, 310

Reptiles, 203; how to preserve, 482

Resemblances, protective, 442; spe-
cial protective, 444

Respiration, character and organs,
56; essential act of, 343; effect of
exercise on, 347; effects of tight
clothing on, 348; artificial, 348

Respiratory organs of mouse, *58;
system, 290

Rest, 342

Retina, 372; formation of image on,
diagram, *372

Robin, western, *229

Rodents, 245

Rosalina varians, *122

Roundworm, 146

Ruminants, 250

INDEX

S

Sacculina, *412

Sacrum, 331

Salamander, western brown, *203;
tiger, *204

Saliva, action of, 307

Salivary glands, of man, 307

Salmo irideus, *196

Salmon, 196, 199

Salts, inorganic, function, 298

Sanitation, 382

Sayornis nigricans, nest and eggs,
*219

Scale, cottony cushion, *181; San
Jose, *185;. #186

Scapula, of man, 333

Schoolroom, equipment, 461

- Scientific names, 110

Scolopendra, *156

Scorpion, *164; successive positions
of body and legs in walking, *49

Scutigera forceps, *155; 156

Sea-anemone, 136

Sea-horses, 197; *198

seals, 254> fur, *255;
parasites, *419

Sea-squirt, *193

Sea-urchin, 140

Selection by nature, 401

Sense, organs, special, classification,
368, 290

Senses, special, and their organs, 69

Sepia, 178

Sheep, domesticated 267;
American merino, *270; Rocky
Mountain, 253; wild *271

Shells, sea, 177

Ship-worm, 175

Shoulder blades, in human body, 333

Shrews, 247

Sight, of man, 368, 370, 374; func-
tion and organs of, 75

killed by

races,

Silkworm, domesticated, 274

Skeletal system, in man, 290

Skeleton, of man, *330; functions,
329; axial, 329; appendicular,
329; comparison in adult and
child, 337

Skin as an excretory organ, 350;

352; a52;
as a heat regulator, 355; section,
*353; touch papilla, *369

Skink, blue-tailed, *206

Skull, *332; structure, 332; support,
333

Sleeping sickness, caused by proto-
zoan parasite, 130

Slug, California giant yellow, *176

Smell, organs and function, 71; of
man, 370

Smelling pits of antenna of carrion
beetle, *72

Snails, 176;
ture, 5; in aquarium, *6

functions, structure,

pond, external struc-

Snakes, 208; gopher, *208; garter,
*209; king, *210; PA als
rattle, rattles, *211; rattle, poison
fangs, *212; rattle, remedies, 212

Snake, glass, 207

Snowflake, *234

Social life, 426

Sparrow, English, external struc-
ture; 12; *13; habits, 18; feath-

parts, *14, wes-
tern chipping, *220

Species, defined, 112

Spider, 165; eyes and mandibles,
*166; spinnerets, *167; hunting,
167; trap door, *167; jumping,
*168; running, *168; web-weav-
ing, 168; crab, 167, *168

Spinal column, *330; cord, struc-
ture, 362

Spinnerets of spider, 167

rattle,

ers, types, 14;

494 INDEX

Spirilla, 379

Spizella socialis arizone, *220

Sponges, 133°) sexample< ‘of, +133;
skeleton, *134

Spontaneous generation, 80

Sprain, 337

Spraying, apple trees, *184; mix-
tures for, 184

Spreading of animals, 408

Squid, 179; giant, *178

Squirrels, 247

Starch, manufactures, 297; test for,
297

Starfish, 140, *140; dissection, *141

Steapsin, 312

Stentor, *121

Sterilization, 381

Sternum, in human body, 332

Stimulants, 301

Stomach, in man, form and struc-
ture, 308; asa food reservoir, 311;
digestion in, 311

Struggle to live, 399, 400

Suffocation, 348

Sulphur, as a cell element, 291;
properties, 292; in proteid, 296

Sun animalcule, *119

Sunfish, 194; external structure, 8;
Eupomotis sp., *9; habits, 12

Swan, domesticated races, 269

Synovial membrane, in human body,
336; fluid, 336

Systems of the human body, 289;
functions of, 290

Systole, 325

ge

Tactile corpuscle of the skin of man,
*70

Tadpoles, structure and habits, 98;
*99

Tapeworm, *147; *415

Taste, function and organs, 70; in
man, 368; papilla of calf, *71
Teeth, 305; structure, 305; kinds,
305; care, 306

Temperature, regulation in body,
305

Tendon, 339

Teredo, 175

Termites, insect guests of,
beetle guest of, *424

Termitogaster texana, *424

Testudo, *205

Texas cattle fever, caused by proto-
zoan parasite, 130; tick, *130

Thalessa, *417

Thamnophis parietalis, *209

Theobaldia eggs,
and pup, *189

Theridide, 168

Thomiside, 1607, *168

Thorax, and viscera, in human body,
*309; showing skeleton and dia-
phragm, *330

Thrasher, sickle-billed, *232

Thrush, russet-backed, *217

Ticks, 164; dog, *166; wood, *166;
Texas fever, *130

Toad, 201; horned, 207; anatomy,
r22:

424.

incidens, larve,

19; dissection, eggs and
hatching, 97; life history, 97; in
garden, *98; *101
Tongue, 303; showing taste papilla,
*3,70
Tools of ancient man, *394
Tooth, vertical section, *306
Torpedo, electric, 198
Tortoise, Galapagos, land, 205
Touch, sense, 70;
skin papilla, *369
Trachea, 343
Trachina spiralis, 147; *414
Tremex, *417

in man, 368;

INDEX 495

Trochilus colubris, nest and eggs,
*221

Trout, rainbow, *196

Triceraiops, extinct, *284

Trypsin, 312

Tuberculosis, 380

Turdus ustulatus, *217

Turkeys, domesticated races, 271

Turtles, 205

Tylosaurus dyspelor, fossil skeleton,
*278

Typhoid fever, 380

Tyroglyphus siro, *165

U
Ungulata, 250
Urea, 317
Ureter, 350
Uvula, 304

Vv

Valves of heart, of man, mitral, 318;
tri-cuspid, 319

Veins, in human body, pulmonary,
320; portal, 314;
cending, 323; vena cava descend-
ing, 323; renal, 350;
320

Veliger, 171

Ventilation, 349

Ventricle, of heart of man, 318, 319

Venus mercenaria, 171

vena Cava as-

coronary,

Vermes, 143

Vertebre, of human body, 331; cer-
vical, 331; lumbar, 331; sacrum,
Sod -eoccyxs, ook

Vertebral column, 331

Vertebrate, diagram of eye, *76

Vertebrates, structure, 191

Villi, of small intestine, 311

Vinegar-eel, 146

Viscera of abdomen and thorax, of
man, *309

Vorticella, structure and behavior,
Ae TAD

WwW

Wapiti, *251

Wasps, mimicked by moths, *448

Water, as food nutrient, 295, 298;
boatman, *161; bugs, 160; moc-
casin, 212; strider, *158;
*160

Whales, 249

Wildcat, 256

Wolf, Thibet, *262

Wolves, 254

Wood-lice, 154

Worms, 143

tiger,

26

Yellow fever, caused by protozoan
parasite, 130
Yellow-hammer, *231

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