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CORNELL UNIVERSITY LIBRARY

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Cornell University

Library

The original of this book is in
the Cornell University Library.

There are no known copyright restrictions in
the United States on the use of the text.

http://Awww.archive.org/details/cu31924089530053

ANIMAL ACTIVITIES

ANIMAL ACTIVITIES

A FIRST BOOK IN ZOOLOGY

BY

NATHANIEL S. FRENCH, Pu.D.

Teacher of Zodlogy in the Roxbury High School
Boston, Mass.

With WMlustrations

NEW IMPRESSION

LONGMANS, GREEN, AND CO.
gi AND 93 FIFTH AVENUE, NEW YORK
LONDON AND BOMBAY

1905

HE
a

GLY4s
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ISIS

Copyright, 1901,
BY
LONGMANS, GREEN, AND CO.

First Edition, March, 1902;
Reprinted, January, 1903.
Reprinted, August, 1905.

ROBERT DRUMMOND, PRINTER; NEW YORK.

INTRODUCTION.

THE book here presented is the outgrowth of fifteen
years of teaching the subject to large classes in a high
school. Its aim is to interest and guide pupils in the
study of living animals. Young people are usually
ready to be made acquainted with their immediate
neighbors in the animal world, and it is hoped that
this book may be of assistance to them.

In the choice and arrangement of topics the powers
and interests of young students have been kept in view
rather than the demands of strictly logical description
and exposition. Chapter I outlines the animal kingdom
in such a manner as to be useful for reference purposes.
Chapter II gives directions for assisting the student in
procuring his own specimens for study. Chapter III
describes the activities common to all animals. With
Chapter IV work on the Arthropoda begins. Animals
of this group are selected for the early part of the work
because living specimens can be easily collected and
observed in the fall, at which time Zodlogy is begun
in most schools. After the study of the Arthropoda,
the book follows the natural order, beginning with the
simplest animals and ending with the most complex.
In some schools it will doubtless be better to begin
with Chapter XI, and study the Arthropoda directly
after the chapter on ‘‘ The Earthworm’’. This latter
order of subjects is advised when the Zodlogy course
begins in the winter or spring.

Throughout the book adaptation to environment is
constantly pointed out. Much is made of habitat in

Vv

vi INTRODUCTION.

connection with the manner in which an animal per-
forms its life-functions.

The directions for laboratory work are mainly in the
form of questions which must be answered from direct
observation. Comparisons and inferences are con-
stantly required of the pupil. The exercises for review
of note-book work enable pupils to systematize their
knowledge. Useful vocabularies are frequently in-
serted.

For many valuable suggestions the author is in-
debted to Miss Helen A. Gardner and Miss Mary E.
Winn of the Girls’ High School, Boston, and Prof. B.
H. Van Vleck of Boston University, who read the
manuscript; and to Mr. Frank M. Whitney, principal
of the Watertown, Mass., High School and Miss E. O.
Patch of the Girls’ High School, Boston, who ex-
amined the proof-sheets. Mr. Lyman G. Smith of the
Roxbury High School and Mr. Arthur E. Sanford
assisted in preparing some of the drawings, and many
of the illustrations have been reproduced, by per-
mission, from Agassiz’s ‘‘ Seaside Studies’’ (Houghton,
Mifflin, & Co.), ‘‘The Horse’’ by W. H. Flower
(D. Appleton & Co.), various works published by
Longmans, Green, & Co., and other sources.

A LIST OF BOOKS.

All the books on the list given below have been
found useful to pupils, and nearly all of them have been
reported as ‘‘interesting’’ by many pupils who have
read them. Such books may be used to advantage in ~
the preparation of Reports. The list was first printed
by a branch of the Agassiz Society connected ‘with the
Roxbury High School of Boston, Mass.

ABBoTT, CHARLES ConrRAD:
A Naturalist’s Rambles about Home.
Bird Land Echoes. Illustrated.
Agassiz, ELizaBrETH and ALEXANDER:
Seaside Studies in Natural History. Illustrated.

INTRODUCTION.

ALLEN, GRANT:
Flashlights on Nature. Illustrated.

Apcar, AusTIN C.:
Birds of the United States. Illustrated.

Bapenocu, L. N.:
Romance of the Insect World. Illustrated.

Bauscu, Epwarp:
Manipulation of the Microscope.

Bateman, G. C.:
The Vivarium. Illustrated.

Bearp, JaMEs CarRTER:
Curious Homes and their Tenants. Illustrated.

Bepparp, Frank E.:
Elementary Practical Zodlogy.
A Text-book of Zoégeography.

Boies, FRANK:
At the North of Bearcamp Water.

Brooks, W. K.:
The Oyster. Illustrated.

Buckiey, ARABELLA B. :
Life and her Children. Illustrated.
The Winners in Life’s Race. IJ1lustrated.

Burroucus, JOHN:
Birds and Bees and Sharp Eyes.
Riverby.
Wake Robin.
Locusts and Wild Honey.

CarrinctTon, Epitu:
Animals’ Ways and Claims. Illustrated.

CuHapMAN, Frank M.:
Bird Life. Illustrated.

Cuatty Reapines in ELeMEntary Scrence (Longmans):
Nature Knowledge, Books I, II, III. Illustrated.

Cornisu, C. J.:
Animals of To-day. Illustrated.
Animals at Work and Play. Illustrated.
Wild Animals in Captivity. Illustrated.

vii

viii INTRODUCTION.

Corey, C. B.: :

How to Know the Shore Birds. Illustrated.
Darwin, Cuares R.:

What Mr. Darwin saw in his Voyage Round the World

in the Ship ‘‘ Beagle’’. Illustrated.

The Formation of Vegetable Mould. Illustrated.
Davig, OLIVER:

Nests and Eggs of North American Birds. Illustrated.
De Kay, CHARLES:

Bird Gods. Illustrated.
Drxon, CHARLES:

Curiosities in Bird Life.
Dousiepay, N. B. DEG.:

Birds that Hunt and are Hunted. Illustrated.

Bird Neighbors. Illustrated.
Duncan, P. Martin:

The Transformation of Insects. Illustrated.
Davenport, C. B. and G. C.:

Introduction to Zodédlogy. Illustrated.
Epwarps, CLARENCE E.:

The Campfires of a Naturalist. Tlustrated.
Emerton, J. H.:

The Structure and Habits of Spiders. Illustrated.
Ficuier, GurttaumeE Louis:

The Ocean World. Illustrated.

The Insect World. Illustrated.
FLower, Wititiam Henry:

The Horse. Illustrated.
Forses, Epwarp:

A History of British Starfishes. Illustrated.
Frencu, G. H.:

The Butterflies of the Eastern United States,
Furneaux, W.:

The Out-door World. Illustrated.

Life in Ponds and Streams. Illustrated.
GraHam, P. ANDERSON :

Country Pastimes for Boys. Illustrated.
Hottanp, W. J.:

The Butterfly Book. Illustrated.

INTRODUCTION. 1x

Jorpan and KELLocc:
Animal Life. Illustrated.
Kearton, R.: ,
Wild Life at Home. How to Study and Photograph it.
Illustrated.

Kinestey, Joun STERLING:
The Riverside Natural History, five volumes. Illus-
trated.

Lovett, M. S.:
Edible Mollusks of Great Britain.

Lussock, Sir Joun:
On the Origin and Metamorphosis of Insects.
The Beauties of Nature and Wonders of the World.
Ants, Bees, and Wasps. _ Illustrated.

Manein, ARTHUR:

The Mysteries of the Ocean. Illustrated.
Manton, Wa Ter P.:

Taxidermy without a Teacher.

Insects, How to Catch and Prepare.
Matuews, F. ScHuyLer:

Familiar Life in Field and Forest. Illustrated.
McCook, Henry C.:

The Honey Ants of the Garden of the Gods. Illustrated.
Merriam, FLorENcE A,:

Birds of Field and Village. Illustrated.

Birds Through an Opera Glass. Illustrated.
Merriam, C. Hart:

Mammals of the Adirondack Region.
Miatt, Louis Compton:

The Natural History of Aquatic Insects. Illustrated.

Round the Year. Illustrated.
MIcHELET, JULES:

The Insect. Illustrated.

The Bird. Illustrated.
Mitrer, Oxtve THorne:

Little Brothers of the Air.

Four-handed Folk. Illustrated.

Bird Ways.

In Nesting Time.

Little Folks in Feathers and Fur. Illustrated.

x INTRODUCTION.

Morgan, C. L.:
Animal Sketches. Illustrated.
Neepuam, James G.:
Outdoor Studies. Illustrated.
Neurwine, Henry:
Native Birds of Song and Beauty. Illustrated, two
volumes.

Oswa.p, Feurx L.:
Zodlogical Sketches. Illustrated.

Pacxarp, A. S.:
A Guide to the Study of Insects. Illustrated.

ParkuurstT, H. E,:
The Birds’ Calendar. Illustrated.

Porter, J. HamMppEn:
Wild Beasts. Illustrated.

Russ, Kar:

The Speaking Parrots. Illustrated.
ScuppER, SamuEt H.:

The Life of a Butterfly. Illustrated.

Butterflies: Structure, Changes, and Life-histories.
Semper, Frank W.:

Injurious Insects, and Use of Insecticides. Illustrated.
SHaver, NaTHANIEL S. :

Domesticated Animals. Illustrated.
Srmmonps, P. L.:

Commercial Products of the Sea. Illustrated.
Sroxss, A. C.:

Microscope for Beginners,
Tuomson, WILLIAM:

Great Cats I Have Known. Illustrated.
Tuompson, ERNEST SETON:

Wild Animals I Have Known. Illustrated.
Torrey, BRADFORD:

Birds in the Bush.
Wattacre, ALFRED RUSSELL:

Darwinism. Illustrated.
Weep, CLARENCE Moore:

Life-histories of American Insects. Illustrated.

INTRODUCTION. xi

Witson, Sir DANIEL:
Left-handedness.

Woop, THEODORE:

The Farmers’ Friends and Foes, Illustrated.
Woop, Rev. J. G.:

Homes Without Hands, Illustrated.
Wricut, Maser Oscoop:

Four-footed Americans. I]lustrated.
Bird Craft. Illustrated.

TABLE OF CONTENTS.

PAGE

INTRODUCTION sia eiecg:sisgisjareisre: gis 'gi0 6 Sig rane ee tote cease acces Sree 6 Sara. b arattouace: (VAL
CHAPTER I.

ANIMALS CLASSIFIED, ....e0ee cece eeeecee a visle sinieie ease eisle's sie 0
CHAPTER II.

MATERIAL FOR STUDY .c0cceweenseuaan ve aieisasnete BP ieee vaca eae ee,

CHAPTER III.

ACTIVITIES COMMON TO ALL ANIMALS......cccsccevecsvecsees 24

CHAPTER IV.

GRASSHOPPERS AND CRICKETS.......eeeeeee ee peieslsiterieaiaee “32

CHAPTER V.

BUTTERFLIES AND MOTHS WITH THEIR PROTECTIVE DEVICES... 45

CHAPTER VI.

SoME INSECTS CLASSIFIED... ....0.cceeccceeeee ereeeseseseeees 57

CHAPTER VII.

A CHAPTER OF LIFE-HISTORIES. 2... . ccc cece ence een c en enee . 68

xiv TABLE OF CONTENTS.

CHAPTER VIII.

SoME INSECT ADAPTATIONS.........000-eeeeee Jc biaRrwcesee SO

CHAPTER IX.

A SPIDER’s ACTIVITIES,.....0+e+cceees PiAGRORe Hee ekeeawae es OB

CHAPTER X.

HOMOLOGIES AMONG CRUSTACEA....... wee vccncccccsccccesess IOL

CHAPTER XI.

THE ACTIVITIES OF ONE-CELLED ANIMALS AND SPONGES....... 116

CHAPTER XII.

THE HypRA AND SOME C@HLENTERATES WHICH LIVE IN COLONIES 128

CHAPTER XIII.

THE STARFISH AND CLOSELY RELATED ANIMALS..... sesecccee 140

CHAPTER XIV.

THE EARTHWORM AND His Work..... CRE SwReeN eS esese. 148

CHAPTER XV.

MUSSELS AND SNAILS,........06- settee cee cece ces eesceeerees 155

CHAPTER XVI.

THE STRUCTURE AND ACTIVITIES OF A FISH..............0... 169

CHAPTER XVII.

‘TADPOLES “AND! FROGS baiiere pee e gy sain emaelauetime RORY ae sare uasien 179

TABLE OF CONTENTS.

CHAPTER XVIII

CHAPTER XxX.

THe DISTRIBUTION OF ANIMALS
:

CHAPTER XXI.

ANIMAL RELATIONSHIPS.... 0.00 eeecee eer eeeeeeeeeee

XV

i
a

Oy PY Yo

. An Insect-net

. A Duckweed
. Other Pondweeds
. The Hydra [2]
. Water-fleas and Cyclops
. Caddis-fly Cases [2]...

. The Larva of Dragon-fy...
. Larva of Dyticus.......... .
. Larva of Whirligig Beetle
. Larva of a May-fly
. Side View of Crayfish [5]
. A Campanularian Hydroid Colony [6]
. A Sertularian Colony [6]
. A Net for Collecting at the Seaside
. Sea-anemones
. A Starfish [6]
. A Sea-urchin

. A Shrimp
. Tumbler with Chloroform
. A Cockroach [x]
. Mourning-cloak Butterfly
. A Wasp’s Nest [3]
. Cocoon of Cecropia
. Eggs of Frog Just Laid [2]
. Eggs of Frog a Few Hours After Laying [2]

. Apparatus for Removing Oxyyen from Air
. Heating a Test-tube
. The Parts of a Locust

LIST OF ILLUSTRATIONS.

Nore.— The figures in brackets [1] followiny the titles re-
Jer to the list, printed below, of books from which the
illustrations are, by permission, respectively borrowed.

The House-cricket [1].
A Cabbage-butterfly
Spider and Web
As Wate resiiall yciccse aetna ieve ce ea Shoe kde aw ew ses He
Shell of a Fresh-water Mussel [2]
An American Pondweed
The Hornwort

Apparatus for Decomposing Water......... pS shies eh

xviii LIST OF ILLUSTRATIONS.

FIG. PAGE
40. The Trachea of an Insect [2].......... 0. ce eee e eee eee tt 38
41. Cockroach and Cast Skin [1].......... ce. cee ce ee eee rere 39
42. The Nervous Chain of a Cockroach [1]..........0000e eee ett 40
43. Portion of the Cornea of a Fly’s Compound Eye [1]...---++-- 41
44. The Hearing Organ ofa Cricket [1]...........000 00 eee ree 41
45. The Stridulating Organ of a Cricket [1]...........-0 0 eee 42
46. Antennze of Lepidoptera [4]...... 0.6... cee eee ee eee eet 46
47. Eggs of Lepidoptera [4]......... 0.00. cece eee ee ee ee eres 47
48. Some Larva of Lepidoptera............ 0. cece cece eee tes 48
49. Some Cocoons and Chrysalids [4].............c0 ee eee eee 48
50. A Cabbage-butterfly .......... ccc ce cece eee eee nents 49
51. Head of a Moth.......... cece cece cece eee ee ee ere eeete 50
52. The Kallima....... 2... cece eee cee cece cence eee n eee tees 51
53. Catocala Nupta [4]....... cece eee e cece cece teen nee cence 52
54. The Milkweed-butterfly 53
55. Limenitis Ursula ........... Taeseatostornielw ais 53
562, Moth at Rest... soci ieee eae saibieaswe toate mene een ene 55
56d. Butterfly at Rest... 0.0... ccc ccc ccc nen enn ee etneeenes 55
57. Larva and Pupa of the House-fly [1].......... ee eee eee eee 53
58. Right Winglet of Bluebottle [1]..... 0.2... ce eee e ee eee ee eee 58
59. Balancer of Bluebottle [1] ........... eee cece eect eee e cena 58
60. Portion of a Fly’s Foot [1]..... 0... .e cece ee cee e tence eens 59
61. Side View of Proboscis, partly opened [1]...........2s0eeeee 59
62. Head of Bluebottle [1]......-.... cece eee eee ee eee eens 59
63. Eggs of Milkweed-butterfly ....... 00... cece eee renee - 68
64. Larva of Milkweed-butterfly.... 0.0.0... cece cece e eee - 69
65. Pupa of Milkweed-butterfly ........ 0... 0. cece eee cece eee 69
66. Female and Male Aphis... 0.2.0... ccc cece eee ee eee eee eee 71
67;, A. Microgaster Flyin os cas ceancea seine gadeas eaeenienet aes 75
68. ‘The Dragon-fly [2]. isc 0s 00 cscaswsewns sue swan ve 77
69. The Imago of a Dragon-fly [2] 78
70. Caddis-fly, Adult and Larval Cases [2]............0. eee eee 79
71. The Growth of a May-fly [2]..... 0... cece cece eee eee eee 80
72a A Water boaltinain occa cose creas, arivesacguavaiayin ei sie eh aussavbedpdvenscese rang sloniosd 81
730: Dytieus Mar ginalis 3 3...< sers.csxeinivene dieie ds aie een oaielednc ere 81
Te. MOUtR OF a, BUG isa. sse.cssie dia sxcchacoccxerarabinccrane eta a seisiawers viata Wels 82
75. The Egg-raft of a Mosquito [3].......... 00sec eeeeeeeeeeee 82
76. The Life-history of a Mosquito ........... 0. 0c cc ee ce eee eee 83
77. The Mouth of a Female Mosquito [2] .........-....2ceeeeee 84
78. The Leg of a Cockroach [1] 2.0... 0... cece eect cece eens 86
79; As Mole=criCket xis seiees wivcareescoranais ane an vs ERB ice ne Poa 86
80, Fore Legs of a Water-bug [2].............. 0. ccc cece neces 87
Sr. Legsiof Dyticus: [allie saison aulee see we eevee hase dooq eased acane 87
82. Fore Leg of a Butterfly [q].............. ccc cece eee ee eee 88
83; Alive bees 0: yieccsore-sa's ea aieseaeias a aia aanse SB sid seers corey secrag satan eare cence go
84. Fertilization of a Flower by an Insect....................0., 9
85. A. Spider's; Leg [2] o-ccswswamadse act scan Ste nen nomi Peg 94
86. Water-spider and Nest ........... 0.00. e cece eee eee eee, 96
87. Side View of Crayfish [5].............. 02 cece eee eee e eee ee 101
88. Dorsal View of Crayfish [5]............ 0.0 eee e eee eee eee, 102
89. Ventral View of Crayfish [5]......... 00 cee eee eee e eee e ey 103

LIST OF ILLUSTRATIONS. xix
FIG. PAGE
90. Fourth Abdominal Segment of Crayfish [5]..........-..... 104
gl. Crayfish Appendages [5].......0. cece ce eee e ence eeene 105
92. Longitudinal Section of Crayfish [5]..........e eee eeeeeeee 106
93. Walking Appendage of Crayfish with Gill Attached [5]...... 107
94. ThesCommon Crab ioe: sisiaisisiniasiawivisnaie aioe 00 8 6 oud 6 oie wiete nee 108
95. Early Stages of Shore-crab s+e+ 108
96. Water-flea [2].......ccceccccce eee e tent teen eee eeeereas 109
07s Cyclops [2)iisveiwasemseaeesanisiee gees oes cae eee see 109
98: A Barnacle scsssnwswredsseiuwiese cays essa e ee sewer emer 110
99: Formsof AmC@b@iccscceri wre coe ses eee oe 22 oes weseuleese 117
100: Ameeba Feeding [2] .0.0sssa seas secxessiassaciesmennwwars 118
tor. Amoeba Dividing [2].............. cece ee cee eee eee 119
to2. One of the Foraminifera........... 06. cece eee ee ener ees 120
103., The Oniginof Chalk. sig coe. ov ons acd Shae Reames 120
104. Infasorial, Barthes esos noc ee aie eee Pape SA nectar eee 121
TOS; UN SUSOMANS icopeteecsuncardnmuaiaranare weer id ta dase see Pao SS Sse wes HE 121
106. Vorticella [8]....... cece cece ence ee terre nett ne eeenees 122
107. A Paramecium [5 Joos sve nie neti een e eee einen epee nial niet eiee 123
108. Structure of a Sponge.... 62... cece eee ee eee eee teen ee eas 124
109. Sponge Spicules [2]... 60000002 sce cede wenn eee cwes 125
TIO; “Ghread-cells:. [a]sisa saa wee seugetaus sacs aus eernmaesaeine 130
tir. Forms of Hydra [8] ......... ee cece cece eee ener e ee eneee 131
112. Hydractinia [6]... ccc cece sce c sete eee e eect eaten teenees 132
113. Medusee of Campanularian Hydroid [6]................... 134
114. The Origin of a Scyphozoan Jelly-fish............-..020005 135
115. The Structure of a Sea-anemone............ 0.0 eee eee eee 136
B16. A. Star hish ors weeds egies sys esd Sees eee eee Re E RoR 142
pry, & Brittle: Starfishiess sa5 0 ¢ esses 230s eee pee enexesas 144
118. The Structure of a Sea-urchin. 2.0... .. 2. cece eee eee eee ee 146
E19. A Seaccucumberis « ive cssi 9 sees ees snes coe amen mesmmacs x 146
120. An Earthwormins ss oss os sa0ss s00 eae Seamer reewas wwe vs 149
127. A Worm's Stttinssiscs cede as ce vesous repenewstewens wea s 150
422, Wormncastsi so: s9sigss sacs aacms omen eegamee wea. 150
123. A Fresh-water Mussel Showing Position of Foot and Siphons.. 157
124. Fresh-water Mussel with One Valve Removed [5]........... 159
125. Digestive Tube of Fresh-water Mussel [5]..........-.-.++- 160
126, Cross-section of Anodon [5].........c cece cece cece eeeeee 161
127. Nervous System of Anodon [5]............eeeeeeeeeeeeeee 161
DBs PA SLU ease 8 iar ean oats ens ce Gilet dk ap ay cvdioeear ee alouadncsp bing 52% 163
DAQY ASSIST pctce sisse Sasso Dacwa.6 aida rasayeicernsns onasbr an n avn buaenacaunsante sites lasses 165
TBO) AGO Quid [5-06 oases SiziG eussiv nes csayceaes wine asutlermumaamnomm aunt ae 166
131. Part of a Lingual Ribbon. .......... 0... cece eee eee eee 166
132. The Circulation of Blood in a Fish...............-.2-.000- 171
133. Antetnal Organs Of TSH... «...0.synscnemeacaesemaaivics Saks 172
134. Skeleton Of BiSh. « o.cene seancomeaerdar edie eeanvesetniwiet gous ey 173
TQ5. VON gue Gl a POG ccc sis sapseasaanp acseansraaySrcimyer a teaca preciagingy sista a sg 182
136. A Young Tadpole Showing External Gills [2].............. 182
137. Under Side of Tadpole Showing Coiled Intestine and Internal
Gills: (2) gota wacarter amg aime matamateicadten: Wee = 183
138. Heartoof Adult) Frog [2]... sa5 secdsssnaesenmaccraws sexes 183
139. Blood-cells of a Frog [9]......... cc cee cee c eee e cece eeees 183

XxX LIST OF ILLUSTRATIONS.

FIG. PAGE
140. Blood-corpuscles of Man [9]............eceeeee eee ee eeeee 184
T4ts. ViscerarOf Proge sissies vere ae saa oeieldomsiaparemghe tphce a Roe wA ve 185
142, Digestive Organs of Man [9].......... 0. cece eee eee e eee 186
143. Growth of Frog’s Lung from Primitive Fuod-tube........... 187
144. Growth of Frog’s Egg [2] ......... 02 ccc e cece ce eee teens 188
145. Very Young Tadpoles [2].................5 Retad (bea eas

146. Various Stages of Tadpole [2]....... 0... 2... ce ee cee eee eee

147. Young Frogs [2]......----eeeeeeeeee

148. The Use of a Muscle.................

149. Striped Muscle-fibres [g].......-. 20 ccc c eee ce ee eee serene

150. Unstriped Muscle fibres [9].........-.eee cee eee eee cence
151. A Frog’s Skeleton ......0 gece cccccccvccvececcccssonesens

152. A-Man's: Skeletonts.0:< sisc-aie dudes sods eerste ees: gerd

T53.: BrainOf Progi 4. ocisis cen Schl esddacaees Swen ersae MRE EAM Ase

154. Brain and Spinal Cord of Man............seeeeer ee eeeeees

155. Beaks of Various Birds...........2ce eee ee cee eee e eee eens

156. The Digestive Organs of a Bird... ....... 00sec cence eee

157. Diagram of the Heart of a Bird [3]

158. The Skeleton of a Bird... 1... ... ec cece cece cece eee e ees

159. A Swallow Feeding Her Young.............0eceeee ee eeeee i
160. Arm of Man, Fore Leg of Dog, Wing of Bird............... 204
TOD AL Birds, Wang ieee actie'0 6 och svnie sr ciotein wie. aca 8764 ace pete: Aneneseieia Wee ed 204
162. The Sternum of a Shrike 2.0.0... 0... cece cee eee ee eee 205
TO3 0 THeath ers ssc ite teccs Hate ata He Sansa GS Seine ds aRanele ete es 206
164s, A. Birds Le gd: rissid a 'a's ¥en g <igierstensapeig WA: CGO ans Seer os 207
1605. Feéctiof Birds.ninccecesaiaegeeteeaieds: Ss vans nsw d § 208
166.. "The Archaeopteryx. isc 552065 enevaceae oes eeg es ned eden vs 209
167: ‘Teethiof Man: [g}vasss¢ 22422 nensecaters cas et see eeweGe ses 212
HOS: "Teethiob Dog x /oats. caine 28 Sea ais aarti peisiastea oot ale i Rvayensanns Aue 212
169. Teeth of a Sheep [3] ....-- see ee cece eect cece ec ee ee enees 213
DOs TESthsOb are sivcovtyesa:anaye. tian e1a.b, a eieeasove twos ashe da asegio wale waters 213
171. Skull of Cow Showing Teeth........... 0. cc cece eee e eee eee 214
172. ThectHuman By saicwnadiaa diesels setae da thea tnceae OMe 214
173. Skeletons of Man and Horse [10].......-....00eeeeeeeeeee 215
174. Bones of Leg and Arm of Man [11] .......-.... eee seeeeee 216
175. Vertebral Column of Man [11]............ cece eee eee eee 216
176. Human Skull [11] .cscweniie ceed deeds wenemeee ene es ccamnaes 217
177. First and Second Vertebrae of Man [9].............eeeee00s 219
178. Skeleton of Gorilla, wsisss crave ay o05 40 4 sievceaieue ae aareie sreiare 220
179. Diagram Showing Circulation of Blood in Man [r1]......... 221
180. Skeleton of Bat Showing Wings...............0cceseccueee 222
181. Arm and Hand of Man [11] ........... 0... ccc eae ee ee eee 223
182. Skeleton of Chimpanzee Showing Hand..................., 223
183. Fore Foot of Mole...... 0.0... 0. cece cece ec eee e ee eneeeneey 224
184. FOE: FOOtrof Cats ic sc seis sinveiessiasie.t 08 eye wis ecier Vg dnek eae baie c-, 224
185; Fore Heet OF COW si. ans dvewcuduen eth ae aietaghs acces SeN ea 225
186.. Fore Feét:0f Horses o.cien i sees denies eo side sige lier vay cus 225
187, Foot of Hlephanti icc wsccccaciax ohoades seeieeem siete... 225
E88. Feet of Beare 3sic:s aise apanesinscetads 865% 4 aa Aa Oates Sx oes 225
189. Sole of Foot of Man, of Dog, and of Horse [z0]............. 226
Igo. Finger of Man and of Horse [10]............ 0. .e eee eee ae 227

LIST OF ILLUSTRATIONS. xxi

FIG. PAGE
Igt. Feet of Ancestors of Horse ..........0 cece eee ene e ee eee ee 228
192. Growth of Hair [9]....... 0. cc cece eee eee ee cette eee 229
193. Horns of Sheep, Cow, and Deer....... 0.0.0.0. c cee eee 230
194, Skull of Cow Showing the Bone of the Horn .............-+ 231
195. A Manlike Ape Walking.......... 020 c cece cece ee ee ee eeeee 232
196, Ac (Chimpanze on icccemcunicwe se eed op adsed J16 ak ws eee Gee 233
197. Feet of Ancestors of Horse... 2... 0... cee cece eee ee nee 244
198, AsPterodachyl ccc ccncmas vasa tee ode sy sedad dod eee adane ee 245
199, The Archecopteryx. ss ccaiscswecenevees dens ened eee ences 246
200, Diagram of a Sea-squirt..... 2... cece cece e ee en ee eeeee 247
201, AMpPhiOXUSs. ware ain cies ds aise yee gh bese ea ee ee eae oe Ore 247
202. Growth of Frog’s Lung from Primitive Food-tube....... wee. 248
203. Morula Stage [7] cs cawieciwss sana dees ceeve guns so ets cee eets 249
204, Gastrula. Stage [7] a csressursmianiremued sede ue een yee pe es a 249
205. A Genealogical Tree [7]........ 0: eect eee cece ee cnet eeeee 252
1. Our HousEHOLD Insects. By £. A. Butler, Longmans, Green, & Co,
2. LirE IN PONDS AND

STREAMS§ 5 oa oei4s's 3s By W. Furneaux, ee Ke ee

THE OUTDOOR WoRLD...Sy W. Furneaux, ae ae ae

. BUTTERFLIES AND Motus. By W. Furneaux, fe ue He

. PRACTICAL ELEMENTARY

BIOLOGY ..........4.. By Fohn Bidgood, be “ ee

. SEASIDE STUDIES IN NATU-

RAL History....8y £. and A. Agassiz, Houghton, Mifflin, & Co.
THE STORY OF CREATION. By Edw. Clodd, Longmans, Greed, & Ce,

. ANIMAL BIOLOGY....... By C. L. Morgan, as
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THE HORSE..........4. By W.H. Flower, D, Appleton & Co.

. HUMAN PHYSIOLOGY..... By W, Furneaux, Longmans, Green, & Ca

ANIMAL ACTIVITIES.

CHAPTER I.
ANIMALS CLASSIFIED.

IN the course of these lessons on Animal Activities
the student will be called on to observe many forms of
animal life and to learn many new and perhaps strange
names. In order that he may keep his bearings and
feel somewhat at home from the start, the following
classification of the animal kingdom is given. The
student should read over this table carefully, noting
especially the meaning of the names in the light of
their derivation, and he should refer to it frequently.
Later in the book more will be said about classification.

The animal kingdom is divided by zodlogists into
subkingdoms. As these subkingdoms are supposed
to consist of animals related through their ancestry,
they are sometimes called phyla ( phylum, a tribe).
Since Zodlogy is a rapidly growing science, authorities
differ in regard to the number of divisions, or phyla,
and also in regard to the names for some of the
divisions.

2 ANIMAL ACTIVITIES.

Phylum fear eb | a

or Sub- | Name of Sub- | Derivation of | 4 Few Characteristics. ! Familiar Examples
kingdom. kingdom. Name.

I, |Protozo’a.| Gr. protos, | One-celled ani- | Amoeba, para-
first, andJ| mals. mecium, vor-
zoon, ani-| They donot re- | ticella, chalk
mal. produce by eggs.|} animals.

Il. | PormeRA.| Lat. gorus, | Animals having | All sponges.
apore,and| many cells
fero,tobear| much alike.

Food enters the

body by numer-

ous openings.

Ill. | Cw .ente-| Gr. oz/os, | Animals having | Hydras, hy-
RA’TA. hollow, and| hollow cylindri- | droids, jelly-
enteron, in-| cal bodies with | fish, corals,
testine. only one open- | sea-anemones

ing, the mouth.

IV. Ecuino- | Gr. echinos, | Animals having | Starfish, sea-

DER/MATA. | ahedgehog,| very distinct ra- | urchins, sea-
and derma, | dial symmetry, | cucumbers,
skin, having hard| and stone-

plates in the | lilies.
skin, and fre-

quently covered

by spines.

Vv. VeER’MES. | Lat. vermis, | Include a great | Earthworms,

a worm. variety of worm- | leeches.
like animals.
Some have seg-
mented bodies.
VI. | AR THROP’O-| Gr. avthron, | Animals having | Grasshoppers,
DA. a joint, and | segmented bod- | butterflies,
pous (pod), | ies and jointed | spiders, cray-
a foot. appendages. fish, crabs,
centipedes.
VII. | Mot us’ca.| Lat. modlis, | Soft-bodied ani- | Clams, snails,
soft. mals, often en- | the nautilus,
closed in hard | and the squid.
shells.
VII. |Cuor pa’ta.| Gr. chordé, | Almost all have | Fishes, frogs,
a string. back bones |_ turtles,
made upof parts | snakes, birds,
called vertebra. | horses, and

man.

ANIMALS CLASSIFIED 3

In the following pages directions are given for the
laboratory study of the activities, as well as of the
structure of the animals mentioned below.

A paramectum, belonging to Protozoa.

A sponge, belonging to Porifera.

A hydra and a hydroid colony, belonging to Celen-
terata. :

A starfish and a sea-urchin, belonging to Echino-
dermata.

An earthworm, belonging to Vermes.

A grasshopper, a butterfly, a house-fly, a potato-
beetle, a spider, a centipede, and a crayfish or a lobster,
belonging to Arthropoda.

A mussel, a slug, and a snail, belonging to Mollusca.

A fish, a frog, and a bird, belonging to Chordata.

Directions for a short study of some domestic animals
related to man are also given.

CHAPTER II.
MATERIAL FOR STUDY.

In order to study the activities of animals it is neces-
sary (1) to have apparatus, (2) to collect many forms
of animal life and provide suitable conditions for them,
and (3) to prepare and preserve specimens. All work
of this kind can best be done by the members of the
class. Itis a good plan for small groups of volunteers
to assume responsibility for carrying out the directions
of the several paragraphs which follow.

APPARATUS AND REFERENCE BOOKS.

Not much apparatus is needed. A net for collecting
insects may be made by bending a piece of telegraph-
wire into the shape indicated in Fig. 1, fastening it to

Fic. 1.—An Insect-net. Drawn by A. E. Sanford.

a pole, and sewing it into a bag made of mosquito-
netting. For water collecting, a tin strainer attached
to a wooden handle answers admirably. Fruit-jars and
jelly-tumblers with tin covers make good collecting
vessels. A few books should be at hand for reference.
Bulletin No. 39, U. S. National Museum, can be had

4

MATERIAL FOR STUDY. 5

by sending to the National Museum in Washington.
It contains valuable directions for collecting and pre-
serving animals, and no school need be without it.
‘©The Out-door World’’, Furneaux, (Longmans,) is
a useful help in this work.

Write your name plainly on a label affixed to the
jar or other vessel in which you have placed your col-
lections. Write a brief statement telling where and
under what circumstances your specimens have been
collected. Hand jar and statement to the teacher at
the same time.

LIVING MATERIAL FOR FALL USE.

Grasshoppers and Crickets. Collect these insects
and place them in tumblers, or similar glass vessels,
covered with netting. Put earth
in the bottom of each tumbler and
keep it moist. Feed the insects
with lettuce, or similar vegetable
food. Watch the movements of
male crickets while chirping.
Female crickets may often be seen
depositing eggs. The females
may be recognized by the long,
slender, egg-depositing organs at
the end of the abdomen. Use
these specimens with the directions
in Chapter IV. Grasshoppers and
crickets may be fed on bread.

Wasps and Butterflies. Place
wasps in tumblers in a similar
manner, and feed them on sugar Fic. 2.—The House-
and water. Try, also, butterflies cricket.
and moths in the same way, using larger glass vessels.
If eggs are deposited, examine them carefully and
watch their growth.

6 ANIMAL ACTIVITIES.

Caterpillars. Keep these singly in tumblers with
fresh supplies of the plant on which they are found
feeding. When many caterpillars are needed for class
study a ‘‘breeding-cage’’ may be made by placing
earth in the bottom of a
large box, covering the
box with netting, and
supplying plenty of food
and moisture. If panes
of glass can be set in the
sides of the box, so much
the better. Cabbage-
worms are easily ob-
tained, and the butterflies
can be reared from them
with very little care. The
cabbage - butterflies are
sometimes called
‘‘whites’’. In observ-
ing butterflies and cater-
pillars use the questions
in Chapter V.

Flies. Allow adult
bluebottle flies to deposit
eggs on pieces of meat or
fish in tumblers. Watch
Fic. 3.—A Cabbage-butterfty, a, the growth of the eggs.

larva; 4, pupa; ¢, egg; @, imago. Keep in a fairly warm

place and furnish mois-
ture. See further suggestions in Chapter VI. House-
flies may be watched in tumblers. Feed them on
sugar and watch their movements. Early in the
fall house-flies will deposit their eggs on stable-
manure.

Spiders. All our common spiders are harmless.
To collect spiders invert a tumbler over them, and im-
prison the insects by covering the mouth of the tumbler
with a card. The garden-spider is a good one to

MATERIAL FOR STUDY. 7

observe. Provide flies and other small insects for food,
and watch the web-making, the feeding, and other
activities. Further questions
and suggestions will be found
in Chapter IX.

Earthworms. Fill one or
two large battery-jars with
moist earth and decaying
leaves and put in each jar
several earthworms. Cover
the jars and keep the earth
well moistened. Keep all
winter. Watch in connec-
tion with directions in Chap-
ter XIV.

Turtlesand Snakes. Line
the bottom of a large box
with sheet-lead or zinc and
place panes of glass in the
sides for windows. Put
earth, stones, and moss, Fic. 4.—Spider and Web.
and, if convenient, a few
growing ferns in the box. This makes a good home
for turtles and snakes. Snakes caught late in the
fall will probably not eat anything through the winter,
and they can be set at liberty in the spring. Turtles
seldom eat in the winter, but will take flies, bits of
meat, or pieces of cracker soaked in milk when
hungry. ‘‘The Vivarium ’’, an illustrated book by G.
C. Bateman, will be of great assistance to pupils who
are willing to care for these animals.

Frogs. Ina box like that described in the preceding
paragraph keep several frogs. In the winter frogs do
not commonly take food. Live frogs can usually be
bought in the markets.

Slugs. These animals are easily kept if provided
with moisture and food. They eat bread or cracker
as well as many kinds of vegetables.

8 ANIMAL ACTIVITIES.

Snails and Mussels. Collect pond-snails and put
in a vessel of water with sticks, dead leaves, and
growing plants. Place in the bottom of
the dish two or three inches of sand and
introduce one or two fresh-water mussels. —
Watch the movements of both snails and
mussels. Find out how they breathe.
The plants furnish food for the snails, and
the mussels thrive without feeding, living
Fic. 5.—A for years in an aquarium like that just de-
Water-snail scribed. Watch for the eggs and growing
(Planorbis). Sounge, Use directions in Chapter XV.

Aquaria. The mussels just mentioned breathe the
air dissolved in the water, and, on this account, fresh
air must be supplied. There are several ways of doing
this. The simplest method consists in furnishing

Fic, 6.—Shell of a Fresh-water Mussel (Axodon).

growing plants enough in the aquarium to take up
the carbon dioxide gas exhaled by the animals, and at
the same time to give the water a supply of oxygen.
Such plants may be easily collected while looking for
snails. Water-plants are also for sale at bird stores.

MATERIAL FOR STUDY.

9

Another method of purifying the air in water consists

in forcing a stream of air
through it. This is not prac-
ticable in most schoolrooms.
Pouring fresh water against
the side of the aquarium in
such a way that many bub-
bles of air are caught in
the descending stream is a
common and easy method.
Large aquaria frequently have
a constant supply of running
water with a regular outflow.
Such aquaria are hardly neces-

sary in most schools. Small py¢, 7.—An American Pond-

rectangular glass vessels and
common battery-jars answer
every purpose.

weed.

Of course water

Fic. 8.—The Horn-
wort.

lost by evaporation must be re-
placed. With the aquatic animals
mentioned here it is a good plan
to depend partly on plants to
change the air in the water, but
in addition to this it is better to
remove the greater part of the
water from time to time and to
replace it by a fresh supply. An
easy way to accomplish this is to
have all the aquaria placed on a

shelf a little higher than the faucet
from which water is to be supplied.
A hose can be attached to the faucet
for the purpose of filling the aquaria.
In order to empty the vessels, it
is only necessary to unscrew the
hose from the faucet while it is still
filled with water, being careful to

Fic. 9.—A Duck-

weed.

keep the end of the hose in thé aquarium under water.

Io ANIMAL ACTIVITIES.

In this way the water siphons over into the sink. To
prevent the passage of insects through the siphon, attach

Fic. 10.—Other Pondweeds.

growing fresh-water plants, an

it to a_ tunnel
having the open-
ing covered with
wire gauze.
Hydra. Collect
small sticks and
dead leaves, with
some mud and
water, froma fresh-
water pond, or from
ditches used for
draining swampy
places. Place
these in glass with

d renew from time to

Fic, 11.—The Hydra (magnified).

time the water lost by evaporation. Collect from
several localities in separate jars, and label the jars

MATERIAL FOR STUDY. Ir

for convenience. Watch carefully for the appearance
of either brown or green hydras.

They may be seen without a magnifying-glass. If
only eggs are present, they may not hatch for months,

Fic. 12.—Water-fleas and Cyclops (magnified),

but sometimes adult hydras are captured attached to
duckweed or other objects. Have several jars, and
watch them all. Look for the appearance of buds on
the sides of the hydras. Minute crustacea (water-fleas
and Cyclops) may appear in some of the jars. These
are good food for hydras, and themselves furnish pleas-
ing objects for study, both with and without the micro-
scope. If either crustacea or hydras appear, notice
whether they prefer the light or the dark side of the
jar. Add water only to replace that lost by evapora-
tion.

Some Water-breathing Insects. While collecting
the hydras, look for objects that appear like moving
sticks, or small moving rolls made of bits of leaves or
pieces of sand. These are the larve of caddis-flies.
Watch them feed, and add material to the tubes which
protect their delicate bodies. Keep plenty of plants
about them. Larvez of other insects may be collected

12 ANIMAL ACTIVITIES.

at the same time and kept in aquaria. If possible
collect a water-boatman. Fig. 72 shows this insect

Fic. 13.—Caddis-fly Cases.

as it appears while swimming and while flying. A
powerful aquatic insect is the large water-beetle (Dity-
cus Marginalis). Fig. 15 shows the young and Fig.

Fic. 15.—Larva,of Dyticus. Fic. 16.—Larvaof Fic. 17.—Larva
Whirligig Beetle. of a May-fly,

73 shows the adult forms. The whirligig beetles seen
in large numbers on the surface of fresh water have
eyes adapted for seeing enemies in the air above and

MATERIAL FOR STUDY. 13

in the water below at the same time. A young
whirligig is shown in Fig. 16. Watch mode of
breathing and of carrying air about. Observe also
the manner of ‘‘feathering’’ the oars. Feed the
beetle and larve on bits of meat or small in-
sects.

Leeches. ‘‘ Blood-suckers’’, as the boys call them,
are harmless and interesting tenants of an aquarium.
Watch some of these animals, noting especially the
mode of movement by means of contracting longi-
tudinal and circular muscles. They feed only occa-
sionally, and can be set at liberty before they suffer
forfood. At liberty they suck the blood from living
animals.

Crayfish. These may be bought alive in the mar-

Fic. 18.—Side View of Crayfish. amv, antenna; 7, rostrum; cep, cephalic
portion; ¢ho, thoracic portion of cephalothorax; a4, abdomen.

kets. They may be kept in shallow water in aquaria
and fed on bits of fish or meat.

Tadpoles. These may be caught in ponds and
brooks even late in the fall. Collect several sizes and
keep them in a jar or jars. They feed on vegetable
matter, eating chiefly the small green plants (confervz)
which grow so rapidly in stagnant water exposed to
sunlight. Select a particular individual and sketch his

14 ANIMAL ACTIVITIES.

actual size from time to time, dating the sketches.
Make these sketches as accurate as possible. When
not convenient to catch tadpoles it is easy to buy
them.

Fishes. Obtain alive, by using a net, either horned
pout (catfish) or bream. Goldfish can be bought in
case of failure to get others. Feed with fish-food, a
preparation of gelatin sold by dealers in goldfish. Use
plants in the aquarium, and change the water about
three times a week. Use a rectangular aquarium.
Shield from the direct rays of the sun.

Hydroids and Jelly-fish. Unless a school is situated
where it is easy to obtain an abundant supply of salt
water, not many marine animals can be well kept.
Before undertaking seashore work, a copy of ‘‘ Seaside

oes

Fic. 19.—A Campanularian Hydroid Colony (Eucope diaphana). a,
whole colony, one half natural size; 4, single zooid magnified;
¢ and d, stages of jelly-fish, magnified.

Studies ’’ (Agassiz) should be accessible to both teacher
and pupils. There are many small marine animals
resembling the hydra. Among the most abundant of
these are the campanularian hydroids, colonies of hydra-
like animals. The colonies are brown in color, and
look like mosses or similar plants. They grow on

MATERIAL FOR STUDY. 5

sea-weeds, on logs and sticks, and are sometimes at-
tached to the shells of mussels. Find them at low
tide and transfer them to a marine aquarium, made by
filling a jar with salt water and introducing some marine
plants collected on the rocks where
the campanularians are found. Some
closely related colonies are called
sertularians. Hydractinia is the
name given to a colony consisting
of pink, salt-water hydroids found
growing on the snail-shells occu-
pied by hermit-crabs.

Sea-anemones. These animals
are hardy and may be transported
for some distance in jars or pails of
salt water. To obtain them, look
in pools left by the tide in rocky
places, or on rocky bottoms below se allan Sars
lowtide. They are sometimes found Agassiz. si "
attached to the piles of wharves or
bridges. They can be removed from the rocks by
quickly slipping a broad, thin knife between the
anemone and the rock. Their resemblance to hydras
and to coral animals
should be especially
noted. Except as
living specimens they
are not of much value
to beginners, as the
prepared specimens

are commonly too
Fic. 21.—A Net for Collecting at the much distorted to
Seaside.

‘ ay)

show structure well.
Starfishes and Sea-urchins. These animals may
be found in the same localities as the anemones. They
are quite hardy and will live in salt-water aquaria. As
they can be collected at any time during the year, it is
as well to get the living specimens when ready to study

16 ANIMAL ACTIVITIES.

Chapter XIII. Keep one animal in each battery-jar
with sea-water and a few marine plants.
Sea-cucumbers. These animals are often found on
beaches after a storm. They may be found on rocky
bottoms in a depth of from three to six feet of water at

2 ———— = =

Fic. 22.—Sea-anemones.

low tide. It is easy to take them with a dip-net when
once found. They are hardy and live well in aquaria.
Compare with starfish and sea-urchin.

Shrimps and Sand-fleas. Shrimps may be used in-
stead of crayfish in studying Chapter X. They may be
caught with a dip-net in shallow water at low tide. They
can be kept in aquaria. Sand-fleas, sometimes called

MATERIAL FOR STUDY. 17

sand-hoppers, are easily collected by overturning rocks
left by the tide.
Compare with
shrimps. Collect
also hermit-crabs.
Marine Fish.
Where there are
conveniences for
salt-water animals,
a few small marine
fish may be kept.
No special direc-
tions are necessary.
Compare with
other specimens of
fish and use with
Chapter XVI.

THE PREPARATION AND CARE OF SPECIMENS.

Prepared Specimens. In addition to living animals
it is always necessary to have at hand a plentiful supply

Fic. 23.—A Starfish. After Agassiz.

Fic. 24.—A Sea-urchin. Part of the spines have been removed.

18 ANIMAL ACTIVITIES.

of prepared specimens so preserved as to be examined
to the best advantage. It should be a part of the work
of the pupil to prepare at least a portion of this material.

Killing the Specimens. Place some pieces of blot-
ting-paper saturated with chloroform or ether in the

Fic. 25.—A Sea-cucumber. Fic, 26.—A Hermit-crab.

bottom of a jelly-tumbler provided with a tin cover
(Fig. 28). In this grasshoppers, butterflies, and other
small insects may be painlessly killed. It must be
remembered that chloroform and ether are poisonous

Fic. 27.—A Shrimp.

substances, and that they must not be brought near a
lighted lamp or fire, as they ignite very readily.

MATERIAL FOR STUDY. 19

The cyanide bottle described in Part F of Bulletin
No. 39, U. S. National Museum, can be used instead
of the tumbler if desired. Animals larger than insects
may be killed by chloroform or ether. Earthworms
should be killed in dilute alcohol. Starfish and sea-
urchins are often killed by placing
them in hot, but not boiling, water.

Preserving Specimens in Alcohol.
Part M of Bulletin No. 39 already
mentioned gives valuable directions
for the preservation of specimens.
Alcohol is the most important pre- 5. og Tumbler
serving fluid. For most specimens ~~ Vith "Chloroform.
50% alcohol should be used at first. Drawn by A, E.
This should be changed in a few “Sanford.
days to a stronger solution, about 60%. If the speci-
mens are to be permanently kept they should be
transferred again to 70% alcohol. Strong alcohol as
bought of the dealers is about 95% pure. This should
be diluted some days before the specimens are put in
it, to prevent the collecting of bubbles on the surface
of the animals. Parts of animals for dissecting
should be hardened gradually in alcohol. Hydras,
hydroids, snails, mussels, and worms are best kept in
alcohol.

Preserving Specimens in Formalin. This liquid as
usually bought is a solution of formaldehyde in water.
For most purposes it should be diluted with water to
make a 2% solution. Specimens to be used are kept
in this fluid.

Dried Specimens. For class use, butterflies may be
kept in a tightly closed box containing naphthalin or
camphor. Such specimens usually need to be preserved
for a few months at most and can then be thrown away.
Dragon-flies and other insects may be kept in the same
box. Starfish may be dried by a slow heat after
immersing for a time in hot water, not boiling, or after
gradually hardening in alcohol. Sea-urchins may be

20 ANIMAL ACTIVITIES.

preserved in the same way, but they make better speci-
mens for study, if preserved in formalin or alcohol.

Shells and Bones. To remove snails from their
shells put them in hot water for a few moments. The
shells may then be cleaned and dried. To clean fleshy
matter from a skeleton like that of the starfish use a
dilute solution of caustic potash. Sometimes it is well
to boil specimens in that liquid. The bones of larger
animals can be cleaned enough for class use by simply
boiling and removing the fleshy parts. When such
specimens are to be kept for a long time more care is
needed, and books containing more specific directions
should be consulted. Part C of Bulletin No. 39, pre-
viously mentioned, is helpful.

MATERIAL FOR WINTER AND SPRING.

The preceding directions are for classes which begin
Zodlogy in the fall. When the work begins in the
spring the order of
work should be modi-
fied somewhat, begin-
ning with Protozoa and
reaching the subject of
Arthropoda after warm
weather brings the
living specimens again
within easy reach.
Even in winter much
material can be pro-
cured by the pupils for
their study.

Cockroaches. Cock-
roaches were originally
southern insects. They
are now distributed
almost everywhere, and
are fairly abundant even
in cold weather. They are most easily collected at

Fic. 29.—A Cockroach.

MATERIAL FOR STUDY. 21

night in warm places where there is a plentiful supply
of household food. A sugar-refinery often furnishes
an abundant supply of these insects. They may be
kept alive as in the case of grasshoppers. With a few
obvious changes in the directions and questions, the
cockroach may be substituted for the grasshopper in
studying Chapter III.

Butterflies and Moths. Although adult forms of
these insects are not abundant in cold weather, their
eggs, cocoons, and chrysalids are easily obtained. In
late winter or early spring pupils should collect speci-
mens of the large mourning-cloak butterfly (Vanessa

Fic. 30,—Mourning-cloak Butterfly (Vanessa antiopa).

antiopa), which shows the wear due to its winter sleep,
and is ready to produce eggs for the summer brood.
The eggs may be reared, the larve feeding on leaves
of willow or birch. On apple- and cherry-trees may
be found the eggs of the tent-caterpillar moth. These
eggs are glued to the stem in a mass. The large
grayish-brown cocoons of the Cecropfia moth are often
found on pear-trees or other fruit-trees. Eggs, cocoons,
and chrysalids should be brought to the schoolroom
and placed under such conditions that hatching and
growth may be watched.

22 ANIMAL ACTIVITIES.

Other Insects. Eggs of spiders are easily found in
winter. They should be kept in tumblers and watched.
Nests of paper-making wasps are interesting. They
often contain sleeping queens waiting for a higher tem-

——

Z Dyfi
ee

Fic. 31.—A Wasp’s Nest. Fic. 32.—Cocoon of Cecropia.
From a Photograph.

perature in order to start other colonies. Insects in
various stages of metamorphosis pass the winter hidden
away from birds and other enemies. Locality and cir-
cumstances must determine what sort of specimens
pupils should search for. With the advent of spring
one can obtain nearly, if not quite, all the specimens
already mentioned as obtainable in the fall.

MATERIAL FOR STUDY. 23

For Aquaria. Hydroids, hydras, and jelly-fish
for the most part die off in win-
ter, but sea-anemones, starfish,
hermit-crabs, shrimps, and cray-
fish can all be obtained through-
out the year. Snails and mussels “
are also easily kept at all times, Fi 33,— Eggs of Frog
as are also tadpoles and frogs. erreeecd
In the spring the eggs of frogs and toads should be
placed in aquaria and watched.

Birds. Winter is the best time to begin the out-
door study of birds. Familiarity with the birds which
remain north throughout the winter prevents much of

the confusion which so annoys the novice when he tries
to observe the newcomers at the time of the spring
migration. A study of crows, blue jays, and chicka-
dees, during cold weather should form a part of the
work for winter. English sparrows must not be
despised as objects of study, and their habits, both in
captivity and out of doors, should be watched.

CHAPTER III.
ACTIVITIES COMMON TO ALL ANIMALS.

Matter. The books on physics tell us that matter
is anything having extension, i.e., having length,
breadth, and thickness. Living matter we call or-
ganic, and matter which is not alive, and, as far as we
can see, never has been alive, we call inorganic.

Living Matter. Living matter dies. It always
returns sooner or later to the inorganic world from
which it derives the materials by means of which it
keeps its living machinery active.

Organisms grow, not by adding matter to the out-
side, as do crystals when they increase in size, but by
taking substances into the body, and there building
them into matter like themselves.

Before growth ceases, plants and animals reproduce.
Some small portion of the body separates from the rest
and begins an independent existence, repeating, very
nearly, the life-history of its parents. In most cases the
part which separates for the new life must join with a
part of another individual before it can grow. Doubt-
less pollen and ovule are familiar terms to all who will
use this book.

Living things, too, seem to be capable of movements
which differ from the movements of inorganic things.
A living tree moves with the wind just as inorganic
things move, but it also has going on within it move-
ments which differ entirely from any movements of
which inorganic matter is capable.

24

ACTIVITIES COMMON TO ALL ANIMALS. 25

Plants and Animals. The differences between
higher animals and plants are so obvious that we need
never mistake one for the other; but, as we shall see,
the differences grow less and less as we consider simpler
and simpler organisms. Among the simplest living
bodies the processes of life go on; but we do not know
whether to call the living things themselves plants or
animals.

Definitions. The science which treats of living
matter is Biology. The branch of Biology treating of
plants is Botany, and the branch treating of animals is
Zodlogy.

The study of the form, structure, and position of the
parts of a plant or an animal is Anatomy. Minute
Anatomy studied with the microscope is Histology.’

The study of the functions or uses of all parts of an
organism is Physiology.

Activities of our own Bodies. We may learn what
the most important activities of animals are by con-
sidering the chief activities of our own bodies. While
our ability to move readily from place to place, and to
perform the many muscular acts of daily life, is doubt-
less the most noticeable sort of activity which we share
with other animals, it is not the most fundamental.
Back of all movement there must be a source of power.
In these days, men make machines which seem almost
alive. In these some sort of power which we can
understand causes all the movements. Springs and
weights move clocks, steam-pressure turns the wheels
of factories, and electric currents move our street cars.

Our Bodies Chemical Engines. Sources of power
can usually be traced back to heat. The movements
of a steam-engine are due to energy set free by the
burning of coal. The burning of coal is a chemical
activity. The heat is caused by the union of two
elements, carbon and oxygen. It has been found that
the movements of living things are also due very
largely to chemical action. Just as coal burns or

26 ANIMAL ACTIVITIES.

oxidizes in a furnace and produces energy or power to
work, so the various materials of which our bodies are
made oxidize and set free the energy by which we
perform the varied movements of our bodies. In a
very true sense, then, our bodies may be called chemi-
cal engines.

Waste and Repair. The furnace which furnishes
power for any kind of machinery must constantly
receive new material and give out waste products.
Without a constant supply of coal and air, the fire goes
out and work stops. The chimney must be kept clean
in order to allow the gases produced by the fire to pass
out, and the ashes must be raked away as fast as they
are formed, to make space for new fuel. In the same
way every living animal takes into its body substances
corresponding to the fuel of a furnace, and it as con-
stantly gives out the waste products which would soon
cause death if they should remain. In order that we
may know these substances better, a few simple experi-
ments may be considered.

Experiment. Water. Using the apparatus shown
in Fig. 35, pour water and a
little sulphuric acid into the U
tube, and place test-tubes filled
with water over the ends of the
wires. When the circuit is
closed notice that bubbles of
gas arise from the wires and
collect in the upper part of the
test-tubes. Note the fact that
water is separated by a current

saree of electricity into two invisible
sa Spee oe ae & gases, and that, after a time,

Drawn by A. E. San. One tube contains twice as much

ford. gas as the other. The larger
amount of gas is hydrogen, and

the smaller, oxygen. Light the hydrogen, noting the
fact that it burns very readily. Into the top of the

’

ACTIVITIES COMMON TO ALL ANIMALS. 27

tube containing oxygen thrust a glowing coal (carbon)
and see that it relights. Water is composed of two
gases. Hydrogen burns easily in air, and oxygen aids
the burning of hydrogen, of carbon, and of other sub-
stances.

Elements and Compounds. Because hydrogen and
oxygen cannot be further separated into other sub-
stances they are called elements. Water, because it
is formed by the union of two elements, is called a
compound. Carbon is also an element.

Experiment. The Oxidation of Magnesium. Mag-
nesium is anelement. To a piece of wire made of this
element apply a lighted match and notice the produc-
tion of heat and light. Examine the white powder
produced. The oxygen from the air has united with
magnesium and formed magnesium oxide. This white
powder, the magnesium oxide, weighs more than the
magnesium used. The process is oxzdatzon.

The oxidation of hydrogen produces hydrogen oxide,
or water. The oxidation of carbon produces carbon
oxide, commonly called carbon dioxide. Magnesium
oxide is a solid, hydrogen oxide is a liquid, and carbon
dioxide is a gas. In all cases heat and energy are
produced by oxidation.

Experiment. The Oxidation of Phosphorus. Phos-
phorus is an element obtained from the bones of ani-
mals. Caution must be used in experiments with
phosphorus as it ignites so readily. Remove a piece
of phosphorus from the water and allow it to dry ona
piece of blotting-paper. Note the smoke arising. This
is phosphorus oxide. Touch the phosphorus with a
warm wire. Note the increased rapidity of the oxida-
tion. The same amount of heat is produced by the
oxidation of phosphorus whether the oxidation is slow
or rapid. Phosphorus oxide is formed in both cases.

Experiment. Nitrogen in the Air. Air is almost
wholly a mixture of nitrogen and oxygen. Cover the
top of a large cork with asbestos and put on it a small

28 ANIMAL ACTIVITIES.

piece of phosphorus. Float the cork on water in a
soup-plate and light the phosphorus, at the same time
lowering over it a jar of air, in such a manner that the
mouth of the jar just dips below the
surface of the water in the plate (Fig.
36). The phosphorus oxide formed
dissolves quickly in the water. The
water rises in the jar to replace the
oxygen used up, showing that about
one fifth of air is oxygen.
Remove the jar from the plate
and thrust into the gas a lighted
aan match. This colorless gas forming
Fic. 36.—Apparatus about four fifths of the air is nitro-
for Removing . .
Oxygen from Air, gen. It will not burn or aid the
Drawn by A. FE. burning of other substances. This

Sanford. element is found in all animal bodies
united with other elements to form
compounds. Bread and meat contain compounds

partly composed of nitrogen.
Experiment. The Element Carbon in Starch and
Sugar. Heat in the bottom of a test-
tube a small amount of sugar (Fig.
37). Notice the water which col-
lects on the sides of the tube. What
are two elements found in sugar ?
Heat slowly until no more steam
escapes, break the tube and examine
the residue. It is charcoal, a form
of carbon. What three elements in

sugar ?
Repeat this experiment, using starch Fic. 37.—Heating
and wood a Test-tube,
ei Drawn by A. E.
Graphite and diamond are other Sanford.

forms of carbon.

Experiment. Carbon Dioxide. Burn in a covered
bottle a little charcoal attached to a wire. When it
ceases to glow remove it, and shake up the gas in the

ACTIVITIES COMMON TO ALL ANIMALS. 29

bottle with lime-water. The milky appearance of the
water proves that the gas, carbon dioxide, is present
in the bottle. How did the gas get in the bottle ?

Experiment. Carbon Dioxide in the Breath. Breathe
through a glass tube into a test-tube containing a little
lime-water. What does the milky appearance of the
lime-water prove ?) Whence came the carbon dioxide ?
How was it produced ?

Experiment. The Oxidation of Hydrogen in our
Lodies. What collects when we breathe on a cold
glass? Whence comes the water? The hydrogen
enters the body with the food. How does the oxygen
enter the body ?

Substances Taken into the Body and Substances
Excreted. It has been found that the greater part of
the substances taken into the body are compounds of
hydrogen, oxygen, nitrogen, and carbon. These
enter the body as food. Oxygen also enters the
body in breathing. It has been found that the sub-
stances regularly excreted from the body by the lungs,
by the skin, and by the kidneys are carbon dioxide,
water or hydrogen oxide, and a compound containing
nitrogen and hydrogen, called urea. In this way the
four elements which enter the body as complex com-
pounds are all finally excreted as very simple com-
pounds.

A Summary of Activities. All animals take food
of some kind. As in our bodies, so in the bodies of
all other animals, the food must be chemically changed
to build up tissues and furnish material for oxidation.
Although all other animals do not have lungs, skin,
and kidneys like ours, they nevertheless must excrete
the materials which result from the oxidations and
other chemical changes in the body. All animals also
reproduce. All are capable of movements different
from the movements of inorganic things. All, too, are
able in some way to establish communication with the
outside world. For this purpose we are endowed with

30 ANIMAL ACTIVITIES.

special organs for seeing, hearing, smelling, tasting,
and feeling. By these organs we discover the world
about us. Many animals have not these organs of
sense. Many, indeed, have no organs of any kind,
yet all animals secm to possess, to some extent, the
ability to discover their surroundings. If no other
sense be present, something like our sense of feeling
seems to be always active.

We may summarize the most important activities of
animals as follows:

(a) Taking food and oxygen.

(4) Nutrition.

(¢) Excretion.

(2) Reproduction.

(¢) Movement.

(/) Discovery.

Respiration combines in most animals the two im-
portant functions of taking oxygen and excreting waste
matter.

Physiology and Anatomy. In studying animals
we wish most of all to know their activities. But in
order to understand these activities one must know
certain facts about the structure of the animals to be
studied. A sewing-machine has only one activity or
function, but one must know the form and position of
many parts before one knows just how the sewing is
done. When we speak of the six activities mentioned
we are dealing with Physiology. When we study the
parts of an organism to learn their positions and shapes
we aredealing with Anatomy. Evidently, then, anat-
omy and physiology must be studied together in the
science of Zodlogy. We do not study anatomy in
order to become familiar with many new names, but in
order to understand the activities or uses of the parts.

ACTIVITIES COMMON TO ALL ANIMALS. 31

VOCABULARY.

Anat’omy (Gr. ava, up, and
temno, cut), the science which
treats of the structure of organ-
isms.

Bi ol’o gy (Gr. dios, life, and logos,
a discourse), the science of living
things,

Bot’a ny (Gr. dofania, a plant),
that part of Biology which treats
of plants.

Car’bon (Lat. carbo, coal), an ele-
ment found in all organic com-
pounds; charcoal, graphite, and
diamonds are forms of this ele-
ment.

Car’bon di ox’ide, a heavy, color-
less gas, formed by the breathing
of animals and by the burning
of substances containing car-
bon.

Ex cre’tion (Lat. ex, out, and cer-
no, separate), the act of throw-
ing off waste matters from the
body.

Func’tion (Lat. fungor, execute),
the action of any part or organ of
a plant or animal.

His tol’o gy (Gr. Azstos, a web, or
tissue, and /ogos), the study of
minute anatomy.

Hy’dro gen (Gr. Aydor, water, and
Gignomai, be born), a colorless,

gaseous element forming a part
of water.

In or gan’ ic, not organic.

Mag ne’sium (Gr, Magnésios, a
district in Thessaly), a silver-
white, solid, metallic element.

Mat'ter (Lat. materia, stuft), any-
thing having extension.

Ni'tro gen (Gr. witron, nitre, and
gignomai), a colorless, gaseous
element composing four fifths of
the air.

Nu tri’tion (Lat. xutrio, feed), a
series of processes by which liv-
ing things maintain their life and
growth by appropriating food.

Or gan’ic (Gr. organon, an organ),
pertaining to plants and animals.

Ox i da’tion, the process of uniting
chemically with oxygen.

Or’gan ism, a living plant or ani-
mal.

Ox’y gen (Gr. oxys, sharp, and
gignomat), a colorless, gaseous
element, forming one fifth of the
alr.

Phys i ol’o gy (Gr. physis, nature,
and Jogos), the science which
treats of living things.

Zo ol’o gy (Gr. zoon, an animal,
and /ogos), that part of biology
which treats of animals.

CHAPTER IV.
GRASSHOPPERS AND CRICKETS.

Directions for Work. Collect full-grown and partly
grown locusts or grasshoppers. Place some of the
living insects in tumblers with fresh lettuce-leaves.
Allow ventilation. Why? Watch the insects care-
fully and compare with a prepared specimen. In your
note-book answer the questions below.

Shape of Body. What is the shape of the body?
Are the two sides alike (bilateral symmetry) ?

Is the skeleton or hard part of the body external or
internal ?

The Abdomen. The chief divisions of the body are
the head, thorax, and abdomen. How many scyments
has the abdomen ?

Count the segments of the abdomen in several
specimens. Is the number the same in all cases ?

Do you find a row of breathing-holes (spiracles)
along either side of the abdomen ?

Do you find a ridge running lengthwise along the
abdomen just below the spiracles? This ridge repre-
sents the softer parts of the segments. These softer
portions enable the insect to move the upper and lower
parts of the segments farther apart to take in air while
inhaling. When they are brought together again the
air is expelled. The upper hard part of each segment
is called the tergum, the under part is the sternum,
and the more flexible part on either side the pleurum.
Can you see the movement of the abdomen made by
breathing ?

32

GRASSHOPPERS AND CRICKETS. 33

Do you find the so-called ear-drum ‘tympanum, on
the first segment «7 the abdomen ?

The female grasshopper has organs at the end of the
abdomen for placing her eggs in the ground (oviposi-
tors).

Do you find both mz:e and female grasshoppers ?
Sketch a side view cf a grasshopper’s abdomen xX :.

The Thorax. What appendages are attached to the
thorax 2? How many segments in the thorax ?

How many leg: do vou find? Are they jointed ?
How do they differ in size? Sketch one of the hind
legs, indicating all the parts x <.

How many wings do you see? Are any of the
wings folded? How? Sketch a front and a hind
wing fully extended ~ 5.

To what segments are the wings attached ?

What can you say of the grasshopper’s powers of
locomotion > How many times its length can a grass-
hopper jump? Do the grasshoppers you have seen use
their wings when they jump? How do the wings of
young grasshoppers compare with those of full-grown
insects ?

The Head. How many feelers do vou find on the
front of the head (antennz):’ Are they segmented ?
What is their shape 7 How does their length compare
with the length of the body? Sketch a side view of
the head showing feelers.

How many eves do you find? Compound eves are
made up of parts called facets. Small, simple eyes are
called ocelli. How many compound eyes has the
grasshopper > How many ocelli? Where are the
eyes and ocelli situated? Sketch a part of a com-
pound eve as seen under a microscope.

What is the shape of the upper lip (labrum) ?
Sketch.

Under this lip do you find hard jaws (mandibles) ?
How many? What color? What shape? In what
direction do they move? Sketch.

34 ANIMAL ACTIVITIES.

Do you find a tongue ?

Do you find a pair of softer jaws (maxillz) behind
the mandibles? Sketch.

What is the shape of the lower lip (labium) ?

Do any of the mouth-parts have feelers (palpi) ?
Where situated? How many ?

Does the insect bite or suck its food? Notice the
movements of its mouth-parts.

Touch gently the grasshopper’s feelers with a tooth-
pick or stick. Touch in the same way other parts of
the body. Where is it most sensitive to touch ?

How far can a grasshopper see? How do you
determine this? Can the grasshopper hear? Give a
reason for your answer. Does the grasshopper have
the sense of smell ?

What can you now say about the grasshopper’s
mode of taking food ? its respiration ? locomotion ? its
organs of sense or discovery ?

Summary of Drawings. (a) Side view of abdomen

XxX 5-

(6) Sketch of one of the second and one of the third
pair of legs x 5.

The parts of the leg. beginning at their union with
the body, are coxa, trochanter, femur, tibia, and tarsus.
Indicate these parts in your drawing.

(¢) Sketch of front and hind wings X 5.

(@) Side view of a grasshopper’s head X 5.

(e) Sketch of mandible xX Io.

(7) Sketch of maxilla x Io.

(g) Sketch of upper lip X 20.

(2) Section of compound eye (microscope).

Internal Structure. If we wish to examine the
internal structure of a grasshopper, we may prepare
specimens by hardening them in alcohol. This changes
the color and to some extent alters the size and general
appearance of the organs. On this account it is well
to examine a freshly killed specimen along with the
alcoholic specimen for purposes of comparison,

GRASSHOPPERS AND CRICKETS, 35

For the purpose of dissection a female grasshopper
should be pinned to the bottom of a dissecting-pan and
covered with water. The dorsal wall of the abdomen
should then be cut away with a pair of scissors, care
being taken to notice the delicate tube, the heart, lying
along the back. In the freshly killed specimens, the

Fic. 38.—The Parts of a Locust. w«, head; 4, eye; ¢, antenna; d, f, 7,
thorax; a4, abdomen.

trachee, or air-tubes, connecting with the spiracles on
the outside, and ramifying to all parts of the body,
may be easily seen. At the same time a cluster of
long, oval, yellow eggs may be seen on each side of
the body, near the anterior part of the abdomen. From
these a tube, the oviduct, leads backward to the ovi-
positors. Below the heart the digestive canal may be

36 ANIMAL ACTIVITIES.

seen, consisting of the cesophagus, or gullet, a large
crop, a stomach with many tubes called gastric ceca,
and an intestine reaching to the anal opening. Lying
along the ventral portion of the abdomen are masses
of nerve-matter called ganglia, a double mass or pair
of ganglia to each segment. These are connected by
nerves. All the ganglia, with one exception, the
supracesophageal ganglion, or brain, lie below the
digestive tract.

This arrangement of organs, the heart dorsal, the
nervous system ventral, and the digestive tube-between
is characteristic of insects. It is interesting to observe

A

P

Fic. 39.—Comparison of Grasshopper and Man. 4, anterior; P, pos-
terior; D, dorsal; V, ventral; #, nervous system; 4, heart; /, food-
tube.

how this arrangement compares with that in the human
body (Fig. 39).

Taking Food. The grasshopper lives entirely on
vegetable food. Although its mouth-parts appear
much complicated, they are well adapted for their

GRASSHOPPERS AND CRICKETS. 37

work. The palpi feel about and locate the juicy parts
of plants, the manillz seize and hold them in position,
while the hard mandibles tear the food into bits and
pass it along to the digestive organs.

Plants are able to build from mineral substances the
materials which are useful food for the grasshopper,
thus illustrating the well-known fact that without plants
animals would die. Even animals which never eat
plants subsist on other animals which depend on
plant-food. As far as we know animals are unable to
take nitrogen unless it has been previously made into
plant-tissues which are suitable for animal food.

Nutrition. It is not our purpose here to describe
in detail the processes of nutrition in animals having
so highly developed a digestive system as we find in
the grasshopper. It is enough to say that the food
passes through a long tube extending from the mouth
to the anal opening at the posterior part’ of the body.
This tube is often called the food-tube or alimentary
canal. In the grasshopper and similar insects it
is enlarged in one place to form a gizzard or grind-
ing stomach. In some grasshoppers this gizzard is
armed with teeth. There are also two other enlarge- |
ments known as the crop and the stomach. In its
course through this tube the food is acted upon by
fluids which soften it and change it chemically so that
the nutritive portion is able to soak through the walls
of the food-tube into the blood, which distributes it to
all parts of the body, where it is used to build up tissue
or to serve as fuel for heating the body. The portion
of the food which is not so softened passes through the
tube and is finally expelled from the body at the anal
opening.

Respiration. Taking Oxygen and Excreting Waste
Substances, Food is useless to animals without a
supply of air and an outlet for carbon dioxide, water,
and urea. Man regularly inhales and expels air about
eighteen times a minute. This process is so important

38 ANIMAL ACTIVITIES.

that we often speak of the ‘‘ Breath of Life’’. If we
cover the holes along the sides of the grasshopper’s
body, so that no air can enter, he dies, just as we
should die if deprived of air. Throughout animal life
this same necessity for air exists.
The air used by the grasshopper for breathing pur-
poses enters the body through little holes along the
sides of its abdo-
men and thorax.

A Eight of these
}) } i} openings may be
re easily seen on
Fic. 40.—The Trachea of an Insect (magni- each side of the
Seed). abdomen, and
two others on
each side of the thorax. These holes, or spiracles,
open into air-tubes, called trachez, which divide and
subdivide in order to send branches to every part of
the body, even into the wings. These tubes and their
branches are surrounded by blood-vessels through
which blood is constantly coursing. The oxygen of
the air filters through the walls of the trachex into
the blood, and the carbon dioxide, water, and other
“waste substances in the blood pass through the same
walls in the opposite direction. Such an interchange
of gases through a membrane is called osmosis. Not
only do these breathing-tubes carry oxygen to the
blood and remove the waste products of respiration,
but they also render the body very light, enabling the
insect to rise easily in the air. In addition to excreting
waste substances by breathing, the grasshopper pours
urea into the food-tube and thence out of the body.
Reproduction. But animals or plants never eat
enough to make them grow or live forever. In many
common plants a single cell, called an ovum, is set
apart and fertilized by union with another cell to form
a seed, which, under proper conditions, reproduces the
plant. In the grasshopper the egg corresponds to the

GRASSHOPPERS AND CRICKETS. 39

seed of the plant. It, too, is a single fertilized cell set
apart for reproduction. The grasshopper deposits her
eggs in the ground, using for this purpose the oviposi-
tors at the end of her abdomen. From these eggs
there hatch tiny insects much like their parents in
shape, but destitute of wings. After a few days of
eating, the little grasshopper becomes too large for his
hard skin (exoskeleton), and proceeds to change it.
The process of crawling out of the old skin is called

Fic. 41.—Cockroach and Cast Skin.

moulting. In this way he moults five times, after each
moult appearing in every way more like the parent
grasshopper. Like most other insects grasshoppers
deposit an enormous number of eggs.

Discovery. If one touches a stone it does not move,
but if, on the other hand, one touches the feelers of a
grasshopper, or moves a stick in front of its eyes, there
is a movement in response to the irritation. This
movement is usually entirely involuntary, like the

40 ANIMAL ACTIVITIES.

movement of the eyelids when a sudden blow is
threatened. Very simple and familiar illustrations of
this power are common even among plants. In higher
animals the response to external stimuli is often so
complicated with voluntary movements that the two
can hardly be distinguished, but in every animal there
doubtless exists the power to respond in some way to
movements of the world outside its own body. These
movements may affect the animal through simple
touch, or through any or all of the other senses.
Every animal has at least one of the five senses.

Fic. 42.—The Nervous Chain of a Cockroach.

Sight. Although the eyes of the grasshopper are
large and composed of many parts, his power of vision
is doubtless far inferior to ours. Many experiments
have been made on the sight of insects, and all seem
to show that they can neither see far nor clearly. The
compound eyes of insects, as we have seen, are made
up of many hexagonal facets. Each of these facets
has a tiny lens for focussing the rays of light on a
nerve which transmits vibrations caused by these rays
to the nerve-centres within.

Hearing. The hearing of the grasshopper is prob-
ably more acute than his sense of sight. Vibrations
of the air set in motion the ear-drum on the first seg-
ment of the abdomen, and these are conveyed to
nerves which connect with nerve-centres in the thorax.
The fact that grasshoppers and their relatives are able
to make noises which doubtless are understood by
their friends is a reason for believing that they can
hear. These noises do not issue from organs of speech

GRASSHOPPERS AND CRICKETS. 4I

like ours, but are more like the sounds we produce
when playing on a violin. Careful observation of a
male cricket will best show
us a method of strzdulating,
as this process of insect-talk-
ing is called. Watching a
cricket as he stridulates,
one can see that the outer
wings are raised and rapid-
ly moved from side to side.
If, now, the wing be ex-
amined with a microscope,
a clear membrane remind-
ing us of a drum-head will Fis. 43-—Portion of the Cornea
be seen on each wing, and bt @ Dies eempoind Bye

: : (magnified),
on the under side of each
outer wing will be found an enlarged roughened cross-
vein which is used like the bow of a violin, being drawn
across the edge of the opposite wing-
cover to set in motion the membranous
drum-heads.

The cricket’s organ of hearing is situ-
ated on the tibia of the front leg. Some
insects hear by means of hairs on the
antennze or elsewhere which move in
unison with vibrations about them. In
some cases insects may be able to hear
sounds entirely inaudible to human ears.

Taste and Smell. The sense of taste
probably resides in the palpi. That the
Fic. 44.—The grasshopper can smell is evident from

Hearing the way in which he chooses his food,

oo oa and also from the fact that certain odors

(magnified), Seem disagreeable to him.

Touch. That the grasshopper pos-
sesses the sense of touch is easy to prove, and that
the antennz are especially sensitive as tactile organs
is equally evident. The antenne are provided with

atetenetens'
a hatete®
ERAS
aheteses
eeekens
rs
en ekes,
xh

2

42 ANIMAL ACTIVITIES.

hairs which seem to increase their sensibility, and they
are connected with the nerve-centres within the body,
as are the other organs of sense.

Movements. In addition to the motion called forth
by irritation of the sense-organs, the grasshopper is
evidently able to move on his own account. He can
walk, fly, or jump where and when he wishes. The

Fic. 45.—The Stridulating Organ of a Cricket. u, large vein; 4,
roughened cross-vein; c, membrane,

adaptation of the legs to the mode of life needs no
comment. The structure of the wings, however, may
be briefly considered. The wings are outgrowths of
the hard exoskeleton. They are composed of a frame-
work of double tubes over which is stretched a mem-
brane. The inner tube of one of the veins carries air.
The outer tube surrounding this is filled with blood.
Thus the wing becomes an organ of respiration as well
as an organ of flight. Lightness and strength are also
obtained at the same time.

Comparison of Grasshopper and Cricket. Crickets
are easily collected. They may be studied in the same
way as the grasshopper. In writing notes concerning
the cricket, make use of the new descriptive words
learned while studying the grasshopper. Write in your
note-book only such facts as can be made out from the
specimens. At the top of the page in your note-book
write ‘‘Grasshopper and Cricket’’. Draw a vertical

GRASSHOPPERS AND CRICKETS. 43

line down the middle of the page. At the top of one
column write ‘‘ Resemblances’’, and at the top of the
other column write ‘‘ Differences’’. In these spaces
write all the resemblances and differences you can
make out from actual observation.

Notice with especial care the tibia of the front leg in
order to see the ear-drum.

Look on the under side of the wing-cover of the
male cricket for the roughened vein used in stridulating.

The pair of appendages at the end of the abdomen
are called stylets.

Make a drawing of a cricket as you see it.

Questions. 1. How do a grasshopper’s activities
differ from those of man ?

2. Is it an advantage in insect-life to have the
nervous system on the ventral part of the body?
Why?

3. In what respects is a segmented body an advan-
tage to an animal ?

4. At what time of year are grasshoppers most
abundant ?

5. Whence come the grasshoppers seen in the fields
in spring ?

6. Would it be wise to rid the world of grass-
hoppers? Why?

7. Why does the grasshopper breathe? What
chemical changes occur in breathing ?

8. What is the color of the grasshopper’s blood ?

g. What senses has the grasshopper ?

10. What are the differences between organic and
inorganic things ?

11. What are the points of similarity ?

12. What are some of the differences between plants
and animals ?

Topics for Reports. The Locust Scourge. Locusts
as Food. Howto Destroy Locusts. The Life-history
of a Locust. The Cockroach. Crickets. Walking-
sticks.

44

ANIMAL ACTIVITIES.

VOCABULARY.

Ab do’men (derivation uncertain),
the posterior part of the body in
insects.

An ten’na, pl. antenne (Gr. ana,
up, and fezzo, stretch), a feeler
growing from the head of an in-
sect.

An te’ri or (Lat.
front.

Bi lat’er al (Lat. 42s, twice, and
Jatus, side), having two sides
alike.

Chi’tin (Gr. chiton, a tunic), the
horny substance forming the exo-
skeleton of insects.

Cox’a (Lat. coxa, the hip), the joint
of an insect’s leg next the body.

Dor’sal (Lat. dorsum, the back),
opposed to ventral.

Fac’et (a diminutive of face), a part
of a compound eye.

Fe’mur (Lat. femur, the thigh),
the thigh.

La’bi um (Lat. /adium, lip), the
lower lip of an insect.

La’brum (Lat. /adrum, lip), the
upper lip of an insect.

Man‘di ble (Lat. mando, chew),
the hard, biting jaw of an insect.

Max il'la (Lat. macero, soften),
the softer jaw behind the man-
dibles of an insect.

Mes 0 tho’rax (Gr. mesos, middle,
and ¢horax), the middle segment
of the thorax.

Me’ta mor’pho sis (Gr. meta, over
or beyond, and morpho, form),
the changes which take place in
an animal from egg to adult.

Met a tho’rax, the posterior seg-
ment of the thorax.

Moult (Lat. muto, change), the
shedding or casting of the exo-
skeleton.

Nymph (Gr. nymphé, a bride), a
name applied to the young of
some Masects, asthe grasshopper.

ante, before),

O cel’lus (Lat. dim. of oczzlus, eye),
a small eye.

O vi pos’i tor (Lat. ovum, egg, and
pono, place), an instrument for
depositing eggs,

Pal’pus, pl. palpi (Lat, palpo, feel),
a feeler growing from one of the
mouth-parts.

Pleu‘rum (Gr. p/euron, rib), the
side of the segment of an insect.
See Fig.

Pos te’ri or (Lat. ost, after), hind-

er.

Pro tho’rax (Gr. fro, before, and
thorax), the first segment of the
thorax.

Spir’a cle (Lat. spiraculum, air-
hole), a breathing-hole.

Ster’num (Gr. s¢ernon, breast), the
ventral portion of the segment of
an insect.

Strid u la’tion (Lat. s¢rzdo, creak),
a creaking noise made by in-
sects.

Tar’sus (Gr. ¢arsos, a flat surface),
the foot of an insect.

Ter’'gum (Lat. ¢ergum, back), the
dorsal part of the segment of an
insect.

Tho’rax (Gr. thorax, the chest),
the middle division ofan insect’s
body.

Tib’i a (Lat. iba, shin-bone), the
part of an insect’s leg between
the femur and foot.

Tra’che a (Gr. ¢racheia, rough),
one of the breathing-tubes of an
insect.

Tro chan’ter (Gr. ¢recho, run), a
part of an insect’s leg between
the coxa and femur.

Tym’pa num (Gr. tympanon, a
drum), an ear-drum.

Ven’tral (Lat. venter, the belly),
pertaining to the belly, the part
opposite the back.

CHAPTER V.

BUTTERFLIES AND MOTHS WITH THEIR
PROTECTIVE DEVICES.

Directions for Work. Watch the caterpillars which
have been collected in accordance with the directions
previously given. Record the changes that occur.

How many segments of the caterpillar have legs?

How many of these legs are jointed ?

If the jointed legs are attached only to the thorax,
how many segments has the thorax ?

Does the caterpillar have eyes? antenne ? palpi?

Do you find mandibles and maxille ?

Some of the caterpillars will change to chrysalids
soon after collecting.

In one of these chrysalids can you find head, thorax,
and abdomen ?

Is the chrysalis capable of any movement ?

Can you fiud antennz, eyes, or palpi?

Do you find wings or legs ?

Can you see parts of any organs under the skin ?

Collect several common yellow butterflies, or the
white cabbage-butterflies.

Where do you find them ?

At what time in the day do they seem to be most
active ?

On what plants do they feed ?

How do they take their food ?

Notice how they fly and how they walk.

How do they hold their wings when at rest ?

Secure some eggs, if possible, and watch their
development.

45

46 ANIMAL ACTIVITIES.

The Prepared Specimen. Examine the butterfly
after it has been killed, and write the resemblances
and differences for butterfly and grasshopper as in the
case of grasshopper and cricket. Consider all the
points noted concerning the grasshopper. Consider
the stages of growth.

Study with care the coiled tongue, or proboscis.
Uncoil it and find out how it is used.

Remove the dust from a part of the wing. Is this
part of the wing now colored? With a microscope

d

Fic. 46.—Antennez of Lepidoptera. 4, of butterflies; 8, of moths.

note the shape of the particles of dust (scales). Note
also how they are arranged on the wing.

Measure the spread of the wings, the length and
width of the anterior wings and of the posterior wings,
the length of the body, and the length of the antenne.

Describe the color above and below, and state the
color and location of the markings you find.

Notice the color of the feet, the antennez, and the
eyes.

Re the description of this butterfly in a good refer-
ence book, and compare your own observations wit!
those there recorded.

BUTTERFLIES AND MOTHS. 47

Write a description of a butterfly whose name is
unknown to you.

Write a description of a moth.

Summary of Drawings. (a) The wings as seen
from above when fully extended.

(6) Side view of butterfly with wings closed.

(c) Side view of head—enlarged—showing proboscis
and eye.

(@) Imaginary cross-section of proboscis.

(e) Larva, pupa, and imago of some butterfly not
figured in the text-book.

(7) The scales from a butterfly’s wing as seen with
a microscope.

(g) A portion of a wing, showing the arrangement
of the scales.

How to Tell Moths from Butterflies. Butterflies
and moths are much alike. They may generally be
distinguished by the fact that the butterfly has knobbed
antenne, holds its wings erect in repose, and flies more
often in the daytime. The moths often have feathered
antennz, fold their wings horizontally over the back
when at rest, and more often fly at night.

Metamorphosis. The internal structure of the
butterfly closely resembles that of the grasshopper, but

Fic. 47.—Eggs of Lepidoptera.

a striking difference appears in its metamorphosis, or
the change it undergoes during its period of growth.
The young grasshopper when it emerges from the
egg looks much like the adult insect; from which it
differs chiefly in its smaller size and in possessing
smaller wings. A series of changes like that observed
in the case of the grasshopper is spoken of as incom-

48 ANIMAL ACTIVITIES.

plete metamorphosis. On the other hand, there
emerges from the egg of the butterfly a worm-like
animal totally unlike its parents, who, could they
see their offspring, would doubtless disown it. This

Fic. 48.—Some Larve of Lepidoptera.

larva, as we have seen, has biting mouth-parts, fit-
ting it to subsist on the leaves of plants. It eats
voraciously, consuming many times its weight of food
during its short life, and increasing rapidly in size. It

Fic. 49.—Some Cocoons and Chrysalids.

moults from time to time as its skin becomes too
small for its fast-growing body. During this period
of its life it is usually a destructive pest. The ravages
of many caterpillars are already too well known.

BUTTERFLIES AND MOTHS. 49

Finally, the larva seems to have eaten enough. It
brings to a close its life of unceasing feeding and pre-
pares for a period of sleep. Often it spins a silken
cocoon in which it rests throughout the winter; some-
times it hangs by a single thread to a rock or fence-
rail, its exoskeleton making a beautiful chrysalis
ornamented with spots
of burnished silver, jet,
and gold; again it buries
itself in the ground to
await the genial warmth
of returning spring. In
any case it takes no
food and seldom moves,
but within its body
changes progress, until
the full-grown butterfly
or moth breaks through
the hard case of the
pupa, stretches and
dries its wings for a
short time, and _ flies
away for its brief period
of aerial life.

The full-grown but-
terfly, or imago, no
longer eats the coarse
food familiar to its lar-
val stage. In fact, it ye, 50.—A Cabbage-butterfly. a,
could not do so if it larva; 4, pupa; ¢, egg; d, imago.
would, for its mouth is
no longer fitted for biting, but is provided with a long
proboscis with which it sucks honey from its favorite
flowers. This series of changes is known as com-
plete metamorphosis (Fig. 50).

Structure of the Proboscis. The proboscis is a
curious organ and well repays careful study. It is
composed of two long half-tubes which are produce.

5° ANIMAL ACTIVITIES.

by the elongating of the maxille of the caterpillar
while it is in the pupa stage. These join by their
edges to form a complete
tube which the butterfly can
coil or uncoil at will and in-
sert in the flower on which
it feeds. At the upper part
of this proboscis there is a
pump-like cavity provided
with a valve. When this
enlarges, the tip of the tube
being inserted in the cup of
honey, the liquid flows up
the tube and fills the cavity.
The cavity then contracts
under the influence of the
Fic. 51.—Head of a Moth. surrounding muscles. This

a, upper lip; 4, mandibles; :

@ proboscis; @ under lip;~¢ Causes a pressure which

antenna; f, eye. compels the valve to close

and forces the honey for-
ward into the stomach (Fig. 51).

Depositing Eggs. At the adult period of its life,
however, the butterfly is not a great eater. Its most
important function, now, is reproduction, and for this
purpose the female butterfly searches for the plant
which will furnish suitable food for her young brood
of caterpillars and deposits there her eggs, dying soon
after the performance of this function. The eggs of
the clover-butterfly are placed upon the under side of
clover-leaves, one to each leaf. The eggs of the tent-
caterpillar, so common on apple- and cherry-trees, are
laid in large clusters glued to the branch of the tree
by a gummy substance produced by the moth deposit-
ing the eggs. In many cases the eggs of butterflies
and moths show beautiful markings when studied with
the aid of the microscope.

Butterfly Enemies. If all the eggs of all the butter-
flies and moths should be allowed to reach maturity

BUTTERFLIES AND MOTHS. 51

during a single season they would kill all vegetation
on the earth. The number of eggs deposited is
enormous, and the few which reach the caterpillar
stage make great havoc with our orchards, and often
with our shade-trees. The gypsy-moth alone, in spite

Fic. 52.—The Kallima, natural size,
A. E. Sanford.

Drawn by

of great efforts, still does much damage. The number
and activity of caterpillar and butterfly enemies in
most cases holds them in check and allows only a
small number to come to maturity. Both two-winged
and four-winged flies deposit their eggs on the larve
or pupz of butterflies or moths. When these eggs
hatch they produce larve which feed on the fat and
muscle of their involuntary host and finally destroy its
life. <A living, but nearly dead, caterpillar bearing on

52 ANIMAL ACTIVITIES.

its back a great number of pupa-cases of such flies is no
uncommon sight (Fig. 67). Birds, too, devour im-
mense numbers of insects in all stages of growth.
Doubtless they would kill and eat all the insects were
it not for the fact that many of them are so wonder-
fully protected by their color or shape, or both.
Protective Coloration. A butterfly or moth when
pursued often disappears as if by magic, and only the
most careful search reveals its presence. Then it is

Fic. 53.—Catocala Nupta.

seen that the insect has been rendered invisible, not
by the helmet of Perseus, but by its resemblance to
some natural object common in its vicinity. The
Kallima, a large and brilliant butterfly of India, folds
its wings and alights on a branch. The folding of the
wings conceals every brilliant color, and the under side
of the wing, which is now alone visible, resembles so
accurately a leaf that a bird could find it only with
great difficulty (Fig. 52).

Some of our common moths, belonging to the genus
Catocala, have outer wings so closely resembling the
bark of birch-, poplar-, or willow-trees that when they
alight on one of these trees they cannot be seen by a
casual observer. Other cases of protective coloring are
to be met with at every turn in the study of Zodlogy,
and it is a part of the work of the student to find and
describe them.

BUTTERFLIES AND MOTHS. | 53

Mimicry. The common milkweed-butterfly has a
disagreeable odor and probably a disagreeable taste.
On this account it is not a favorite food for birds. The

Fic. 54.—The Milkweed-butterfly. «w, dorsal view; 4, ventral view.
One half natural size. Drawn by A. E. Sanford.

Fic. 55.—Limenitis Ursula. a, dorsal view ; 4, ventral view. One half
natural size. Drawn by A. E. Sanford.

Limenitis ursula, a smaller butterfly, furnishes a dainty
morsel for bird palates. It would soon be exterminated
were it not for the fact that it so closely resembles in
color and markings the milkweed-butterfly, to which

54 ANIMAL ACTIVITIES.

it is not closely related in structure or in mode of
growth (Figs. 54 and 55).

Such imitations of other animals less likely to suffer
from enemies are common throughout the animal king-
dom. In these cases, neither the mimic nor the animal
mimicked is supposed to act consciously. No intelli-
gence on the part of the animal itself is shown by such
mimicry, for even if it intelligently wished to change
its color, no butterfly could do so.

The theory which is now generally believed by
scientists to account for these protective devices and
the thousands of others that have been observed may
be briefly illustrated by considering the family history
of the moth whose wings resemble birch-bark.

Natural Selection. It is supposed that the earlier
members of this family did not have the outer wings
so marked, but that from a brood of caterpillars there
hatched moths like the parent moths, yet varying to
some extent on account of unknown causes. Some of
these varying moths had markings on the outer wings
which made them resemble in some slight degree the
birch-tree on which they were accustomed to alight.
It is evident that these protected moths would be less
likely to be eaten than those not resembling the birch-
tree; hence they would be preserved to deposit eggs,
while their less fortunate brothers and sisters would be
eaten. The next brood of moths, resembling their
parents as they must, would be likely to include a
greater number of protected individuals, and probably
some even better protected than their parents. Those
best protected would be allowed to produce offspring,
while the less favored would be destroyed. In this
way after many generations the protective resemblance
becomes more and more pronounced. This process
has been called ‘‘ natural selection’’. It is thought
to explain many of the changes which have taken place
in the history of both animals and plants. It is easy
to see that there is really no rational selection on the

BUTTERFLIES AND MOTHS. 55

part of the animals themselves. The name was given
because the process resembled somewhat the process
by which bird-fanciers obtain different varieties of
pigeons by ‘‘selecting’’ birds with peculiar markings
for breeding purposes, or by which gardeners obtain
new varieties of flowers by continually ‘‘ selecting ’’
the few having desirable peculiarities and obtaining
seeds from these for the production of more and more
desirable plants. In natural selection there is no bird-
fancier and no gardener. On this account the process

Fic, 56¢.—Moth at Rest. Fic. 564.—Butterfly at Rest.

has been spoken of as the ‘survival of the fittest’’.
In this case the ‘‘ fittest ’’ is the individual best adapted
to his surroundings and best protected in every way.
In these days the student of animals or plants is con-
stantly on the watch for new illustrations of adaptation
to surroundings on the part of living organisms.

Questions. 1. How do moths differ from butterflies
in structure and in habits ?

2. What are the differences between complete and
incomplete metamorphosis ?

3. How much can a butterfly see ?

4. How much can a caterpillar see ?

5. Do either caterpillar or butterfly have a sense of
smell? of hearing ?

6. What are some enemies of butterflies ?

56 ANIMAL ACTIVITIES.

7. How are butterflies protected ?
8. Does the pupa of a butterfly breathe ?
g. Do you know any common animals which are

protected by their color?
Topics for Reports.

pia.
Food.

The Metamorphosis of Lepidoptera.
Destroy the Most Injurious Lepidoptera.

The Silk-worm. The Gypsy-
moth. The Clothes-moth.

The Life-history of Cecro-
How to
Insects as

VOCABULARY.

A’nus (Lat. anus, a ring), the
opening of the digestive canal
opposite the mouth.

Chrys’a lis (Gr. chrysos, gold), the
naked pupa of a butterfly.

Cos tal (Lat. costa, a rib), the ante-
rior part of a wing.

Co coon’ (Lat. concha, a shell), the
silken covering of a pupa.

Gan’gli on (Gr. ganglion, a tumor),
a herve-mass.

Haus tel/late (Lat. haustrum, a
water-drawing machine), having
mouth-parts fitted for sucking.

I ma’go (Lat. zmago, likeness), the
adult insect.

Lar’va (Lat. /arva, a mask), the
stage of metamorphosis immedi-
atelv succeeding the egg.

Man di bu late (Lat. mando, chew),
having mouth-parts fitted for
biting.

No’tum (Gr. zofos, back), the dor-
sal surtace.

Pri‘ma ry wings (Lat. primus,.
first), the first pair of wings.

Pro bos‘cis (Gr. fro, before, and
bosko, feed), the sucking tongue
of a butterfly.

Pu pa (Lat. pupa, a doll), the stage
of metamorphosis after the larva.

Sec’on dary wings (Lat. secun-
dus), the second pair of wings.

Vein (Lat. vena, a blood-vessel),
one of the vein-like ribs of an
insect’s wing.

Vein'ules, branches of veins.

CHAPTER VI.

SOME INSECTS CLASSIFIED.

The Bluebottle Fly. Expose a piece of fresh meat
in a sunny place for a short time and these flies will
collect on it. Capture some of the flies and observe
them carefully.

How does the fly feed? You can study the mode
of feeding of the common house-fly by fastening a piece
of sugar toa slide and placing it under a microscope
in a place where flies are plentiful.

What kind of food does a common house-fly prefer ?
How do you know ?

Devise an experiment for determining what kind of
food the house-fly particularly likes. In experiment-
ing with foods try sugar, honey, salt, pepper, water,
and other substances.

Does sight or smell seem to guide the fly to its food ?

How does a low temperature affect flies? How do
you know?

How do the flies make their buzzing ?

Keep a few bluebottle flies under a tumbler with a
bit of meat until eggs are deposited. Remove the flies
and watch the development of the eggs. Does the fly
have complete or incomplete metamorphosis ?

How many wings has the fly ?

How many segments has the fly’s abdomen ?

See if you can find a winglet behind the wing.

Using a lens, do you find a pair of balancers behind
wing and winglet ?

Is one of the segments of the thorax larger than the
rest ?

57

58 ANIMAL ACTIVITIES.

Do you find spiracles on either thorax or abdomen ?

Do you find eyes and ocelli?

Do you find antennz ?

Write resemblances and differences for fly and grass-
hopper.

Fic. 57.—Larva and Pupa_ Fic. 58.—Right Fic. 59.—Balancer
ofthe House-fly. 4, larva Winglet of of Bluebottle
(magnified); ¢, pupa (mag- Bluebottle (magnified .
nified ). (magnified).

Summary of Drawings. (a) A fly as seen from
above with the wings extended at right angles to the
body xX 5.

(0) The larva and pupa of a fly x 5.

(c) One wing X 5.

(2) A balancer much enlarged.

(ec) One antenna as seen with the microscope.

(7) One leg and foot as seen with the microscope.

SOME INSECTS CLASSIFIED. 59

Fic. 60.—Portion of a Fly’s Fic. 61.—Side View of Proboscis,
Foot (magnified). partly opened. 4, basal division;
¢, central division; 4, labella; m,

maxillary palpi.

Fic. 62 -Head of Bluebottle. a, antennz; ¢, eyes; m, maxille; 9,
proboscis (magnified ).

60 ANIMAL ACTIVITIES.

(g) A foot highly magnified, showing the two claws
at the end of the last segment and the sucking-disks
by which the fly walks on a ceiling.

(2) The proboscis as seen with the microscope.

The Colorado Beetle. This beetle is often called
the potato-bug or potato-beetle. Its destructive ravages
are well known. A visit to a potato-field anywhere
while the plants are growing will commonly provide
the collector with an abundance of specimens in all
stages of growth from the egg to the adult. Look for
eggs on the under side of a leaf. The pupa stage is
spent underground, and specimens are more difficult
to find. Keep in formalin.

Examine a living beetle.

Notice how it eats, how it walks, and how it flies.

See if you can make out how its wings are folded.

How does the folding compare with the folding of
the wings of a grasshopper ?

Notice the eggs and the various stages of growth.

How many segments has the beetle’s abdomen ?

Of how many segments is each foot composed ?

Examine a dead specimen with care and write resem-
blances and differences for beetle and grasshopper.

The Dragon-fly. Near fresh-water ponds and streams
adult dragon-flies may be easily caught. The larve
are usually plentiful where decaying leaves furnish
food for the small animals on which they live. The
imago may be mounted like a butterfly and then ex-
amined.

How many wings?

Are the wings ‘folded ?

Are the wings alike ?

How does the veining compare with that of a fly’s
wing?

Is the head easily movable ?

How does it compare with the other insects you have
studied in regard to the size of its eyes?

Has it ocelli?

SOME INSECTS CLASSIFIED. 61

How do the mouth- parts compare with those of a
butterfly ? with those of a grasshopper ?

Do you find toothed mandibles ?

Are the segments of the thorax of equal size ?

Are the legs strong or weak ?

How does the abdomen compare with that of the
grasshopper ?

How many segments has the abdomen ?

Do you find spiracles ?

Examine one of the larvz and tell how it differs from
the imago.

Examine with particular care the mouth of one of
the larve.

Summary of Drawings. (a) The imago as seen
from above X 2.

(6) One antenna, magnified (microscope).

(c) Side view of mask of larva, magnified (micro-
scope).

(2) Side view of larva x 3.

Mud-wasps can be easily collected in almost any
locality. Obtain specimens and write resemblances
and differences for wasp and beetle.

Squash-bug. Write resemblances for squash-bug
and potato-beetle.

Resemblances. The number of insects is so great
that it is practically impossible for one person to learn
their names, to say nothing of being able to know their
habits and structure.

When, however, one has become familiar with only
a limited number of forms, certain resemblances thrust
themselves upon the attention. These points of like-
ness are-of great assistance in extending our acquaint-
ance, for when we know one insect well we have some
knowledge which applies to all. If we hear of a new
insect we at once suppose that it has those peculiarities
which we have found common to all insects we know,
and in so supposing we are not likely to be mis-
taken.

.

ANIMAL ACTIVITIES.

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SOME INSECTS CLASSIFIED. 63

By comparing the notes we have already made we
find that the insects so far studied have Jd2lateral
symmetry, jointed bodies, and jointed appendages, as
legs and antenne. They have three parts to the body;
head, thorax, and abdomen. All have six jointed
legs, and in the adult stage one or both sexes are
usually provided with wings. Commonly two pairs of
wings and a pair of compound eyes are present.

An examination of the internal structure of insects
shows a series of ganglia connected by nerves situated
along the ventral portion of the body. Above this is
found the digestive cavity, consisting of a tube more
or less branched extending lengthwise of the body,
from the mouth to the anus. Near the dorsal part of
the body is found a large blood-vessel which performs
the function of a heart.

Breathing is carried on by means of spiracles con-
nected with trachee. Naturalists have agreed to call
animals having these characteristics ‘‘ Insecta ’’.

Differences. But the class Insecta contains so many
individuals that we readily see the necessity of classify-
ing them in some way. The divisions of classes are
called orders. If we can divide the class Insecta into
orders we make our future study more systematic and
more satisfactory in many ways. Such a classification
must depend on differences as well as resemblances.
If we should study the mouth-parts alone of the insects
we have already examined, we could easily put them
into two orders or subclasses, one comprising those
insects which have biting mouth-parts and the other
those which have sucking mouth-parts. This division
is sometimes used, but for our purpose it will be
better to find some differences which will give us a
greater number of orders, and so greater convenience.

A mode of separation based on peculiarities of the
wings has been much used, and the common names
for some of the orders as now most often written
attempt to describe peculiarities of wing-structure.

64 ANIMAL ACTIVITIES.

But this scheme of classification seems too artificial,
that is, too much like the classification of inanimate
things like tables or chairs, which may be arranged for
convenience into classes according to use or shape.
The course of development from egg to adult is also
an important factor in classifying living things, because
it is thought to show better than anything else the
natural relations or affinities, or we might say the
blood-relations of animals: hence in classifying insects
the matter of metamorphosis must be considered. In
a superficial way we might divide insects into those
having complete and those having incomplete meta-
morphosis, or into those having terrestrial larve and
those having aquatic larve; but more careful study
shows that these differences alone are not sufficient for
a clear and systematic classification, nor do they,
alone, indicate relation by descent. In fact, it has
been found that with the best of effort in the matter of
classification, so many intermediate forms occur that a
series of individuals rather than a few orders result.
Still convenience demands a classification of some
kind. Taking into consideration as many differences
as possible, and ignoring some of the less obvious
peculiarities, we may include all insects in nine orders:

Name. Typical Insect.
Thysanura. Springtails.
Pseudoneuroptera. Dragon-fly.
Orthoptera. Grasshopper.
Hemiptera. Squash-bug.
Neuroptera. Caddis-fly.
Coleoptera. Colorado beetle.
Diptera. House-fly.
Lepidoptera. Butterfly.
Hymenoptera. Bee.

Characteristics of the Orders. We give below the
characteristics of these orders, noting chiefly the facts

ee

SOME INSECTS CLASSIFIED. 65

concerning wings, mouth-parts, and metamorphosis.
There are, of course, many insects which do not fall
easily into one of the orders as we have defined them,
but it must be remembered that no classification of
living things can be made to include all individuals.
Some authors make a greater number of orders of
- Insecta, but the list here given is thought to conform
to the best usage of writers on natural history.

Thysanura. These are small wingless insects with
biting mouth-parts and incomplete metamorphosis.

The Pseudoneuroptera have two pairs of wings,
very nearly alike in most cases. Their wings are very
thin and transparent and closely veined and not
capable of being folded. The mouth-parts are fitted
for biting and the metamorphosis is incomplete.

The Orthoptera commonly have two pairs of wings,
the under wings being folded like a fan, and protected
by the outer pair. The jaws are strong and fitted for
biting, and the metamorphosis is incomplete.

The Hemiptera, though sometimes wingless, have
more often two pairs of wings. In some hemiptera the
outer wings overlap on the back, the overlapping half
of each wing being thin and membranous, hence the
name. The mouth-parts are fitted for sucking, being
prolonged into a beak used for piercing. They have
incomplete metamorphosis.

The Neuroptera resemble the pseudoneuroptera in
wings and mouth-parts and have complete meta-
morphosis.

The Coleoptera have hard outer wings called elytra
which protect the inner, gauzy wings, which are folded
both lengthwise and crosswise. The mouth-parts are
fitted for biting and the metamorphosis is complete.

The Diptera have only two wings. The mouth-
parts are fitted for sucking and the metamorphosis is
complete.

The Lepidoptera have four wings covered with
scales. The wings do not fold. The mouth is fitted

66 ANIMAL ACTIVITIES.

for sucking, having a long proboscis formed of the two
maxilla. The metamorphosis is complete.

The Hymenoptera have four membranous wings
with few cross-veins, the fore and hind wings being
commonly hooked together for flight. The mouth-
parts are fitted for both sucking and biting and the
metamorphosis is complete.

Names of Insects. Animals, like plants, are desig-
nated in scientific works by two names, the first the
name of the genus, and the second the name of the
species. Thus, Danatis archippus means that the
butterfly bearing that name belongs to the genus
Danais and the species archippus. We also distin-
guish men by using two names. Stuyvesant, Peter,
as found in a directory, means that the man in question
belongs to the family Stuyvesant, and that he is the
particular member of that family known as Peter.

Questions. How does the grasshopper differ from
all the other insects studied ?

How does the butterfly differ from the beetle? from
the dragon-fly ? from the other insects studied ?

How does the fly differ from the other insects ?

How does the beetle differ from the other insects ?

How does the squash-bug differ from the beetle ?
from the grasshopper.

How does the wasp differ from the fly? from the
other insects studied ?

How does the dragon-fly differ from the wasp ? from
the butterfly ?

In what respects do all the insects studied resemble
one another ?

Topics for Reports. House-flies. Insects in Brooks.
Agricultural Ants. Insects in Ponds. Earwigs. The
Cicada. Insects in Houses. Insects on Apple-trees.
How to Prepare Insects for Cabinets. How to Kill
Injurious Insects. Length of Life among Insects.
Insect Friends. Sounds Made by Insects.

SOME INSECTS CLASSIFIED. 67

VOCABULARY.

Bal’an cer (Lat. 62, two, and /anx,
dish), one of the poisers of a

* dipterous insect.

Cole op’te ra (Gr. 4oleos, sheath,
and pteron, wing), beetles.

Dip’te ra(Gr. di, two, and fferon),
two-winged insects.

El’y tron, pl. e/ytra (Gr. elytron,
a shield), a thickened fore-wing
of an insect.

Ge'nus, pl. genera (Lat. genus, a
race), a group of animals or
plants commonly made up of
two or more species.

Hal'ter, pl. Aalteres (Gr. halteres,
jumping weights), a balancer of
one of the diptera.

Hem ip’te ra (Gr. emz, half, and
pteron), an order of insects in-
cluding the true bugs.

Hy men op'tera (Gr. hymen, a
membrane, and féeron), an order
of insects including bees and
wasps.

In sec’ta (Lat. prefix 2, and seco,
to cut), a class of Arthropoda
including all true insects.

Lep idop'te ra (Gr. Zepis, a scale,
and fteron), an order of inse
including butterflies and mot.

Neur op’tera (Gr. mewron, ner
and fPteron), the name of an
order of insects.

Or'der (Lat. ordo, order), one
of the divisions into which
classes of plants or animals are
arranged.

Or thop’te ra (Gr. orthos, straight,
and pteron), an order of insects
including grasshoppers.

Pseudo neurop’tera (Gr. pseu-
dos, false, and meuroptera), the
name of an order of insects dif-
fering from neuroptera in hav-
ing incomplete metamorphosis.

Spe’cies (Lat. species, outward ap-
pearance), a subdivision of a
genus.

Thy sa nu'ra (Gr. thysanos, fringe,
and oura, tail), the name of an
order of small insects.

Wing’let, a small winglike fold
behind the anterior wing in the
Diptera.

CHAPTER VII.

A CHAPTER OF LIFE-HISTORIES.

The Milkweed-butterfly. In speaking of protective
coloring we have already mentioned the large and
beautiful butterfly commonly known as the milkweed-
butterfly. It is known to scientists as the Danazs
archippus or sometimes as the Anosza plexippus. On
account of its large size, great beauty, and very general
distribution, it has been much studied and its life-his-
tory is well known.

The female butterfly deposits her eggs one by one
on the under side of milkweed-leaves. These eggs
when examined with
the microscope are
seen to be very regu-
larly carved in a beauti-
ful and delicate pattern.
The shape of the egg is
shown in Fig. 63.

In a few days a little
Fic. 63.—Eggs of Milkweed-butterfly. black-headed caterpil-

a, single egg, magnified; ¢, eggs on

leaf, one half natural size. After lar, perhaps a tenth of

Riley. an inch long, emerges

from the egg, eats its
empty shell for breakfast, and dines upon the milk-
weed-leaf, on which it continues to feed for several
weeks. At the end of one week, having eaten so much
and grown so fast that its skin can no longer hold its
body, it spins a bit of silk upon the leaf, waits until its
coat splits down the back and then crawls out of the

68

A CHAPTER OF LIFE-HISTORIES. 69

slit thus made, a larger and handsomer caterpillar.
It moults in this way twice more, and at last looks like
Fig. 64, having a pair of horns at each end of its body
and being striped with black, white, and yellow.

It will be noticed that its first three pairs of legs are
jointed and furnished with claws. The other legs, ten
in number, are merely
fleshy prolongations of
the skin, provided with
suckers or hooks to aid
in crawling. These are
called pro-legs, to distin-
guish them from the three Fic. 64.— Larva of Milkweed-
pairs of jointed legs com- pacha eee Balt Hareval Stee:
mon to all Insecta. Its
mouth is provided with strong mandibles, and its
digesting power is enormous. The caterpillar has now
reached a length of two inches. After a little time it
again becomes restless, leaves the plant on which it
has so far lived, and lodges on a neighboring fence or
stump. Here it spins a little silk, entangles its hind
legs in the threads thus produced, and hangs head
downward for a day and a night. Its skin then splits
along the back and the caterpillar performs the difficult
feat of crawling entirely out of its old covering without
the use of legs or mandibles, for these
disappear with the old skin. The little
spike at the end of its tail is fastened
into the web of silk, and its body sus-
pended thereby for a period of rest. The
skin hardens and the rich ornamentation
se vi of green, black, and gold appears. We

butterfly, one do not wonder that it is called a chrysa-
half natural lis (Fig. 65).
iio =e There is now no mouth for feeding,
y :
for the mouth-parts are undergoing a
wonderful change just beneath the skin. The maxille
elongate to form a proboscis, the wings appear and

79 ANIMAL ACTIVITIES.

may be seen undeveloped within the chrysalis, as may
also the antennz, the legs, the segments of the thorax
and abdomen, and even the spiracles. At this time
the young butterfly must live by using the stored-up
energy developed by its enormous appetite in the
larval stage. The change now going on is termed
pupation.

Again moulting occurs, and the imago emerges.
At first it is soft and flabby, but the blood pumped into
the baggy wings quickly distends them and they dry
and harden in the sunlight. The body soon attains its
full strength and the insect flies away to enjoy a life
entirely different from its previous phases of existence.
Now it rejoices in two pairs of large and strong wings
covered with beautiful scales arranged in regular pat-
terns. It sucks honey from flowers by means of its
long coiled proboscis. This interesting piece of
machinery has already been described. It is doubtful
if this magnificent aerial creature, leisurely floating in
mid-air, or bravely buffeting the winds, and sometimes
sipping a bit of nectar, would recognize one of its
brothers or sisters in either its gormandizing larval
stage or its inactive pupal condition. Indeed, the
graceful mother seems neither to recognize nor to care
for the offspring crawling from the eggs she deposits
from day to day.

Our milkweed-butterfly lives much longer than most
of her lepidoptera relatives while in the imago stage.
She even migrates when autumn comes and with others
of her kindred seeks a warmer climate for the winter.
Some of those which do not migrate hide in sheltered
crevices to emerge in the spring battered and frayed,
but ready to deposit eggs for the new broods which are
to people the air of the coming summer.

The Cricket. The common black cticket so often
seen in the fields and about our gardens in the late
summer and during the autumn is known as Gryllus
abbreviatus. His pleasant chirp attracts us to an

A CHAPTER OF LIFE-HISTORIES. 71

examination of his ways. Putting him under a tumbler
over a flower-pot filled with earth, and feeding him
with bits of apple or potato and sometimes a little
clover, we may easily observe his movements. If we
are looking at the male we must watch for the source
of his cheerful music, for the males do the talking
among crickets. We shall see, when the shrill sound
is made, that the outer wings are raised a little and

Fig. 66.—Female and Male Aphis.

moved rapidly from side to side. A careful examina-
tion shows on the inside of the membranous wing-cover
a vein extending diagonally across the wing and fur-
nished with teeth like those on the corner of a file.
On the other wing-cover, near its inner margin, there
is a hardened part which scrapes over the file, causing
it to vibrate. The membranes of the wing re-enforce
the vibration. Thus its voice comes not from its throat

72 ANIMAL ACTIVITIES,

but from its back. In this respect it resembles many
other insects.

If we are looking at the female cricket we are struck
with the length and size of the ovipositors, which con-
sist of a pair of grooved appendages which fit together
to form a long tube with a sharpened point. In the
autumn the cricket bores a hole in the ground with
these sharp points and deposits her eggs, where they
remain through the winter. In the spring the warmth
of the sun causes them to hatch and the little crickets
appear. Here we have something very different from
the hatching of the milkweed-butterfly’s egg. No
caterpillar appears here, but a tiny cricket, much like
its mother, but lacking wings. These little crickets
moult from time to time, at each moult growing more
like their parents, until about midsummer, when they
attain their full size. Before winter they die.

The Aphis. Plant-lice are very familiar pests,
whose ravages on the leaves of rose-bushes are well
known. There are many kinds of these little destroyers
inhabiting as many kinds of plants. They are called
A phides, any one insect being an Aphis.

A single aphis with its beak stuck into the juicy part
of a leaf, from which it never moves unless forced to
do so, constantly filling its stomach with sap, seems,
indeed, a mere glutton, but the whole brood of aphides
when watched for a summer are a wonder-working
community. The laboratory for the study of these
strange creatures is ready-made everywhere. Wher-
ever rose-leaves grow, a lens will reveal the happenings
we are about to relate. :

In the month of October in temperate climates the
wingless female deposits her eggs about the buds of
rose-bushes, so that when these develop into leaves
and branches in the coming spring the young aphis
may have at hand a bountiful supply of rich food.
Here the egg stays until the warm sun of March or
April assists in the process of hatching.

A CHAPTER OF LIFE-HISTORIES. 73

There hatch from these eggs a brood of females, very
small at first, but, after several moultings, as large as
their mothers, and resembling them in many ways.
No males are hatched from these winter eggs. The
leaf soon becomes covered with a swarm of female
insects. Indeed, there are no fathers in these armies
of pigmies. They produce no eggs, but proceed to
fasten their beaks in a juicy spot and eat and reproduce
in a most marvelous manner.

From the abdomens of these strange mothers there
issues day after day a numberless horde of children like
themselves. These children grow from the mother as
buds grow on plants, and then break away to lead an
independent life. Each tiny bud in a few days becomes
a mother in the same way, and shortly, from a single
egg, thousands of wingless mothers sit side by side,
sucking sap and budding out young with remarkable
speed. Ifa man should live a hundred years and
count at the rate of one a second, he could not begin
to count in his hundred years the progeny of a single
aphis for a month.

Now and then winged forms appear, and sometimes
an aphis goes through something like a larval and
pupal stage, while the colony keeps on increasing with
incredible rapidity by the budding of generation after
generation. This reproduction without males is called
parthenogenests.

Toward autumn winged males are produced, and
again the cycle of existence is renewed.

In studying the life-history of the aphis one should
notice the relations existing between ants and aphides.
As the aphis sucks the sweet sap from its shrub it
obtains an excess of sugar; that is, in order to get all
the muscle-forming food it requires it must eat more
sugar than it needs. This excess of sugar is known
as honey-dew, and it often covers the leaves with a
sticky film. It comes from two projections on the end
of the abdomen of the aphis. This honey-dew, not

74 ANIMAL ACTIVITIES.

needed by the aphis, is relished by other insects,
notably the ants, which may be seen stroking the pro-
jections from which the honey-dew exudes and eagerly
eating the sweet fluid.

So much do the ants appreciate this honey-dew that
they take great pains to care for their friends the
aphides, in many cases herding them as men herd
cows, and sometimes carrying their attentions so far
as to take the winter eggs of their cows into their own
houses to keep them from frost and enemies. With
returning spring these eggs are taken out again and
placed upon their proper food-plants to hatch in the
warmth of the sun and produce another colony of
aphides.

The Ichneumon-fly. Teachers of Zodlogy fre-
quently have brought to them for identification and
explanation a caterpillar, having his back covered with
a mass of silken cocoons. If we wait for the cocoons
to hatch we may see coming from each a black four-
winged insect from one eighth to one fourth of an inch
in length. The female of this insect, when mature,
deposits great numbers of small eggs directly under
the skin of a living caterpillar. These eggs soon hatch
into small grubs or maggots which live on the fat of
their host, not interfering with his digestive apparatus
or other vital organs. After a time the full-grown
larve bore holes through the caterpillar’s skin, come
out of their living prison and spin cocoons, fastening
each to the caterpillar’s back by a thread of silk. In
these cocoons the pupa stage is passed and the adult
insect gnaws his way out to begin another cycle.
These insects are often called microgaster-flies. They
belong to the order Hymenoptera (Fig. 67).

The Sand-wasp. Still another method of preparing
fresh meat for the young has been invented by some of
the wasps. These wasps catch a caterpillar, a spider,
or some other insect, and sting him in such a way
in the thoracic ganglia that the victim becomes

A CHAPTER OF LIFE-HISTORIES. 75

paralyzed but is not killed. The wasp then drags her
prey into her hole, and deposits an egg on the motion-
less but living insect, apparently knowing that death
will not occur until her egg has become a larva and
requires food. When the larva appears he finds his
food still living, and makes it last until he is ready to
assume the pupal condition. This is a remarkable
insect adaptation for the preservation of food.

There are many of these wasps. Some of them live
in holes in the ground, which they stop up and conceal

Fic. 67.—A Microgaster Fly (magnified). c, larva of a microgaster in
the caterpillar of a cabbage-butterfly..

in very ingenious ways after the egg and its provender
have been stored away.

Others build their nests or cells of mud, enclosing
the young and its food in earthen jars.

A full-grown mud-wasp may be kept in confinement
for a time and fed on sugar and water. Her mem-
branous wings, four in number, are folded over her
back when at rest, but during flight they are spread
out and the fore and hind wings are fastened together
in such a way by hooks and grooves that they appear
like a single pair.

76 ANIMAL ACTIVITIES.

The ovipositor differs from that organ as we have
seen it in the cricket and grasshopper in having, in
addition to the grooved sheath through which the eggs
pass, a pair of lances which pierce the insect it wishes
to paralyze or kill. The paralysis is probably caused
by a bit of formic acid which is secreted by a small
gland in the wasp’s abdomen and injected into the
body of her victim.

The sting, then, in this case as in the bee and other
hymenoptera, is a modified ovipositor.

The care with which the wasp cleans its body and
performs its toilet is worth noting. In fact, many
things may be learned by watching one of these intelli-
gent little workers.

The Dragon-fly. To study insects which spend a
part of their life in the water an aquarium is helpful and
pays well for the trouble it costs.

To study the young dragon-fly one should visit a
pond or pool of fresh water, provided with a small] net
and a supply of fruit-jars. The young dragon-flies
may be recognized by their flat square heads, their
rudimentary wings, and their six strong legs. They
frequent the bottom of the pool in which they live and
their color protects them from observation, but careful
watching will soon reveal their presence. One sweep
of the net will sometimes bring several nymphs to the
collector’s jar. One must at the same time collect
some aquatic plants to keep in his aquarium, and also
a supply of small insects for dragon-fly food. A little
mud from the pool with some submerged sticks and
leaves will furnish insect-food for several days, after
which a fresh supply should be provided. With a little
sand in the bottom of a jar, a few growing water-plants,
and a supply of dragon-fly nymphs of varying sizes, we
are ready to learn something of the life-history of the
mosquito-hawks, as dragon-flies are sometimes called.

While collecting the young, one is likely to see the
adult females dipping the tip of the abdomen beneath

A CHAPTER OF LIFE-HISTORIES. 77

the surface of the water in the act of depositing eggs.
These eggs soon hatch into tiny nymphs, which live
in the water, and, moulting from time to time, produce
the various sizes found by the collector.

If we compel a few of these nymphs to go without
food for a day and then feed them with insects, wé
shall be able to watch the use of the strange mask
which hides the face, or perhaps we should say the
mouth. This mask is really a very strange develop-
ment of the so-called lower lip, the structure of which
may be understood by examining one of the nymphs
and comparing it with the accompanying sketches
(Fig. 68). After all, it is not so much a mask as a

Fic. 68.—The Dragon-fly. A, larva; 8, pupa; C, dragon fly emerg-
ing from pupa-case.

formidable grasping organ capable of reaching suddenly
forward, seizing an unsuspecting victim, and dragging
him back to the hard mandibles.

78 ANIMAL ACTIVITIES.

Breathing of a Dragon-fly Nymph. An insect
living in the water must breathe, and it is interesting
to observe how insects which have chosen an aquatic
life have adapted their breathing-organs to the medium
in which they live. The dragon-fly larva does not
trouble himself to come to the surface for air, but
simply takes his oxygen from the air dissolved in the
water. The spiracles which would allow water as well
as air to enter the breathing-tubes are closed and covered
by the hard exo-skeleton, but the trachez or breath-

Fic. 69.—The Imago of a Dragon-fly.

ing-tubes, like those in the grasshopper, convey the
air throughout the body. To get the air, the water is
drawn in through the anal opening, where it comes in
contact with some modified air-passages which have
somewhat the function of gills. In these air-passages
the carbon dioxide and other impurities await the
opportunity to pass by osmosis to the water, while the
oxygen penetrates through the membranes into the
breathing-tubes. If a fine stream of bright-colored
liquid be put near a nymph by means of a small
pipette the currents produced by the breathing may be
seen.

A CHAPTER OF LIFE-HISTORIES. 79

Possibly some of the larger nymphs in the aquarium
may crawl up a stick or other object and, fastening
their feet firmly, await their final metamorphosis from
aquatic to aerial life.

At this time the exo-skeleton of the nymph splits
down the back and there emerges the beautiful creature
we so often see hovering over the surface of streams
and ponds. The two pairs of delicately veined wings

Fic. 70.—Caddis-fly, Adult and Larval Cases.

are never folded like those of the grasshopper or beetle,
but remain extended even while the insect alights.
The lower lip has lost its mask-like appendage, the
mandibles are hard and toothed, the eyes are very
large, the abdomen is long and tapering, the legs are
small and bunched together for security in alighting.
It is now a fine creature of wonderful agility and grace.
Harmless to man and larger animals, it devours mos-

80 ANIMAL ACTIVITIES.

quitoes and other small insects, catching them on the
wing with hawk-like flight and precision of aim.
The dragon-flies belong to the pseudoneuroptera.
By some they are put in a separate order, the odonata.
Other Aquatic Insects. While collecting and
observing the young dragon-flies one cannot help
noticing the fact that many other insects spend a part

Fic. 71.—The Growth of a May-fly. 4, larva; B, pupa; C, imago.

or the whole of their life in the water. It will be
interesting to watch the young caddis-jfles (Fig. 70),
young may-fies (Fig. 71), the adult water-boatman
swimming on his back with his legs modified to form
oars (Fig. 72), the dtycus or large water-beetle carry-
ing a bubble of air under his elytra and feathering his
oars as he dashes through the water (Fig. 73), and
the giant water-bug with powerful piercing beak and

A CHAPTER OF LIFE-HISTORIES. 81

mighty fore legs for holding his victims while sucking
their life-blood (Fig. 74).

The Mosquito. Among aquatic insects the familiar
mosquito or gnat deserves a paragraph. The female
mosquito, which by the way is said to do all the biting

|

A y

( ( |
Ny ee a ua i) l

It

Fic. 72.—-A Water-boatman. A, in the water; 2, while flying.

and all the singing, leaves her eggs, sometimes two
or three hundred in number, glued together in a sort
of raft which floats upon the water (Fig. 75). Ina few
days the tiny larve open the under side of the eggs

Fic. 73.—Dyticus Marginalis. A, male; B, female.

and descend into the water, where they swim rapidly
about with a peculiar jerking motion. The large head
is usually downward, always so while at rest near the
surface of its pool. Just back of the head is a large

82 ANIMAL ACTIVITIES.

joint commonly called the body, and back of that the
smaller joints of the abdomen. The end of the tail is
double as shown in the figure.
One projection is the insect's
propeller, and the other its
breathing-tube, which it is
constantly using when at
rest, opening or closing at
will the tiny valve at its cx-
tremity. The mosquito larva,
then, breathes air directly
and does not take it from the
water like the young dragon-
fly. Like its mother, the
larva is bloodthirsty and
always hungry. At the end
of about two weeks, after

PO es moulting several times, the
dibles and maxille: “, eye. larva changes to a pupa,
bending its head under its

body as seen in the fouls and losing its mouth alto-
gether, but retaining its power of active movement.
The breathing-tube at the end of its body disappears
and it now takes air by two tiny projections on its
back. Finally, the pupa rises to the surface of the
water and again moults, producing the adult mosquito,
which uses its cast-off skin as a boat on which it floats
until its wings are dry and it is ready to fly away.
Should its frail boat capsize and wet its wings the
mosquito would drown. It has been
found that a little kerosene spread
upon the water of stagnant pools
will not only kill the egg-rafts as
they float about but will also destroy

P Fic. 75.—The Egg-
the perfect insects as they emerge if aMieaullo,

from their pupa-case boats.
The imago now breathes, like other insects, by the
spiracles along the sides of its body. It has but one

A CHAPTER OF LIFE-HISTORI=_.

GA
Lor)

84 ANIMAL ACTIVITIES.

pair of wings, and its mouth-parts are fitted for suck-
ing. The mouth of the male mosquito is adapted for
sucking honey from flowers and
it leads a mild and peaceful life.
The female mosquito, on the
other hand, has, in addition to
the proboscis for sucking blood, a
number of sharp lances with which
she pierces the skin of her victim.
At the time of piercing she also
injects an irritating fluid into the
puncture (Fig. 77).

The music made by the mos-
quito is produced in two ways,
first by the rapid movement of
the wings, and second by the
passage of air in and out of the
spiracles. The humming thus
- made is thought to be heard by
Fic. 77.—The Mouthof the male mosquito, whose ears

a Eeinale Mosquila. consist of tufts of hairs on his

antenne. These hairs are said
to vibrate in unison with the tones made by the wings
and spiracles of the female. Experiments seem to
show that some varieties of mosquitoes are respon-
sible for spreading both malaria and yellow fever.

A comparison of the life-histories here outlined gives
one a notion of the great variety of modifications of a
common plan of structure to compass different objects.
How these modifications have come about in the
progress of insect-life is one of the most interesting
problems before the student of nature’s ways. The
change from a caterpillar with biting mouth-parts to a
butterfly with his long proboscis gives a hint of the
possibilities of evolutionary growth.

Questions. 1. Have you observed closely the life-
history of any insect? If so, what are some of the
changes you have noticed ?

A CHAPTER OF LIFE-HISTORIES. 85

2. What advantages and what disadvantages must
be experienced by a larva living in water ?

Topics for Reports.

The Life-history of a Beetle.

A Life-history I have Observed.

VOCABULARY.

Aphis, pl. aphides (Gr. apheides,
lavish), a plant-louse.

Cad‘dis-fly, a name given to an in-
sect whose larva lives in the
water and builds for itself a
tubular case.

Gnat, a mosquito.

Ich neu’mon (Gr. zchneuo, to hunt),
a genus of insects belunging to
the hymenoptera.

Mi cro gas’ter (Gr. mitvws, small,
and gastfer, stomach, a small
hymenopterous fly.

Mo squi’to (Lat. musca, a fly), «
well-known dipterous insect.

Par then o gen’esis (Gr. parthe-
nos, a virgin, and gzgnomui, to
be born), reproduction by means
of unfertilized eggs.

Pro’leg, one of the fleshy abdom-
inal legs of insect larvz.

Pu pa’tion (Lat. supa, a doll), the
process of undergoing the pupal
condition.

CHAPTER VIII.
SOME INSECT ADAPTATIONS.

Structure and Habits. Fig. 78 shows the parts of
the hinder leg of a cockroach, an
insect whose legs are well adapted
for running. Comparing this leg
with the corresponding legs of a
grasshopper, we find the same
parts present but modified for
jumping. Looking at the legs
of a mole-cricket, we find again
the same parts, but.in this case
altered for digging. Among the
large water-bugs, which live by
hunting, the legs are fitted for
seizing and holding prey. In .
some of these bugs, a portion of Fic. 78.—Leg ofa Cock-

roach. a, coxa; 6
the le g trochanter; <¢, femur;
forms a d, tibia; ¢, tarsus.
sheath into

which another portion shuts
like the blade of a
pocket-knife when
not in use (Fig. 80).
Aquatic insects
like the water-boat-
x man (Notonecta)
Fic. 79.—A Mole-cricket. and the large water-
beetle (Ditycus)

have legs made into powerful oars, which they are

86

SOME INSECT ADAPTATIONS. 87

even able to feather as they row along, yet here, as
elsewhere, the plan of structure is the same as that

’

Fic. 80.—Fore Legs of a Water-bug. 2, open; A, closed; C, enlarged
to show sheath.

seen in the cockroach and grasshopper. Some butter-
flies of strong flight use their legs so little that their
front legs are mere threads, yet they retain the marks

Fic. 81.—Legs of Dyticus. A, hind legs for swimming; JB, fore leg
with suckers.

of the same plan we have found in the other insects
examined.
What is true of the legs is also true of other impor-

88 ANIMAL ACTIVITIES.

tant organs. Devices for defence, for eluding enemies,
and for procuring appropriate food among insects are
everywhere seen to be varied modifi-
cations of the same organ or organs.
In general such structures are found
in any particular insect as best help
it to preserve its life inthe particular
Fic. 82,—Fore Leg environment in which it lives. So
of a Butterfly. much does the structure tell us about
the mode of life, that we are often
able to infer the habits of an insect which we have
never seen alive from the study of dead specimens, and
even from fossil remains.

Changes of Organs Because of Changes of Habit.
That these variations of similar organs have arisen
gradually, through changes of habit made necessary
by changes in surroundings, is generally believed.
At first sight the long delicate proboscis of the butter-
fly, the lapping tongue of the house-fly, the beak of
the aphis, the hard, biting jaws of the beetle seem very
different structures, but when we watch the caterpillar
of the butterfly and the grub of the beetle with mouth-
parts so much alike at the start, and see that in one
case the maxillz elongate into the coiled proboscis,
and in the other the mouth-parts grow into the formid-
able and destructive biting-organs of a carnivorous
beetle, we wonder less at the divergence than at the
resemblance. We see, too, how it may have been
possible for organs very unlike to have arisen from
similar beginnings. The great variety seen in the
breathing-organs of aquatic insects furnishes another
illustration of the change of organs necessitated by a
change of habit. From the fact that all aquatic insects
breathe air by trachea at some period of their life it is
believed that their ancestors, as well as the ancestors
of insects having aquatic larve, were originally terres-
trial. Either driven by enemies or lured by more
abundant food, at some distant period, these insects

SOME INSECT ADAPTATIONS. 89

began an aquatic life to which they became gradually
adapted by a process similar to that by which the
butterfly obtains his protective coloring. In fact the
aquatic life is a protection, either from destructive
enemies or from starvation.

Insect Communities. In speaking of the life-history
of the aphides we mentioned the fact that ants some-
times keep these insects to provide them with honey-
dew. It is also true that some ants capture the pupz
of ants of other communities than their own and rear
them as slaves. To obtain these pupz wars are often
waged, hence codperation is necessary. Codperation
leads to life in communities and life in communities
makes necessary a division of labor, so that we find
nurses, foragers, soldiers, queens, and drones working
together in the same community, all developed from
eggs which are apparently just alike.

This production of seemingly different insects seems
to be sometimes a matter of choice on the part of the
rulers of the community, for ithas been found that a
worker grub, among bees, may be developed into a
queen by the use of special food and the building of a
royalchamber. This division of labor is best illustrated
among bees, ants, and wasps.

Hive-bees. In a bee community there is one female
called the queen who produces all the eggs. There
are a small number of males called drones. All the
rest of the inmates of the hive are workers. The
workers are in reality immature females. They are
provided with stings which are modified ovipositors.
The wax is produced within the bodies of these workers
and issues from between the segments of the abdomen,
whence it is taken and skilfully built into the honey-
comb, with which all are familiar. The honey, when
taken from the nectaries of flowers, passes into a sort
of crop, or honey-bag, where it undergoes changes
which alter its flavor. It is then brought to the hive
and stored in the cells of the honeycomb. The young

go ANIMAL ACTIVITIES.

bees hatch from the egg as larve, or maggots, in cells
much like the honey-cells. In these cells they find a
bountiful supply of food, known as bee-bread, which
is composed of honey and pollen gathered by the
workers. In these cells, too,
the young bees pass through the
stages of complete metamorpho-
sis.

Insects and Plants. Besides
the adaptations which fit insects
to codperate with one another,
there are also equally wonderful
adaptations of structure fitting in-
sects to codperate with plants to
their mutual advantage. It is
well known that plant-seeds, as
well as the fertile eggs of animals,
are produced only by the union of
two kinds of cells, the male ele-
ment being called the fertilizing
cell. Among plants, pollen-cells
grown on the stamens of flowers
must fall upon the stigma and be
conveyed thence to the ovary
before seeds suitable for repro-
duction can be formed. In many
cases the pollen from one flower
must be conveyed to the stigma
Fic. 83.—Hive-bees, 1, Of another flower before fertiliza-

female; 2, male; 3, tion can také place. Thiscarry-

Srorken. ing of pollen from flower to flower

is the work of insects which visit
the flowers for the purpose of getting honey. On the
visit, the pollen adheres to the hairs or other parts of
the insect’s body, and is rubbed off by the stigma of
the next flower approached.

Each flower seems to depend on a particular insect
whose proboscis just fits its own honey-cup. Thus,

SOME INSECT ADAPTATIONS. gt

red clover cannot grow without the help of bumblebees.
No more can bumblebees flourish without the honey
prepared by the growing clover. When this partner-

Fic. 34.—Fertilization of a Flower by an Insect. wu, calyx; 4, curved
upper lip; ¢, under lip, on which the bee stands while sucking the
honey; 4, pistil; d@’, pistil at a later stage; ¢, stamen; e¢’, stamen
shedding the pollen from its anther on the back of the bee; /, bee’s
proboscis, with which it reaches the honey.

ship between the bee and the clover began we cannot
say, but there is reason to believe that passing years,
with their new generations of both bees and clover,
only increase the dependence of each upon the other.

92 ANIMAL ACTIVITIES.

If you examine a head of the common white clover,
so abundant everywhere, you will see a part of the tiny
flowers of which the head is composed standing erect
and looking their best and prettiest. These are the
flowers not yet visited by the bees; the dry and
withered flowers hanging down near the stem have
been fertilized, and each one now contains a pod in
which the tiny clover-seeds are ripening.

Not only do we find the proboscis of an insect fitted
in structure for the plant on which it habitually feeds,
but we find the plants, also, ordering their ways to
conform to the habits of their insect friends. Thus,
stamens grow in such a way that they must dust
their pollen on the insect as he reaches the honey-cup,
while stigmas reach out in their growth to occupy at
maturity a position in the pathway of the pollen-laden
insect. Not only do stamens and stigmas seek the
insect, but the petals call their friends by color-signs
and point out by brilliant lines the direction of the
honey-cup, while hostile barbs and pointed hairs below
the cell of nectar prevent the approach of honey-loving
ants and small insects not useful to the plant.

Questions. What structures would lead you to sus-
pect that an insect leads an aerial life ? an aquatic life ?
a terrestrial life ?

Knowing an insect to be capable of strong flight,
what might you reasonably predict concerning this
insect’s legs ?

What might the mouth-parts of an insect indicate
concerning its food ?

What adaptations have you noticed in insects you
have observed ?

In what ways have you known insects to be espe-
cially protected from enemies ?

Why do some insects commonly fly at night ?

What insects have you observed at work at night ?

What insect communities have you observed ?

Have you seen insects carrying pollen?

CHAPTER IX.
A SPIDER’S ACTIVITIES.

PLACE a living spider in a large glass jar and watch
its movements for several days. Get a garden-spider
if possible, and keep it well supplied with flies and
other insects.

How does it take its food ?

From what part of its body does its web issue ?

Do all spiders make the same kind of web ?

Where have you seen spiders ?

Where have you seen the eggs of spiders ? How do
they look ?

Have you seen cast-off skins tangled in spiders’
webs? If so does that indicate anything about the
spider’s mode of growth ?

Can the spider smell? Test this point by bringing
near the insect first a clean glass rod and then a rod
dipped in a liquid having a strong odor.

Can the spider see? How far from her body can
she see ?

Using an alcoholic specimen, write resemblances and
differences for spider and grasshopper.

How many divisions of the body ?

Simple or compound eyes? How many?

How many legs ?

How many segments in each leg ?

Examine the feet with a microscope.

At the end of the mandibles find the poison-fangs.

Where are the spinnerets ? How many do you find ?

93

94 ANIMAL ACTIVITIES.

Under the abdomen near the cephalothorax find two
openings to the air-sacs or rudimentary lungs.
Summary of Drawings. (2) A spider seen from
above X 3.
(6) A front view of the mandibles x 5.
(c) A view of the top of the head showing the ocelli.
(2) A hind foot much enlarged. .
The Spider’s Activities. We have already con-
sidered the activities of the grasshopper, classifying
these under six heads. We
have spoken of these six
kinds of activities as the six
functions of living things.
In the spider these activities
are carried on by the aid of
finely adjusted machinery
Fic. 85.—A Spider’s Leg. which we can only describe
somewhat roughly here.
Taking Food. The devices by which spiders of
different kinds procure their food are well worthy of
study. Nearly all spiders are aided in this work by
silken threads spun from their own bodies. In the
lower part of the spider’s abdomen there is a bag in
which is secreted a glue-like substance which issues
from the spider’s body at will, and hardens on exposure
to the air. The wart-like projections on the lower side
of the abdomen near its posterior end are pierced with
many hundreds of minute holes, through each of which
proceeds a microscopic thread of the glue-like fluid we
have mentioned. The wart-like projections are called
spinnerets. The hundreds of tiny threads from the
spinnerets are grasped by the spider’s claws and twisted
into several strands, which, woven together, make the
fibre of which webs are built. A spider’s thread, then,
is a rope of several strands, and each strand is com-
posed of many hundred lines, yet it is so light that it
floats in the air, so strong that it easily holds up many
times the spider’s weight, so elastic that it does not

A SPIDER’S ACTIVITIES. 95

break easily, but stretches when struck heavily by large
insects, and so pliable that it can be moved into any
shape. No wonder, then, that the spider values so
highly her magic thread, and economizes it to such an
extent that she even eats the broken webs rather than
have them wasted.

The spider’s web is used in different ways by different
members of the spider family. The trap-door spider
- builds her cylindrical home underground, lining it with
the most delicate silk, and fitting it with a hinged cover
which she closes in time of danger, holding it firmly
shut with her claws.

The water-spider builds her dome-shaped home
under water, arranging it like a diving-bell, and carry-
ing to it bubbles of air from the surface (Fig. 86).
Some spiders weave irregular, sprawling tangles of web
to trap. their prey, while others build in accordance
with a methodical pattern. One spider spins her web
in such a way that it entangles in its meshes particles
of warm air, thus forming a balloon with which to float
in the air. The wheel-shaped web of the common
garden-spider is a marvel of skill. To make it the
spider first spins a thread where the wind can waft it
to an anchorage on some distant twig, or other support.
This line she hauls taut with her claws, and then,
dropping and swinging, always holding a thread, she
makes the somewhat irregular outside framework for
her more accurate geometrical web. She then puts in
the spokes with great care, and beginning at the
middle, winds a spiral thread to the circumference, and
another back to the centre. The second spiral thread
is covered with little, sticky, transparent beads stand-
ing side by side, ready to catch the luckless fly by
wing, or leg, and hold him fast. A touch of the finger
to such a thread shows the adhesive quality of the
beads, and a look at them under the microscope reveals
their beauty.

Such a web is not a nest, or a house; it is a trap.

96 ANIMAL ACTIVITIES.

Commonly the spider builds her home at one side of
the trap, and, holding in one claw a thread which she

Fic. 86.—Water-spider and Nest.

has connected with the trap, she awaits the vibration
which warns her that an insect is ready to be eaten.
If the pull on the line indicates a fly, she simply goes

A SPIDER’S ACTIVITIES. 97

directly to it, holds it in her mandibles, sucks the fluids
from its body and throws away the shell. If, however,
the pulling indicates a wasp or bee the movements are
of a different kind. Then the spider shows both
caution and alertness. If the insect is evidently too
large to attack, the spider snaps a few threads of her
web and sets the captive free with as little loss of the
precious web as possible. If, however, there is a
chance of victory, the spider spins more threads and
winds them round and round her victim, until she has
him so hopelessly entangled that she can safely kill
and eat him at her leisure.

The entrance to the spider’s mouth is guarded by a
pair of mandibles with sharp fangs at their tips. These
tips have holes near the ends, which lead by tubes to
a poison-bag in the head. From these fangs the
poison is squeezed into the body of the fly or other
insect.

Nutrition. The spider’s food is always liquid, and
is pumped up into her stomach in somewhat the same
way as the butterfly’s honey. In the stomach it
receives fluids which change it chemically, so that it
can be used to nourish the body.

Respiration. Like the insects we have studied, the
spider has spiracles for breathing, but so active and
energetic an animal requires more oxygen than this
arrangement seems able to give, and so it is provided
with rudimentary lungs or air-sacs. These sacs are
situated in the anterior part of the abdomen near its
junction with the cephalothorax, and open by two
minute holes just behind, the last pair of legs. The
chemistry of breathing is the same in all animals.

Reproduction. The spider deposits her eggs in a
cocoon of silk which she makes with great care,
shaping it with her body as a bird shapes her nest.
This cocoon, with its eggs, is fastened in a sheltered
place. The young spiders are hatched quite complete,
like their mothers, and begin at once to spin each a

98 ANIMAL ACTIVITIES.

tiny thread. They moult often, and very soon, with-
out any teaching, they know how to spin their tiny
wheel-shaped webs. They cat other insects, as do
their clders, and often dine on one another, lor them
the struggle for existence is a fieree one, and domestic
relations count for little, the mother cating not only
her own children, but often making a meal of her
husband. In the spider family the mother is supreme
and husbands and children fare but ill.

Discovery. An examination shows how larpe is
the nerve-mass concealed in the cephalothorax of the
spider. Several ganglia have grown toyether and
produced a sort of second brain, considerably larper
than the nerve-mass which lics above the throat.
Not only is this brain large, but as it is made by the
concentration of many smaller nerve-masses, or pan-
glia, it represents a great concentration of power.
These nerve-masses are connected with the outside of
the spider’s body everywhere by nerves, which carry
to the central organs notice of all vibrations from with-
out. he spider then is extremely sensitive to any
change in its surroundings. It scces, though not very
clearly, by means of eight cyes placed on the front part
of the cephalothorax; it hears, if at all, by the vibration
of the hairs on its body. It tastes and sinclls, we have
no doubt; but its keenest sense is that of touch.

Movements. ‘Vhe spider is capable of few move-
ments and performs these exceedingly well. What
she loses by the absence of wings she gains by increase
of power and skill in the use of her legs, The making
of a web often requires the most delicate movement
and the greatest precision; and the spider shows this
delicacy and precision to perfection. The wonderful
thing about the spider’s automatic movements is the
accuracy with which they are controlled,

The Lithobius. For purpose of comparison a little
time may be devoted to the imany-legyed brown insects

which disappear so hurriedly when onc overturns a

A SPIDER’S ACTIVITIES. 99

board or stonc, in almost any field or garden. In
some localities these animals are called ‘‘ earwigs ’’, in
other places they arc known as centipedes. Another
name for the most common species is lithobius. Speci-
mens may be easily obtained by using tweezers or a
piece of cloth. They may be kept in alcohol or
formalin.

In note-books answer these questions:

What is the habitat of this animal ?

Does it prefer light or darkness ?

Does it prefer moist or dry places ?

Does it bite or suck its food ?

In what respects does it resemble the spider? The
grasshopper ?

How does it differ from both spider and grasshopper ?

Does the number of segments correspond with the
number of legs ?

The front feet have poison-claws. Do these feet
have the same shape as the others ?

Drawing. A sketch of lithobius.

Questions. 1. How do the breathing-organs of a
spider differ from those of the insects previously
studied ?

2. Do you think the spider’s breathing has any rela-
tion to his activity ?

3. Have you noted any protective devices among
spiders ?

Topics for Reports. The Cochineal Insect.
Aphides. Shellac. The Silk-worm. The Manufac-
ture of Silk Goods. The Caddis-fly. May-flics. The
Ant-lion. The Noises of Crickets, Mosquitoes, and
Bees. The Habits of Honey-bees. The Carpenter-
bee. Agricultural Ants. Mud-wasps. How Flies
Walk on Ceilings. The Senses of a Fly (experiments).
The Senses of a Spider (cxpcriments). Spider-
webs. Water-spiders. Trap-door Spiders. Scorpions.
Cheese-mites. Ccntipedes. Thousand-legs. Stings
and Poisons. The Sense of Sight in Spiders. Where

100

I Have Found Spiders.
The Mosquito’s Boat.

Butterflies. Lightning-bugs. Injurious Insects.
Aphides as Cows of Ants.

Insect Friends.

Substances Furnished by Insects.
Do Insects Talk ?

makers.

ANIMAL ACTIVITIES.

Are Spiders of Any Use?
My Experience in Rearing

Some
Valuable
The First Paper-
Insects I Dislike.

VOCABULARY.

Ae'rial (Gr. aer, the air), inhabit-
ing the air.

Aquatic (Lat. agua, water), in-
habiting the water,

Cephalotho’rax (Gr. ephale,
head, and ¢horax), the union of
head and thorax in one division
of the body.

Drone, a male bee.

Fau'na (Lat. Fauna, the sister of
Faunus, the god of agriculture),
the characteristic animals of
a district.

Hab'itat (Lat. Aadito, to dwell),

the natural abode of an ani-
mal.

Ma rine’ (Lat. mare, the sea), in-
habiting the salt water.

Range, the region in which an
animal naturally lives.

Spin ner et’, one of the projections
from which the spider’s web
issues.

Su ture (Lat. sao, to sew), a seam
or joint.

Ter res’tri al (Lat. evra, the earth),
inhabiting or living on the land.

CHAPTER NX.

HOMOLOGIES AMONG CRUSTACEA.

LiwiInG eravmsh cs

- study their

J
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= View of Cra
gfe. tees

me. ncn, deiaian Gimisre vada fad ay ae te ot teas Besa otis
Mens OStaks SU SaaS Ihe Se Dor ston SNSS SS on SHS
srrimio:

Fees the

TOS GS Thee oO

Gk as
{seins
Touch the antenns wich

RS > eae
aX WLS oe

sess,
eas

wh raed

pagaeds

102 ANIMAL ACTIVITIES,

Place some colored liquid from a pipette just in front
of the thorax at the opening of the gill-cavity.

For individual work by the pupil, the use of the
shrimp is suggested because of the small expense and
because of the necessary comparisons with the crayfish.
Compare also with a lobster. The questions may be
used with crayfish, shrimp, or lobster.

Place the shrimp, crayfish, or lobster in a saucer
with the head turned from you.

Fic. 88.—Dorsal View of Crayfish.

In what ways does the shrimp resemble the grass-
hopper ?

How does it differ ?

In what respects does it resemble a spider ?

How does the exo-skeleton compare with that of the
insects ?

How many segments do you find in the abdomen ?

Can you find any indications of a division between
head and thorax ?

HOMOLOGIES AMONG CRUSTACEA. 103

Are there any evidences of segmentation on the
under side of the thorax ?

The appendages attached to the abdomen are called
swimmerets. At the end of the abdomen is the Ze/son,
which forms with the last pair of swimmerets the tail
of the shrimp. The large claws used for grasping prey

Fic. 89.—Ventral View of Crayfish.

are the first pair of legs. Count the legs and swim-
merets. In what ways do the swimmerets differ from
the legs ?

Are all the legs alike? What differences do you
observe ?

In front of the legs are three pairs of foot-jaws used
for passing food from the large claws to the mouth.
These are called maxtllipedes. In front of the maxilli-
pedes are two pairs of maxille. In front of the maxille
are the mandibles.

How many pairs of antenne do you find? Are they
branched ?

How do the eyes differ from those of a grasshopper ?

104 ANIMAL ACTIVITIES.

Notice the form of one of the swimmerets on the
second or third abdominal segments and compare all
the swimmerets with this.

How do the other swimmerets
differ from the ones first exam-
ined ?

Infer a use for the sixth pair of
swimmerets.

Sketch a swimmeret, naming
parts.

Compare the ends of the legs
Fic. 90.— Fourth Ab- having pincers with those which
dominal Segment of a ety th H
Crayfish. 7, tergum; 40 not have those organs. ow
st, sternum; #/, pleue much extra growth would be
rum; pr, protopodite; needed to produce a pair of

en, endopodite; ex, ex- : .

opodite. One append- pincers on the last pair of legs?

age has b eenremoved. Examine all the jointed ap-

pendages on one side of the
body. How many do you find? Counting a pair of
appendages to each segment or somzte, how many
segments has a crayfish or shrimp ?

How do the mouth-parts of a crayfish or shrimp differ
from those of a grasshopper ?

Remove one side of the carapace and expose the
gill-cavity. Do you find gills at the base of all the
legs? Do you see the spoon-shaped gill-scoop? Of
what appendage is it a part?

Look on the inside of the basal joints of the legs to
find the outlets of the reproductive organs. Among
crayfish the females have these openings on the middle
pair of legs and the males on the last pair.

With the help of the drawings find the openings of
the green glands (renal openings).

Find the ear.

Where is the anal opening ?

Internal Structure. With an alcoholic specimen
one can make out the parts indicated in the figure
below. The position of the heart, digestive tube, and

HOMOLOGIES AMONG CRUSTACEA. 105

nervous system should be especially noted. In looking
for the heart remove the top of the carapace where you
see the depression just behind the line between head
and thorax.

Summary of Drawings. (a) Side view of shrimp
X 4 (omitting appendages).

Fic. 91.—Crayfish Appendages. 4, antennule; 4, antenna; C, man-
dible; D, second maxilla; Z, second maxillipede.

(6) The carapace seen from above X 4.

(c) Side view of thorax with carapace removed to
show gills x 4.

(d) An eye seen from above X 6.

(ce) Large antenna x 6.

(f) Small antenna X 6.

(g) First, second, and last leg X 4.

106 ANIMAL ACTIVITIES.

(2) A swimmeret from the third abdominal segment
seen from behind x 6.

(¢) Sixth swimmeret.

Homologies. In the lobster, shrimp, and crayfish,
the antennz, claws, legs, and swimmerets are seen to

Fic. 92.—Longitudinal Section of Crayfish. a,
anus; d.a., dorsal artery; 4.g., intestine or hind-
gut; 4, heart; m.g., midgut; , liver; s, stom-
ach; 4, kidney; ¢a, labrum or lip; s.a., sternal
artery; #.c., nerve-chain; v.a., ventral artery.

be similarly situated and to bear a strong resemblance
in structure. If we should study the growth of these
three animals, we should find that these appendages
arise in a similar way in the process of development.
Parts of animals similar in position, structure, and origin
are said to be homologous. The wings of the butterfly
are homologous with those of the grasshopper. The
three pairs of jointed legs in the caterpillar are homol-
ogous with the legs of the butterfly.

When parts correspond simply in use and not in
origin or structure, they are said to be analogous.
Thus the wing of a bird and the wing of a butterfly are
analogous but not homologous.

HOMOLOGIES AMONG CRUSTACEA. 107

Serial Homology. In comparing the jointed appen-
dages of the different segments of the abdomen of a

lobster or crayfish with one another,
we note the fact that each is com-
posed of a basal joint of two seg-
ments and a pair of jointed branches.
One part of the basal joint is called
the Jdasipodtte and the other the cox-
opodite; both together are called the
protopodite. The inner branch is
the endopodite, and the outer branch
the exopodite. In the other jointed
appendages we find striking similarity
to the swimmerets. They are also
similar in origin; starting as bud-like
outgrowths from the rings or somites
of the embryo. Indeed, each seg-
ment is homologous with every
other. This kind of homology is
called serial homology. It is very
noticeable among the crustacea.

Laboratory Exercise. Examine
a sand-hopper and an asellus.

How does each compare with the
shrimp in regard to:

(a) The number of legs?

Fic. 93.—Walking
Appendage of
Crayfish with Gill,
&, Attached.

(6) The number and form of swimmerets ?

(c) The number of antennz ?

(2) The number of segments?

(¢) The divisions of the body?

(7) The eyes?

(g) The carapace ?

(Z) The position of the gills ?

(¢) The general form of the body?

Name parts of the sand-hopper which are homol-

ogous with those in the shrimp.

Name an organ in the sand-hopper which is anal-
ogous to one in the shrimp but not homologous with it.

108 ANIMAL ACTIVITIES.

Compare the eyes in the three animals.
The Importance of Homologies. We have already
pointed out the fact that parts may be homologous and

Fic. 94.—The Common Crab.

yet appear very unlike. Parts which arise in the same
way in the processes of development may become so

Fic. 95.—Early Stages of Shore-crab.

variously modified that their real homologies could not
be known without a study of embryology. Hence it

HOMOLOGIES AMONG CRUSTACEA.

109

frequently happens that animals bearing only slight
external resemblance to one another in adult life are

classified together because
in embryological life they
show so many resem-
blances.

Among the ten thou-
sand or more species of
crustacea, there are many
strange forms which de-
part from what might be
called the typical crusta-
cean structure. Compar-
ing the common crab
(Cancer irroratus) with the
shrimp or crayfish, we
notice the small size of
the abdomen folded under
the flattened carapace. In
the hermit crab the abdo-

Fic. 96. — Water-flea (Daphnia
pulex).

men is soft and has lost part of the swimmerets, be-
cause of its habit of using the shell of a snail for pro-
tection, yet in the young the abdomen of this animal

Fic. 97.—Cyclops.

A, dorsal view; 2B, side view.

is essentially like that of the young crayfish and bears

homologous parts,

IIo ANIMAL ACTIVITIES.

Among the lower crustacea there are many which
show greater variations from the typical form. The
cyclops is a small lobster-like crustacean often found
in drinking-water. Specimens can usually be obtained
by tying a piece of muslin over the end of a faucet and
allowing the water to run for a little while and then
rinsing the muslin in a glass of water. The horseshoe
crab is an ancient form sometimes classified with the
spiders because it seems to have more homologies with
them than with the common forms of crustacea.

Degeneration. The lower crustacea are called Exto-
mostraca. Among these are found many forms which
would not be recog-
nized as allies of the
crayfish and crab, but
for the study of their
embryology. The
common barnacle
(Balanus) found on
all salt-water shores
between high and
low tide bears no re-
semblance to a cray-

~ fish, yet soon after
Fic. 98.—A Barnacle. hatching from the
egg it is a_ free-
swimming active crustacean, provided with organs of
sense and looking much like a young shrimp. After
a short time it seems to tire of its active life, and,
looking about for a place of rest, it glues its head to a
rock and lies feet uppermost kicking food into its mouth
from the surrounding water. It builds around itself a
conical shell which it opens and closes at pleasure.
Thus sitting at ease and catching food as it comes, it
has no use for organs of sense or locomotion and so
loses these marks of higher animal life. It finally
becomes a blind and stupid mass, capable of little
else than the digestion of food brought to it by the

HOMOLOGIES AMONG CRUSTACEA. IIt

waves, an excellent illustration of the loss of powers
by disuse.

There are also many forms of fish-lice which live a
parasitic life by attaching themselves to a portion of
some fish and living on either the blood or food of their
host. These bear very little resemblance to the cray-
fish. Some have even lost the gills and breathe only
by the external surface of the body. These fish-lice
hatch from the egg as free-swimming larve, bearing
a striking similarity to other crustacea at this stage
of growth. The common larval form is called the
nauplius. (See first stage in Fig. 95.) Ithas a single
eye and three pairs of appendages. The higher crus-
tacea pass through this nauplius stage before hatching
from the egg. From this stage, the higher forms of
crustacea which lead an active life develop more ap-
pendages, and more acute sensibilities, with a corre-
sponding increase of complexity in the nervous system,
while the parasitic forms lose the eyes and locomotive
appendages, and their whole structure degenerates into
machinery for digestion and reproduction.

AN EXERCISE FOR THE NOTE-BOOK.

Rule a page in your note-book in the manner indi-
cated on p. 112 and fill the blank spaces with such
descriptive terms as you have learned in the previous
lessons.

Classification of the Arthropoda. We have already
noted the characteristics of the class ‘‘Insecta’’ by
selecting the points of resemblance among them. We
readily see that the spider, the lithobius, and the cray-
fish cannot be classed as Insecta without changing our
present definition. We find it more convenient to
include all the animals thus far studied in a larger class
which naturalists have agreed to call Arthropoda.
The Arthropoda are called a sub-kingdom or phylum
because they constitute one of the large divisions of the

II2 ANIMAL ACTIVITIES.

Grass-

hopper. Spider, | Lithobius.| Shrimp.

Bilateral ?

Are appendages
jointed ?

Wings, antenne,
legs, and swim-
merets.

Divisions of
body.

Respiration.

Locomotion.

animal kingdom. Sub-kingdoms are divided into
Classes, classes into Orders, orders into Families,
families into Genera, genera into Species. Thus the
milkweed-butterfly belongs to the sub-kingdom Ar-
thropoda, the class Insecta, the order Lepidoptera, the
family Nymphalide, the genus Danais, and the species
Archippus. Such an arrangement must be to some
extent artificial, because animals are not run in molds
like bullets or stamped with dies like coins. Never-
theless, the great number of animal forms compels us
to adopt some scheme of classification to prevent con-
fusion.

Examining our notes concerning the Arthropoda,
we find that all are bilateral, all have an exoskeleton,
segmented bodies, and jointed appendages. These

HOMOLOGIES AMONG CRUSTACEA. 113

peculiarities we may call the most important character-
istics of the Arthropoda. Animals not having these
marks must be classified under other sub-kingdoms.
In Chapter I we have classified all animals into eight
sub-kingdoms. The sub-kingdom Arthropoda includes
probably half of the animals of the earth, the Insecta
alone having more than half a million species. Nat-
uralists are not agreed yet as to the number of classes
properly belonging to the Arthropoda, but usually
animals like the shrimp and crayfish are called Crus-
tacea, those like the lithobius Myriapoda, those like
the spider Arachnida, and those like the grasshopper
Insecta. The Insects have already been described.

The Arachnida have eight legs, simple eyes, and a
cephalothorax and abdomen.

The Myriapoda have many segments with at least
one pair of jointed legs for each segment.

The Crustacea breathe by gills throughout life.
They pass through the nauplius stage in the course of
development.

Further study shows other marks for identifying
these classes. Many exceptional forms are found and
great patience and care are necessary in order to
classify accurately. Nevertheless, it is profitable prac-
tice to attempt to classify animals as we see them, even
if we do it somewhat roughly at first.

Laboratory Exercise for Review. A variety of
forms kept separately in small numbered boxes and
bottles may be used. Write in the note-book:

(1) The number of the specimen.

(2) Its mode of locomotion.

(3) Its habitat, inferred from its structure and its
resemblance to forms already known, with the reason
for your answer.

(4) Its food and its mode of procuring it, inferred
from an examination of its mouth-parts, from other
points of structure, and from resemblances to forms
already known, with the reason for your answer,

II4 ANIMAL ACTIVITIES.

(§) The class to which it belongs, with reasons for
the answer.

(6) In the case of Insecta, name the order to which
the insect belongs, with reasons for the answer.

Questions. (1) Why are the animals just studied
called crustacea ?

(2) How does their manner of breathing compare
with that of Insecta ?

(3) Do lobsters breathe air? Explain.

(4) What is meant by homology? By analogy?

(5) What is serial homology ?

(6) Where may one find cyclops ?

(7) Why is cyclops so named ?

(8) How do the crabs differ from the shrimp ?

(9) In what way do barnacles resemble the shrimp ?

(10) How does the hermit-crab differ from other
crabs?

(11) In what cases among crustacea does the mode
of life seem to affect the shape of the body ?

(12) What occurs when the limb of a crustacean is
broken off? What reason have you for your answer ?

(13) What is phosphorescence ? How do you ex-
plain it?

(14) Do the crustacea moult? How do you know?

(15) Do you know any animals which do not have
both sides alike ?

(16) Give examples of differentiation.

Topics for Reports. The Hermit-crab. Robber-
crabs. Lobsters. Cyclops. Phosphorescence. Giant
Crustacea. Degeneration. Uses of Crustacea.

HOMOLOGIES AMONG CRUSTACEA.

115

VOCABULARY.

Anal’o gous (Gr. axa, according
to, and /ogos.) Analogous organs
are those having the same use
but not necessarily the same
structure or origin.

Bas ip’o dite (Lat. daszs, base, and
Gr. fous, foot), part of a crus-
tacean appendage.

Car’a pace (Lat. capara, a hood),
the hard covering of the cephalo-
thorax in crustacea.

Cephaliza'tion (Gr. ephale,
head), a tendency to aggregate
nerves and organs of sense near
the head.

Cox op’o dite (Lat. coxa, hip, and
Gr. fous), the joint of a crusta-
cean appendage nearest the body.

Crus ta’ce a, a class of arthropoda
commonly having a hard shell.

Dec’a pod (Gr. deka, ten, and gous),
an order of crustacea having ten
legs.

Dif fer en tia’tion (Lat. ds,apart,
and fero, to carry), the setting
apart of tissues and organs to
perform special kinds of work.

Em bry ol’o gy (Gr. embryon, an
embryo, and Zogos), the study of
embryonic life.

En dop’o dite (Gr. ez, in, and ozs),
the outer branch of a swim-
meret.

Ex u'vi um (Lat. exzo, to strip off),
the cast-off skin of an insect or
crustacean.

Fang, a hollow tooth emitting
poison.

Fer til i za’tion (Lat. fro, to bear),
the union of male and female
cells to produce living seeds or

eggs.

Gill, an organ for breathing the
oxygen dissolved in water.

Ho mol’o gous (Gr. omos, same,
and /ogos), having the same rel-
ative position and structure.

T’so pod (Gr. sos, equal, and fous),
an order of crustacea having the
legs of equal length.

Max il/li ped (maxz//a, and fous),
a foot-jaw.

Os mo’sis (Gr. osmose, pushing),
an interchange of gases or
liquids through a slightly porous
substance.

Pro top’o dite (Gr. protos, first,
and fous), a part of a swimmeret
consisting of the basipodite and
coxopodite.

Re’nal (Lat. renalis, kidney), per-
taining to the kidneys.

Ros‘trum (Lat. rostrum, a beak),
a weapon of defence on the front
of the carapace of a crustacean.

Sed’entary (Lat. sedeo, to sit),
inactive.

Ses’sile (Lat. sedeo, to sit), joint-
ed to the body without stems or
stalks.

So’mite (Gr. soma, a body), a
segment of the body of one of
the arthropoda.

Swim mer et’, a jointed appendage
on the abdomen of a crustacean.

Tac’tile (Lat. ¢ango, to touch),
having the sense of touch.

Tel’son (Gr. ¢e/son, a boundary),
the posterior somite of a crus-
tacean.

Tet ra dec’a pod (Gr. Zetra, four,
deka and pous), an order of
crustacea having fourteen legs.

CHAPTER XI.

THE ACTIVITIES OF ONE-CELLED ANIMALS AND
SPONGES.

Tuus far we have been dealing with animals having
more or less complicated machinery for carrying on the
activities of life. We know that an egg is a single cell
and that as it grows it changes by increasing the num-
ber of cells and by setting apart groups of these cells
to perform different duties. In a single cell life is
reduced to its lowest terms. In an egg we may see
the process of unfolding and get greater insight into
the workings of living machinery. So in studying
living animals which never develop beyond the single-
cell stage of existence we may gain a knowledge of
animal activities not otherwise obtainable.

These animals are so small that a complete study of
them makes necessary the use of the compound micro-
scope, but as it is not proposed to burden this course
with the details of microscopic manipulation, we must
content ourselves with verbal descriptions for the
present.

The one-celled animals are put in a sub-kingdom by
themselves, called Protozoa. They are very small and
for the most part inhabit the water. There are many
of them, but their ways may be very well understood
by studying descriptions of a few forms.

The Ameba. This minute animal has been much
studied and its modes of life are well known. It may
be found in stagnant water in small shallow pools. It
is less than a hundredth of an inch in diameter and

116

ONE-CELLED ANIMALS AND SPONGES. 117

under the microscope looks like a drop of moving jelly
of irregular outline. The greater part of the Amceba
is granular in structure, being surrounded by an outer
film of clearer jelly. In the midst of the cell is a
nucleus, a little more opaque than the rest of the cell
but made of the same substance. The jelly-like sub-
stance of which the whole Amceba is made is called

Fig. 7,

Fic. 99.—Forms of Amcebee (highly magnified), 2 and 3 were drawn
from the same specimen; 5, 6, 7, and 8 were drawn from another
specimen; JV, nucleus; P, pseudopodia.

protoplasm. The same substance is found in the cells
in our own bodies, as well as in the living cells of other
animals and plants. Every plant and every animal
begins its life as a single cell of protoplasm. Within
the Amceba’s cell may be also seen a round clear spot
which from time to time contracts and temporarily dis-
appears. This is called the contractile vacuole.

118 ANIMAL ACTIVITIES.

Taking Food. Not only is the Ameeba destitute of
jaws and sucking-tubes, but it even lacks a mouth.
Its food consists largely of minute one-celled organisms
which it swallows at any part of its body by simply
flowing over and around them.

Nutrition. The particles of food which have been
swallowed are gradually dissolved and chemically
changed so as to become a part of the protoplasm of
the Amceba’s body. The shell of the plant is thrust
out through the Amceba’s covering at any point when
all the nutritious matter has been taken from it. Dis-
solving and chemically changing the food is digestion.
Making it a part of the Amceba’s protoplasm is asszm-
lation. There is no stomach or intestine, but the food
while digesting moves about with the granular proto-
plasm in a somewhat regular way.

Respiration. There are no organs for breathing,
but oxygen from the surrounding water enters the living
protoplasm and carbon dioxide and other impurities
are given off.

Reproduction. When the Amceba has eaten and
digested food until it has grown to be too large, the
nucleus shows signs of divid-
ing, the Amceba assumes a
dumbbell shape and finally
splits into two Ameebas,
each equally capable of

Fic. 100.—Ameeba Feeding. leading an independent ex-
istence. Parent and off-

spring are alike, if either can be called parent. This

mode of reproduction by division is called fission.

Discovery. If touched the Amceba contracts. It
is then sensitive to touch, but there can be no special
parts of the body fitted to receive impressions from
without. It is everywhere equally sensitive.

Movements. Not only does the Amceba withdraw
when touched, but it seems capable of self-directed
movement as well. The method of procedure consists

ONE-CELLED ANIMALS AND SPONGES. 119

in projecting outward a portion of the body in the
direction in which the animal wishes to move. The
little swelling thus made is called a pseudopodium or
false foot. Such false feet may appear at any time on
any part of the body. When this pseudopodium has
extended itself sufficiently the rest of the body seems
to glide into it by a sort of flowing motion. The varying
position and size of the pseudopodia give it its irregular
outline when seen under the microscope. The Amceba’s
power of ‘‘ contractility ’’’ is sometimes spoken of as a
separate activity corresponding to the contractility
noticed in the muscles in higher animals.

Thus this simple bit of protoplasm performs the same
functions which are common to higher animals, all the
activities in this case being carried on by a single cell.
As we examine other animals we find it easy to arrange
a series in which each animal is only a little more
specialized than the one next below it, but such a series
does not include all animals. It is interesting to note
that such a series bears a strong resemblance to the
various stages through which an egg (a single cell) of
one of the more specialized members of the series
passes in its growth.

Rhizopoda with Shells. Some of the Ameeba-like
animals cover their bodies with bits of mineral matter
to form shells with openings
through which the pseudopodia
extend to gather food and as-
sist in locomotion. In many
cases these shells are secreted
by the animal, thatis, theyare yg. rox.—Amceba_ Divid-
formed from the protoplasm ing.
of the body as our finger-
nails are formed from our blood. Sometimes the
pseudopodia resemble the roots of plants and hence
these Protozoa which move by pseudopodia are called
Rhizopoda.

Some of the Rhizopoda secrete shells of calcium car-

120 ANIMAL ACTIVITIES.

bonate or limestone. When these shells are perforated
with many holes the animals are called Foraminifera.

|
NN
\ \ Ly | ,
WB
oS

Fic. 102.— One of the Foraminifera.

Some of these foraminifera have been found of large
size and in such great numbers that their fossil remains
make great deposits of limestone.

Fic. 103.—The Origin of Chalk. A, chalk (magnified); B, ooze (mag-
nified).

Chalk. At present there live near the surface of the
ocean great numbers of these shelled Rhizopods.

ONE- CELLED ANIMALS AND SPONGES. 121

When they die their shells fall to the bottom and,
mingling there with other similar shells, form a soft
white mud which may harden to form chalk. The
chalk cliffs of England were doubtless produced in this
way.

Tripolite. Some of the Rhizopoda have shells made
of the finest possible bits of glass or silica. Deposits
of these shells with similar shells of one-celled plants
form ¢ripolite, a substance used as a polishing powder.

Infusoria. If hay be placed in warm water and
allowed to stand in a warm place for a few days the

Fic. 104.—Infusorial Earth Fic. 105. — Infusorians
(magnified). * (magnified).

water will be found to be filled with many minute, one-
celled, rapidly moving animals. A look at these
through the microscope shows that their movements
are due to the motion of hair-like projections on the
body. These hair-like bodies are called czla. One-
celled animals which move by cilia are called /ufusoria
because some of their kind appear when infusions of
hay or other vegetable matter are allowed to stand.
Some of the Infusoria are fixed by a stalk, or stem, like
the bell-animalcule, or vorticella, shown in the figure,
and some are rapidly moving free animals like those
found in infusions of hay.

122 ANIMAL ACTIVITIES.

One of the Infusoria found in infusions of vegetable
matter is the Paramecium, or slipper-animalcule (Fig.
107). This may be found and stud-
ied very easily. Where a compound
microscope is available the follow-
ing exercise may be used.

Laboratory Exercise. Examine
in a watch-glass by using a low
power of the microscope a few
drops of stagnant water known to
contain Infusoria.

1. Does the Paramecium have a
definiteshape? Isit bilateral? Is
the Ameeba bilateral ?

2. Place a few drops of water
containing the slipper-animalcule
on a slide with a few fibres of cot-
ton and examine with a higher
power of the microscope. Is the
body divided into parts or cells?

J 3. Do you see the movement of
a ee cilia? On what part of the body
tended; Z, contract- are they situated ?

ed; C, in fission. 4. Do you find a groove sur-

rounded by cilia ?

5. Do you find a mouth ?

6. Do you find a nucleus ?

7. Are there any contractile vacuoles ?

8. Feed the animal with bits of indigo. Where do
the blue particles go ?

Summary of Drawings. (a) A sketch of several
animals as they appear when viewed with a low power
of the microscope.

(4) Sketch of a single animal showing as many parts
as you have seen.

In the Paramecium the activities of life are carried
on much as they are in the Amceba. There is, how-
ever, a greater specialization of parts, especially the

ONE-CELLED ANIMALS AND SPONGES. 123

nouth for taking food and the two kinds of cilia, one
for locomotion and one for producing currents of water
to drive food into the
mouth. Even a single
cell then may have its
parts specialized for per-
forming different kinds of
work.

Characteristics of the
Protozoa. The Protozoa
are minute animals
having but a single cell
of protoplasm, moving by
pseudopodia, or cilia, and
reproducing withouteggs.

Sponges. Itis not rec-
ommended that sponges
be studied in the labora-

tory in an elementar
y y Fic. 107. ~A Paramecium (highly

course, but for purposes magnified). 0.g., oral groove;
of comparison it is neces- ph, pharynx.

sary to become familiar
with the most important facts concerning their structure.
Sponges are composed of many cells but slightly
specialized. A single sponge really seems almost as
much like a colony of Protozoa as like a distinct animal.
The outer layer of cells which is simply a sort of skin
is called the ectoderm, the inner layer or lining of the
cavities of the body is called the exdoderm. Between
the ectoderm and the endoderm lies the mesoglwa, in
which the skeleton is produced. The flesh of the
sponge taken altogether is called sarcode. The com-
mon bath-sponge as we use it is only the skeleton.
We may imagine that the hard parts we see have once
been imbedded in fleshy matter (mesoglcea); that the
fleshy matter was covered with a skin (ectoderm); and
that the cavities so apparent in the skeleton were lined
with another skin (endoderm).

ANIMAL ACTIVITIES.

124

The kind of sponge commonly called the hard-head

The smaller

holes on the outside correspond to openings in the

ectoderm through which currents of water flow to the
The large holes at the top are out-

gives a general idea of sponge-structure.

interior cavities.

8,
Pr

AN

\

A, section of sponge;

&, part of a digestive sac; C, one cell from a digestive sac.

ANS

Fic. 108. — Structure of a Sponge (magnified).

Along the passageways from

lets for these currents.

(oscula) there are enlargements which act like stomachs,
that is, they take up the food as it passes along in the

these outer holes (inhalent pores) to the larger holes

The endoderm cells which line

currents of water.

ONE-CELLED ANIMALS AND SPONGES. 125

these cavities are provided with flagella which by their
constant movement keep the water moving along from
the inhalent to the exhalent openings. As the water
passes along it brings
within reach of the

flagella minute animals | AN
and plants which are =)

seized and pushed back

into the cells where
they are dissolved and

assimilated in much VA
the same way as the
food of the Amceba is
assimilated in its cell.

The breathing, too, is

carried on by the indi- Fic, 109.—Sponge Spicules.
vidual cells as in the

Ameeba. Nutriment from the endoderm cells is passed
along from cell to cell to nourish the rest of the body.
From this nutriment the material for building the
skeleton is secreted. This skeleton is often in the
shape of spicules of hard material. Spicules may be
calcareous, stlicious, or horny, producing these three
kinds of sponges. Only the horny or feratose sponges
are of any commerical use.

So nearly independent are the individual cells com-
posing the sponge-structure that if a few of them be
separated from the original body, they go on living
and divide and subdivide, making new cells and build-
ing the structure of a new sponge. If a living sponge
be cut into hundreds of pieces, each piece grows into
an independent animal.

Such an aggregate of cells may be considered as
only a transition step between a Protozoon and a
many-celled animal of more highly specialized struc-
ture. Hence some naturalists have classed sponges as
Protozoa, some make a separate sub-kingdom Porifera,
while others class them with the sub-kingdom Ccelen-

126

terata.

ANIMAL ACTIVITIES.

For our purpose it seems best to regard the

Porifera as a separate sub-kingdom.

Questions.
the canals in a sponge?

1. What force propels the water through

2. Write the functions of the sponge in columns as
we have previously written the functions of other

animals.

3. In what respects does the sponge resemble the

Paramecium ?

4. How does a sponge differ from an Amoeba ?
5. Where are sponges found ?
6. Why are sponges called animals rather than

plants ?

Topics for Reports.
covery of the Microscope.
Sponge-fisheries.

Chalk. Tripolite.

The Dis-

How to use a Microscope.

VOCABULARY.

Animal’cule (Lat. dim. of ani-
mal, from anima, breath), a
very small animal.

As simila’tion (Lat. ad, to, and
similis, like), the process of
making digested food into living
tissue. :

Calca’reous (Lat. ca/x, lime),
made of carbonate of calcium.
Cell (Lat. ced/a, a small room), a
bit of living protoplasm contain-

ing a nucleus.

Cil'ia (Lat. pl. of cium, a hair),
hair-like bodies capable of rapid
movement.

Ec’to derm (Gr. ekfos, outside, and
derma, skin), the outer layer of
cells in a sponge.

Ec’to sarc (Gr. ektos, and sarx,
flesh), the outer film surround-
ing one of the Protozoa.

En’doderm (Gr. endon, within,
and derma), the inner layer of
cells in a sponge, the layer
which forms the lining of the
digestive channels.

Fis’sion (Lat. fissus, a cleft), the
process of reproducing by cell-
division.

Fo ram i nif’e ra (Lat. foramen, a
hole, and fevo, to carry), Proto-
zoa having shells punctured with
many small holes.

In fu so’ria (Lat. pl. of infusori-
um, an infusion), Protozoa mov-
ing by means of cilia.

Ker’atose (Gr. #eras, a horn),
horn-like.

Mes'‘oderm (Gr. mesos, middle,
and derma), the part between
ectoderm and endoderm.

Nu’cle us (Lat. dim. of zx, nut),
a denser bit of protoplasm in a
cell.

Os’cu lum (Lat. dim. of os, mouth),
a minute pore or mouth.

Pseudo po'dium (Gr. psendoi,
false, and fous, foot), a project-
ing portion of an Amceba’s cell,
a false foot.

Pro’to plasm (Gr. profes, first, and
plasma, form), the substance of

ONE-CELLED ANIMALS AND SPONGES. 127

which living cells are mainly | Sili’cious (Lat. sz/ex, flint), made

composed. of a substance like glass.

Rhi zop’o da (Gr. rhiza, root, and | Spic’ule (Lat. dim. of spicum, a
pous), Protozoa having pseudo- spike), a bit of hard material
podia for locomotion. formed in the tissues of sponges

Sar'code (Gr. sarx, flesh) the fleshy and other lower animals.

part of a sponge.

CHAPTER XII.

THE HYDRA AND SOME CC@ELENTERATES WHICH
LIVE IN COLONIES.

Fresh-water Hydra. In warm weather hydra may
be found near the surface of fresh water on leaves or
sticks or attached to the stems of aquatic plants. If
such leaves or plants be collected and placed in a plate,
or jar of water in the sunlight, hydra may be seen in a
short time. As soon as they have been found, transfer
them with the plants on which they feed to an aquarium,
where they may be easily kept all winter. They feed
on cyclops, daphnia, and other small crustaceans.
These are commonly found in the same places as the
hydra and probably will appear in the water with the
leaves collected. If they do not appear keep on col-
lecting dead leaves from different localities until they
are found. Both hydra and its food may be found
almost anywhere if patience and care be used in collect-
ing. When wanted for use it is easy to transfer hydras
to a watch-glass by removing them from the side of the
aquarium with a knife and dipping them out with a
glass tube.

Note the appearance of hydras as you see them in
the aquarium.

What is their size? their shape? Do all have the
same shape ?

Look for branches and buds. How many do you
find on any hydra?

What is the color of hydra ?

What movements can the hydra make ?

128

HYDRA AND CCELENTERATES. 129

In what part of the aquarium with reference to light
are they most abundant ?

Place a hydra in a watch-glass in water and observe
it more closely with a magnifying glass. What do
you see ?

Watch one take a particle of food.

Notice the foot, the body, the tentacles, the hypo-
stome, and the mouth.

What happens when you touch a tentacle ?

In what tespects does the hydra resemble the
sponge ?

How do the two animals differ ?

Cut a hydra in several pieces and place these in a
dish in clear water. Watch the pieces for several
days.

Place a single budding hydra in a battery-jar with
water and food. At frequent intervals count the
number of hydras present.

Summary of Drawings. (a) A single hydra with
tentacles showing X IO.

(6) A hydra with tentacles contracted x Io.

(c) A single hydra showing buds and branches X Io.

(2) Several hydras in different positions taken in
locomotion X Io.

The Activities of the Hydra. Taking Food. The
hydra uses the tentacles surrounding the upper end of
its cylindrical body for the purpose of seizing its prey
and conveying it tothe mouth. These tentacles are
covered with minute nettling-cells which paralyze the
small crustacean as soon as he is seized. These cells
have within them a very minute coiled thread which is
uncoiled when the cellis touched. This thread pierces
the victim which has been unwittingly the cause of the
uncoiling and poisons the part it pierces. These
nettling-cells are sometimes called thread-cells or
lasso-cells. They are characteristic specializations of
the sub-kingdom Celenterata.

Digestion. The food after being pushed into the

130 ANIMAL ACTIVITIES.

mouth by the tentacles passes into the body-cavity,
which is also a stomach.

The hydra is really a bag, being hollow, even out in

the tentacles. The food moves about inside of this

bag and is dissolved there. The

hard and useless parts of the food

are pushed out through the mouth,

which is the only opening into the

bag. The nutriment is assimi-

lated by the cells lining the bag

or stomach-cavity. This lining

is called the endoderm and its

AX cells are very little differentiated

from the ectoderm, or outside

cells.
| Respiration. The cells of the
hydra breathe independently, as

do those of the sponge.
Fic. 110,—Thread-cells ' Reproduction. i ae Eydia ts

(highly magnified), divided into several pieces each

piece reproduces the missing parts
and becomes an active individual. A common method
of reproduction is by the process of budding. The buds
appear first as swellings along the sides of the parent
hydra; they gradually develop a row of ales. a
mouth breaks through into the common cavity of both
parent and offspring; the base of the branch into which
the bud has now grown constricts and finally breaks
away entirely from the parent; and the hydra, free and
independent, seeks its own place of feeding.

But the hydra also reproduces by means of eggs.
These appear as swellings on the side of the parent in
much the same way as the buds just mentioned. Above
the egg just below the fentacles another swelling
appears. This contains the fertilizing or male cells
(sperms). The swelling containing the sperm-cells is
called the testis. The ova as they mature float away
into the water, as do also the sperms. A sperm swims

HYDRA AND CCELENTERATES. 131

actively about and finally coalesces with an ovum from
another hydra. This process is called cross-fertiliza-
tion. Animals which produce in the same individual
both ova and sperms are said to be hermaphrodite.
We can see that this cross-fertilization does not differ
materially from that already described as occurring in
the white clover. The eggs after fertilization are called
odsperms. These odsperms develop into hydras like
the parents. In the autumn, eggs are produced with

Fic. 111.—Forms of Hydra (magnified). A, half retracted; 2, fully
retracted; C, extended; /, foot; ovm., ovum; 4, bud; ¢s., sperm-cells;
h.s., hypostome; ¢, tentacles.

thick, hard shells to withstand the cold and thus pre-
serve the species until spring.

Discovery. The hydra has no nervous system,
though a few nerve-cells are developed. It is sensitive
to light and extremely so to touch.

Movement. The hydra moves without muscles. It
can move by pushing its sucking-disk or foot along the
leaf to which it is attached or it can march by somer-
saults to its destination. The tentacles seem to move
at will.

The Hydractinia.. Division of Labor. A salt-
water animal which resembles the hydra is Hydractinza,

132 ANIMAL ACTIVITIES.

It is often found attached to snail-shells inhabited by
hermit-crabs. The individuals live in a colony and
vary according to the work each has todo. They all
grow together at the base, and so are connected by
living tissue through which digested food may be passed
from one to another.

Here one individual (a) does the eating for the colony
with the help of others like himself; another (4) attends
entirely to the work of reproduction; while still another
(c) protects the colony from enemies. These hydra-
like individuals, which are not strictly individuals
because they do not lead an independent existence,
are called zoords. Such an assembly of zooids is called

Fic. 112.—Hydractinia (magnified). After Agassiz. A, male colony;
B, female colony; a, feeding zooid; ¢, tentacles; 4, reproductive
zooid; ¢, protective zooid; d, e, 7, g, 4, 2, stages of jelly-fish.

acolony. Again we notice the setting apart or differ-
entiating of zooids to perform each its own work.

At the base of the zooids of Hydractinia a hard skele-
ton is built, which resembles coral in its nature.

Commensalism. As stated above, the Hydractinia
is commonly found on shells inhabited by hermit-crabs.
The Hydractinia colony is thus carried about and
brought constantly into contact with a new food-supply.

HYDRA AND CCELENTERATES. 133

The hermit-crab, on the other hand, is probably pro-
tected from enemies by the moss-like growth on its
shell. The two animals seem to find this association
mutually advantageous. The word commensalism is
applied to animals living together in this manner.

Campanularian Hydroids. These colonies may be
easily collected, being found attached to logs or sea-
weed, just at the level of low tide. The zooids may
be stained with carmine solution for the purpose of
making out the parts more easily. If there is time the
pupils should note the following points:

Examine a specimen, natural size, kept in formalin.
How does it resemble a hydra?

Do you find bilateral symmetry, either in the colony
or the zooids ?

Place a specimen in a watch-glass and examine it
with a simple microscope. How many kinds of zooids
do you see?

In the feeding zooids can you see tentacles, hypo-
stome, and a thickened body in a protecting, bell-
shaped case?

In other longer cases in the axils of branches do
you see a number of round masses?

These are really buds growing in the reproductive
zooid. When fully mature, these masses float out at
the top of the protecting case and swim away as small
jelly-fishes.

Examine both kinds of zooids, using a compound
microscope.

Summary of Drawings. (a2) A Campanularian
colony of natural size.

(0) A single feeding zooid slightly magnified.

(c) A single reproductive zooid slightly magnified.

Alternation of Generations. The jelly-fish which
swim away from the reproductive zooid do not attach
themselves to rocks, but remain free as long as they
live. They are umbrella-shaped bodies, the mouth
being at the end of the handle, their shape being like

134 ANIMAL ACTIVITIES.

that of an inverted hydra, with a greatly overgrown foot-
forming the covering of the umbrella. These jelly-fish
are often called medusz, because in some similar forms
the long tentacles around the edges of the umbrella
covering are supposed to resemble the snaky locks of
the mythical monster. The tentacles surrounding the
umbrella of the Campanularian medusze are not large,
but they have at their bases minute spots connected
with nerve-masses. These are thought to be eyes or

Fic. 113.—Medusz of Campanularium Hydroid (Zucope diaphana). a,
whole colony, one half natural size; 4, single zooid magnified;
A, young medusa magnified; 2, adult medusa magnified. After
Agassiz.

ears. These jelly-fishes swim through the water with
a slow flapping of the umbrella edges.

After a time eggs are produced which float out into
the water and produce, not jelly-fish, but the branching,
fixed Campanularians. Thus the young resemble the
grand-parents instead of the parents. The children of
these young, however, resemble the jelly-fish. Such
a phenomenon is not uncommon in the animal world
and is called alternation of generations.

Scyphozoa. Besides the jelly-fish just described
there are other free-swimming medusz whose origin is

HYDRA AND CCELENTERATES. 135

somewhat different. The egg from one of these meduse
grows into a fixed, more or less hydra-like form which
at maturity splits horizontally into a number of saucer-
like disks. These finally break away and become the
large jelly-fish we so commonly see in salt water (Fig.
114).

Sea-anemones. In its cylindrical shape, the position
of its mouth and tentacles, and in possessing thread-

Fic. 114.—The Origin of a Scyphozoan Jelly-fish (M/edusa aurita).
uw, adult; 4, ¢, a, e, 7, g, earlier stages.

cells, the sea-anemone resembles the hydra. The
larger size of the sea-anemone makes it easy to study
in localities where it can be used alive.

In the anemone the hollow body is traversed by
radiating partitions called mesenteries. These serve
to increase the area exposed to digested food. There
is no hypostome present, and the internal cavity is
reached by a passageway called the gullet.

Corals. The coral animals resemble the sea-anemone
in structure. They differ chiefly in the fact that they
deposit a hard skeleton. In the more common corals
the skeleton shows septa corresponding to the mesen-
teries in the living animal. These animals live for the
most part in colonies, the single individuals, or polyps,
being connected at their bases in such a way that nutri-
ment may pass from one to another. The examination

136 ANIMAL ACTIVITIES.

of coral skeletons shows some facts concerning coral
growth.

Examine the skeleton of Fungza. Remember that
this is the skeleton of an animal something like the

Fic. 115.—The Structure of a Sea-anemone. 4, longitudinal section;
B, transverse section; #, mouth; 0, eggs; ¢, tentacle.

sea-anemone. What are some peculiarities of this
skeleton ?

Examine pieces of Galaxea skeleton. How does
Galaxea differ from Fungia ?

Count the septa in several tubes of Galaxea. How
many? The parts of the tubes projecting above the
general structure are called the ¢hece.

Examine a branch of Madrepora. How does this
differ from Fungia ? from Galaxea ?

Do you find thecz and septa in Madrepora ?

Were all the polyps of the same size ?

How did the branches in Madrepora arise ?

Were the lateral polyps connected with the central
polyps? Use branches sawed longitudinally to show
this point.

How did the lateral polyps arise in the course of
growth?

How did the colony develop from a single polyp ?

Summary of Drawings. (a) Fungia skeleton, nat-
ural size.

(4) Galaxea skeleton showing several tubes x 3.

HYDRA AND CC2LENTERATES. 137

(c) Two tubes of Galaxea skeleton with outline
sketch of the polyps that built the skeleton as you
think they may have appeared x 5.

(2) Branches of Madrepora skeleton, natural size.

(e) Longitudinal section of branch of Madrepora
skeleton.

Other Coral-like Animals. There are many other
kinds of corals and coral-like animals. The red coral
of commerce is produced by polyps which deposit the
solid matter in such a way that no traces of septa show
in the skeleton. Something like these red-coral polyps
are those which deposit a horny substance instead of
calcareous matter, forming the sea-fans, sea-pens, and
other similar growths of tropical regions.

Characteristics of the Celenterates. The Ccelen-
terates may be said to be animals having hollow cylin-
drical bodies provided with a single opening at one
end. This opening is commonly surrounded by tenta-
cles and these are provided with nettling-cells.

Classes of Celenterates. Animals like the hydra,
having the whole body-cavity used as a stomach, and
bearing a hypostome at the mouth-end of the body are
called Hydrozoa.

Sea-anemones and coral polyps have the hypostome
inverted to form a gullet. Radiating partitions or
mesenteries are found in the body-cavity. These
animals are called Actznozoa.

Our largest jelly-fishes, briefly described on page 133,
are called Scyphozoa.

Laboratory Exercise for Review. Using specimens
in numbered bottles or boxes, as indicated on page
113, write in note-books, or on paper, as fully as you
can concerning the topics indicated below. Specimens
not previously seen by the pupil are especially valuable
for this work.*

*Of course all these activities cannot be inferred correctly from
structure in every case, but the attempt to make the inference is valu-
able, and success is more frequent than failure.

138

Habitat.
Mode of Locomotion.
Mode of Breathing.
Kind of Food Used.
. Classification.
Topics for Reports.
Sea-anemones.
Coral Reefs.
Florida.
Islands.
Commensalism.
lecting Ccelenterates.

mBpdw hd x

ANIMAL ACTIVITIES.

The Portuguese Man-of-war.

Coral Islands.
How Corals Have Helped to Build
The Origin of Plants and Animals on Coral
Examples of Alternation of Generation.
Colonies.

The Origin of Atolls.

Experiences while Col-

Parasitism. Symbiosis.

VOCABULARY.

Cam panula’rian (Lat. dim. of
campana, a bell), a kind of hy-
droid whose feeding zooids live
in a bell-shaped case.

Com men’salism (Lat. cum, to-
gether, and memnsa, a table), a
state of living together for mutu-
al advantage, asin the case of the
hermit-crab and hydractinia.

Her maph’ro dite (Gr. Hermaphro-
ditos, the son of Hermes and
Aphrodite), having both male
and female reproductive cells in
the same animal.

Hy’dranth (Gr. hydor, water), one
of the nutritine zooids of a hy-
droid colony.

Hypo stome (Gr. Aygo, under, and
stoma, a mouth), the part of a
hydroid animal bearing the
mouth at its summit.

Las’so cell (Lat. /agueus, a snare),
a sensitive nettling-cell contain-
ing a coiled thread.

Me du’sa (Lat. Medusa, one of the
Gorgons), an umbrella-shaped,
free-swimming jelly-fish.

Mes’en tery (Gr. mesos, middle,
and exteron, intestine), one of
the radiating walls in the body
of a:polyp.

O’vum (Lat. ovum), an egg.

Pol’yp (Gr. polys, many, and fous,
foot), a feeding zooid of a hy
droid or coral-forming colony.

Sep’tum (Lat. septum, a fence), a
radiating portion of a coral skel-
eton. ‘

Ten’'tacle (Lat. ¢ento, to try ‘to
hold), a feeler around the mouth
of a ceelenterate.

The’ca (Gr. theké, a case), a
portion of a coral skeleton.

Zo’oid (Gr. zoém, an animal, and
oid, like), one of the members of
a coelenterate colony.

139

HYDRA AND CCELENTERATES.

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CHAPTER XIII.
THE STARFISH AND CLOSELY RELATED ANIMALS.

The Starfish. The common starfish (Asterias vul-
garis) may be easily found at low tide along:the New
England coast. To obtain the dried specimens for
study, kill the animal by immersing it in warm fresh
water. It may then be preserved by hardening it in
alcohol or in boiling water and drying quickly. or by
packing in salt. If possible get a living starfish and
place it in a pail of salt water.

How does the starfish move? Observe the amébu-
lacral feet.

Do you see the eye-spot at the end of each arm ?

Where is the madreporic body ?

Is the animal bilateral ?

Is each ray bilateral ?

Are all of the rays of the same size? How do you
explain any differences ?

Are any of the spines movable ?

Which is the oval and which the adoral surface ?

With a magnifying glass examine the aboral surface
for the purpose of finding the minute pincer-like bodies
called pedicellaria.

Can you find projections of the skin used in breath-
ing?

Examine a dried specimen.

Are all the spines of the same shape ?

How many kinds of spines do you find ?

How many kinds of plates do you find ?

140

THE STARFISH AND CLOSELY RELATED ANIMALS. 141

The walking, or ambulacral, surface is called the
ambulacral area.

How many rows of ambulacral plates in each ray?
How many rows in all ?

Do the ambulacral feet pass through these plates or
between them?

The regular plates situated on either side of the
ambulacral areas are called cxterambulacral plates, and
the surfaces they cover are called interambulacral
areas. How many rows of interambulacral plates do
you find in each ray ? How many rows in all ?

How do the spines on these plates differ from those
on the irregular plates of the aboral surface ?

The plates on the aboral surface may be called
body-plates. Can you find the single plate with its
ambulacral foot at the end of each ray ?

With a partly dissected specimen, which has been
prepared by hardening in alcohol, laying open the
upper or aboral surface of one of the rays and removing
the digestive organs, notice the ampulle or internal
enlargements of the ambulacral feet. What is the use
of the ampullze in locomotion ?

These ampullze are connected with a tube running
along the ray in the angle made by the two rows of
ambulacral plates. Trace this tube, which supplies the
ambulacral feet with water, up to the tube running
around the mouth. Find the stone canal connecting
this tube with the madreporic body. What do you
think may be a use of the madreporic body ?

Examine portions of the skeleton of a starfish which
have been decalcified by allowing them to soak in
about ten per cent. nitric acid for a few days. Compare
these with similar portions which have been treated
with weak caustic potash until the fleshy matter has
been removed. Are the plates formed inside of the
fleshy skin or outside of it?

Write resemblances and differences for starfish and
hydra.

142 ANIMAL ACTIVITIES.

Compare this starfish with the brittle starfish.

Summary of Drawings. (a) Sketch of a living
starfish.

(4) Sketch of a portion of an ambulacral area show-
ing the relative positions of the plates and the openings
for the ambulacral feet.

(c) Cross-section of an arm to show the relative posi-
tion of feet, water-tube, plates, and spines.

(2) Ambulacral feet with ampulle.

(e) Sketch of a brittle starfish.

Activities of the Starfish. The starfish belongs to
the sub-kingdom Echinodermata, animals having hard
plates in the skin.
Their movements
are slow and all
their activities are of
a low order, yet they
are more highly
specialized than the
Ccelenterates we
have just been con-
sidering.

Taking Food.
The mouth of the
starfish is situated
on the under side,
hence this side is

Fic. 116.—A Starfish. After Agassiz. called the oral side.
There are no teeth,

yet the starfish lives on oysters, clams, mussels, and
other hard-shelled animals. The stomach is an
elastic bag which fills the central part of the body
and extends into all the arms or rays, thus making the
shell simply a protection for this branching, walking
stomach. This stomach secretes a fluid which par-
tially paralyzes its prey. If a mussel is too large to
pass through the mouth, the starfish stretches a part
of its stomach outside of its body, and enfolds its

THE STARFISH AND CLOSELY RELATED ANIMALS. 143

victim until the shell opens andthe contents can be
sucked out.

Nutrition. Outside the stomach, throughout the
cavities in the rays there is a glandular mass, the liver,
which secretes a digestive fluid and pours it into the
stomach. Here the food is digested and the nutriment
absorbed. There is a very short intestine opening
opposite the mouth. It is so small in diameter that
the waste of the food cannot pass through it, and must
therefore be ejected through the mouth.

Respiration. For the most part breathing takes
place at all parts of the body, but there are folds of the
skin over the aboral surface which are supposed to act
somewhat like gills.

Reproduction. The reproductive organs, of which
there are two in each ray, lie on the floor of the ray;
their ducts opening in the angles between the rays.
These openings are called the genital openings. After
the eggs of the female and the sperms of the male
have been discharged into the water, the eggs are fer-
tilized by the sperms. From these fertilized eggs de-
velop young starfish, which are at first bilateral, and
bear no resemblance to their parents.

Discovery. The only specialized sense-organs are
the eye-spots at the ends of the rays. The nervous
system consists of a nerve around the mouth with a
branch extending into each ray and ending in the eye-.
spot just mentioned. The sense of feeling is apparently
dull, and the starfish seems to suffer no hardship by
the deprivation of one or two of its rays, which quickly
grow again when once broken off.

Movements. The starfish and its relatives have a
method of locomotion very different from other animals.
Along the oral surface of the rays are the cylindrical
tube-feet, or ambulacral feet, bearing suckers at their
extremities. These tubes extend through the skeleton
into the body-cavity, where they enlarge into bulbs
called ampulle. Each bulb connects by a small tube

144 ANIMAL ACTIVITIES.

with a larger tube running lengthwise of the ray, and
this in turn connects with a tube surrounding the
mouth. With this oral tube the radiating tubes all
unite and from this there extends the stone canal
(another tube) reaching to the madreporic body on the
aboral surface. The ambulacral feet have muscular
walls. The madreporic body is pierced with minute
holes through which water can enter the water-system.

UWI i

Fic. 117.—A Brittle Starfish.

When the starfish wishes to advance, some of the am-
bulacral feet are elongated in the direction of progres-
sion by squeezing the ampulle and forcing the water
into the feet. When the feet are fully extended the
sucker at the end of each foot fastens itself to the rock,
or other support near, and the longitudinal muscles of
the tube contract, shortening the ambulacral foot and
pulling the starfish to the rock.

THE STARFISH AND CLOSELY RELATED ANIMALS. 145

The Sea-urchin. If possible get a living sea-urchin
and watch its movements in a pail of salt water, or
better, in a salt-water aquarium.

What is the shape of the body?

Do you find oral and aboral surfaces ?

What is the shape of the spines? How do they
move ?

Do you find the ambulacral feet ?

Examine the mouth and notice the manner of feed-
ing.

Hold the living animal in the hand and observe its
mode of locomotion.

Place it upside down in the water and watch it.

Does it have bilateral symmetry or any kind of sym-
metry ?

Examine the test or shell which has been freed from
spines.

How can you tell the ambulacral from the inter-
ambulacral plates ?

How many rows of each kind of plates do you find ?

What is the shape of these plates ?

Look at broken pieces of tests.

Do you find a single plate or tentacle at the end of
each ambulacral area, as in the starfish (ocular
plates) ?

At the ends of the interambulacral areas do you find
the genital openings ? How many do you find ?

The small plates, in the circle surrounded by the
genital plates, correspond to what plates in the starfish ?

Do you find the madreporic body ?

What changes would have to occur in the body of
the starfish to give it the form of the sea-urchin ?

What parts of the sea-urchin are homologous with
parts of the starfish ?

Examine the teeth. How many teeth do you find?

Write resemblances and differences for starfish and
sea-urchin.

Compare a sea-cucumber with a sea-urchin.

146 ANIMAL ACTIVITIES.

Summary of Drawings. (a) A living sea-urchin,
natural size.
(4) A single spine showing mode of attachment to
the shell.
(c) Several ambulacral and interambulacral plates.
(d@) External form of a sea-cucumber.

Fic. 118.—The Structure of a Sea-urchin. A, interior of shell; B,

teeth.

Activities of the Sea-urchin. The activities of the
sea-urchin resemble those of the starfish. One pecul-
iarity deserves mention. The mouth of the sea-urchin

Fic. 119.—A Sea-cucum-
ber.

is provided with a complicated
arrangement of teeth, five in
number, uniting at a point.
This whole apparatus is called
Aristotle’s lantern in honor of
the philosopher who first de-
scribed it. With these teeth and
possibly by the aid of oral secre-
tions the sea-urchin is enabled
to burrow into solid rock.
Other Echinoderms. Sea-
cucumbers of many kinds, the

worm-like Synapta with its

anchor-shaped plates, the great
variety of starfishes, sand-dol-

lars, Crinoids both fossil and present, with other less
common forms all bear a striking resemblance to the

two forms studied.

THE STARFISH AND CLOSELY RELATED ANIMALS. 147

Characteristics of Echinodermata. This sub-king-
dom enjoys the distinction of being the most exclusive
division of the animal kingdom. These animals secrete
bony plates in the skin; they have marked radiate
structure, almost always being divided into five radiat-
ing parts. With the radiate structure we may also
trace a bilateral condition. (In the case of the starfish
this condition may be seen by drawing a line through
the madreporic body and the opposite ray.) The
water-system with its ambulacral feet is peculiar to this

sub-kingdom.
Topics for Reports.
Sea-cucumber as Food.
Have Seen Echinoderms.
Young Starfishes.

Basket-fish.

All are marine.
The Burrowing of Sea-urchins.
Radiate Structure.

Where I
The Senses in a Starfish.
Stone-lilies.

VOCABULARY

Ab o’ral (Lat. a3, from, and os,
mouth), the surface opposite the
mouth.

Am bu la‘cral (Lat. amdbulo, to
walk about), a word applied to
the walking areas of Echino-
derms.

Am pul’la, pl. ampulle (Lat.
ampulla, a flask), the enlarged
end of one of the tube-feet of
an Echinoderm.

De cal’cify (Lat. de, from, and
calx, lime), to remove the calca-
reous matter.

Gen’i tal o pen ings, the openings

for the passage of eggs and sperm
in starfishes and sea-urchins.
Mad re por’ic body, a hard plate
pierced with holes through
which water filters into the tube-
feet of a starfish or sea-urchin.
O’ral (Lat. os, the mouth), pertain-
ing to the mouth.
Pedicella’ria (Lat. pediculus, a
small foot or stalk), a minute
pincer-like organ on the skin of
an Echinoderm.
Ra'diate (Lat. radius, a ray),
having the parts regularly ar-
ranged around a centre.

CHAPTER XIV.
THE EARTHWORM AND HIS WORK.

THE earthworm or angleworm belongs to the sub-
kingdom Vermes. It also belongs to the class Azuu-
lata, which includes the most highly organized and
most intelligent animals belonging to this sub-kingdom.
In studying it we must note how it differs from any or
all of the Arthropoda, and discover if possible why
naturalists have not classified it with this sub-kingdom.

The earthworm may be easily observed alive by
placing several individuals in a glass jar with loam and
dead leaves, and occasionally feeding them with bits
of meat or vegetables.

Is the body bilateral ?

Can you distinguish a head ? a head end? a neck?
a dorsal and ventral surface ?

Is the body anywhere flattened ?

Are there any divisions in the body like those in the
Arthropoda ?

Are there any jointed appendages ?

Do you find any eyes? Is the worm sensitive to
touch ? to light? to strong odors ? to irritating fluids ?

While the worm is feeding can you see any teeth?
Do you see something which looks like a proboscis ?

Do you see the red blood-vessel near the dorsal sur-
face ?

Earthworms tanned by the use of chromic acid make
good specimens for class use. They may be prepared
as follows: Place the worms in dilute alcohol for three
or four days and then transfer them to strong aicohol,

148

THE EARTHWORM AND HIS WORK. 149

where they may remain for several weeks. Then put
them in a one per cent. solution of chromic acid for five
or six days. Remove
them from this solu-
tion, wash them thor-
oughly in water and
place them in a dish
with turpentine, al-
lowing them to re-
main there for a few
days longer. They
may then be dried, Fic. 120. — An Earthworm.
when they are ready

for use. The worms should be spread out in flat-
bottomed dishes during the processes of tanning.
With specimens thus prepared or simply hardened in
alcohol, the class should write the answers to the fol-
lowing questions:

Do the worms all have the same number of seg-
ments ?

Do you find several rings together which seem to be
enlarged? This is the cltellum or reproductive girdle.

How many segments from the clitellum to the head
end?

Is the body of the angleworm smooth? Does it
appear more rough when the finger is moved in any
special direction? The roughness is caused by bristles
or set@. Do they all point in the same direction ?

How many rows of sete along the body? How
many setz on a single segment?

Does the worm have an internal skeleton? Does a
thin cuticle separate easily from the body of a worm
which has been soaking in water for a time ?

Can you make out the shape of the segment in front
of the mouth ?

Summary of Drawings. (2) The whole worm, nat-
ural size.

(6) The segments near the head x 6.

150 ANIMAL ACTIVITIES.

(c) A cross-section of one segment to show the setz
x 6.

Taking Food. The earthworm has neither hard
mouth-parts for biting food nor a tube for sucking. Its
mouth is simply a hole bounded
by fleshy lips. The segment in
front of the mouth forms a sort of
proboscis or elongated upper lip
which is used to push the food
Fic. 121.—A Worm’s into the mouth. The food con-

Setee. sists of fallen leaves or any organic

matter found in or around its bur-

row. Decaying vegetable matter forms the greater
part of its food, and if it cannot get decayed leaves it can
pour out of the mouth a fluid which makes the leaf
decay and blackenat once. Since the worm gets much
of its food beneath the surface of the earth, it builds a
burrow for its home. Such a burrow isa plain hole
usually slanting from the surface down to a depth of
four or five feet, always extending below the frost of
winter. At the bottom of this hole is a small round
room carefully lined with stones or seeds. In making
this burrow the worm not only eats the vegetable matter

Fic. 122.—Worm-casts.

in the ground but swallows the earth as fast as he
excavates it, thus mixing his food with loam.
Nutrition. The worm has no teeth and no jaws; so
his food passes down the gullet or cesophagus to an
enlargement of the alimentary canal called the crop.

THE EARTHWORM AND HIS WORK. I5t

Next it goes on to the gizzard, which is filled with little
stones to make a mill for grinding the food. After
being ground, the food passes into the intestine, where
the nutritious matters are taken into the blood and
carried to the tissues of the body, while the part which
cannot be digested is cast out at the end of the body,
usually near the opening of the worm’s burrow. The
blood which carries the nutritious matter to the parts
where it is needed is of a reddish color, but the color
is in the liquid part of the blood and not in the corpus-
cles, as is the case in our own bodies.

Respiration. An examination of the earthworm’s
body reveals neither spiracles nor gills. In fact it has
no breathing organ, but takes oxygen from the air at
all parts of its skin and sends out or excretes carbon
dioxide and other impurities at the same time. The
blood-vessels are so near the surface that the necessary
interchange of gases can easily take place as long as
the worm’s skin is moist. Worms cannot live long in
the sunlight or in dry sand because they cannot breathe
under such conditions.

Reproduction. On the under side of the fourteenth
and fifteenth segments in a common species are to be
found some small openings which lead to the ovaries or
egg-producing organs. Several segments in front of
these, there are tiny holes in the grooves between the
segments. These open into receptacles containing the
male cells or sperms.

When the time for depositing eggs arrives certain
glands of the clitellum become very active and pour
out on the surface of the body a fluid which hardens
into a tough membrane, making a girdle around the
body, the reproductive girdle. A jelly-like liquid
remains between the girdle and the body while it is
gradually pushed forward. When the girdle passes the
openings to the ovaries the eggs are discharged into it,
and when it passes the segments from nine to eleven
the sperms pass into the fluid with the eggs. The

152 ANIMAL ACTIVITIES,

girdle then passes over the head and closes at both
ends, forming a capsule containing the reproductive
cells. Here fertilization takes place, and the cpps
hatch finally into litthe worms which rapidly grow by
the addition of new segments.

Discovery. We find no cycs, cars, or other organs
of sense on examining the earthworm, yet we know
that he has to some slight extent a sense of smell, for
he enjoys the smell of onions, cabbayes, and other
dainty articles of earthworm dict. Possibly, too, he
can hear a little, for he is disturbed by sounds which
shake the earth near his burrow, though utterly dis-
regarding the loudest noises made in the air above him.
Although without cyes he can tell daylight from dark-
ness; the power of doing this is said to reside in the
first few scpments of his body in which his brain is
found. He is probably somewhat sensitive to light in
all segments of his body.

His sense of touch is keenest of all and, indeed, his
whole body seems to he a sort of fecler.

Movements. The earthworm doubtless controls his
own movements to a considerable extent. Ife even
shows sig'ns of intelligence, though of i very low order.
The most brilliant thing the carthworm does is to plug
up the opening of his burrow to hide it from his
enemics. For this purpose he selects his mittcrial with
some care.

Leaves, bits of paper, twigs, wool, and sometimes
stones are used by the worm to make this plug, or door,
to his hole. Ile seizes with his lips the substances to
be used and fits them neatly to the mouth of the
burrow. When he uses a leaf he drags it in by the
part best suited by its shape to fit the place intended
for it. Mr. Darwin noticed that sometimes a worm
would let go a leaf and then try a new way of pulling:
it into his hole.

The worm also moves up and down his burow at
will, and if necessary he can travel some distance from

THE EARTHWORM AND HIS WORK. 153

home, crawling over very difficult roads and even
scaling perpendicular walls. The controlling mechan-
ism for these movements lies in a small brain situated
above the cesophagus and hence sometimes called the
supracesophageal ganglion, and in a series of ganglia
lying under the alimentary canal, a pair in each seg-
ment. These ganglia are connected with each other
and with the brain by nerves, and branches ramify from
them to all parts of the body. This arrangement of
nerve-masses along the ventral portion of the body is
decidedly advantageous to a crawling animal, giving
him constant information concerning the ground over
which he travels.

Locomotion in the earthworm is accomplished by
the use of three sets of muscles under the control of his
nervous system. One set of muscular fibres runs
lengthwise of the body, another surrounds each ring,
and a third layer sends its fibres diagonally across the
segments. When an earthworm wishes to go forward
he fixes his setz in the ground in such a way that his
body cannot move backward, but will easily move for-
ward. If, now, his body is already extended its full
length, he contracts his longitudinal muscles, thus
shortening his body and making it much thicker. He
then contracts the circular muscles surrounding the
segments, elongating the body and making it much
smaller in circumference. Since the sete prevent the
body from going backward, it must move forward. The
sete are curved near the end to make them more useful
in holding the body in place. The diagonal muscles
are used in moving the body from side to side.

The Usefulness of the Earthworm. In spite of his
apparent insignificance the earthworm is the farmer’s
loyal friend. He is a ploughman of ancient lineage
and his work is most efficient. He brings to the sur-
face fresh subsoil to replace the exhausted layer which
the farmer has been cultivating. He grinds up organic
matter and leaves it finely powdered in his castings for

154 ANIMAL ACTIVITIES.

the use of plants. He renders the earth porous for the
better spread of moisture and the more rapid pushing
of plant-roots. He buries rocks far beneath the soil
and covers old fields with fresh loam. All pupils
should read Mr. Darwin’s book entitled ‘‘ The Forma-
tion of Vegetable Mould.’’

The Earthworm’s Relatives. Along with the
earthworm are classified many animals which outwardly
bear no resemblance to him. It sometimes seems as if
naturalists reserved the sub-kingdom Vermes as a sort
of waste-box in which to place all creatures not easily
classified elsewhere. The strange ways of the Vermes
must be studied by the help of other books.

CHAPTER XV.
MUSSELS AND SNAILS.

The Fresh-water Mussel (Anodon or Unio). These
mussels may be easily obtained on the sandy bottoms
of fresh-water ponds or streams. A few should be
placed in an aquarium which has a few inches of sand
on the bottom. They do well without feeding. Little-
neck clams make good individual specimens for the
work here outlined. Boil the clams to harden them.

Notice the color and shape of the shell. How many
parts has it ?

Do you see any markings on the outside ? What do
these seem to indicate?

Does the shell seem to be covered? Compare it
with a dried shell. Is the entire surface covered?
How do you explain your observation? The bared
projection is called the wo.

How are the two parts of the shell held together ?
Is the hinge you find at the dorsal or ventral margin of
the valves? How can you tell?

In what direction does the animal move ? How fast?

Is the umbo nearer the anterior or the posterior
end? How can you tell?

Find the right and left valves.

Observe the foot. How is it used ?

Is it at the anterior or posterior end of the body ?

At the end opposite the foot find the fringed open-
ings. When the shell is open and the animal is feed-
ing comfortably, color the water directly in front of
these openings with a little indigo or cochineal solution

155

156 ANIMAL ACTIVITIES.

introduced by a pipette. What do you learn from this
concerning the manner of feeding ?

What happens when you touch the animal on its
shell and at different places on its fleshy parts when it
is feeding quietly ?

Examine a mussel or clam which has been boiled,
or hardened in alcohol.

Press the valves together and quickly release them.
Why do they fly open again ?

When the mussel was alive what held the valves
together? Explain the manner of opening and closing
the shell.

Place the mussel on its side in a dish of water so that
the dorsal portion is away from you. Is the anterior
portion of the mussel near your right hand, or your left
hand ?

Carefully remove the upper valve without disturbing
the soft parts beneath. Have you removed the right
or left valve ?

The membrane lining the interior of the shell is the
mantle which secretes the material of which the shell
is formed. Does this mantle line the entire shell? Is
it of equal thickness in all parts?

How many muscles held the valves together ?

On a dry shell do you find the marks which show
where the muscles were attached? Do you find the
muscles themselves ?

Determine which is the posterior adductor muscle and
which is the anterior adductor muscle.

Find the mark which the mantle makes where it
adheres to the inside of the shell. Call it the pal/al
line. Do you find any other markings on the inside of
the shell? Compare mantle outside of pallial line
with that above. What is the relation of mantle to
shell ?

Raise the mantle and notice the striated leaf-like
gills. How many do you find ?
Look for the Jabial palps near the anterior portion

MUSSELS AND SNAILS. 157

of the gills. How many do you find? The mouth is
between the palps.

Examine the ventral and dorsal passages of the
siphon. Are they connected? Into what cavity does
each lead ?

See if you can find the heart near the dorsal margin.

Have you found that the mussel has a head? What
organs of sense have you found ?

Examine mussel-shells which have been burned for
some hours ina hot fire. Compare with them some

Fic. 123.—A Fresh-water Mussel (47odonx) Showing Position of Foot
and Siphons.

shells which have been immersed in weak acid for
several days. Examine, also, oyster-shells which have
been prepared in the same way. Describe the structure
of a shell.

On the dorsal margins of the valves of a shell find

158 ANIMAL ACTIVITIES.

the hinge-teeth if there are any. How many teeth do
you find on each shell ?

Compare the shell of the common salt-water clam
(Mya Arenaria) with that of the mussel (Cxz0). How
do the teeth and hinge-ligament differ ?

How do the markings on the inside of the shell differ ?

What differences in the structure of the animals do
these markings indicate ?

In the same manner compare the shell of oysters,
pectens, and other bivalves.

Write a description of a shell you have not previously
seen and compare your description with that given in
Woodward’s Mollusca or a similar book.

Summary of Drawings. (a) Sketch of a living
mussel showing foot and siphons.

(4) Cross-section of valves showing action of hinge.

(c) Inside of shell showing all muscular impressions
and the pallial line.

(2) Sketch of mussel in its shell.

(e) Cross-section of the body of the mussel near the
umbo.

(/) Shells of several bivalves.

Activities of the Clam or Mussel. Feeding. We
have already noticed currents of water flowing in and out
of the siphon at the posterior end of the body. The
water enters by the ventral opening and goes out by
the dorsal opening. The dorsal and ventral passages
are separated, and this separation continues through
the body of the clam, dividing it into two chambers,
the dorsal or cloacal chamber and the branchial or gill-
chamber. In many marine clams the mantle-edges
unite again below the branchial siphon, but in the
fresh-water clam they are free along the ventral border.
As water enters the lower siphon it brings with it food
and oxygen into the branchial chamber. In_ this
chamber hang the two pairs of ridged leaf-like gills
bearing cilia which by their movements keep the cur-
rents of water in motion. These cilia also select from

MUSSELS AND SNAILS. 159

the water the minute animals and plants which nourish
the clam. These bits of food are collected along the
ridges on the gills and thence passed to their ventral
edges, on each of which there is a groove leading to the
mouth. Along this groove the food passes, whipped
on by the cilia, until it enters the mouth, which is

Fic. 124.—Fresh-water Mussel with One Valve Removed. 4, peri-
cardium; f.a., posterior adductor muscle; @.a., interior adductor
muscle; a, anus; ¢.s., exhalent siphon; z.s. , inhalent siphon; /.7.,
cut edge of mantle; o.g., outer gill; v.g., inner gill; /, foot; Z2.,
labial palps.

situated between the labial palps at the anterior end of
the body.

To understand what becomes of the water that brings
in the food we must remember that each gill is a fold
of membrane pierced with tiny holes. In order to pass

from the branchial chamber to the cloacal chamber the ---

water must pass through these holes. A cross-section
of a gill has a V shape, and the water goes through the
sides of the V into the opening above and thence passes
out of the cloacal chamber by the upper siphon,

160 ANIMAL ACTIVITIES.

Nutrition. In the clam the various processes con-
cerned in nutrition are more distinctly separated than
in any of the other sub-kingdoms below the Arthrop-
oda. When the food enters the mouth it passes down
the throat to the stomach. The dark portion of the
body surrounding this alimentary canal is the liver,
which secretes digestive fluids and pours them on the
food. The intestine beyond the stomach passes directly

Fic. 125.—Digestive Tube of Fresh-water Mussel (Anodon’. m, mouth;
Z, liver; s, stomach; z and 7, intestine; «, anus; #, pericardium;
R, kidney; s.c., chamber above gills; g, gullet.

through the heart and opens into the cloacal chamber
in the current of water which passes out of the upper
siphon.

The digested food is taken up by the blood and
carried to all parts of the body by the circulating
system. The most important organ of this circulating
system is the heart, which is situated just below the
hinge. It has a ventricle and two auricles.

In its course, part of the blood is purified by the gills

MUSSELS AND SNAILS. 161

and passes from these organs to the auricles. Part of
the blood also flows through the renal organs, which
take from the blood (excrete) the nitrogenous waste
matters and empty them into the outgoing current of
water. The ventricle forces the blood, constantly
coming to the auricles, away from the heart all over
' the body.

As in other animals, the separate cells take from the
circulating liquid the substances necessary to produce

eg
PY:
0.9.

Fic. 126.—Cross-section of Fic. 127.—Nervous System of Ano-
Anodon. n, intestine; v.e., don. ¢.g.,ganglia near the mouth;
heart; z.g. and o.g., gills; P8&., ganglia of the foot; o.¢.,
J, foot; .é., mantle. ganglia of the posterior adductor.

more cells like themselves or to manufacture intercel-
lular structures. The-cells of the mantle secrete
carbonate of lime, which forms in layers on the inside
of the shell and along its edges, thus increasing both
its thickness and its size. If the mantle be irritated by
the introduction of minute particles of foreign matter or
by disease the secretion of carbonate of lime at a defi-
nite point is hastened and a pearl is formed.
Respiration. As the water passes through the gills
it flows over and around many blood-vessels, through

162 ANIMAL ACTIVITIES.

whose walls the interchange of gases common in all
breathing takes place.

Reproduction. The eggs of the fresh-water mussel
pass from the ovaries to the cavity of the outer gill,
where they hatch. The number of young is enor-
mous. They remain for a time within these gills and
then pass out to grow or to be destroyed, as the case
may be.

Discovery. The senses of the mussel are not acute
and there are no special organs of sense. Touch is
more acute in the foot and at the margins of the
mantles, as might be expected, these being almost the
only exposed parts. There is a so-called ear-sac in
the foot, but it is not probable that the mussel can hear.

The nervous system consists of three pairs of ganglia
connected by nerves. One pair form a sort of brain
(the supraesophageal ganglia), one pair lie directly
under the posterior adductor muscle (the wisceral
gangla), and the third pair are imbedded in the tissue
where the foot joins the body (pedal ganglia).

Motion. The opening and closing of the shell at
will is brought about by the action of an elastic hinge-
ligament anda pair of adductor muscles. When the
muscles contract the shell is closed; when they relax
the hinge-ligament acts like a door-spring and forces
the valves apart.

The foot is protracted partly by muscular activity
and partly by increasing its size by pumping its vascular
vessels full of blood. When left lying on its side in
the aquarium the animal rises to an erect position by
sinking its foot into the sand. It plows its way through
the mud or sand by muscular contractions of this foot.

The Garden-slug. Obtain some garden-slugs, or,
better still, some of the larger slugs found in damp
cellars or green-houses. Keep them in a box with
plenty of moisture and feed them with cabbage-leaves
and bread. Watch the mode of locomotion. Allow
the animal to crawl on a piece of glass and watch the

MUSSELS AND SNAILS. 163

movements of the foot. Examine the trail of mucus
left as the animal advances.

Do you find the place from which this mucus comes?

Do you find a head? a neck?

What organs of sense do you find? Describe their
position.

How does the slug feed ? Has it a shell ? a mantle?

On which side of the body is the breathing orifice ?

How often does the slug breathe ?

How often do you breathe ?

Is there any relation between rapidity of breathing
and rapidity of movement ?

Do you call the slug’s body warm or cold ?

Fic. 128.—A Slug.

Does the rate of breathing have anything to do with
the snail’s temperature ?

Write resemblances and differences for slug and fresh-
water mussel.

Sketch the slug as you see him.

Pond-snails. These animals are found in almost
all ponds, crawling on dead leaves or aquatic plants.
They may be easily kept in a jar of water for class-
study. Get some pond-snails and keep them in a jar
of fresh water. Watch all their movements.

Write resemblances and differences for snail and
slug. Note all points mentioned in regard to slug and
mussel.

164 ANIMAL ACTIVITIES.

Can a snail leave its shell and return ?
’ Can it close its shell ?

Examine different kinds of snails for this charac-
teristic.

Do all the snails you have seen breathe in the same
way?

(Can a snail swim ?

Can it walk on the surface of the water ?

Is the snail bilateral ?

Compare a land-snail with a water-snail.

Study several shells and notice the swtures, the
apex, the spire, the whorls, the lines of growth, the
aperture, and the “~. Compare these parts in snail-
shells of different kinds.

Notice all other differences and tabulate your obser-
vations. The columella is the axis of the spire. The
piece which closes the snail’s shell is the operculum.

Hold the shell with the apex upward. Is the aper-
ture toward the right (dextra/) or the left (s¢zzstral) of
the columella ?

Is the aperture xotched or entire ?

Describe a shell from observation of the specimen
and compare your description with that found in a’
standard work.

Summary of Drawings. (a) A pond-snail as it
appears while crawling xX 3.

(4) A shell of litorina or similar shell.

(c) A shell of purpura or a similar shell.

(Z) A shell of a limpet.

(e) Right valve of an oyster.

(7) Various shells showing different structures.

Snail and Mussel. A comparison of the snail and
mussel shows on the part of the snail a distinct advance
in the collecting of organs of sense at the anterior por-
tion of the body and the growth of a head there. The
possession of a head with a brain and active sense-
organs is apparently associated with the matter of food-
supply and feeding. So long as a soft-bodied animal

MUSSELS AND SNAILS. 165

can have all the food he wishes brought to him by
currents of water there is no use for head, or eyes, or
sensitive feelers. On the other hand, an animal which
must forage for his food can do it more advantageously
if he learns to walk head foremost. In order to make
great progress in this way he must have some means
of discovering obstacles in his pathway. Hence the
necessity of feelers and eyes. In the struggle for food
among animals the headward growth and specialization
is a great advantage.

Active exercise in earning a living in competition
with other animals which desire the same food not only

Fic. 129.—A Snail.

sharpens the wits but actually increases the physical
development of those organs on whose activity intelli-
gence depends, just as vigorous muscular exercise
develops the parts trained.

Mussels and snails belong to the sub-kingdom Mol-
lusca. The mussels, clams, oysters, and similar
bivalves are members of the class Pelecypoda. These
animals are sometimes called Lamellibranchiata be-
cause they have four leaf-like gills, and sometimes
Acephala because they have no heads.

Univalves like the snails and the limpets, and slugs
which have no shells, are classed as Gastropoda.

166 ANIMAL ACTIVITIES.

Another important class of mollusks is the Cephalop-
oda. The squid belongs to this class, as do the

Fic. 130.—A Squid. P,
its pen.

octopus, the argonaut, and the
pearly nautilus.
Characteristics of Mollusca.
The name Mollusca is given
on account of the fact that the
bodies of these animals, ex-
cepting the shell, have no hard
parts. In Mollusca the body
is typically bilateral. There is
a mantle present which in most
cases secretes a shell which is
as much a part of the animal
as is the mantle itself. These
shells increase in size as the
animal grows, and .so exhibit
lines of growth. A fleshy foot
is also present. The nervous

system consists of three pairs of ganglia connected by
nerves. Eyes are present in many forms and in the

higher cephalopods they closely re-
semble the eyes of Vertebrates. In
all but the Pelecypoda the mouth is
provided with a lingual ribbon, which
is a sort of rasp in the mouth by
which in many cases thick shells may
be bored entirely through.

Questions. How do the sense-
organs of mollusks. which forage for
food compare with those of sedentary
mollusks ?

What protective devices do you
observe among mollusks ?

How can one compel an oyster to
produce a pearl ?

Topics for Reports. Tyrian Dyes.

BIQIRE

IVI ne

A40

Sta

c nae ‘

r

aX

Fic. 131.—Part of
a Lingual Rib-
bon (magnified).

Eye-stones.

The Octopus and Squid. The Chambered Nautilus.

MUSSELS AND SNAILS.

The Argonaut.
Oyster Farming.
The Ship-worm.
Scallop.

167

Some Fabulous Monsters of the Sea.
Pearl Fisheries.
Wampum and Suckanhock.

Famous Pearls.
The

VOCABULARY.

4Adduc’tor (Lat. ad, to, and duco,
lead), a word applied to the
muscles which hold together the
shells of bivalves.

An’o don (Gr, «, priv., and-edous, a
tooth), a genus of fresh-water
mussels having no hinge-teeth.

Bi'valve (Lat. 42, two, and vadva,
a leaf of a door), having two
shells which open and shut.

Bran’chia (Gr. éranchia, gills, pl.
of branchion, a fin), gills.

Bys’sus (Gr. dyssos, a kind of flax),
a bunch of tough threads by
means of which some bivalves
attach themselves to rocks.

Car niv’orous (Lat. caro, flesh,
and vore, to devour), flesh-eat-
ing.

Columel'’la (Lat. dim. of colu-
men, a column), the upright pil-
lar in the axis of a univalve shell.

Dex'tral (Lat. «dexter, right),
right-handed,

E pider’mis (Gr. ef¢, upon, and
derma, skin), the outer skin of an
animal.

Her biv’o rous (Lat. herda, grass,
and voro, to devour), vegetable-
eating.

Hinge Lig’a ment (Lat. “igo, to
bind), an elastic substance forc-
ing open bivalve shells when the
muscles relax.

Lin’gual Rib’bon (Lat. dingua,
tongue), a rasp-like organ used
in boring holes through shells.

Man'tle (Lat. manus, hand, and

tela, aweb), the soft outer cover-
ing of the body of a mullusk,
commonly just under the shell.

Na’‘cre, mother of pearl.

soph’a gus (Gr. o7so, will bear
and phagein, to eat), the tube
leading from the mouth to the
stomach,

O per’culum (Lat. operculum, a
lid), the lid closing the aperture
of a snail’s shell.

Pal’lial Line (Lat. pa//ium, a man-
tle), the mark on the inside of a
mollusk-shell made by the man-
tle.

Se’te (Lat. pl. of seta, a bristle),
bristles.

Sin‘is tral (Lat. s/xzs¢er, left), left-
handed.

Si’phon (Gr. siphon, a siphon), a
tube for passing water through
the gill-cavity of a mollusk.

Su’pra @ soph a ge’al (Lat. supra,
above, and esophagus), an ad-
jective applied to the ganglion
above the throat.

Um bil'icus (Lat. wmbdtlicus,
navel), an opening near the cen-
tre of the base of some spiral
shells.

Um'bo (Lat. wmbo, the boss of a
shield), a prominence near the
hinge of a bivalve shell.

Un’io (Lat. wns, one), a genus of
fresh-water mussels. :

Whorl, one turn of the spire of a
univalve shell.

ANIMAL ACTIVITIES.

168

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CHAPTER XVI.
THE STRUCTURE AND ACTIVITIES OF A FISH.

GOLDFISH or other small fish from streams or
ponds are easily kept in aquaria. With a few living
fish placed where pupils can observe them, and a
smelt or perch from the market as an individual
specimen for study on each bench, the following ques-
tions may be answered:

Shape and Covering, Is the fish bilateral? Esti-
mate length, thickness, and depth.

What is the shape of the body ?

Do you find a head? a neck?

Do you find scales? Do they cover the entire
animal ?

Are the scales joined edge to edge (¢esselated) or
do they overlap (¢méricated)?

Remove some of the skin. What is the appearance
of the muscle below ?

Notice the line extending along the side of the fish
from head to tail (/a¢eral line). Do the scales cover-
ing this line differ from those found elsewhere on the
body?

The Fins. How many fins do you find? How
many are dorsal? How many ventral? How many
are paired ?

Which fins correspond to the limbs on our own
bodies ?

The paired fins nearest the head of the perch are
_called the pectoral fins, those somewhat farther back
nearer the anal opening are called the pelvic fins. The
large fin along the back is the dorsal fin. The unpaired

169

170 ANIMAL ACTIVITIES,

fin along the median ventral line is the aval or ventral
fin. The fin at the end of the tail is the camdad fin,
Sketch a fish with fins extended. Indicate the names
of the fins.

Of what use are the bones in the fins (finsrays)?

Docs the fish swim by using: its fins, or its tail, or
both ?

The Head. What organs of sense do you find ?
The cars are internal.

Are the eyes movable?) Do they have lids? Plow
docs the eye of the fish resemble the eye of man? ol
the grasshopper? Flow dees it differ from these ?

Do the nostrils open into the mouth? Use a tooth
pick for a probe. Arc the nostrils of ase in breathing: ?
Of what use are they ?

Docs the mouth open vertically, or laterally 2? Where
wre the teeth situated ? What is their shape? Whit
about the shape and position of the tonpue ¢

Gills and Heart. What movements does the fish
make while breathing: ?

Kaise the gill-cover of the specimen on the bench.
‘low many gills do you find? Tow many pill-cletts
yy Spaces between the pills ?

The bony supports of the gills are called AramAfal
arches. Vhe soft delicate red branches from these
arches are the gil-filaments. In these the blood is
purified. What is the color of the blood of a fish?
Can you see the branchial arches by lookinge inte the
mouth of a fish ?

Kemove the skin and muscular walls from that por-
tion of the ventral cavity directly behind the galls,
This exposes the heart. Can you cee the swellinges
indicating the two cavities of the heart, the analy and
the ventricle 2 The ventricle has the form of a tris
angular pyramid, “Uhe auricle is thin-walled andl tiled
with venous blood, hence it looks like a clot of blood
attached to the ventricle. ‘The Jarge blood-vessel
from the heart to the gills is the ventral aorta. [hs

THE STRUCTURE AND ACTIVITIES OF A FISH. 17%

enlargement near the heart is called the arterial bulb.

The 9 blood-vessels
bringing blood to the
heart are called veins.
Do you find the ventral
aorta, the arterial bulb,
anda large vein? Make
a sketch to show their
position.

Sketch a single gill
from a cod, or other
large fish. Indicate the
parts observed. Trace
the course of the blood-
vessels in an injected
specimen.

Internal Structure.
With a sharp knife
make a cross-section
of the body of a fish a
little in front of the
anal opening. Sketch
the appearance of the
section, showing the
location of the vertebral
column or back-bone,
the spinal nerve within
the neural cavity, the
visceral cavity, and the
muscles surrounding
all. Do you find any
large blood-vessels ?

Place the fish on
its side in the bottom
of a pan containing
water enough to cover
it. With scissors re-

Fic. 132.—The Circulation of Blood in
a Fish. <A, aortic bulb; ZH. heart; B,
arteries supplying gills; V, veins; b.
veins conveying aérated blood from
the gills to the dorsal aorta; Z, vessels
of liver; A’, kidney.

move the portion covering one side of the digestive

172 ANIMAL ACTIVITIES.

cavity, being careful not to disturb the organs within.
Do you find the body-cavity ?

Pass a probe down the mouth until you are able to
make out the stomach, the cesophagus, extending from
the mouth to the stomach, and the intestine, extending
from the stomach to the anal opening. This is the
alimentary canal. Is the intestine coiled or straight?
Sketch this alimentary canal.

Do you find a membrane holding the stomach and
intestine in place? This is the mesentery. Do you
see blood-vessels in the mesentery ?

In the front of the body-cavity do you see the large,

Fic. 133.—Internal Organs of Fish. @, cesophagus; dca, stomach; /,
duct of swimming-bladder; 4, swimming-bladder; 4, ovary.

brownish liver? Can you find a gall-bladder, green
or yellow in color, attached to the liver ?

In the body-cavity can you see the reproductive or-
gans? Usually these are smooth and whitish in the
male and yellow and granular in the female.

Directly under the back-bone do you find the air-
bladder? This organ is homologous with the lungs of
higher vertebrates. Do you also find a large blood-
vessel above the air-bladder ?

Brain and Nerves. Use the head of a large fish
obtained from the market. With great care remove
the upper part of the skull. Commonly it is better to
use preparations previously dissected by the teacher.
These may be kept in formalin, or alcohol. The

THE STRUCTURE AND ACTIVITIES OF A FISH. 173

largest pair of globular masses are the opizc lobes. In
front of these we find the cerebral lobes, corresponding
to the cerebrum or front brain in man. Behind the
optic lobes the cerebellum is situated. Sketch the brain
showing all these parts, showing also the olfactory
nerves extending to the nostrils, the optic nerves lead-
ing to the eyes, the auditory nerves leading to the
ear-sac with its ‘‘ear-stone,’’ and the sfzza/ nerve
extending along the back.

The Bones of a Fish. Skeletons or parts of skele-
tons can be easily prepared for laboratory use by soak-
ing in hot water. Heads and backbones of large fish
can be obtained without cost at the markets in most
places.

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Fic. 134.—Skeleton of a Fish.

With the skeleton of a fish notice the visceral cavity
and the neural cavity. What is the relation of these
cavities ?

Notice the brain-cavity. Where was the brain con-
nected with the spinal cord ?

Do you find openings for nerves extending to ears,
eyes, and nostrils ?

Do you see how the skull is joined to the vertebral
column ?

174 ANIMAL ACTIVITIES.

How is the lower jaw suspended from the skull ?

Separate the back-bone, or vertebral column, into
parts (vertebra). Are the vertebre near the tail like
those near the head? Study particularly one of the
vertebrzee near the tail. The main part of a vertebra
is the centrum. Is the centrum entirely solid? What
is its shape in a longitudinal section after removing all
soft parts? Sketch front and side view of a vertebra,
and a longitudinal section.

Do you find the cavity for the spinal cord? Call
this cavity the neural cavity, and the processes at-
tached to the centrum and enclosing the neural cavity,
the neural arch, and the spine above it the neural
spine. Is this spine dorsal or ventral? Does it
point towards the anterior or the posterior part of the
body ?

Do you find the cavity for the passage of the large
blood-vessel ? Call this the hemal arch, and the spine
attached to it the hemal spine. This arch protects
the dorsal aorta. Are there any ribs present?

Using one of the vertebrz above the visceral cavity,
find how it differs from a vertebra near the tail.

Summary of Drawings. (a) Side view of fish with
fins extended.

() Side view of head of a fish showing as many parts
as possible.

(c) Gill of a fish showing parts. Heart of fish with
arteries and veins.

(d) Cross-section of the body of a fish a little in front
of the anal opening. Sketch of alimentary canal.

(e) Brain of fish with nerves.

(/) End view of a vertebra from near the tail.

(g) End view of a vertebra above the visceral cavity.

(2) Longitudinal section of a vertebra.

Vertebrates. The study of a fish introduces us to
the class Vertebrata of the sub-kingdom Chordata.
The possession of a back-bone made up of vertebra
gives this class its name. This back-bone furnishes a

THE STRUCTURE AND ACTIVITIES OF A FISH. 175

flexible axis for the body, and separates the neural
from the visceral cavities.

In the young of all vertebrates a rod of cartilage
called the notochord runs through the body between
the two cavities just mentioned. In some of the lower
vertebrates this rod persists throughout life, but in nearly
all cases it disappears with the hardening of the centra
of the vertebrz. The soft substance extending through
the centra of the vertebrz of the fish probably repre-
sents in that animal the remnant of a notochord. In
all adult vertebrates higher than fishes there is left no
trace of this structure.

The neural cavity, as its name implies, contains the
main nerve of the body, the spinal cord. This cord is
enlarged at its anterior end in almost all vertebrates,
forming a brain. In all higher vertebrates and in by
far the greater part of those lower in organization, this
brain is enclosed in a bony box called the skull.
Paired organs of sense are connected with the brain.
The visceral cavity contains the organs of digestion,
the heart, and organs of reproduction. In higher
vertebrates it also contains the lungs.

In the great majority of vertebrates there are two
pairs of limbs. These are, in the higher vertebrates,
usually attached to the main axis of the body by con-
necting bones called respectively the pectoral girdle
and the pelvic girdle. Even in vertebrates which have
no arms or legs rudiments of these girdles may some-
times be found.

Fishes. The fishes (Pisces) include animals which
live in water and breathe by gills. The body is usually
covered with scales, and the form is adapted for loco-
motion through the water. The paired fins are chiefly
used for balancing the body, and the caudal fin is the
principal organ of locomotion. Although nasal sacs
and nostrils are present, they do not connect with the
mouth or throat. There are no external: ears. In
most fishes an air-bladder is present, often connecting

176

with the gullet.

specific gravity of the fish in the water.
is used in producing a noise.

ANIMAL ACTIVITIES.

This bladder serves to vary the

Sometimes it
It is homologous with

the lungs of higher vertebrates.
The heart in fishes consists of one ventricle and one

auricle.

Impure blood, collected by the veins, gathers

in the auricle and passes to the ventricle, whence it is
forced through the gills where the ordinary interchange

of gases takes place.

all parts of the body by arteries.
What do you mean by saying that a fish

Questions.
is cold-blooded ?

The blood is then distributed to

See Fig. 132.

How much can a fish see ?

How much can it hear ?

What is meant by saying that a fish’s ears are
probably organs of equilibrium ?
Where are organs of equilibrium situated in some

other animals ?

How does the tail of a shark differ from that of a

salmon ?

How do the skeletons of the two animals differ ?

Topics for Reports.

The Migrations of Salmon.
The Sea-serpent.

Electric Eels.

The Nests of the Stickleback.

Bream. Trout. Sharks.
Flying Fish.

VOCABULARY.

Aor'ta (Gr. aeiro, to raise), the
large artery of the body.

Ar’te ry (Gr. arteria, windpipe),
a tube carrying blood away
from the heart.

Caudal (Lat. cada, tail), pertain-
ing to a tail.

Centrum (Lat. centrum, a centre),
the body of a vertebra.

Cerebel’lum (Lat. dim. of cere-
érum), the hind brain. It con-
trols combined muscular action.

Cer’e brum (Lat. cerebrum, brain),
the front brain, the seat of the
reasoning faculties.

Chor da’ta (Gr. chordé, a chord).
The sub-kingdom including the
back-boned animals.

He'mal (Gr. haima, blood), per-
taining to theblood. Sometimes
used with the same meaning as

. visceral.

Het erocer’cal (Gr. heteros, differ-
ent, and serkos, tail), applied to
the tails of fishes having unequal
lobes.

Homocer'cal (Gr. omos, same,
and kerkos), a word applied to
the tails of fishes having equal
lobes.

THE STRUCTURE AND ACTIVITIES OF A FISH.

Im’brica ted (Lat. zmdrvex, gutter-
tile), overlapping.

Max'illary (Lat. macero, to soft-
en), pertaining to the jaw; com-
monly to the upper jaw.

Mes’entery (Gr. mesos, middle,
and enxteron, intestine), in verte-
brates the membrane holding
the intestines in place.

Neu’ral (Gr. zeuron, a nerve), per-
taining to the nerves. In verte-
brates it is applied to the dorsal
cavity of the body.

No tochord (Gr. zotos, back, and
chordé, a cord), a rod of carti-
lage from which the vertebral
column develops in vertebrates.

soph’a gus (Gr. o7sd, will carry,

177

and phagein, to eat), the tube
connecting the throat with the
stomach.

O per’culum (Lat. operculum, a
lid), the gill-cover in fishes.

Pec’toral (Lat. pectus, breast),
pertaining to the breast.

Tes’sellated (Lat. Jsessel/atus,
checkered), formed in squares
like mosaic.

Ver'te bra (Lat. verto, to turn),
one of the sections of the verte-
bral column.

Vis’ce ral (Lat. viscera, internal
organs of the body), pertaining
to the internal organs; applied
to the ventral cavity in verte-
brates.

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CHAPTER XVII.
TADPOLES AND FROGS.

In the study of the frog, aquaria are indispensable.
The expense, however, need not be large. In one
aquarium tadpoles should be placed together with a few
aquatic plants. The minute green plants which grow
on the sides of the aquarium will furnish food enough.
The adult frogs can be kept in a box with glass sides
with only a small amount of water in the bottom and
a netting to cover the top. In warm weather frogs
feed on insects; in winter they go without food.

The Tadpole. Is it bilateral ?

Is the skin naked or scaly? Do you see a lateral
line?

In what ways does it resemble a fish ?

How does the tail of a tadpole differ from the tail of
a fish?

In any of the tadpoles can you see the beginnings of
limbs ? Which limbs appear first ?

In a young tadpole how do the gills appear ?

Can you see the gills in an older tadpole? Do tad-
poles come to the surface of the water to breathe ?

Can you find in a specimen which has been hardened
in alcohol a gill-cavity ? Can you find an opening into
this cavity?

Are the jaws hard or soft? Watch the tadpoles
feeding on the sides of the aquarium, or jar.

How does the size of the mouth compare with that in
the adult ?

179

180 ANIMAL ACTIVITIES.

In a specimen which has been hardened in alcohol
do you find vertebre ? Do you finda notochord? Do
you find muscles like those in the fish? Notice the
spirally coiled intestine.

Hold the tail of a living tadpole under a compound
microscope and observe the movement of the blood.
Notice the corpuscles.

Summary of Drawings. (a) Side view of tadpole.

(4) Dorsal view of a young tadpole to show gills.

(c) Sketch to show blood-vessels as seen under the
microscope.

The Frog Alive. How does the frog resemble the
fish ? the tadpole?

Do you find scales, hair, claws, or nails?

Do you find tail or fins? How about legs?

What is the frog’s mode of locomotion on land? in
water ?

How many divisions have the hind limbs? the fore
limbs ? How do they compare with the limbs of the
human body? Do the joints move in the same way as
ours? Do you find arm, forearm, and wrist ?

How many fingers? How many toes? Are fingers
or toes webbed? Do you find a thumb ?

How does the frog take its food? How does the
tongue act?

What movements are made in breathing? Are
there any gills? How long can a frog live under
water?

Does the frog have the same senses and the same
organs of sense as man ?

Do you find ears? eyelids? Do you finda mem-
brane covering the eye (nictitating membrane) ?

Frog Hardened in Alcohol. Look in the mouth.
Do you find any teeth? How many? Where are
they ?

What is the shape of the tongue?

Do the nostrils connect with the mouth ?

Does the ear-cavity connect with the mouth?

TADPOLES AND FROGS. 181

(Eustachian tube.) Cut open the membrane covering
the ear and use a probe.

Using a prepared specimen showing the internal
ergans, do you find the peritoneum? the mesentery ?
the stomach * the intestine? the liver? the heart ?

Do you find the lungs?

Is there a diaphragm separating the heart and lungs
from the stomach, liver, and intestine ?

Dorsal to the viscera in a freshly prepared specimen
look for nerves branching out from the spinal cord.
Do you find nerve-masses (ganglia) on these nerves on
each side of the spinal column? Are these ganglia
connected by a nerve running lengthwise? Call this
the sympathetic system of nerves.

In a prepared specimen notice the brain and spinal
cord. Sketch the brain in outline. How does this
sketch compare with the sketch you have made of the
brain of the fish ? c

In what ways does a frog resemble a fish? How
dees the frog differ from the fish ?

Summary of Drawings. (a) Outline of organs seen
in the visceral cavity.

(4) Sketch of ganglia of sympathetic system with
connecting nerves.

(c) Outline sketch of brain of frog.

Activities. Both the structure and the activities of
the frog interest us because they are so much like those
of man himself. The frog has been much studied
because of the remarkable changes in structure and
habits which the animal undergoes after leaving the
egg.
Taking Food. The frog lives on insects, worms,
and other small animals. As a rule frogs eat only dur-
ing the summer months, remaining torpid without food
in winter. The tongue of the frog is peculiarly adapted
for catching insects. It is fastened to the lower jaw
by its front end, and turns a somersault when shot out
at a fly. The hinder end is covered with a sticky

182 ANIMAL ACTIVITIES.

saliva which holds the fly a prisoner until the jaws
close over him. The ease and quickness with which
an insect disappears are
always a surprise to the
observer.

When feeding on large
animals the frog seizes his
prey with jaws and front
legs, and hurriedly crowd-
ing his luckless victim into
his mouth, swallows him
alive. Teeth are present
Fic. 135.—Tongue ofa Frog. onthe upper jaw and on the

palate or roof of the mouth.

Taking Oxygen. When the young frog emerges
from the egg it takes air from the water by means of
external gills. Into these the blood is pumped directly
from the heart, as in fishes. Here the oxygen passes
into the blood for purification, and thence is conveyed
to all parts of the body.

In a few days these external gills disappear, and
other gills grow under the opercular membrane. This

Fic. 136.—A Young Tadpole Showing External Gills.

membrane is joined to the body-wall except on the left
side, where an opening for the passage of water remains.
The young frog now breathes like a fish. The

TADPOLES AND FROGS. 183

heart, too, like that of a fish, has only two chambers,
an auricle and a ventricle.

After a time lungs develop, and the tadpole, while
still using his gills to some extent, finds it necessary
to come to the surface of the water occasionally for air.
Finally the gills disappear and the frog breathes only

Fic. 137.—Under Side of Tadpole Showing Coiled Intestine and Internal
Gills.

by lungs. While these changes are going on, the
heart develops another auricle on the left side for the
reception of the purified blood from the lungs. The
right auricle receives the impure blood returning from
the circuit of the body.

Not only does the frog, at different times, breathe in
the three ways just mentioned, but at all times it

Fic. 138.—Heart of Fic. 139. — Blood-cells
Adult Frog. a, of a Frog. a, red cor-
auricles ; v, ven- puscle; 4, colorless cor-
tricle. puscle.

breathes by the entire surface of the body, the skin
being especially rich in blood-vessels.

184 ANIMAL ACTIVITIES.

The adult frog pumps the air into the lungs by the
movements of the muscles of the throat and lower part
of the mouth-cavity. When the mouth-cavity enlarges,
air rushes in through the nostrils. When the cavity
contracts, valves close the openings to the nostrils and
the air is forced down into the lungs. The frog has

Fic. 140.—Blood-corpuscles of Man. 5s, 7’, 7’, red corpuscles; ~ and
&, white corpuscles; ¢, crystals.

neither ribs nor diaphragm—organs of great importance
in our own breathing.

The oxygen, once taken by the blood, is carried by
the red corpuscles, or blood-cells, to all parts of the
body, where in the capillaries it is given up to burn,
or oxidize, tissues and food substances in order to
produce heat and energy.

Nutrition. Food passes from the mouth to the
stomach, where it is acted on by fluids like those in our
own bodies. It then passes to the intestines, where
the bile secreted by the large liver and the pancreatic

TADPOLES AND FROGS. 185

juice from the pancreas are poured upon it. Here
further changes take place and the digested food is
absorbed and taken to the blood-vessels. The un-
digested portions of the food pass along the intestine
to the cloaca, which is the common receptacle for use-

Fic. 141.—Viscera of Frog. Si./n., small intestine; Z.Z, large intes-
tine; Ur. B/., bladder; Ze.ca., pericardial cavity; V, ventricle; 7.4.,
large artery; Ao, aorta; ~, pulmonary artery; Px, pancreas.

less substances from the food-tube, and the kidneys
and eggs or sperm-cells from the reproductive organs.
Thence the useless matter and the reproductive cells
pass from the body.

When the tadpole first comes from the egg, the food-
tube quickly grows into the long coiled tube shown
in Fig. 137 and this in turn gives place to the tube as
we have seen it in the adult frog.

It is interesting to note that the lungs, liver, and
pancreas are outgrowths from the side of the food-tube,

186 ANIMAL ACTIVITIES.

produced by a pushing out of the walls of the tube
itself (Fig. 143).

Excretion. Carbon dioxide and water are taken by
the blood-corpuscles to the breathing organs and to the
skin, where they are thrown out of the body. Urea and

GATE

(PYLORUS). STOMACH

12 INCH PIPE
DUODENUM —

SMALL Ewin LARGE
INTESTINE = é INTESTINE

THE COLON

Fic. 142.—Digestive Organs of Man.

water are taken from the blood by the kidneys and
passed along to the urinary bladder and thence out ot
the body.

Reproduction and Metamorphosis. The female
frog deposits her eggs in the water in spring in large
jelly-like masses. As soon as hatched the young tad-

TADPOLES AND FROGS. 187

poles cling in clusters to plants, or other objects; life
being sustained by the food-yolk within the body.
After a few days, a mouth with horny jaws develops
and the animals begin to feed.

The tadpole now eats plants, being especially fond
of the green conferve so common on the sides of
aquaria.

Growth is now rapid, and in a few months the legs
appear and the tail is absorbed.

E
Fic, 143.—Growth of Frog’s Lung from Primitive Food-tube.

Movements. The most important organs of motion
are the muscles. A muscle causes movement by
shortening itself, and thus bringing nearer together its
two ends with whatever is attached to them. In gen-
eral, muscles are attached to bones. How muscle and
bone together produce movement may be well under-
stood by studying Fig. 148 in connection with the
movements of the human arm.

188 ANIMAL ACTIVITIES.

(

\

A muscle shortens because the cells of protoplasm
tility. The cells

(~) all contract in one
SZ SZ the whole muscle

Fic. 144.—Growth of Frog’s Egg. shorter and thicker.
are under the control of the nerves.

A number of muscle-cells make one of the fibrille.
fibre. The fibres are wrapped in bundles, and these
bundles are covered by a thin layer of tough connective
and fibres unite to form tendons by which the muscles
are attached to the bones (Figs. 149 and 150).
the leg of a frog or of a man, show peculiar cross-mark-
ings. Muscles not under the control of the will, like
are commonly unstriped.

The bony skeleton of the frog,
the movements of the body, has
an axis of nine movable bones,
long bone, the urostyle, reaches
to the hips, and in front is at-
skull and large jaws. On the
base of the skull are two rounded
which fit into corresponding de- Tadpoles.
pressions on the atlas-bone, the

The fore limbs are attached to the axial skeleton by
muscles and ligaments. A shoulder, or pectoral girdle,

of which it is composed all have the power of contrac-
direction, making
These contractions
Several of these fibrilla wrapped in a sheath form a
tissue. The sheaths or coverings of muscles, bundles,
Muscles under the control of the will, like those in
those of the intestine or stomach,
on which the muscles act to cause
the vertebra. Behind these a
tached the head with its broad
prominences called condyles, Fre, 145.—Very Young
first bone of the vertebral axis (Fig. 151).
consisting of several bones is present. The hinder

TADPOLES AND FROGS. 189
limbs are attached to the axial skeleton through the

pelvic girdle. The bones of the arm consist of the
humerus, or forearm, the radio-ulna, corresponding to

Fic. 146.—Various Stages of Tadpole.

the two bones, the radius and ulna in man, the carpal
or wrist-bones, the metacarpal or hand-bones, and the
fingers or phalanges. In the leg are the femur or
thigh-bone, the shin-bone corresponding to the ‘67a

Fic. 147.—Young Frogs.

and fidula in man, the ¢arsal bones, two of which are
much longer than the others, the me¢atarsal or ankle-
bones and the phalanges (Fig. 152).

Controlling the organs of motion and extending into

190 ANIMAL ACTIVITIES.

every muscle for that purpose is the nervous system.
This consists of a brain connected with the spinal cord,
and a series of ganglia with nerve connections in the
visceral cavity. From these centres nerves run to all
parts of the body. The division between brain and spinal
cord is not so sharpasin man. The brain itself has the
same parts as the brain of man, but these parts do not
have the same shape or relative size (Figs. 153 and 154).

BICEPS MUSCLE | iif
t} i]

i,

\ )
'RICEPS
H MUSCLE

Fic. 148.—The Use of a Muscle.

Notice how large the olfactory and optic lobes appear
in the frog. In man they are small and do not show
in the figure. In man, too, the cerebrum or forebrain
has grown so large that it occupies almost the whole
of the brain-cavity. These facts of structure would
seem to indicate that sight and smell are of more im-
portance to the frog than memory or reason.

Discovery. It is the duty of the nervous system to
keep in touch with the outer world, in order that the
movements made may be useful to the animal.

TADPOLES AND FROGS. Ig!

Sight. The optic lobes just mentioned are con-
nected with a pair of eyes very much like our own.
Each eye is really a camera obscura with its lens and
darkened walls. The image of an external object is
thrown on the ve¢zza, which corresponds to the ground
glass of a camera and is composed of nervous tissue
forming the end of the opzzc nerve. The frog sees well,

Sel pa ee erig ee OTS

Fic. 149.—Striped Muscle-fibres. A, a fibre much magnified; 2B, a
fibre breaking up into fibrilla.

as is evidenced by the precision with which he strikes
a fly with his tongue.

Hearing. On either side of the head is a dark cir-
cular spot which indicates the position of the ear. This
ear is wholly internal. Under the skin is a membrane,
or ear-drum, and under that a cavity, the middle ear.
This cavity connects with the mouth by the eustachian
tube as in man. Back of this cavity is another, the
inner ear, containing the nerves which conduct sound
vibrations to the brain.

Smell. In the nasal cavities fibres of the olfactory
nerve are spread out to receive the sensations of smell.

192

ANIMAL ACTIVITIES.

Taste. Special organs of taste are found on the
tongue and on the membrane lining the mouth.

Fic. 150.—Unstriped Muscie-fibres.

Touch. The skin is well supplied
with nerves, and there are special
tactile areas.

Classification. The frog belongs
to the division of Vertebrata known
as Amphibia or Batrachia. They
receive their name Amphibia from
the fact that the young live in water
breathing by gills, while the adult
forms breathe air. As might be ex-
pected, there are exceptions to this
general rule. The Amphibia are
destitute of scales, the skin being
perfectly naked, and in most cases
provided with peculiar glands. They
have no claws. The Amphibia differ
from the fishes in having a connection
between the mouth and nostrils, and
also between mouth and ear. The
heart in the adult has three chambers,
a ventricle and two auricles. In the
larva the heart is two-chambered.
All live in fresh water. To this class
belong the toads, frogs, and sala-
manders.

Reptiles. Questions similar to
those used concerning the frog may
be answered about turtles and snakes.
Living turtles and snakes are easy to
obtain and fairly easy to keep alive.
A large box with glass sides covered
with wire netting makes a good vi-
varium. Sand and gravel and a dish

of water should be kept in the bottom of this box. A
little moss provides a carpet.
The class Reptilia resemblesin many ways the

TADPOLES AND FROGS. 193

Amphibia. The class includes many animals resem-
bling toads and salamanders, besides the well-known
turtles, snakes, crocodiles, and alligators. Among
Reptiles the body is more or less completely covered

Fic. 151.—A Frog’s Skeleton.

by scales, and when there are any toes these are armed
with claws. The heart is three-chambered, as in the
case of Amphibians, except in alligators. The young
do not breathe by gills as in Amphibia. The eggs are

194 ANIMAL ACTIVITIES.

commonly large and when deposited for hatching out-
side of the body are covered with a limy shell. A

CLANICLE/

Fic. 153.—Brain of
Frog. O/, olfactory
lobes; CH, cerebral
hemispheres ; OpZ,
optic lobes; C7,
cerebellum; 7/0,
medulla oblongata,

Fic. 152.—A Man’s Skeleton.

peculiarity of the skull of Reptiles is the presence of
the quadrate bone, a characteristic shared also by
birds.

TADPOLES AND FROGS. 195

OEREBRUM

MEDULLA 5
OBLONGATA_}
CEREBELLUM

SPINAL CORD

SPINAL OOLUMN

——

és a OuT ENDS OF
i WOE SPINAL NERVES
e

Fic. 154.—Brain and Spinal Cord of Man.

ANIMAL ACTIVITIES.

For NOTE-BOOK.

Fish,

Tadpole.

Frog.

Turtle.

Head and
Neck.

Limbs.

Claws.

Covering of
Body.

Teeth.

Skeleton.

Heart and
Lungs.

Organs of
Sense.

Movements.

CHAPTER XVIII.
BIRDS.

IN birds the skin produces feathers instead of scales
as in fishes and reptiles. For the study of birds,
pigeons or English sparrows are easily obtained. Birds
that are sold for food may be bought at the markets
and used to illustrate different parts of the work. Living
birds of some sort should be kept in the laboratory for a
time while bird-study is going on. Of course nothing
can take the place of out-of-door work with this class of
Vertebrata. In answering the following questions a
living bird should be observed, and stuffed specimens
of the English sparrow should be in the hands of the
pupils.

The Sparrow. Note the shape and color of differ-
ent parts, method of locomotion, both in walking and
flying, how it eats and drinks and cares for its feathers.

Do you find eyelids? Do you find a wzctitating
membrane? This is a thin membrane at the inner
corner of the eye. How does the membrane act?

Does the bird have ears? Where are they?

Does it have teeth? How would you describe the
mouth ?

Do you find nostrils? Is the breathing rapid or
slow? What do you think about the bird’s tempera-
ture ?

Does the bird use its wings while walking ?

What seems to be the use of the tail ?

Does the bird moult ?

197

198 ANIMAL ACTIVITIES.

Where does the bird find the oil used in preening its
feathers ?

How does-the size of a bird’s egg compare with the
size of its body? How does the size of a frog’s egg
compare with the size of its body ?

Are the senses of the bird keen or dull? Does the
bird have the same senses as man?

How would you describe the song of the bird you
are studying ?

The Wing. What is the shape of the wing?

How many joints has it?

Do you find bones corresponding to those of your
own arm, forearm, wrist, palm, and fingers? Use a
prepared skeleton of a wing.

How many bones in arm, forearm, wrist, and palm ?
How many fingers? Is there a thumb? Sketch the
skeleton of the wing.

Does the skeleton of a frog show a similar structure
of the arm? How does the arm of a turtle compare
with the wing of a bird?.

Do you find feathers on the thumb? on the hand ?
on the forearm ? on the arm?

The Leg and Foot. Do you find thigh, shin, ankle,
foot, and toes? Where is the heel? Sketch the
skeleton of the leg.

How many toes? Do all the toes point in the same
direction ?

Are there feathers or scales or both on the tarsus ?

When scales are present what is their shape ?

Are there webs between the toes?

In a fresh specimen can you find the tendon which
moves the toes? How do the toes act in perching ?

Feathers. Obtain some large feathers from the
wing or tail of a pigeon or a barn-yard fowl. Notice in
a single feather the shape as seen in outline. Do you
make out the shaft and the vane? Sketch a feather.

Can you separate the parts of the vane into branches
of the shaft (barbs) ?

BIRDS. 199

Using a simple microscope, can you find that the
barbs themselves bear branches (barbules)? Sketch
a magnified barb showing barbules. :

What seems to be the use of the barbules ?

Do the feathers from different parts of the body seem
to have the same parts?

Examine a downy feather and a pin-feather. How
do those compare with the other feathers ?

What is the appearance of the skin of a fowl from
which the feathers have been plucked ?

Are the pits from which feathers grow equally dis-
tributed over the body ?

Summary of Drawings. (a) Sketch of skeleton of
a wing, naming humerus, radius, ulna, carpal, and
metacarpal bones, and phalanges.

(4) Sketch of a wing covered with feathers.

(c) Side view of foot and leg, naming femur, fibula,
tibia, tarsus, metatarsus, and phalanges.

(@) Sketch of whole feather.

(e) Sketch of a barb showing barbules (magnified).

a
oC

ol

fis. 1§5.—a, beak of snipe, fitted for probing in soft mud; 4, beak of
sparrow, fitted for cracking seeds ; ¢, beak of eagle, fitted for tear-
ing flesh ; d, beak of parrot, fitted for cracking nuts; ¢, beak of
swift, fitted for seizing insects while on the wing ; /, beak of duck,
fitted for skimming the water.

The Activities of the Bird. Taking Food. Very
noticeable is the difference between the bill of a bird

200 ANIMAL ACTIVITIES.

and the jaws of a frog or fish. Noticeable, too, is the
resemblance between the bill of the bird and that of the
turtle. The hard toothless mandibles, however, are well
fitted for the purpose of securing the insects and seeds on
which most birds feed. Before man invented tweezers,
the woodpeckers pried into the bark of trees and pulled
out the hidden insects with their long, strong pliers.
These illustrations show some of the forms the beak
takes to make it a better tool for procuring the particu-
lar kind of food on which the bird lives. In addition
to its other uses the beak often serves as a hand.
Birds and Insects. Insect-eating birds devour tons
of destructive pests in our orchards and fields. It has
been estimated that a single chickadee may destroy
mre than a hundred thousand canker-worm eggs in

Fic, 156.—The Digestive Organs of a Bird. a, cesophagus; 4, crop;
C, stomach; ¢, gizzard.

one day. Even crows feed on insects more than on
corn. Hawks and owls keep in check field-mice and
frogs, gulls clean the shores of decaying matter, and
many of the smaller birds live on the seeds of noxious
weeds. The importance of preserving bird life cannot
be easily overestimated.

BIRDS. 201

Nutrition. The processes of nutrition are carried
on in much the same way as in other vertebrates. In
most birds the food, when swallowed, passes down the
cesophagus to an enlargement called the crop, where it
remains for a short time. It then goes to the stomach,
which frequently consists of two
parts, the proventriculus, where
gastric fluids are poured on the
food, and the gizzard, where it
is ground. This gizzard is most
highly developed in seed-eating
birds, and commonly contains
stones which the bird has swal-
lowed and which grind up the
food that has been softened in
the crop and mixed with gastric
juice in the proventriculus. Fic. 157.—Diagram of the

Respiration. Breathing Heart of a Bird.
occurs by lungs, the air enter-
ing and leaving because of the increase and decrease
of the size of the body-cavity produced by movements
of the bones and muscles surrounding it. The expan-
sion of the lungs in breathing is very slight. The lungs
connect with air-sacs which extend among the other
internal organs, and even into the bones. These serve
to increase the bulk of the bird without adding to its
weight, thus forming a sort of hot-air balloon.

Reproduction. Eggs are produced in the ovaries,
and pass from these organs through the left oviduct,
the right ovary being suppressed in birds, to the cloaca
and thence out of the body. The cloaca is the
common cavity into which the alimentary canal, the
kidneys, and the oviduct empty.

In its passage through the oviduct the egg receives
from the walls of this tube its layer of white albumen and
its calcareous shell. The eggs hatch outside of the body
and are cared for by the parent birds with much solici-
tude. Except with a few of the most intelligent insects,

202 ANIMAL ACTIVITIES.

there is very little attention given to the young of animals
lower in the scale of life than birds. Here maternal
and paternal duties seem of the greatest importance.

Discovery. The senses of birds are very keen,
especially those of sight and hearing. There is an
external opening to the
ear surrounded by regu-
larly arranged feathers.
The nervous system re-
sembles that of the fish
and frog, but the brain
is much larger in com-
parison with the size of
the body, the cerebrum
and cerebellum being
greatly developed.

Motion. In this func-
tion birds surpass all
other animals. Not
only can some _ birds
move through the air
more rapidly than the
fastest express train, but
others can swim most
skilfully in the water,
and still others are able
to run faster than a race-
horse on land. Of
course, no one bird can do all these things, for when
wings are greatly developed for very rapid flight, as in
the swallow, feet are weak and almost useless; and
when running is specialized, as in the ostrich, wings
become small and of little use. The swallow does not
alight even for the purpose of feeding her young.

In the wing, as we have seen, the bones resemble
those in the human arm (Fig. 160). At the elbow
the arm is bent, and the space between the arm and
forearm is filled with a strong web bearing feathers and

Fic. 158.—The Skeleton of a Bird.

BIRDS. 203

assisting in spreading the wing. There are only three
fingers, and the bones of these and of the palm and
wrist are so grown together that it is difficult to distin-
guish them. Connected with the wing are two clavi-
cles, or collar-bones, which unite at their ends to form
the wish-bone. These, with the scapulars or shoulder-
blades and the coracoid bones, form the pectoral girdle
holding the wings in place.

While the chief organ of flight is the wing, it must
be remembered that the whole body aids in aerial navi-

ile, as joe 8

Fic. 159.—A Swallow Feeding Her Young.

gation. The sternum or breast-bone is large and
strong and fastened firmly to the ribs. Its surface is
often increased by a ridge of bone along the middle
called the keel (Fig. 162). The muscles of the breast
attached to this sternum move the wings. These
muscles are dark colored and tough in birds of great
wing-power and white and tender in barn-yard fowls
which have lost the power of continuous flight.

204 ANIMAL ACTIVITIES.

Besides this machinery of bone and muscle, the
whole body of the bird is to some extent a balloon.

Fic, 160,—A, arm of man; B, fore leg of dog; C, wing of bird; 4,
humerus; 7, radius; #, ulna; c¢, carpus’ m, metacarpus; #,
phalanges.

a b

Fic. 161.-—A Bird’s Wing. «a, when flying; 4, at rest.

The feathers increase greatly the amount of air dis-
placed, and hence aid the buoyancy without adding

BIRDS. 205

“materially to the weight. The whole plumage of a
common fowl weighs only about three ounces.

Having plumage filled with air heated by the body,
carrying air-sacs in viscera and bones, breathing faster
than other animals, pumping
blood more rapidly to all parts
of its body, and with it, oxygen
to replenish the internal fires,
the bird easily rises on the atmos-
phere much as an iron ship floats
on the ocean.

Other Voluntary Movements.
Swimming birds have the toes
webbed to serve as paddles and
the form of the body is modified
to fit it for motion through the
water. The legs are placed
farther back so that the propel-
ling power may act from behind.
In running and wading the struc-
ture of legs, feet, wings and beak
are wonderfully fitted for their
peculiar work. é

Not only can birds move from Fic, 162.—The Sternum
place to place in search of food, of a Shrike,
or in undertaking their long
migrations, but by voluntary movements they are also
able to perform skilled labor in the building of nests,
to carry on warfare, and to express the most varied
emotions.

Birds and Reptiles. Birds resemble reptiles in
many ways. They have epidermal scales on some part
of the body, the digits end in claws, the lower jaw is
connected to the upper jaw by a quadrate bone, the
skull is fastened to the first vertebra by a single con-
dyle, true ribs are present, there are no gills, the eggs
are large, and the digestive, reproductive, and excre-
tory organs empty into a single cavity, the cloaca.

206 ANIMAL ACTIVITIES.

Some fossil birds had teeth like reptiles, and at least
one bird had a long reptilian tail (Fig. 166). Because
of these resemblances birds and reptiles have sometimes
been classed together as Sauropsida.

Classification of Birds. Birds have been most com-
monly classed in accordance with their most easily

Fic. 163.—Feathers. «, a quill-feather; 4, quill-feathers fastened to
wing ; ¢, a shape-feather ; d, a down-feather.

recognized points of external structure; this structure
being dependent largely on the hahits of the birds.

These groups of birds are often spoken of as orders;
but these orders do not correspond to orders among
insects.

BIRDS 207

I. The Running Birds (Struthii). The legs are long and
the wings small. The keel of the sternum is lacking.
There are two or three toes. Ostrich, emu, kiwi.

II. The Scratching Birds (Rasores). They have three
toes in front, and a fourth a little higher, behind. Grouse,
pheasant, common hen.

Fic. 164.—A Bird’s Leg.

III. Swimming Birds (Natatores). The legs are short,
and there is a web between the front toes. Penguin, duck,
gulls, etc.

IV. Wading Birds (Grallatores). The tarsus is long and
partly naked. The neck is also long and often the bill.
Great blue heron, snipe, etc.

V. Birds of Prey (Raptores). These birds have stout
curved beaks, strong feet with sharp claws, and large wings.
Hawk, eagle, owl, etc.

208 ANIMAL ACTIVITIES,

VI. The Pigeons (Columbine). These birds resemble
the rasores but have weaker legs, pointed wings, and a fleshy
membrane at the base of the beak. Pigeon,

VII. Climbing Birds (Scansores). Two toes are directed
forward and two backward, fitting the feet for climbing.
In parrots the beak is also used for climbing. Parrots,
woodpeckers,

_ VIII. Perching Birds (Passeres). ‘There are three toes
pointing forward and one pointing backward, all on a level.
Here belong almost all our common song birds.

Fic. 165.—A, foot of a pelican; &, foot of a perching bird; C, foot of
a kingfisher.

Questions. What are some common birds of very
rapid flight ?

What special adaptations of structure to habit among
birds can you enumerate ?

Why do birds migrate ?

What birds should be exterminated ?

What birds should be protected ?

Do birds reason ?

What evidences of intelligence have you observed
among birds ?

Topics for Reports. A List of Birds I Know. A
List of Birds I have Seen in Winter. Order in which

BIRDS. 209

I Saw New Birds in Spring. Description of a Bird I
Know Edible Birds’ Nests. Birds on Oceanic
Islands. The Future of the Domestic Sparrow. Bird
Pets. Bird Courtships. Bird Migrations. Bird In-
dustries. Superstitions about Birds. Canaries. Do-
mesticated Birds. Parrots. Crows. The Robin.
Birds in Millinery. Uses of Gulls. What Mr. Bur-

Fic. 166.—The Archzopteryx.

roughs says in ‘‘ Birds and Bees and Sharp Eyes.’’
Bird Homes. Shapes and Colors of Birds’ Eggs.
Length of Life among Birds. Falconry.

VOCABULARY.

Am phib’ia (Gr. amphi, around, or | Barb’ule (Lat. dim. of davda), one
on both sides, and dzos, life), a of the projections along the edges
class of vertebrate animalsbreath- of the barbs of a feather.
ing by gills when young, Bat ra’chia (Gr. batrichos, frog),

Au'ricle (Lat. auris, ear), a cham- another name for the Amphibia.
ber of the heart for receiving | Car’pus (Gr. arpos, wrist), the
blood from the veins. wrist.

Barb (Lat. darba, beard), one of | Cloa’ca (Lat. c/oaca, a sewer), a
the side branches of a feather. common cavity into which the

210

alimentary canal, the kidneys,
and the oviducts empty.

Con’dyle (Gr. Londylos, knuckle),
a bony projection.

Eu sta’chian Tube, a passage
from the throat to the ear.

Fe’mur (Lat. femur, thigh), the
thigh-bone.

Fib’u la (Lat. fula, a clasp), the
outer of the two bones of the leg
below the knee.

Hu’merus (Lat. humerus, the
shoulder), the bone of the upper
part of the arm.

Keel, in birds, the ridge of bone
along the ventral side of the ster-
num.

Met acar’pus (Gr. meta, beyond,
and carpus), the group of bones
between the wrist and fingers.

Met atar’sus (Gr. meta, and far-
sus), the group of bones between
the tarsus and phalanges.

O’viduct (Lat. ovum, egg, and
duco, to lead), a tube for the
passage of eggs.

Phalanx, pl. phalanges (Gr. pha-
tanx, battle-line or bone of finger
or toe), one of the finger- or toe-
bones.

ANIMAL ACTIVITIES.

Ra’dius (Lat. radius), one of the
bones of the forearm.

Ret’i na (Lat. rete, a net), the inner
coat of the eye.

Reptilia (Lat. repéilis, a rep-
tile), a class of vertebrate ani-
mals.

Shaft, the midrib of a feather.

Ster’num (Gr. stevnon, breast), the
breast-bone.

Tar’sus (Gr. ¢avsos, a flat surface),
the ankle.

Ten’don (Lat. ¢endo, to stretch),
a cord or band of connective
tissue usually binding muscles to
bones.

Tib’ia (Lat. ¢/déa), one of the bones
of the leg below the knee.

Ul'na (Lat. w/na, elbow), a bone of
the forearm.

U'ro style (Gr. oura, tail, and sty-
Zos, a column), the long bone at
the end of the vertebral column
in the frog.

Vane, the web of a feather with its
shaft.

Ven'tricle (Lat. ventriceulus, dim.
of venler, the belly), a chamber
of the heart for forcing blood
into the arteries.

CHAPTER XIX.

MAN’S NEAR RELATIVES (MAMMALS).

WITH slight variations, the questions which follow
can be made to apply to many other animals than the
cat. With the limited time usually allowed for the
study of mammalia, abundant material among common
domesticated animals is easily within the reach of all
pupils.

The Living Cat. With what is the body covered ?

Do you find the same parts of fore and hind limbs as
in the frog?

How many toes has the cat on the fore foot ? on the
hind foot ?

Can the claws of the cat be withdrawn ?

Can the claws of a dog be withdrawn ?

On your own hands where are the parts correspond-
ing to the pads on the fore foot of the cat?

Can you find the cat's elbow, wrist, knee, and heel ?

Does the cat ever walk or creep with the heel touch-
ing the ground?

In the human body the tendon of Achilles is the
strong band connecting the heel with the muscles of
the calf of the leg. Can you find this tendon in the
cat?

Are the cat’s vertebre capable of more or less motion
than those of the frog? Than those of a bird ?

Do the vertebra extend into the tail ?

Does the sternum seem as large as in most birds?
Why should there be a difference ?

21r

212 ANIMAL ACTIVITIES.

Do both upper and lower jaws move? Can the
jaws move sidewise ?

How many teeth has a cat? How do they differ in
shape from those in the human body ?

The dental formula for man is written 23, c}, py $,
m3. This means that in man there are in each half-
jaw two incisors, or cutting teeth,
one canine or pointed tooth, two
premolars, small grinding teeth,
and three molars, large grinding
teeth. Write the dental formula
for the cat.

What peculiarity do you notice
Fic. 167.—Teeth of Man. about the tongue of the cat ?
Are the long hairs near the
cat’s mouth especially sensitive? Do you think they
are of any use to the cat in searching for prey?

What is the shape of the external ear of the cat?
In what direction do the ears point? Are they better
fitted to hear noises in front or behind ?

Fic. 168.—Teeth of Dog.

How do the cat’s ears compare with those of a
rabbit ? What difference in habit may be indicated by
the difference in ears?

MAN’S NEAR RELATIVES (MAMMALS). 213

In the cat's eye can you make out the cornea (white
of eye), the iris, and the pupil ?
Is the pupil of the cat’s eye of the same shape at

Fic. 169.—Teeth of a Sheep,

midday as at night? How do you account for the
difference ?

Do you find the rudiment of a nictitating membrane ?

Does the cat have an acute sense of smell? What
reasons have you for your answer?

How does the cat nourish its young ?

Summary of Drawings. (a) The eye of a cat as
seen at noon, and at night.
(4) Sole of fore foot of cat showing pads.

214 ANIMAL ACTIVITIES.

Using the same questions as have been used con-
cerning the cat, except such questions as obviously do

Fic. 171.—Skull of Cow Showing Teeth.

not apply, write a description of the horse. Answer
also these additional questions:

SCLEROTIC COAT.
CHOROID COAT

CILIARY MUSCLE

CORNEA
AQUEOUS HUMOUR
UPIL

Fic. 172.—The Human Eye.

How does the food of a horse differ from that of a
cat? How do the teeth differ in shape?

MAN’S NEAR RELATIVES (MAMMALS). 215

How does the end of the horse’s toe compare with
the cat’s toes ?
How does the distance between heel and end of toe

Fic. 173.—Skeletons of Man and Horse. After Flower. S, shoulder;
£, elbow; W, wrist; “, hip; K, knee; 4, ankle.

on the horse compare with the same measurement on
the cat?

What difference in habit corresponds to the difference
in structure of the foot and leg ?

Write resemblances: and differences for horse and
cat.

216 ANIMAL ACTIVITIES. |

Fic. 175.— Vertebral
Column of Man. C,
cervical; D, dorsal;

Fic. 174.—Bones of Leg and Arm of Man. ZL, tumbar.

MAN’S NEAR RELATIVES (MAMMALS). 217

Summary of Drawings. (a) Side view of fore and
hind leg of horse.

(6) Side view of head of horse.

Other Mammals. As far as possible the above
questions should be answered for the rabbit, squirrel or

Fic. 176.—Human Skull. .4, base of skull showing condyles at 13, 13.

mouse, cow or sheep, and several other mammals
which can be easily observed by the pupils.

218 ANIMAL ACTIVITIES.

The Mammalian Skeleton. For this study the
class should be provided with at least one entire
mammalian skeleton. A sheep’s head, with the
vertebre of the neck, and a sheep’s legs may be
bought at almost any market. The muscles and
tendons can be easily removed after boiling. Heads
and limbs of fowl, rabbits, frogs, and other ver-

Fic. 176.—Human Skull. J, side view.

tebrates should also be obtained at the markets
and prepared for class use. A human skeleton, or
a large chart showing the bones of the human
body, should be used as a basis for comparison.
Indeed a number of charts, showing parts of
skeletons of a variety of mammals, should be at
hand.

MAN’S NEAR RELATIVES (MAMMALS). 219

The Fore Limbs. The bones of the fore quarter of
a sheep fastened to a board in their proper positions
serve well as the objects of this study.

Do you find humerus, radius, ulna, carpal bones,
metacarpal bones, and phalanges ?

Fie. 177.—First and Second Vertebre of Man. A, axis; 8, atlas; 6, 6,
sockets for condyles.

Do you find the same number of carpal and meta-
carpal bones as in man ?

How many fingers do you find? How do they
compare in position and length with those of man ?

What difference in use corresponds to the differ-
ence in structure of hand and wrist in the sheep and
man?

In the pectoral girdle do you find shoulder-blade
(scapula) and collar-bone (clavicle) as in man? How
do you account for the difference ?

Drawing. Sketch of the fore leg of the sheep,
naming the parts.

The Hind Limbs. Do you find femur, tibia, fibula,
tarsal bones, metatarsal bones, and phalanges?

Do you find the same number of tarsal and meta-
tarsal bones asin man? (See Fig. 174.)

How many toes do you find? How does their
number compare with those in man? Inthe cat? In
the horse? Inthe frog? In the turtle?

220 ANIMAL ACTIVITIES,

How many bones compose the pelvic girdle ?

By what kind of a joint is
the femur attached to the
pelvic girdle ?

Drawing. Hind leg,
naming bones.

The Axial Skeleton. How
many vertebre compose the
back-bone ?

How many ribs are present ?

How many of these are fast-
ened to the sternum ?

How does a mammalian
vertebra compare with a verte-
bra of a fish ?

How does the vertebral
column in a mammal differ
from that in the frog ?

The vertebra on which the
Fic. 178.—Skeleton of Go- Skull moves is called the atlas,

rilla. the vertebra next back of that

is called the axis. Can you

find on the atlas smooth sockets corresponding to pro-
jections on the skull ?

The projections on the skull are called condyles.
How many condyles are there on the mammalian
skull? How many on the bird’s skull ? What purpose
do condyles and sockets serve ?

Do you find a quadrate bone on the mammalian
skull ?

What is the dental formula of the mammal you are
studying ?

What is the dental formula for the horse? For a
squirrel? For a rabbit ?

In the head of a horse, how does the area of face and
cranium compare with the same areas in man ?

(See figures.) Write resemblances and differences
for skull of gorilla and man.

MAN'S NEAR RELATIVES (MAMMALS). 221

(See figures.) Write resemblances and differences
for limbs of gorilla and man.

Fic. 179.—Diagram Showing Circulation of Blood in Man.

Mammalian Viscera. From a tanned or alcoholic
specimen showing the internal organs of a rat or other
small mammal answer these questions:

222 ANIMAL ACTIVITIES.

Do you find the visceral cavity divided by a thin
muscular wall (the diaphragm)? Isthere a diaphragm

Skeleton of Bat Showing Wings.

Fic. 180.

in the frog or fish? Inthe bird? How does the dia-
phragm assist in breathing ?

Can you find the lungs and heart? Are they an-
terior or posterior to the diaphragm ?

MAN’S NEAR RELATIVES (MAMMALS). 223

Ts the liver anterior or posterior to the diaphragm ?
Drawing. The internal organs in position, showing

Fic. 181.— Arm and
Hand of Man.

only lungs, heart, diaphragm,
liver, stomach, and intestine.

The Class Mammalia. The
mammals bring forth their young
alive, and nourish them during
infancy by milk secreted by the
mother. They have warm blood,
and in almost all cases the body
is covered with hair.

The vertebrz in the mammals
are usually flattened. The skull
moves: on the first vertebra by
means of two condyles. There
is no quadrate bone. All have
the fore limbs, and nearly all

Fic. 182.—Skeleton of Chim-
panzee Showing Hand.

have also the hind limbs. Normally there are five

toes on each foot.

Almost all mammals have teeth,

224 ANIMAL ACTIVITIES.

and very many have two sets, the milk-teeth and the
permanent teeth. The visceral cavity is divided by
the diaphragm into two parts, the thorax or chest, and
the abdomen. External ears are present in most cases.
The heart has four chambers (Fig. 179).

The nervous system differs from that of other verte-

Fic. 183.—Fore Foot Fic. 184.—Fore Foot of Cat.
of Mole. a, with claws extended;
6, with claws drawn in.

brates largely in the greater size of the cerebrum or
forebrain. ;

Fingers and Toes. As we have already pointed
out, the mammals have normally five fingers for each
hand or fore foot, and five toes for each hind foot. In
many different ways these digits have been changed
and adapted to their special work, yet the fundamental
plan of structure has remained unaltered. Our own
hands are the most perfect animal tools in existence,
capable of manifold and delicate movements, but they
do not differ as much from the fore feet of cats, bats,
or even whales as we might at first suppose. The chief
point of superiority in the human hand is found in the
position and scope of movement of the thumb. In
some of the higher monkeys the thumb is opposed to
the fingers very much as in man, but in all cases the

MAN’S NEAR RELATIVES (MAMMALS). 225

power of movement is much less, and the whole hand
is far more clumsy; yet the hands of men and the hands
of monkeys possess almost identically the same bones,

Vic. 185.—lore Feet of Cow, tic. 186.—Fore Feet of Horse.

tendons, and muscles. They have also the small
callous, or hard, parts of the palm, with thick cushions
of fat beneath, te protect the working parts between

Fic. 187.— Foot of Elephant. Fic. 188.—Feet of Bear,

the outer skin and the hard bones. These callous
spots are easily seen, too, in the fore feet of cats, dogs,
bears, and many other mammals, and they may, with

226 ANIMAL ACTIVITIES.

Fic, 189.—A, sole of foot of man; 2B, of dog; C, of horse; @, heel; 4,
callous; ¢, cushion; 7.—V., digits. (From Flower, ‘‘ The Horse.’’)

MAN’S NEAR RELATIVES (MAMMALS). 227

some care, be found even in a hand or fore foot so
much specialized as that of the horse.

Hands and Feet. As we have already found, the
bones of the hind feet closely resemble those of the fore
feet, or, in other words, hands and feet are built on the
same plan. The palm of the hand corresponds to the
sole of the foot, showing the same ridges and callosities.
Animals which put the whole sole of the foot, from toe

Fic. 190.—Finger of Man and of Horse. After Flower. a, callous; 4,
cushion; ¢, nail.

to heel, on the ground when they walk are said to be
plantigrade animals. Quadrupeds, like the bear, which
walk in this way have a somewhat awkward gait. The’
more graceful and easy runners among beasts walk on
the ends of their toes. These are said to be digitigrade
animals. The horse presents an extreme illustration
of the digztzgrade foot, walking as he does on the ends
of his middle toes and middle fingers. We, ourselves,
walk on the whole sole of the foot, but when we run
we rise on the toes. If we should attempt to walk on
all fours, bearing the weight of the body on soles and

228 ANIMAL ACTIVITIES.

palms, we could hasten only by rising on fingers and
toes. Should we so rise it is easy to see that the little
finger and the thumb would not touch the ground.
They would hang as useless members behind the
other fingers. Rising still more, the weight would rest
wholly on the middle finger, and two more fingers
would become useless. Something like this has prob-
ably taken place gradually in the development of digi-
tigrade feet.

The Horse’s Foot. The ancestry of the horse has
been traced back very carefully for thousands of years

Fic. 191.—Feet of Ancestors of Horse. The figures indicate the num-
bers of the digits in the five-fingered hand of most mammals.

before man dwelt upon the earth. It has been found
that the horse is probably a descendant of a five-toed
animal not much larger than a sheep. From this
animal the line of descent has been followed down
through the ages, the various forms showing the loss
of toes, one after another, until only one now remains
for each foot. The splint bones seen on each side of
the long metacarpal and metatarsal bones of the horse
are all that remain of the two toes which last dis-
appeared.

MAN’S NEAR RELATIVES (MAMMALS). 229

Growth from the Epidermis. MHair, claws, hoofs,
and horns are all made of the same substance as our
own finger-nails. All are modifications of the epider-
mis or outer skin. In its growth a hair dips down into
the true skin, forming a papilla which is sunken into
the dermis or true skin. This papilla is provided at
its base with glands for oiling the hair, muscles for
erecting, blood-vessels for nourishing, and nerves for

Fic. 192.—Growth of Hair. A, hair-rudiment; 4, hair-rudiment with
young hair formed, but not yet risen through the cuticle; C, hair
protruded.

warning. When the hair is long and twisted we call
it wool, when smooth, fine, and soft we call it fur.
On the pig the coarse, straight hairs are called bristles.
The quills of a porcupine are stout hairs with sharp
points, very useful to the animal in defending itself from
enemies. Hairs are colored by pigment-cells found in
each hair. Commonly among wild animals the color
of the hair serves to conceal the wearer from enemies;

230 ANIMAL ACTIVITIES.

in many cases even changing with the seasons to afford
a better protection. The arctic fox and the northern
hare become near as white as snow in winter. It has
been found that the fact that most animals are lighter
in color beneath than above is really a device for con-
cealing them.

Horns. These defensive weapons are formed from
the epidermis in much the same way as hair. In

FIG. 193.—1, horns of sheep; 2, horns of cow; 3, horns of deer.

domestic cattle the horns have an interior core of bone
over which the skin of horn fits. The horns of deer
are solid, but in the velvet are covered with epidermis.
They fall off each autumn and grow again in the spring.

Structure of Teeth. The teeth of mammals are
composed chiefly of a bony substance called dentine,

MAN’S NEAR RELATIVES (MAMMALS). 231

and a harder substance called enamel. In a human
tooth the enamel covers entirely the outside of that
part of the tooth known as the crown. The root, or
fang, of the tooth is covered by a substance called
cement. The greater part of the tooth is dentine. In
the teeth of many animals which must grind their food
for a long time the enamel and dentine are so folded
together that hard sharp ridges of enamel are produced
above valleys. When these valleys are deep they are
filled with cement, as in the case of the molar teeth of

No-tecth in

front an
Ue ag

Fic. 194.—Skull of Cow Showing the Bone of the Horn,

the horse. As these teeth wear away the dentine and
cement wear faster than the enamel and the ridges
become more prominent.

Gnawing animals, like the squirrel, have teeth fitted
with enamel in front and dentine behind. As the teeth
are used the dentine is worn away and a sharp chisel
of enamel is produced. These teeth constantly increase
in length from below, and, if they are not worn away
fast enough, they sometimes grow so long that they
cannot be used at all and the animal starves. In every

232 ANIMAL ACTIVITIES.

animal the teeth seem to be especially adapted for the
work they must perform.
Questions. Refer to Figs. 178, 198, and 196.

Fic. 195.—A Manlike Ape Walking.

In what way does a gorilla or a chimpanzee resemble

man ?
How does man differ from these animals ?

MAN’S NEAR RELATIVES (MAMMALS). 233

In what respects are the monkeys peculiarly well
fitted for their environment ?

How do monkeys differ from dogs ?

In the struggle for existence what advantages do

Fic. 196.—A Chimpanzee.

monkeys have over dogs? What advantages do dogs
have over monkeys ?

How do monkeys differ from horses ?

In what respects do they resemble horses ?

234 ANIMAL ACTIVITIES.

What are the most easily recognized characteristics
of Fishes? of Amphibians? of Reptiles? of Birds? of
Mammals?

What is the dental formula of an animal you have
examined ?

How do the teeth of a cow differ from those of a
squirrel ?

How does hair differ from wool ?

235

MAN’S NEAR RELATIVES (MAMMALS).

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CHAPTER XX.
THE DISTRIBUTION OF ANIMALS.

Distribution in Land, Water, and Air. We have
already discovered that we must look in different places
to find different animals. We should not think of
searching for bees in a desert, nor for cockroaches in
the fields along with grasshoppers and crickets. We
have learned that the larve of dragon-flies and mos-
quitoes live in the water, while the full-grown insects
inhabit the air. We do not expect to find caterpillars
either swimming or flying. The place in which an
animal lives is called its haéitat. Animals living
mostly in the air are said to be aerza/, those inhabiting
the dry land terrestrial, and those dwelling in the
water aguatic. Aquatic animals may be either fresh-
water or marine forms.

Distribution in Altitude. In either of the above
cases the distribution seems to be influenced by alti-
tude, or, as we speak of it in the case of aquatic animals,
by depth. One species of butterfly is found only on
the summits of the White Mountains in New Hampshire;
others are always seen flying near the ground in the
valleys, while still others live in mid-air. Among
marine animals this dependence on altitude is very
marked. If the piles of a wharf be examined at low
tide we find the animal life marked off into distinct
zones parallel with the various levels of the water.

Distribution Over the Earth’s Surface. We are
familiar with the fact that certain animals are charac-
teristic residents of definite portions of the world.
Animals belonging exclusively to arctic, temperate, or

236

THE DISTRIBUTION OF ANIMALS. 237

tropical regions are well known to every intelligent
person. In the same zone, too, different regions vary
greatly in the life they support. The bison and grizzly
bear belong to North America. The gorilla is found
only in the forests of the western coasts of Africa.
New Zealand has no native mammals except bats.
Monkeys with prehensile tails live only in the New
World. Continents have animals very different from
those living on islands very near their borders.

_On the other hand, the domestic fly flourishes every-
where, and the house-sparrow seems to thrive as well
in America as in Europe. Distribution over the earth’s
surface is often called Geographical Distribution.

All the animals inhabiting a given region constitute
its fauna, just as the plants inhabiting a locality consti-
tute its flora.

The entire region inhabited by a certain kind of
animal is often called its area of distribution. In the
case of animals which migrate or wander from place
to place the area of distribution may be spoken of as
the range.

Dispersals. In modern as well as in ancient times
many animals have greatly extended the areas in which
they live. The changes made in recent years have
been carefully studied, to furnish a guide in explaining
the movements of animals in the past. Doubtless
many of the same causes which influence animal dis-
tribution now have been always active.

The Milkweed-butterfly. The milkweed-butterfly
is an American insect. In about the year 1845 it first
appeared in the Hawaiian Islands. At about the same
time its special food-plant (Asclepias) appeared and
became a troublesome weed. This butterfly soon
spread over many of the Pacific islands, following the
spread of its food-plant. It has also extended eastward
to Bermuda, and is sometimes found in England and
France. In this case the dispersal has been aided by
commerce; for the seeds of the food-plant as well as

238 ANIMAL ACTIVITIES.

the eggs, or young, of the butterfly were doubtless
transported in cargoes carried by ships. It is interest-
ing to note, however, that the animal follows the
spread of the plant on which its larva lives.

The Colorado Beetle. This insect, which was first
described in 1824, was then found only in the neigh-
borhood of the Rocky Mountains. Its food then was a
wild plant, the sand-burr (Solanum rostratum). When
the potato in its westward journey reached this beetle,
the insect eagerly adopted the new food. For about
forty years the potato-beetle has been extending its
ravages, until it now flourishes in large numbers
throughout the United States and Canada, apparently
defying man’s best efforts to keep it in check. Here
a change in the food-plant seems to have been respon-
sible for the change in distribution.

Some Causes of Dispersal. As shown by the cases
just described, dispersal is often brought about by
changes in food. Indeed, most of the wanderings of
animals are doubtless prompted by some impulse con-
nected with food-supply. Other causes, however, like
pressure by enemies, change, in climate, overcrowding,
perhaps even the curiosity of the animals themselves,
have been instrumental in bringing about migrations.
The regular migrations of birds, during which many
thousands of our common birds travel half the length
of a continent in a few weeks, or possibly a few days,
or the somewhat similar migrations of fish, have not yet
been fully explained.

Barriers. Rivers, seas, and sometimes mountains
have often prevented some of the animals of a region
from getting far away from their home areas. These
restricted animals often characterize a region. In a
somewhat arbitrary manner naturalists have divided
the surface of the earth into areas of distribution, for
greater convenience in studying the causes which have
brought our present faunas to their present places.
These areas are often shown by maps.

THE DISTRIBUTION OF ANIMALS. 239

Islands. The ocean is a barrier which land animals
seldom cross. Because of this, islands far from con-
tinents have both a fauna and a flora differing from that
of the nearest mainland, and differing also from one
another. Frogs and toads are not found on oceanic
islands because salt water has prevented their migration
to these places. Bats, birds, and butterflies may,
however, overcome more easily the barrier of the sea,
and make their homes on these islands. Some large
islands, like New Zealand, show faunas curiously
resembling the ancient faunas of Europe or America.
Doubtless, in such cases, the barrier of the sea has
preserved the ancient life by preventing the incoming
of strong invaders. Because of facts like these island
faunas are of great importance to Zodélogists.

Isolated Tracts. Other regions of the earth may
resemble islands in their animal life because they are
surrounded by barriers which certain species cannot
cross. Thus, the part of a river above a cataract will
have aquatic animals different from those below the
falls.

Most arctic animals perish when brought to southern
climates. Animals living in the lowlands of equatorial
regions cannot live on the highlands. Thus heat and
altitude may prove as effective barriers as the sea itself
in isolating species. All over the world there are
tracts characterized by the presence or absence of
certain plants or animals.

Wanderings. Whenever an animal wanders into an
unfamiliar region, differing from its original habitat, we
wish to know what causes operated to bring about the
change of location, how the animal supports its life
under the new conditions, whether it is likely to exter-
minate or reduce the numbers of any of the original
inhabitants of the locality, and, finally, whether its
own structure will be gradually modified to adapt itself
better to the new conditions of life. In regard to
many cases of change of dwelling-place these questions

240 ANIMAL ACTIVITIES.

have been answered. The Colorado beetle has been
able to maintain itself under new conditions. The
domestic (English) sparrow thrives in America. In
these cases the creatures have adapted their mode of
life to new habitats with marvellous rapidity and suc-
cess. Foreign rats have practically exterminated
American species, being able not only to survive, but
to drive out animals already adapted to their environ-
ment. Fishes in caverns have lost the use of their
eyes, either from lack of use, or because eyes in abso-
lute darkness are a disadvantage, and so disappear by
the process of natural selection.

Structure and Habitat. In the chapter on Insect
Adaptations we have called attention to the fitness of
organs for the work they must perform. At first
thought it might seem as if these insects had been
fitted from the start for their peculiar mode of life.
But a little reflection must show that many of these
adaptations, however ingenious they may seem, are
really very imperfect. The breathing-organs of aquatic
insects are clumsy, compared with the gills of a fish.
In fact, they are soon seen to be modifications of organs
intended for another purpose, namely, for breathing
air. If, then, we were to hold that animals were orig-
inally adapted for the localities in which we find them,
the useless eye of the blind fish in a cavern would be
to us aninsoluble problem. Fish made on purpose for,
life in dark caverns should have no eyes, no optic
nerves, and no useless muscles to move the eyeballs.
The fact that all aquatic insects have trachez admits
of no reasonable explanation unless we assume that
these insects are descended from air-breathing ances-
tors. Such ancestors may have entered the water in
search of food, or to escape enemies. In either case,
those whose tracheez were best fitted to use the air
dissolved in the water survived, while their kindred
perished.

The obvious inference from the facts of distribution

THE DISTRIBUTION OF ANIMALS. 241

is that the great majority of animals now inhabiting the
world have become adapted to their present environ-
ment through gradual changes in structure.

Geological Distribution. It is doubtless true that
the present distribution of a species has resulted from
the conditions of its past distribution, even to the
remotest times. Thus time becomes an important
factor in the study of animal life. This is especially
so if it be true that natural selection has operated in
bringing about other changes, just as it has in altering
the color of butterflies. Distribution in time is often
called Geological Distribution. Indeed, to really
understand an animal structure we need to study not
only its present ways, but also the history of the
struggles of its ancestors. In one way or another
habits, structure, adaptations, and present and past
distribution are so closely connected that while studying
one we must study all.

ANIMAL ACTIVITIES.

242

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CHAPTER XXI.
ANIMAL RELATIONSHIPS.

Classification. In the earlier days of zodlogical
“research, animals were classified by their resemblances
and differences as shown by adult forms. As informa-
tion concerning animal structure increased it became
more and more difficult to arrange schemes of classifi-
cation. The well-known classification of Cuvier divided
the whole animal kingdom into four great groups:
Radiates, Mollusks, Articulates, and Vertebrates.
This classification assumed that species are changeless,
and the subject of kinship was not considered of so
great importance as it is now.

Because of the increasing study of relationships,
these groups were gradually abandoned for new ones.
Radiates became Protozoa, Porifera, and Ccelenterata;
and Articulates became Arthropoda and Vermes.
Many other changes have been made, and _ similar
changes are constantly being made, because relation-
ship by descent is now thought to be of so great
importance. Indeed, relationship is nowadays con-
sidered to be of far more consequence than classifica-
tion. ,

Structure. Resemblance in structure must always
be the most important guide in discovering relation-
ship, as it has always been the basis of classification.
But such resemblances must be more than superficial,
and they must be sought for in other than the common
adult forms of animals.

243

244 ANIMAL ACTIVITIES.

Fossil Forms. Much light has been thrown on the
subject of animal kinships by a study of the animals
which have previously lived on the earth. The history
of these animals is written in the rocks where their
rossil remains are found. From a study of these
femains it is generally believed that the first animals
existing on the earth were Protozoa. In general, we
may say that the older the rocks the simpler are the
fossil forms found in them.

Were it not for the evidence furnished by fossils, we
should hardly suspect that the first-known horses were

Fic. 197.—-Feet of Ancestors of Horse. The figures indicate the num-
bers of the digits in the five-fingered hand of most mammals.

five-toed animals about the size of foxes. America
when discovered had no living horses, yet wild horses
are now found in Central and South America. These
wild horses are in part the descendants of domestic
animals brought to this continent by man; but some
are also, doubtless, descendants of animals like those
whose remains are found in American rocks.

Among the fossil forms, too, we find the remains of
many animals having characteristics shared by widely
differing groups of animals of the present day. Such
animals are supposed to be the ancestors of the differ-

ANIMAL RELATIONSHIPS. 245

ent groups which now repeat some of their most im-
portant characteristics. Well-known examples of these
forms are the Pterodactyl, a flying reptile, and the
archzopteryx, a reptile-like bird.

We do not know that any living birds or reptiles
have descended directly from the archzopteryx, but it

Fic. 198.—A Pterodactyl

certainly seems probable that birds and reptiles are in
some manner related by descent. However we may
interpret the records in the rocks, it is certain that no
accurate classification of animals based on kinship can
be made without a careful study of fossils.

246 ANIMAL ACTIVITIES.

Embryology. The sea-squirts, called also ascidians
and tunicates, were once classified as belonging to the
Mollusca, and later to the Vermes. Zodlogists now
class these animals with the Chordata, because a study
of their development shows decided vertebrate charac-
teristics, which disappear with maturity. The larval
forms of some of these animals resemble the tadpoles
of frogs, showing the notochord and the gill-slits
so characteristic of vertebrate animals. Here it is the

Fic. 199.—The Archzopteryx.

larval stage alone which shows the true relationship of
the animal.

As already pointed out, barnacles and fish-lice do
not show in adult life the characteristics which would
place them among Crustacea. In many other cases of
similar degeneracy the true kinship can be found only
by referring to embryonic stages of growth.

Another simple animal classed with the Chordata is
the lancelet, or amphioxus, a headless, semi-trans-
parent, boneless creature, which resembles the early

ANIMAL RELATIONSHIPS. 247

stages of growth of higher Chordata, and never ad-
vances beyond this embryonic condition. These illus-
trations show us that embryonic conditions must be
known in order to classify by relationship.

Fic. 200.—Diagram of a Sea-squirt. «, mouth; 4, vent; ¢, gullet-open-
ing; d, nerve-ganglion; ¢, stomach; /, test or outer layer; g, tunic
or inner layer; 4, branchial sac.

In studying the frog, attention was called to the fact
that the lungs are formed by simply pushing out the
walls of the throat. The air-bladder of a fish, and our
own lungs, are formed in the same way. The air-

Fic. 201.—Amphioxus. a@, mouth; 4, ¢, heart; d, liver; g, respiratory
organs; 4-9, digestive canal; 4, notochord; m, spinal marrow; a,
tail-fin,

bladder of the fish is less complicated than the lung of
the frog, and our own lung is more complicated. The
process of growth, however, is equally simple in all

248 ANIMAL ACTIVITIES.

cases, the difference being only in the amount of fold-
ing. The liver and pancreas of vertebrates arise in the
same way, by folding of the walls of the food-tube.
Other changes take place in as simple a way as this.
Indeed, nearly all the organs of a complex body arise
by foldings and pushings of layers of cells. When the
egg of a very simple animal, like the hydra, develops,
it first divides into a number of cells forming a spherical

: E
Fic. 202.—Growth of Frog’s Lung from Primitive Food-tube.

body, the morula stage. One side of this sphere is
then pushed in until two layers of cells have been
brought near together, the gastrula stage. In animals
higher than the hydra a third layer grows between the
other two, and from these three layers, by pushings
and pullings and foldings, the parts of a complicated
animal body arise. These morula and gastrula stages,
more or less obscured in many cases, have been found
in the development of all the higher animals. The

ANIMAL RELATIONSHIPS. 249

fact that such important changes occur so easily during
growth leads us to believe that adult forms may undergo
modifications by processes as simple as these foldings,
if time be allowed for gradual changes through many
generations.

We have noted the gradual disappearance of the tail
of the tadpole as it reaches maturity. This tail is use-
ful to its possessor for a time, and dwindles away when
no longer needed. The tail, and the gills as well,
suggest a relationship between frogs and fishes. If we

Asoo ---B
ey
ADS
CRESS
Fic. 203,—Morula Fic. 204.—Gastrula Stage. 4, outer layer
Stage. of cells; B, inner layer; C, external open-

ing, or mouth; D, internal cavity.

examine the embryo of a bird we find, at an early
period, a well-formed tail which can be of no possible
use to its owner. This tail disappears, as does that of
the frog, with further growth. Even more strongly
than in the case of the frog is relationship with tailed
vertebrates suggested. Naturalists generally believe
that this tail is a peculiarity inherited from a reptile-like
or fish-like ancestor. Fossil forms like the arche-
opteryx strengthen this opinion. Many other parts of
animal bodies noticed in the process of growth are
equally useless to their owners. These are now com-
monly regarded as inheritances from ancestors to whom
these parts were useful. Thus, the possession of gill-

2590 ANIMAL ACTIVITIES.

slits in the embryos of almost all the Chordata suggests
a kinship, through inheritance, among the group.

Distribution. We have noted that aquatic insects
breathe air by using organs like those of terrestrial
insects. From this fact it is commonly inferred that
the ancestors of such insects were terrestrial or aerial.
Animals which have wandered into a new environment
have sometimes so changed their mode of life and
their structure as to form a new species differing from
the ancestral forms common to the old locality. In
cases like these relationships could not be detected by
structure alone. Hence the facts of distribution must
be reckoned with in determining kinship.

Mimicry and Protective Devices. As we have
seen, the real characteristics of an animal may be
obscured by the devices it has adopted for its better
protection; hence these devices, too, must be con-
sidered in connection with relationships.

Heredity. We expect the young of an animal to
grow into a form like that of its parent. Every egg of
any kind of animal goes through a definite course of
development which is essentially like that of every
other egg of the same species. Eggs of two different
species may develop exactly alike for a time, but they
diverge as development goes on. Each egg is true to
its kind. This fact of the continual repetition of
ancestral traits we call heredity. Experience shows
that there are limits to heredity. The young is the
product of two parents, and these are not exactly alike.
Young animals from the same parents differ in many
ways. In any case, however, the differences do not
impress us much. With heredity it is the resemblance
to ancestors which is the striking fact, and this resem-
blance is of great assistance in tracing an animal’s
ancestry.

Variation. Divergences from the regular path of
heredity are called variations. For the most part we
do not know the causes of variations. That such var-

ANIMAL RELATIONSHIPS. 251

iations occur, and that they may be inherited, is cer-
tain.

If a florist wishes to obtain a new variety of a certain
plant, he watches for variations; and by carefully
selecting those plants which vary in the desired manner,
he is able, after several generations, to produce what
he wishes.

As we have previously pointed out, variations which
help an animal to maintain its place against enemies,
and in the face of obstacles, are the ones likely to be
transmitted to offspring, and so perpetuated. Natural
selection, which depends on both heredity and varia-
tion, must be considered in determining the relation-
ship of animals.

A Genealogical Tree. To show relationships, resort
is often had to devices known as genealogical trees.
These are supposed to show the ancestry of animals.
As so many facts must be known to determine ances-
try, such schemes must always be considered as only
attempts to show relationships in a very general
manner. Greater knowledge may at any time compel
changes to be made.

Classification. A scheme of classification should
tell the same story of kinship as the genealogical tree.
It must also be subject to change, for the same reasons
as the tree. At present there is no classification of
animals acceptable to all the persons qualified to judge
of such matters. What follows is a somewhat pro-
visional extension of the outline presented in Chapter I.

252 ANIMAL ACTIVITIES.

MAN

TAILLESS APES
BIRDS

TAILED MONKEYS

2 UNGULATES
Ce, ELEPHANTS BEASTS OF PREY SEALS

(Primitive) UNGULATES

Primitis cs
RopentTs | aa (Primitive) FLESH-FEEDERS
LEMURS Ss

INSECT-FEEDERS

PLACENTALS INSECTS CRUSTACEA

MARSUPIALS

MOLLUSCA
(Cuttlefish
Oysters )

MONOTREMES

REPTILES

AMPHIBIA

ROTIFERS ?
BONY _FISH DIFNOI

GANOID FISH

ECHINODERMATA
IRTS (Sea-lilies
ANCELE Star-fish)
ANNULOSA
CCELENTERATA
(Jelly-fish SPONGES
Coral-builders) se
PROTOZOA
(Ameebee
Monera)

Fic. 205.—A Genealogical Tree.

ANIMAL RELATIONSHIPS. 253

CLASSES.
Rhizopoda move by pseudopodia. Examples of
PROTOZOA this class are amceba and chalk-animals.

Infusoria move by cilia. Examples of this class
are the bell anirnalcules and paramecium. There
are other classes of Protozoa.

Keratose sponges have skeletons made of horn-like
material.

Calcareous sponges have skeletons composed of spic-
ules of carbonate of lime.

PORIFERA. Silicious sponges have skeletons composed of
quartz-like material, or of a combination of sili-
cious spicules and silk-like fibres.

These groups are not strictly classes. All sponges
belong to the class Porifera.

( CLASSES, ‘

Hydrozoa have the mouth at the top of a sort

of proboscis. The entire body-cavity is a
digestive cavity. Hydra, hydractinia, cam-
panularia, sertularia, and many kinds of
jelly-fish belong to this class.

Scyphozoa are marine jelly-fishes.

COBEED TERS EAS . of deunosa have the mouth-opening into a
stomach-cavity distinct from the body-cay-
ity. The body is also divided by radiating
partitions. Sea-anemones and coral animals
belong to this class.

Ctenophora are transparent or nearly trans-
parent comb-jellies.

( CLASSES.

Asteroidea are animals resembling the com-

mon starfish.

Ophiuroidea are animals resembling the

sand-stars.

ECHINQDERMATA. | gaa are animals resembling sea-

Crinoidea are stemmed forms. As fossils

they occur in great abundance. They are

known as stone-lilies.

Other classes of Echinodermata are largely
fossil forms.

No attempt is here made to give classes of Vermes.
Instead of Vermes many authors now name several sub-
kingdoms or phyla. Some of these are as follows:
Platyhelminthes, or Flatworms. These are worms of

low organization, including parasites like the liver-

VERMES. fluke and tapeworm.

Wemathelminthes, Roundworms. These low forms
have cylindrical bodies. The trichina belongs here.
Rotifers, Polyzoa, and Brachiopoda have been vari-

ously classed, often as members of the sub-kingdom
Vermes. Their position is not fully settled.

254

VERMES. |

[ CLASSES.

Insecta.

ARTHROPODA.

MOLLUSCA.

CHORDATA. 4

Crustacea.

ANIMAL ACTIVITIES.

Annulata. These are the more highly organized worms
like the earthworms and leeches. They are com-
monly regarded as a separate sub-kingdom or phylum.
Thysanura, spring-tails.

Pseudo-neuroptera, dragon-fly.
Orthoptera, grasshopper.
Hemiptera, aphis.
Neuroptera, ant-lion.
Coleoptera, potato-beetle,
Diptera, house-fly.
Lepidoptera butterfly.
Hymenoptera, bee

Spiders.

Arachnida. Scorpions.

Mites.
Centipedes

Myriapoda. | miltipedes

Here belong the crayfish, lobster, shrimp, crab,
sand-hopper, pill-bug, asellus, cyclops, daphnia,
fish-lice, barnacles, and many other arthropoda
which breathe by means of gills.

CLASSES.

Pelecypoda, or bivalve mollusks, like clams, oysters,
and scallops.

Gastropoda, or univalve mollusks, like slugs and snails.

Cephalopoda, including the squid, octopus, and nauti-
lus.

| Amphineura, including the chitons.

{ Omitting some low forms of somewhat doubtful re-

lationship, we may call all animals belonging to this

sub-kingdom Vertebrata and include them in classes as

given below.

CLASSES.

Cyclostomi, including the lancelet or Amphioxus.

Pisces, including all fishes.

Amphibia, including frogs and their allies.

Reptilia, including snakes and turtles.

Aves, including birds.

Mammalia, including the higher animals bearing hair
or fur and provided with glands secreting milk.
Man belongs to this class and to the order Primates,

| to which order the monkeys also belong.

VOCABULARY.

Am phi ox’us (Gr. amphi, on both {| Arche op’te ryx (Gr. archaios,
sides), and oxys, sharp), a small ancient, and pteryx, a wing), a
fish-like vertebrate. It is also fossil bird.
called the lancelet. A’ves (Lat. avis, a bird), birds.

An nu la’ta (Lat. annulus, a little | Di’a phragm (Gr. dia, through,

ring), a divis
By

ion of Vermes in- and phragnymt, to enclose), a

cluding the common earth-worm, muscle characteristic of mam-

ANIMAL RELATIONSHIPS.

mals, separating the thoracic and
visceral cavities.

Dig'i ti grade (Lat. digztus, a fin-
ger, and gradus, astep), walking
on the toes without using the
sole of the foot.

Gas’tru la (Lat. dim. of gaster, the
belly), an embryonic torm of
animals belonging to the Meta-
zoa.

Mam/'‘mal (Lat. amma, breast), a

255

vertebrate animal whose female
has milk-producing glands.

Mor'u la (Gr. moron, a mulberry),
an early stage from the growth of
an egg.

Plan’ti grade (Lat. p/anta, the sole
of the toot, and gradus, a step),
applied to animals which walk
on the sole of the foot.

Pter o dac’tyl (Gr. pteron, a wing,
and daktylos, a finger), an ex-
tinct flying reptile.

INDEX.

A
Abdomen of crustacea, 102
«¢ «© grasshopper, 32
‘¢ s¢ insects, 32

Aboral surface, 140
Acephala, 165
Actinozoa, 137
Activities of amoeba, 116
“6 bird, 199

sc «6 butterfly, 47

« ¢¢ earthworm, 150

sc «6 fresh-water mussel,
158

“+ frog, 181

«¢ «© grasshopper, 36

a ‘* hydra, 129

“¢ «6 spider, 93

« ¢ starfish, 142
Adaptations, 86
Adductor muscles, 156, 159
Air-sacs of birds, 205

‘6 66 spiders, 97
Alimentary canal, 37
Alternation of generations, 133
Ambulacral areas, 141

ie feet, 140

Ameeba, 116
Amphibia, 192
Amphioxus, 247
Ampulle, 141, 143
Analogous organs, 106
Anatomy, 30
Angleworm, 148
Animal kingdom, 2
Animal relationships, 243
Annulata, 148
Anodon, 155, 157, 254
Anosia plexippus, 68
Antenne, 33

‘of crayfish, 105

ag ‘* grasshoppers, 33

Antennules, 105

Aorta of fish, 170
sok frog, 195

Apes, 232

Aphis, 72

Apparatus, 4

Appendicular skeleton of frog, 189

Aquaria, 8
Arachnida, 113
Archzopteryx, 209
Argonaut, 166
Aristotle’s lantern, 146
Arthropoda, 2, I1I
Ascidians, 246
Asellus, 86
Assimilation, 118
Asterias vulgaris, 140
Atlas bone, 188
Auditory nerves, 173
Auricle of fish, 170
Aves, 254

Axial skeleton, 220
“ce cc

B

Balancer of fly, 58, 67

Barnacles, 110

Barriers, 238

Basipodite, 104, 107

Bat, 222

Batrachia, 192

Bees, 89, 90

Bilateral symmetry, 32

Biology, 25

Birds and insects, 200
“reptiles, 205

Blood-corpuscles, 184.

Blue-bottle fly, 57

Bluejay, 23
Bones of fish, 173
“ « frog, 188

of frog, 188

257

258

Botany, 31

Branchial arches of fish, 170
Bream, 14

Breeding-cage, 6

Brittle starfish, 144
Butterflies, 5, 21, 45
Butterfly enemies, 50
Byssus, 167

Cc

Cabbage-butterfly, 49
Caddis-fly and larva, 79
Calcareous sponges, 125
Campanularian hydroids, 14
Carapace, 104

Carbon, 28

Carbon dioxid, 28

Care of specimens, 17

Care of young among birds, 202
Carpus, 194, 204, 210

Case insects, 12

Cat, 211

Caterpillars, 6, 48

Catfish, 14

Catocala, 52

Causes of dispersals, 238
Cecropia, 22

Cell, 117

Centipede, 98, 99
Cephalopoda, 166
Cephalothorax, 101
Cerebellum, 173

Cerebral lobes, 173
Cerebrum, 173

Chalk animals, 120
Characteristics of actinozoa, 137

ae ‘“* amphibia, 192
a “ arachnida, 113
ee “* birds, 205

ee “* coelenterata, 137
ha ** crustacea, 113
“ ** echinodermata
fe “¢ hydrozoa, 147
“ ‘¢ mollusca, 166
- ‘* pisces, 175

‘“ ** protozoa, 123
“ ‘ reptilia, 192

ee “ scyphozoa, 137

Chemistry of life, 24
Chimpanzee, 182
Chitin, 44

INDEX.

Chordata, 2, 174, 254
Chrysalids, 48
Cilia, 121
Circulation of birds, 201
te “ fish, 171
“cb “c frog, 185
as ‘“ man, 221
Classes, 112
Classification of animal kingdom,

2, 243, 253, 254,
255

fs ‘* arthropoda, III
a “ birds, 207
ee ‘¢ insecta, 64
“ ‘* mammalia, 224

Clavicle, 194

Clitellum, 149, 151
Cloaca, 201

Cockroach, 20, 86
Cocoons, 48
Ccelenterata, 2, 128, 129, 137, 253
Coleoptera, 65
Collecting, 4

Colonies, 14, 132
Colorado beetle, 60, 238
Columbine, 208
Commenselism, 132
Common crab, 2, 108
Compound eye, 41
Compounds, 27
Condyle, 188, 210, 217, 219
Contractile vacuole, 117
Coracoid bones, 203
Coral, 2, 135

Cornea, 214
Corpuscles, 184

Costal, 56

Coxa of insects, 34
Coxopodite, 104, 107
Crayfish, 2, 13, 101
Cricket, 5, 41, 42
Crinoids, 146
Cross-fertilization, 131
Crow, 23

Crustacea, 101
Ctenophora, 253
Cyclops, 11, 109

D

Danais archippus, 65
Daphnia pulex, 109

INDEX.

Decomposition of water, 26
Definitions: see vocabularies
Degeneration, 110

Dental formule, 212
Derivations: see vocabularies
Diaphragm, 223
Differentiation, 131
Digestion, 128

Digitigrade feet, 228
Diptera, 64

Discovery, 30

Dispersals, 237

Dissection of grasshopper, 34
Distribution of animals, 236, 250
Ditycus, 80, 87

Division of labor, 131
Dragon-fly, 60, 76
Duckweed, 9

E

Earthworm, 7, 148
Echinodermata, 142
Ectoderm, 123
Eggs of birds, 201

“4 frogs, 23, 188
Elements, 27
Elytra, 67
Embryology, 246
Enamel, 231
Endoderm, 123
Endopodite, 104, 107
English sparrow, 197
Entomostraca, 109
Epidermis of mammals, 229
Eustachian tube of frog, 181
Excretion, 30
Exopodite, 104, 107
Experiments, 25

F

Facets, 33
Families, 112
Fauna, 237
Feathers, 198
Feet of birds, 198
Femur of insects, 34
‘i ‘¢ man, 194
Fertilization of plants by insects, 89
Fibula, 167

259

Fingers and toes of mammals, 224
Fins of fish, 159

Fishes, 169

Fission, 118

Flies, 6, 57

Flight of birds, 202, 203, 204
s¢ « insects, 42

Food of amoeba, 118
“6 « butterfly, 5, 49
‘sé caterpillar, 6, 48
“6 «s crayfish, 13
‘¢ « earthworm, 150

«6 fish, 169
co bE fly, 6, 57
“© frog, 7, 179

‘« 6¢ grasshopper, 36
‘¢ «hydra, 11, 128, 129
se 4 leech, 13

«« «© mussel, 8, 166
bc “ce slug, 7

« «& snail, 8

«© « spider, 6, 94

‘6 6¢ starfish, 142

“ tadpole, 13

se ¢¢ turtle, 7

ee ee wasp, 5
Foot of horse, 228
Foraminifera, 120
Formaldehyde, 19
Fossils, 244
Fresh-water mussel, 155
Frog, 7, 179
Frogs’ eggs 23, 186
Fungi, a, 136

G

Galaxea, 136
Ganglion, 36
Gastropoda, 165
Gastrula, 249
Genealogical tree, 252
Genera, 112
Geological distribution, 237, 241
Gill arches, 170
‘* clefts, 170
‘. filaments, 170
“« slits, 170
Gorilla, 220
Grallatores, 208
Grasshopper, 5, 32
Growth of lungs in frogs, 187

260 INDEX.

H

Habitat, 236, 240
Habits and organs, 88
Hemal arch, 174
“cavity, 174
Hair, 229
Hands and feet of mammals, 227
Haustellate, 56
Head of insect, 33
Heart of frog, 183
Hemiptera, 65
Heredity, 250
Hermaphrodite, 131
Hermit-crab, 18
Hinge ligament, 162
Histology, 31
Homologies, 107
Homologous organs, 106
Hoofs, 230
Horns, 230
Hornwort, 9
House-fly, 5
Humerus of frog, 189
Hydra, 10, 128
Hydractina, 131
Hydrozoa, 137
Hymenoptera, 66

I

Ichneumon-fly, 74
Imago, 49
Incisors, 212
Infusoria, 121
Inhalent pores of sponge, 124
Insect adaptations, 86

“© communities, 89
Insects and plants, 91
Interambulacral areas, 141

ee plates, 141

Isolated areas, 239

J
Jelly-fish, 154, 155

K
Kallima, 61

Keel in birds, 205
Keratose sponges, 125

Labium, 33

Labrum, 33
Lamellibranchiata, 165
Lancelet, 247

Larve of butterflies, 48
Lateral line, 169
Leech, 13
Lepidoptera, 45, 46
Life, 24

Life-histories, 68
Limenitis ursula, 53
Lingual ribbon, 166
Lithobius, 98

Living matter, 24
Lobster, 102

Locust, 32

M

Madrepora, 136
Madreporic body, 140
Mammals, 217
Mammalian skeleton, 218

as viscera, 223
Mandibles, 33
Mantle of mollusca, 156, 161, 166
Mask of dragon-fly larva, 77
Materials for study, 4
Matter, 24
Maxille, 34
Maxillipeds, 103
May-flies, 80
Medulla oblongata, 195
Medusa, 134, 135
Mesenteries of sea-anemone, 135
Mesogloea, 123
Metamorphosis of insects, 47
Microgaster-fly, 75
Migration, 238
Milkweed-butterfly, 68, 237
Mimicry, 53, 250
Mollusca, 2, 165, 166
Morula, 249
Moths, 45
Moulting, 39
Mouth-parts of insects, 33, 34, 35
Mud-wasp, 61
Muscles of frog, 188
Mussels, 8, 155

N

Names of insects, 66
Natatores, 208
Natural selection, 54
Nauplius, 111
Nautilus, 166
Nemathelminthes, 253
Neuroptera, 65
Nettling cells, 129
Neural arch, 173
“cavity, 174
“spine, 174
Nictitating membrane, 197
Nitrogen, 27
Notochord, 177
Nucleus, 117
Nutrition, 30
he of grasshopper, 37

Oo

Ocelli, 33
Olfactory lobes of fish, 173
Oésperms, 131
Operculum of snail, 164
Optic lobes of fish, 173
Oral surface of starfish, 140
Orders, 112

‘6 of insects, 64
Orthoptera, 65
Oscula of sponge, 124
Osmosis, 38
Ovipositor, 33
Oxidation, 27

P

Pallial line, 156
Palpi, 34
Paramecium, 122
Parthenogenesis, 73
Passeres, 208
Pearls, 161
Pectoral fins, 169
Pectoral girdle, 175
Pedal ganglia, 162
Pedicellariz, 140
Pelecypoda, 165
Pelvic girdle, 175
Peritoneum, 181
Phalanges, 189, £99
Phosphorescence, 114

INDEX. 261

Phylum, 1, 2

Physiology, 30

Pisces, 175

Plantigrade feet, 227
Plant-lice: see Aphis
Pleurum, 32

Poison-fangs of spiders, 97
Polyp, 135

Polyzoa, 253

Pond-snail, 163
Pond-weed, 9

Porifera, 125, 254
Preparation of specimens, 17
Preservation of specimens, 19
Primates, 254

Proboscis of moth, 50
Prolegs, 69

Protection of birds, 200
Protective coloring, 52
Protopodite, 104, 107
Protozoa, 116, 123
Pseudoneuroptera, 65
Pseudopodia, 119
Pterodactyl, 245
Pupation, 70

R

Radiate symmetry, 2
Range of animals, 237
Raptores, 208
Reference-books, vi
Repair, 26
Reproduction, 30
we of ameeba, 118
“ ‘* grasshopper, 37
Reptilia, 192
Resemblances, 61, III
Respiration of grasshopper, ‘
Rhivopeda, rr ERE 2

iS)

Sand-wasp, 74
Sarcoda, 123
Sauropsida, 207
Scansores, 208
Scyphozoa, 134, 137
Sea-anemone, 15

“© cucumber, 146
“ squirt, 246
“urchin, 145
Sedentary, 115

262

Senses of grasshopper, 40
Septa of coral, 135

Serial homology, 107
Shrimp, tor

Silicious sponge, 125
Siphon of mussel, 158
Skeleton of bat, 222

ae “ bird, 193
o ‘« chimpanzee, 223
a“ “cc fish, 173
“6 ee frog, 193
ae ‘“ horse, 215
&c ‘“* man, 194

Slugs, 7, 162

Smelt, 169

Snails, 5, 163

Snakes, 7

Somite, 104

Sow-bug, 5

Species, 112

Sperms of hydra, 130
Spicules of sponge, 125
Spider, 93

Spinal cord, 173, 174, 195
Spinal nerve, 173
Spinnerets, 94.

Spiracles, 32

Sponges, 123

Squash-bug, 61

Squid, 166

Starfish, 140

Sternum, 104

Stone-lilies, 2
Stridulating, 41, 42
Structure and habitat, 240
Struthii, 207

Stylets, 43
Supracesophageal ganglia, 167
Survival of fittest, 35
Swimmerets, 103
Sympathetic system of nerves, 181
Synapta, 146

T

Tadpoles, 179
Tanning worms, 148
Tarsus of insect, 34

“ «© man, 197
Teeth of mammals, 231
Telson, 115
Tergum, 32, 104

INDEX.

Thece, 138
Thorax of insects, 33
Thysaneura, 65
Tibia of insect, 34

‘ ¢ man, 194
Tongue of frog, 182
Trachea of an insect, 38
Trochanter of insects, 34
Turtles, 7
Tympanum, 33

U

Unio, 155

Urostyle, 198

Urea, 29

Usefulness of earthworms, 153
Vv

Variation, 251
Ventricle of fish, 170
Vermes, 148
Vertebrata, 174, 254
Visceral cavity, 174
Vocabularies of terms applied to
one-celledanimals andsponges,
126
coelenterata, 147
crustacea, I15
echinodermata, 147
insects, 44, 56, 67, 85
mollusca, 167
vertebrate animals,
210, 255
Vocabularies of general terms fre-
quently used, 31, 100, 255

WwW

176, 177,

Wasps, 5
Waste, 26
Water-boatman, 80, 8
‘¢ fleas, 109
‘spider, 95
Web of spider, 95
Wing of birds, 198
se insect, 42
Winglet, 58

Z

Zooids, 132
Zoology, 30

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