ST BOOK IN ZOOLOC ■IMMMMWiMMWMWBIMII»?n! Colorado College Library ^^. Library f^o.2M-.3--3..-^ \- Digitized by the Internet Archive in 2010 http://www.archive.org/details/animalactivitiesOOfren ANIMAL ACTIVITIES ANIMAL ACTIVITIES ^ A FIRST BOOK IN ZOOLOGY BY NATHANIEL S. FRENCH, Ph.D. Teacher of Zoology in the Roxbury High School Boston, Mass. Iimitb miustratlons NElf^ IMPKESSWN LONGMANS, GREEN, AND CO. 91 AND 93 FIFTH AVENUE, NEW YORK LONDON, BOMBAY, AND CALCUTTA 1907 Copyright, igoi, BY LONGMANS, GREEN, AND CO. First Edition, March, 1902 ; Reprinted, January, 1903. Reprinted, August, 1905. Reprinted, April, 1907. ROBERT DRUMMOND, PRINTER, NEW YORK. ^"^0. V&% INTRODUCTION. The book here presented is the outgrowth of fifteen years on 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 Zoology 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 Zoology course begins in the winter or spring. Throughout the book adaptation to environment is constantly pointed out. Much is made of habitat in V 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 iMiss Helen A. Gardner and IMiss JMary E. Winn of the Girls' High School, Boston, and Prof. B. H. Van Vleck of Boston University, who read the manuscript ; and to ]\Ir. 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 Conrad : A Naturalist's Rambles about Home. Bird Land Echoes. Illustrated. Agassiz, Elizabeth and Alexander: Seaside Studies in Natural History. Illustrated. INTRODUCTION, Vll Allen, Grant: Flashlights on Nature. Illustrated. Apgar, Austin C. : Birds of the United States. Illustrated. Badenoch, L. N. : Romance of the Insect World. Illustrated. Bausch, Edward: Manipulation of the Microscope. Bateman, G. C. : The Vivarium. Illustrated. Beard, James Carter : Curious Homes and their Tenants. Illustrated. Beddard, Frank E. : Elementary Practical Zoology. A Text-book of Zoogeography. BoLLES, Frank: At the North of Bearcamp Water. Brooks, W. K. : The Oyster. Illustrated. Buckley, Arabella B. : Life and her Children. Illustrated. The Winners in Life's Race. Illustrated. Burroughs, John: Birds and Bees and Sharp Eyes. Riverby. Wake Robin. Locusts and Wild Honey. Carrington, Edith: Animals' Ways and Claims. Illustrated. Chapman, Frank TvI. : Bird Life. Illustrated. Chatty Readings in Elementary Science (Longmans): Nature Knowledge, Books I, II, III. Illustratedc Cornish, C. J. : Animals of To-day. Illustrated. Animals at Work and Play. Illustrated. Wild Animals m Captivity. Illustrated. viii INTRODUCTION, Corey, C. B. : How to Know the Shore Birds. Illustrated. Darwix, Charles R. : What I\Ir. Darwin saw in his Voyage Round the World in the Ship " Beagle ". Illustrated. The Formation of Vegetable Mould. Illustrated. Davie, Oliver: Nests and Eggs of North American Birds. Illustrated. De Kay, Charles : Bird Gods. Illustrated. Dixon, Charles: Curiosities in Bird Life. DOUBLEDAY, N. B, DeG. : Birds that Hunt and are Hunted. Illustrated. Bird Neighbors. Illustrated. Duncan, P. ^Iartin: The Transformation of Insects. Illustrated. Davenport, C. B. and G. C. : Introduction to Zoology. Illustrated. Edwards, Clarence E. : The Campfires of a Naturalist. Illustrated. Emerton, J. H. : The Structure and Habits of Spiders. Illustrated. Figuier, Guillaume Louis: The Ocean World. Illustrated. The Insect World. Illustrated. Flower, William Henry: The Horse. Illustrated. Forbes, Edward : A History of British Starfishes. Illustrated. French, 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. Holland, W. J.: The Butterfly Book. Illustrated. INTRODUCTION. IX Jordan and Kellogg : Animal Life. Illustrated. Kearton, R.: Wild Life at Home. How to Study and Photograph it. Illustrated. KiNGSLEY, JOHX STERLING: The Riverside Natural History, five volumes. Illus- trated. LovELL, M. S. : Edible IMollusks of Great Britain. Lubbock, Sir John : On the Origin and Metamorphosis of Insects. The Beauties of Nature and Wonders of the World. Ants, Bees, and Wasps. Illustrated. Mangin, Arthur: The Mysteries of the Ocean. Illustrated. Manton, Walter P. : Taxidermy without a Teacher. Insects, How to Catch and Prepare. Mathews, F. Schuyler: Familiar Life in Field and Forest. Illustrated. IMcCooK, 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. IMerriam, C. Hart: Mammals of the Adirondack Region. MiALL, Louis Compton: The Natural History of Aquatic Insects. Illustrated. Round the Year. Illustrated. Michelet, Jules: The Insect. Illustrated. The Bird. Illustrated. Miller, Olive Thorne: Little Brothers of the Air. Four-handed Folk. Illustrated. Bird Ways. In Nesting Time. Little Folks in Feathers and Fur. Illustrated. X INTRODUCTION. ]\IoRGAX, C. L. : Animal Sketches. Illustrated. Needham, James G. : Outdoor Studies. Illustrated. Nehrlixg, Henry: Native Birds of Song and Beauty. Illustrated, two volumes. Oswald, Felix L. : Zoological Sketches. Illustrated. Packard, A. S. : A Guide to the Study of Insects. Illustrated. Parkhurst, H. E. : The Birds' Calendar. Illustrated. Porter, J. Hampden: Wild Beasts. Illustrated. Russ, Karl: The Speaking Parrots. Illustrated. Scudder, Samuel H. : The Life of a Butterfly. Illustrated. Butterflies: Structure, Changes, and Life-histories. Semper, Frank W. : Injurious Insects, and Use of Insecticides. Illustrated. Shaler, Nathaniel S. : Domesticated Animals. Illustrated. Simmonds, p. L. : Commercial Products of the Sea. Illustrated. Stokes, A. C. : Microscope for Beginners. Thomson, William: Great Cats I Have Known. Illustrated. Thompson, Ernest Seton: Wild Animals I Have Known. Illustrated. Torrey, Bradford : Birds in the Bush. Wallace, Alfred Russell: Darwinism. Illustrated. Weed, Clarence ]\Ioore: Life-histories of American Insects. Illustrated. INTRODUCTION. XI Wilson, Sir Daniel: Left-handedness. Wood, Theodore: The Farmers' Friends and Foes. Illustrated. Wood, Rev. J. G. : Homes Without Hands. Illustrated. Wright, IMabel Osgood: Four-footed Americans. Illustrated. Bird Craft. Illustrated. TABLE OF CONTENTS. PAGB Introduction vii CHAPTER I. Animals Classified i CHAPTER II. Material for Study 4 CHAPTER III. Activities Common to All Animals , 24 CHAPTER IV. Grasshoppers and Crickets 32 CHAPTER V. Butterflies and Moths with their Protective Devices... 45 CHAPTER VI. Some Insects Classified 57 CHAPTER VII. A Chapter of Life-Histories 68 xiii XIV TABLE OF CONTENTS. CHAPTF.R VIII. Some Insect Adaptations., CHAPTER IX. A Spider's Activities CHAPTER X. Homologies among Crustacea CHAPTER XL The Activities of One-Celled Animals and Sponges CHAPTER XII. The Hydra and Some Ccelenterates which Live in Colonies CHAPTER XIII. The Starfish and Closely Related Animals CHAPTER XIV. The Earthworm and His Work CHAPTER XV. Mussels and Snails CHAPTER X\^. The Structure and Activities of a Fish CHAPTER XVII. Tadpoles and Frogs TABLE OF CONTENTS. XV CH AFTER XVIII. PAGE Birds 197 CHAPTER XIX. Man's Near Relatives 211 CHAPTER XX. The Distribution of Animals 236 CHAPTER XXI. Animal Relationships 243 LIST OF ILLUSTRATIONS. Note. — The figures in brackets \\'\/ollo'wirg the titles re- fer to the list, printed be tow, of books frotn which the illustrations are, by permission, respectively borrowed. FIG. PAOE 1. An Insect-net j. 2. The House-cricket [i] 5 3. A Cabbage-butterfly G 4. Spider and Web 7 5. A Water-snail S 6. Shell of a Fresh-water Mussel [2] S 7. An American Pondweed 9 8. The Hornwort 9 9. A Duckweed 9 10. Other Pondweeds 10 11. The Hydra [2] 10 12. Water-fleas and Cyclops 11 13. Caddis-fly Cases [2] 12 14. The Larva of Dragon-fly 12 15. Larva of Dyticus 12 16. Larva of Whirligig Beetle 12 17. Larva of a May-fly 12 18. Side View of Crayfish [5] 13 19. A Campanularian Hydroid Colony [6] 14 20. A Sertularian Colony [6] 15 21. A Net for Collecting at the Seaside 15 22. Sea-anemones 16 23. A Starfish [6] 17 24. A Sea-urchin 17 25. A Sea-cucumber 18 26. A Hermit-crab 18 27. A Shrimp 18 28. Tumbler with Chloroform 19 29. A Cockroach [i] 20 30. Mourning- cloak Butterfly 21 31. A Wasp's Nest I3] 22 32. Cocoon of Cecropia 22 33- Eggs of Frog Just Laid [2] 23 34. Eggs of Frog a Few Hours After Laying [2] 23 35 Apparatus for Decomposing Water 26 36. Apparatus for Removing Oxygen from Air 28 37. Heating a Test-tube 28 38. The Parts of a Locust 35 39. Comparison of a Grasshopper and Man 36 xvii XVIU LIST OF ILLUSTRATIONS. FIG. PAGE 40. The Trachea of an Insect [2] 38 41. Cockroach and Cast Skin [i] 39 42. The Nervous Chain of a Cockroach [i ] 40 43. Portion of the Cornea of a Fly's Compound Eye [i] 41 44. The Hearing Organ of a Cricket [i] 41 45. The Stridulating Organ of a Cricket [i] 42 46. Antennae of Lepidoptera [4] 46 47. Eggs of Lepidoptera [4] 47 48. Some Larvce of Lepidoptera 48 49. Some Cocoons and Chrysalids [4] 48 50. A Cabbage-butterfly 49 51. Head of a Moth 50 52. The Kallima 51 53. Catocala Nupta [4] 52 54. The Milkweed-butterfly 53 55. Limenitis Ursula 53 56a. Moth at Rest 55 ^tb. Butterfly at Rest 55 57. Larva and Pupa of the House-flv [i] 58 58. Right Winglet of Bluebottle [i]! 58 59. Balancer of Bluebottle [i] 58 60. Portion of a Fly's Foot [i] 59 61. Side View of Proboscis, partly opened [ij 59 62. Head of Bluebottle [i] 59 63. Eggs of Milkweed-butterfly 68 64. Larva of Milkweed-butterfly 69 65. Pupa of Milkweed-butterfly 69 66. Female and Male Aphis 71 67. A Microgaster Fly 75 68. The Dragon-fly [2] 77 69. The Imago of a Dragon-fly [2] 78 70. Caddis-fly, Adult and Larval Cases [2] 79 71. The Growth of a May-fly [2] 80 72. A Water-boatman 81 73. Dyticus Marginalis 81 74. Mouth of a Bug 82 75. The Egg-raft of a Mosquito [3] 82 76. The Life-history of a ^losquito 83 77. The Mouth of a Female Mosquito [2J 84 78. The Leg of a Cockroach [i] 86 79. A Mole-cricket 86 80. Fore Legs of a Water-bug [2] 87 81. Legs of Dyticus [2] 87 82. Fore Leg of a Butterfly [4] 88 83. Hive-bees 90 84. Fertilization of a Flower by an Insect 91 85. A Spider's Leg [2] 94 86. Water-spider and Nest 96 87. Side View of Cravfish [5] loi 88. Dorsal View of Crayfish [5] 102 89. Ventral View of Crayfish [5] 103 LIST OF ILLUSTRATIONS. Xix FIG. PAGB 90. Fourth Abdominal Segment of Crayfish [5] 104 91. Crayfish Appendages [5] 105 92. Longitudinal Section of Crayfish [5] 106 93. Walking Appendage of Crayfish with Gill Attached [5J 107 94. The Common Crab 108 95. Early Stages of Shore-crab 108 96. Water-flea [2] 109 97. Cyclops [2] 109 98. A Barnacle 110 99. Forms of Amoebae 117 100. Amoeba Feeding [2] 118 loi . Amoeba Dividing [2] 119 102. One of the Foraminifera 120 103. The Origin of Chalk 120 104. Infusorial Earth 121 105. Infusorians 121 106. Vorticella [8] 1 22 107. A Paramecium [5J 123 108. Structure of a Sponge 124 109. Sponge Spicules [2] 125 no. Thread-cells [2] 130 111. Forms of Hydra [8j 131 1 12. Hydractinia [6] 132 113. Medusas of Campanularian Hydroid [6] 134 114. The Origin of a Scyphozoan Jelly-fish 135 1 15. The Structure of a Sea-anemone 136 1 16. A Starfish 142 117. A Brittle Starfish 144 118. The Structure of a Sea-urchin 146 119. A Sea-cucumber 146 1 20. An Earthworm 1 49 121. A Worm's Setae 150 122. Worm-casts 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] 161 127. Nervous System of Anodon [5] 161 128. A Slug 163 129. A Snail 165 T30. A Squid 166 131. Part of a Lingual Ribbon 166 132. The Circulation of Blood in a Fish 171 133. Internal Organs of Fish 172 134. Skeleton of a Fish 173 135. Tongue of a Frog 182 136. A Young Tadpole Showing External Gills [2] 182 137. Under Side of Tadpole Showing Coiled Intestine and Internal Gills [2] 183 138. Heart of Adult Frog [2] 1 83 139. Blood-cells of a Frog [gj 183 XX LIST OF ILLUSTRATIONS. FIG. PAGE 140. Blood-corpuscles of Man [9] 184 141. Viscera of Frog 185 142. Digestive Organs of Man [9] 186 143. Growth of Frog's Lung from Primitive Food-tul>e 187 144. Growth of Frog's Egg [2J 188 145. Very \'oung Tadpoles [2] 188 146. Various Stages of Tadpole [2J 189 147. Voung Frogs ("2J 189 148. The Use of a Muscle 190 149. Striped Muscle-fibres [9] ' 191 150. Unstriped Muscle fibres [9] 192 151. A Frog's Skeleton 193 152. A Man's Skeleton 194 153. Brain of Frog 194 154. Brain and Spinal Cord of Man 195 155. Beaks of Various Birds 199 156. The Digestive Organs of a Bird 2(X) 157. Diagram of the Heart of a Bird [3] 201 158. The Skeleton of a Bird 202 159. A Swallow Feeding Her Young 203 160. Arm of Man, Fore Leg of Dog. Wing of Bird 204 161. A Bird's Wing 204 162. The Sternum of a Shrike 205 163. Feathers 206 164. A Bird's Leg 207 165. Feet of Birds 208 166. The Archffiopteryx 209 167. Teeth of ^Lan [9'] 212 168. Teeth of Dog 212 169. Teeth of a Sheep [3] 213 170. Teeth of Hare 213 171. Skull of Cow Showing Teeth 214 172. The Human Eye 214 173. Skeletons of Man and Horse [10] 215 174. Bones of Leg and Arm of Man [11] 216 175. Vertebral Column of Man [11] 216 176. Human Skull [11] 217 177. First and Second Vertebrae of Man [g] 219 178. Skeleton of Gorilla 220 179. Diagram Showing Circulation of Blood in Man [11] 221 180. Skeleton of Bat Showing Wings 222 181. Arm and Hand of Man [11] 223 182. Skeleton of Chimpanzee Showing Hand 223 183. Fore Foot of Mole 224 184. Fore Foot of Cat 224 185. Fore Feet of Cow 225 186. Fore Feet of Horse .235 187. Foot of Elephant 225 188. Feet of Bear 225 189. Sole of Foot of Man, of Dog. and of Horse [10] 226 190. Finger of Man and of Horse [10] 227 LIST OF ILLUSTRATIONS. xxi FIG. PAGH 191. Feet of Ancestors of Horse 228 192. Growth of Hair [9] 229 193. Horns of Sheep. Cow. and Deer 230 194. Skull of Cow Showing the Bone of the Horn 231 195. A Manlike Ape Walking 232 196. A Chimpanzee 233 197. Feet of Ancestors of Horse 244 198. A Pterodactyl 245 199. The Archieopteryx 246 200. Diagram of a Sea-squirt 247 201. Amphioxus 247 202. Growth of Frog's Lung from Primitive Food-tube 248 203. Morula Stage [7] 249 204. Gastrula Stage [7] 249 205. A Genealogical Tree [7] 252 1. Our Household Insects. ^j E. A. Butler, Longmans, Green. &Co. 2. Life in Ponds and Streams ByJV. Furneanx, '- " " 3. The OvTDOOR World.. .By If ^. Bureaux, '* ** '* 4. Butterflies Ay-D Moths. Bj' IF. Furn^aux, " " ** 5. Practical Elementary Biology Bj' John Bidgood, '• '' " 6. Seaside Studies in Natu- ral History. . . .By E. and A. Agassi z, Houghton, Mifflin, & Co. 7. The Story of Creation. j5)' Fdiv. Clodd. Longmans, Green, & Co. 8. Animal Biology By C. L.Morgan, " '• " 9. Quain's Anatomy, loth Edition '• " " 10. The Horse By W.H. Flcnver. D. Appleton & Co. 11. Human Physiology By \V. Furneaux, Longmans, Green, & Co* ANIMAL ACTIVITIES. CHAPTER I. ANIMALS CLASSIFIED. Ix 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 zoologists into subkingdoms. As these subkingdoms are supposed to consist of animals related through their ancestry, they are sometimes called phyla {p/iylum, a tribe). Since Zoology 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. ANIMAL ACTIVITIES. Phylum or Sub- kingdom. Name of Sub- kingdom. Derivation of x Few Characteristics". ' Familiar Examples Name. , I. II. m. IV. VI. VII. VIII. Pro to zo'a. Po rif'e ra. cce len te- ra'ta. E CHI NO- der'ma ta. Ver'mes. Ar throp'o- DA. MOL LUS'CA. Chor da'ta. Gr. protos, first, and zoon, ani- mal. Lat. poms, a pore, and /ero,toheai Gr. koilos, hollow, and ettteron, in- testine. Gr. echhios, a hedgehog, and derma, skin. Lat. vermis, a worm. Gr. arthron, a joint, and pous (pod), a foot. Lat. mollis, soft. Gr. chorde, a string. One-celled ani- mals. They do not re- produce by eggs. Animals having many cells much alike. Food enters the body by numer- ous openings. Animals having hollow cylindri- cal bodies with only one open- ing, the mouth. Animals having very distinct ra- dial symmetry, having hard plates in the skin, and fre- quently covered by spines. Include a great variety of worm- like animals. Some have seg- mented bodies. Animals having segmented bod- ies and jointed appendages. Soft-bodied ani- mals, often en- closed in hard shells. Almost all have back bones made up of parts called vertebra. Amceba, Para- mecium, vor- ticella. chalk animals. All sponges. Hydras, hy- droids, jelly- fish, corals, sea-anemones Starfish, sea- urchins, sea- cucumbers, and stone- lilies. Earthworms, leeches. Grasshoppers, butterflies, spiders, cray- fish, crabs, centipedes. Clams, snails, the nautilus, and the squid. frogs, Fishes, turtles, snakes, birds, 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 paramecuun, belonging to Protozoa. A sponge, belonging to Porifera. A hydra and a hydroid colony ^ belonging to Coelen- terata. A starfish and a sea-tirchin, 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 mnssel, a slug, and a snail, belonging to Mollusca. A fish, 2. 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 (i) 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. It is a good plan for small groups of volunteers to assume responsibility for carrying out the directions of the several paragraphs which follow. APPARATUS AND REFERENXE 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. i, fastening it to Fig. I. — 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 IMuseum, 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 and water. Try, also, butterflies and moths in the same way, using larger glass vessels. If eggs are deposited, examine them carefully and watch their growth. Fig. 2. — The House- cricket. y4NIMAL 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 the growth of the eggs. 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 Fig. 3. — A Cabbage-butterfly, larva; b, pupa; c, tgg; d, imago. MATERIAL FOR STUDY, 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. Turtles and 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, 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. In a 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. Fig. 4. — Spider and Web. 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 for years in an aquarium like that just de- scribed. Watch for the eggs and growing young. 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 Fig. 5.— a Water-snail {Planorbis). Fig. 6. — Shell of a Fresh-water Mussel {Anodon). 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. 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 rectangular glass vessels and common battery -jars answer every purpose Fig. 7. — An American Pond- weed. Of course water 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 keep the end of the hose in the aquarium under water. Fig. 8.— The Horn, wort. Fig. 9. — A Duck- weed. 10 ANIMAL ACriyiTlES. In this way the water siphons over into the sink. To prevent the passage of insects through the siphon, attach it to a tunnel having the open- ing covered with wire gauze. Hydra. Collect small sticks and dead leaves, with some mud and water, from a fresh- water pond, or from ditches used for draining swampy places. Place these in glass with growing fresh-water plants, and renew from time to Fig. io. — Other Pondweeds. Fig. The Hydra {rnagnijied). time the water lost by evaporation. Collect from several localities in separate jars, and label the jars MATERIAL FOR STUDY. II for convenience. Watch carefully for the appearance of either brown or green h}'dras. They may be seen without a magnifying-glass. If only eggs are present, they may not hatch for months, vU^ Fig. 12. — Water-fleas and Cyclops {magnijied). 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 larvae of caddis-flies. Watch them feed, and add material to the tubes which protect their delicate bodies. Keep plenty of plants about them. Larvae 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 Fig. i^. — Caddis-fly Cases. as it appears while swimming and while flying. A powerful aquatic insect is the large water-beetle (Dity- cus IMarginalis'i. Fig. 15 shows the young and Fig. Fig. 14. — The Larva of a Dragon fly FiG. 15. — Larva of Dyticus. Fig. 16. — Larva of Fig. 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 e\'es adapted for seeing enemies in the air above and MATERIAL FOR STUDY. 13 in the water below at the same time. A young whirHgig 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 larvae 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 for food. At liberty they suck the blood from living animals. Grayish. These may be bought alive in the mar- FiG. 18. — Side View of Crayfish, ajt. antenna; r, rostrum; cep. cephalic portion; tho, thoracic portion of cephalothorax ; ab, 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 (confervas) 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 Fig. 19. — A Campanularian Hydroid Colony {Eucope diaphand). a, whole colony, one half natural size; b^ single zooid magnified; c and d, stages of jelly-fish, magnified. Studies ' ' (Agassiz) should be accessible to both teacher and pupils. There are many small marine animals resembling tjie 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. 15 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 low tide. They are sometimes found 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 much distorted to show structure well. These animals may They Fig. 20.— a Sertula- rian Colony. After Agassiz. Fig. 21. -A Net for Collecting at the Seaside. Starfishes and Sea-urchins be found in the same localities as the anemones 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 i6 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 Fig. 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 cra}-fish 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. Fig. 23. — A Starfish. After Agassiz. THE PREPARATION AXD CARE OF SPECIMENS. Prepared Specimens. In addition to living animals it is always necessar}' to have at hand a plentiful supply Fig. 24. — A Sea-urchin. Part of the spines have been removed. i8 ANIM/IL 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 Fig. 25. — A Sea-cucumber. Fig. 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 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 iMuseum, 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 ]\I of Bulletin No. 39 already mentioned gives valuable directions for the preservation of specimens. Alcohol is the most important pre- n • 1 t:^ 1 . Fig. 28. —Tumbler servmg fluid. For most specimens ^^^^^ 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 formaldeh}-de 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 ANIMAL ACTIVITIES, preserved in the same way, but they make better speci- mens for study, if preserved in formaUn 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 Zoology 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 w i t h i n 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 Fro. 29- A Cockroach. ''^^"^^'^.^ everywhere, and are fairly abundant even in cold weather. They are most easily collected at 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 Fig. 30, — Mourning-cloak Butterfly {^Vanessa antiopd). antiopa^, which shows the wear due to its winter sleep, and is read}' to produce eggs for the summer brood. The eggs may be reared, the larvae 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 Cecropia 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- FlG. -A Wasp's Nest. Fig. 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 nearh', if not quite, all the specimens already mentioned as obtainable in the fall. MATERIAL FOR STUDY. 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, as are also tadpoles and frogs. 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 Fig. 33.— Eggs of Frog just Laid. Fig. 34. — Eggs of Frog a Few Hours after Laying. 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 cntireh' from any movements of which inorganic matter is capable. 34 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 Zoology. The study of the form, structure, and position of the parts of a plant or an animal is Anatomy. ]\linute 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 activit}'. The heat is caused by the union of two elements, carbon and oxygen. It has been found that the movements of livin^ things are also due verv 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. Experiitient. 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 of electricit}' into two invisible gases, and that, after a time, one tube contains twice as much gas as the other. The larger amount of gas is hydrogen, and Light the hydrogen, noting the Into the top of the T^ - Fig. 35. — Apparatus for Decomposing Water. Drawn -by A. E. San- ford. the smaller, oxygen fact that it burns very readil} 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 ox}'gen cannot be further separated into other sub- stances they are called elcnioits. Water, because it is formed by the union of two elements, is called a coDipoiind. Carbon is also an element. Experiment, The Oxidation of JMagnesitnn. Mag- nesium is an element. 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 oxidation. The oxidation of hydrogen produces h}-drogen 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 on a 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 ^ ^W one fifth of air is oxygen. the a plate Fig. 36. — Apparatus for Removing Oxygen from Air. Drawn by A. E. Sanford. lighted gas forming Remove the jar from and thrust into the gas match. This colorless about four fifths of the air is nitro- gen. It will not burn or aid the burning of other substances. This element is found in all animal bodies united with other elements to form Bread and meat contain compounds compounds. partly composed of nitrogen. Experiment. The Element Carbon Sugar. Heat in the bottom of a test- tube a small amount of sugar (Fig. 37). Notice the Avater 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 in StareJi anei ,^^^ Repeat this experiment, using starch and wood. Graphite and diamond are other forms of carbon. Experiment. Carbon Dioxide. Burn Fig, 37. — Heating a Test-tube. Drawn by A. E. Sanford. 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 ACTiyiTIES 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 tJie BreatJi. Breathe through a glass tube into a test-tube containing a little lime-water. What does the milky appearance of the limie- water prove t Whence came the carbon dioxide ? How was it produced ? Experiment, TJie Qxidaiion of Hydrogen in our Bodies. What collects when we breathe on a cold glass ? AMience comes the water ? The hydrogen enters the bod\' with the food. How does the oxveen 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 so AMMAL ACTIVITIES. special organs for seeing-, hearing, smelling, tasting, and feeling. By these organs we discover the world about us. ]\Iany animals have not these organs of sense. Many, indeed, have no organs of any kind, yet all animals seem to possess, to somic 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. {b) Nutrition. {c) Excretion. (d) Reproduction. (e) 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 are dealing with Anatomy. Evidently, then, anat- omy and physiology must be studied together in the science of Zoology. 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. /iCriVlTIES COMMON TO ALL ANIMALS. 31 VOCABULARY. A nat'o my (Gr. ana, up, and temno, cut), the science which treats of the structure of organ- isms. Bi ol'o gy (Gr. bios, life, and logos, a discourse;, the science of living things. Bot'a ny (Gr. botania, a plant), that part of Biology which treats of plants. Car'bon (Lat. carta, coal), an ele- ment found in all organic com- pounds; charcoal, graphite, and diamonds are forms of tliis 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. fiingor, execute), the action of any part or organ of a plant or animal. His tol'o gy (Gr. histos, a web, or tissue, and logos), the study of minute anatomy. Hy'dro gen (Gr. hydor, water, and gignoinai^ be bom), a colorless, gaseous element forming a part of water. In or gan'ic, not organic. Mag ne'si um (Gr. Magnesios, a district in Thessaly), a silver- white, solid, metallic element. Mat'ter (Lat. materia, stuff), any- thing having extension. Ni'tro gen (Gr. nitron, nitre, and gignomai), a colorless, gaseous element composing four fifths of the air. Nu tri'tion (Lat. nutria, 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 imiting chemically with oxygen. Or'gan ism, a living plant or ani- mal. Oxy gen (Gr. oxys, sharp, and gignomai), a colorless, gaseous element, forming one fifth of the air. Phys i ol'o gy (Gr. physis, nature, and logos), the science which treats of living things. Zo ol'o gy (Gr. Z0071, an animal, and logos\, 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, WTiat is the shape of the bod\- ? 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 segments 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. 2>Z Do you find the so-called ear-drum (tympanum) on the first segment of the abdomen ? The female grasshopper has organs at the end of the abdomen for placing her eggs in the ground (o\'iposi- tors). Do you find both male and female grasshoppers ? Sketch a side view of a grasshopper's abdomen X 5- The Thorax. What appendages are attached to the thorax ? How many segments in the thorax ? How many legs do you find ? Are they jointed ? How do they differ in size ? Sketch one of the hind legs, indicating all the parts X 5- How many wings do you see ? Are any o{ the wings folded ? How ? Sketch a front and a hind wing fully extended X 5- To what segments are the wings attached ? What can you say of the grasshopper's powers of locomotion ? How many times its lengtli can a grass- hopper jump ? Do the grasshoppers }'ou 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 you find on the front of the head (antennae) ? Are they segmented ? What is their shape ? How does their length compare with the length of the body ? Sketch a side view of the head showing feelers. How many eyes do you find ? Compound eyes 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 eye as seen under a microscope. \\^hat is the shape of the upper lip (labrum) "! Sketch. Under this lip do you find hard jaws (mandibles) } How many } What color .^ Wliat shape .' In what direction do they move } Sketch. 34 ANIMAL ACTIVITIES. Do you find a tongue ? Do you find a pair of softer jaws (maxillae) 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 man\' ? 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 X 5- ^ (<^) 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. (c) Sketch of front and hind wings X 5- (d) Side view of a grasshopper's head X 5- (e) Sketch of mandible X lO. (/) Sketch of maxilla X lo. (£■) Sketch of upper lip X 20. (//) Section of compound e}'e (microscope). Internal Structure, If we wish to e.Vamine the internal structure of a grasshopper, we ma\' prepare specimens b\' 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 AKD 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 awa\' 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 Fig. 38. — The Parts of a Locust, a, head; d, eye; c, antenna; d,/, i, thorax; ad, abdomen. tracheae, 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 yINIMAL ACTIVITIES. seen, consisting of the oesophagus, or gullet, a large crop, a stomach with many tubes called gastric c^eca, 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 Fig. 39. — Comparison of Grasshopper and Man. A, anterior; P, pos- terior; D, dorsal; V, ventral; n, nervous system; A, heart; y, food- tube. how this arrangement compares with that in the human bod\- (Fig. 391. Taking Food. The grasshopper lives entireK- on vegetable food. Although its mouth-parts appear much complicated, they are well adapted for their GRASSHOPPERS ASD CRICKETS. 37 work. The palpi feel about and locate the juic\- parts of plants, the maxillae 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 alimentar\- 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 chemicalh' 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 supph- 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 lioles 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. Eight of these openings may be easily seen on Fig. 40.— The Trachea of an Insect {magni- each side of the J^^d)- abdomen, and t w o others o n each side of the thorax. These holes, or spiracles, open into air-tubes, called tracheae, 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 tracheae 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 Qgg 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 httle 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 Fig. 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 e\-elids 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. Fig. 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 the}* 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. 41 each wing, and of each Fig. 43. — Portion of the Cornea of a Fly's Compound Eye {tnagnified). like ours, but are more Hke the sounds we produce when playing on a vioHn. Careful observation of a male cricket will best show us a method of stridiilating, 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- 1\- 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 be seen on on the under side 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 antennae 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 grasshopper can smell is evident from the way in which he chooses his food, and also from the fact that certain odors seem disagreeable to him. Touch. That the grasshopper pos- sesses the sense of touch is easy to prove, and that the antennae are especially sensitive as tactile organs is equally evident. The antennae are provided with Fig. 44.— The Hearing Organ of a C r i c k e t (mapiijied ). 42 /INIMAL ACTIVITIES. hairs which seem to increase their sensibihty, 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 b}- 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 Fig. 45. — The Stridulating Organ of a Cricket. a, large vein; b, 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. i. How do a grasshopper's activities differ from those of man t 2. Is it an advantage in insect-life to have the nervous system on the ventral part of the body t 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. W^hy does the grasshopper breathe } What chemical changes occur in breathing ? 8. What is the color of the grasshopper's blood } 9. What senses has the grasshopper .'* 10. What are the differences between organic and inorganic things } 1 1 . 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. How to 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, pi. antenna: (Gr. ana, up. and teifio, stretch), a feeler growing from the head of an in- sect. An te'ri or (Lat. ante, before), front. Bi lat'er al (Lat. bis, twice, and latiis. side), having two sides alike. Chi'tin (Gr. chiton, a tunic), the horny substance forming the exo- skeleton of insects. Coxa (Lat. coxa, the hip), the joint of an insect's leg next the body. Dor'sal (Lat. dorstwi, 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. labium, lip), the lower lip of an insect. La'bnim (Lat. labmm, 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 t/iorax), 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 ail animal from ^^'g 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. nymp/ic. a bride), a name applied to the young of some insects, as the grasshopper. 0 cel'lus (Lat. dim. oiocidus, eye), a small eye. 0 vi pos'i tor (Lat. ofum, egg. and pono, place), an instrument for depositing eggs. Pal'pus, ^\. palpi (Ldit.palpo, feel), a feeler growing from one of tlie mouth-parts. Pleu'rum (Gr. pleuron, rib), the side of the segment of an insect. See Fig. Pos te'ri or (Lat. post, after), hind- er. Pro tho'rax (Gr, pro, before, and thorax), the first segment of the thorax. Spir'a cle (Lat. spiraculum, air- hole), a breathing-hole. Ster'num (Gr. sternon, breast), the ventral portion of the segment of an insect. Strid u la'tion(Lat. strido. cr&z.'k), a creaking noise made by in- sects. Tar'sus (Gr. tarsos, a flat surface), the foot of an insect. Ter'gum (Lat. tergiun, back), the dorsal part of the segment of an insect. Tho'rax (Gr. thorax, the chest), the middle division of an insect's body. Tib'i a (Lat. tibia, shin-bone), the part of an insect's leg between the femur and foot. Tra'che a (Gr. tracheia, rough), one of the breathing-tubes of an insect. Tro chan'ter (Gr. trecho, 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. Plow 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 ? antennae ? palpi ? Do you find mandibles and maxillae ? 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 chr}'salis capable of any movement ? Can you find antenna, 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 the}' 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 Fig Antennse of Lepidoptera. A. of butterflies ; B, of moths. Note note the shape of the particles of dust (scales). 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 antennae. Describe the color above and below, and state the color and location of the markings you find. Notice the color of the feet, the antennae, and the eyes. Read 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. (^b) Side view of butterfly with wings closed. {c) Side view of head — enlarged — showing proboscis and eye. (d) Imaginary cross-section of proboscis. {e) Larva, pupa, and imago of some butterfly not figured in the text-book. (/) 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 antennae, holds its wings erect in repose, and flies more often in the daytime. The moths often have feathered antennae, 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 ss^ Fig. 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 ^gg 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 MINIMAL ACTiyiTIES. plete metamorphosis. On the other hand, there emerges from the egg of the butterfly a worm-Hke animal totally unlike its parents, who, could they see their offspring, would doubtless disown it. This Fig. 4S. — Some Larvae 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. V Fig. 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. but- or imao- The full-grown Fig. 50. — A Cabbage-butterfly, larva; b, pupa; r, egg; d, imago. terfly, or imago, no longer eats the coarse food familiar to its lar- val stage. In fact, it could not do so if it 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 produced 50 ANIMAL ACTIVITIES. by the elongating of the maxillae 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 surrounding muscles. This causes a pressure which 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 butterfl}' 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 Fig. 51. — lie ad of a Moth. a, upper lip; b, mandibles; c. proboscis; d, under lip; e, antennae; f, eye. 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 Fig. 52. — The Kallima. natural size. Drawn by A. E. Sanford. 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 onh' a small number to come to maturit}-. Both two-winged and four-winged flies deposit their eggs on the larvae or pupae of butterflies or moths. When these eggs hatch they produce larVcX which feed on the fat and muscle of their involuntar}- host and finally destro}' 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. 6"/). 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- fulh' protected by their color or shape, or both. Protective Coloration. A butterfly or moth when pursued often disappears as if by magic, and onh' the most careful search reveals its presence. Then it is Fig. 53. — Catocala Xup 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 Kallivia, 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 Zoology, and it is a part of the work of the student to find and describe them. BUTTERFLIES ASD MOTHS. 53 Mimicry. The common milk\veed-butterfl\' has a disagreeable odor and probably a disagreeable taste. On this account it is not a favorite food for birds. The Fig. 54. — The Milkweed-butterfly, a, dorsal view; b, ventral view. One half natural size. Drawn bv A. E. Sanford. Fig. 55. — Limenitis Ursula, a, dorsal view ; b, ventral view. One half natural size. Drawn by A. E. Sanfurd. Limenitis iirsula, 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 protectiv^e 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 /IND 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 b}- 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 Fig. 56a. — Moth at Rest. Fig. 56^.— 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. i. 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 butterfl}' see } 4. How much can a caterpillar see } 5. Do either caterpillar or butterfl}- 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 ? 9. Do you know any common animals which are protected by their color ? Topics for Reports. The Silk- worm. The Gypsy- moth. The Clothes-moth. The Life-history of Cecro- pia. The ]\Ietamorphosis of Lepidoptera. How to Destroy the Most Injurious Lepidoptera. Insects as Food. VOCABULARY. A'nus (Lat. anus, a ring), the opening of the digestive canal opposite the mouth. Chrys'a lis (Gr. clirysos. 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 nerve-mass. Haus tel'late (Lat. haiistrnm, a water-drawing machine), having mouth-parts fitted for sucking. I ma' go (Lat. imago, likeness), the adult insect. Lar'va (Lat. larz'a, a mask), the stage of metamorphosis immedi- suelv s-ucceeding the egg. Man dibu late (Lat. mando,c)\e\^), having mouth-parts fitted for biting. No'tum (Gr. jioios, back), the dor- sal surface. Pri'ma ry wings (Lat. primus, first), the first pair of wings. Pro bos'cis (Gr. pro, 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 da ry 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 to a 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 ocelH ? Do you find antennae ? Write resemblances and differences for fly and grass- hopper. Fig. 57. — Larva and Pupa of the House-fly. /^ larva {inagiiifiedy, c, pupa (w^^^- nijidd). Fig. 58.— Rio^ht Winglet o f Blu'ebottle {jnapiijied). Fig. 59. — Balancer of B 1 u e b o 1 1 1 e {tnagnijied . Summary of Drawings, in) A fl}- as seen from above with the wings extended at right angles to the body X 5- (d) The larva and pupa of a fly X 5- (c) One wing X 5- (d) A balancer much enlarged. (e) One antenna as seen with the microscope. (/") One leg and foot as seen with the microscope. SOME INSECTS CLASSIFIED. 59 Fig. 6o. — Portion of a Fly's Foot (ttuxgjiijied ). Fig. 6 1. — Side View of Proboscis, partly opened, b, basal division; c, central division; /, labella; 7n^ maxillary palpi. ^ '^ r. O -J -)-> c; > c; ^.z ^ c ^—H 'y; u-> c; o c O c C rt P o -4-> c; CX tx t s >> ^ ^ 1 <5 i O d V. s 3 (U o 11 E.2 3 '-' O tn li S 5 3 -^ 3 o tn S . Complete or incomplete metamorphosis. SOME INSECTS CLASSIFIED. 63 By comparing the notes we have already made we find that the insects so far studied have bilater-al symmetry, jointed bodies, and jointed appendages, as legs and antennae. The}' 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 tracheae. 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 stud}- more s}'stematic and more satisfactor}' in many ways. Such a classification must depend on differences as well as resemblances. If we should stud}' 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 /iNIMAL 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 ^gg 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 larvae and those having aquatic larvae; 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 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 ha\-e 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 b\- 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 elxtra 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 maxillae. 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, Danais arcJiippus means that the butterfly bearing that name belongs to the genus Danais and the species a^'chippus. 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. bi, two, and lanx, dish), one of the poisers of a dipterous insect. Col e op'te ra (Gr. koleos. sheath, a.nd ptero/i, wing), beetles. Dip'te ra (Gr. di, two, and pteron)^ two-winged insects. El'y tron, pi. elytra (Gr. elytrofi, a shield), a thickened fore-wing of an insect. Ge'nus, pi. genera (Lat. genus, a race), a group of animals or plants commonly made up of two or more species. Hal'ter, pi. halteres (Gr. halteres, jumping weights), a balancer of one of the diptera. Hem ip'te ra iGr. hemi, half, and pteron), an order of insects in- cluding the true bugs, Hy men op'te ra (Gr. hymen, a membrane, and//^r^«), an order of insects including bees and wasps. In sec'ta (Lat. prefix in, and seco, to cut), a class of Arthropoda including all true insects. Lep i dop'te ra (Gr. lepis, a scale, and pteron), an order of insects including butterflies and moths. Neur op'te ra (Gr. neuron, nerve, and pteron), 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, ■^x\A pterom, an order of insects including grasshoppers. Pseu do neur op'te ra (Gr. pseu- dos, fal^e, and neuroptera), 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. Thysanu'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 Danais archippiis or sometimes as the Anosia 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 a r seen to be very regu- larly carved in a beauti- ful and delicate pattern. The shape of the ^^^ is shown in Fig. 63. In a few days a little black-headed caterpil- lar, perhaps a tenth of an inch long, emerges from the ^%g, 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 Fig. 63. — Eggs of Milkweed-butterfly. ). After all, it is not so much a mask as a Fig. 68. — The Dragon-fly. A, larva; B, 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 tracheae or breath- FiG. 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 dra\\ n 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 Fig. 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- 8o 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 Fig. 71. — The Growth of a May-fly. A, larva; ^, pupa; C imago. or the whole of their life in the water. It will be interesting to watch the young caddis-flies (Fig. 70), young may-flics (Fig. 71), the adult water-boatman swimming on his back with his legs modified to form oars (Fig. 72), the dityciis 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. 8] 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 b\' the way is said to do all the biting Fig. 72. — A Water-boatman. A. in the water; B, 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). In a few days the tiny larvs open the under side of the eggs Fig. 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, alwa}'s 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 ex- 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 moulting several times, the larva changes to a pupa, Fig. 74. — Mouth of a Bug. a, antennae; /. labium; m, man- dibles and maxillae: t", eve. bending its head under its body as seen in the figure 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 \\ill also destroy the perfect insects as they emerge from their pupa-case boats. The imago now [wreathes, like other insects, by the spiracles along the sides of its body. It has but one --^MB Fig. 75.— The Egg- raft of a Mosquito. A CHAPTER. OF LIFE-HISTORIES. 83 Fig. 76.— The Life-history of a Mosquito. 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 the male mosquito, whose ears consist of tufts of hairs on his antennae. 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 cvolutionar}' growth. Questions. i. Have you observed closely the life- history of any insect ? If so, what are some of the changes you have noticed } Fig. 77. — The Mouth of a Female Mosquito. A CHAPTER OF LIhE-HlSTORIES. 85 2. What advantages and what disadvantages must be experienced by a larva hving in water ? Topics for Reports. The Life-history of a Beetle. A Lite-history I have Observed. VOCABULARY. A phis, pi. 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. ichneuo, to hunt), a genus of insects belonging to the hymenoptera. Mi cro gas'ter (Gr. ruikros, small, and gaster, stomacb <. a small hynienopterous fly. Mo squi'to (Lat. viusca, a fly), a well-known dipterous insect. Par then 0 gen'e sis (Gr. parthe- nos^ a virgin, and gigtiomai, to be born), reproduction by means of unfertilized eggs. Pro'leg, one of the fleshy abdom- inal legs of insect larv^. Pu pa'tion (Lat. pupa, a doll), the process of undergoing the pupal condition. CHAPTER VIII. SOME INSECT ADAPTATIONS. Structure and Habits. Fig. yS 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 bugrs. a portion of shows the parts of Fig. jS.— Leg of a Cock- roach. c2, coxa; fi, trochanter; c, femur; (/, tibia; e, tarsus. have Fig. 79.— a Mole-cricket. legs made a portion the 1 e g forms a 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- m a n (Xotonecta) and the large water- beetle (Dit}xus) into powerful oars, which the>' 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 Fig. So.— Fore Legs of a Water-bug. B, 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 Fig. 81. — Legs of Dyticus. A, hind legs for swimming; B, 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 in the particular Fig. 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 maxilla 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 ma}' 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 tracheae at some period of their life it is believed that their ancestors, as well as the ancestors of insects having aquatic lar\'a.% were originally terres- trial. Either driven b}' 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 pupae of ants of other communities than their own and rear them as slaves. To obtain these pupae wars are often waged, hence cooperation is necessary. Cooperation 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 it has 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 royal chamber. 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 90 y4NJMAL ACTll/ITIES. bees hatch from the egg as larvae, 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 cooperate with one another, there are also equally wonderful adaptations of structure fitting in- sects to cooperate 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 of another flower before fertiliza- tion can take place. This carry- 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, Fig. 83.- female ; worker. Hive-bees, i, 2, male; 3, SOME INSECT ADAPTATIONS. 91 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- FiG. 84. — Fertilization of a Flower by an Insect, a, calyx; b, curved upper lip; r, under lip, on which the bee stands while sucking the honey; d, pistil; d'. pistil at a later stage; e, 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 j4NIMAL activities. If you examine a head of the common white clover, so abundant everywhere, you will see a part of the tin) 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 wa^^s 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. Xot only do stamens and stigmas seek the insect, but the petals call their fi-iends 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 1 What might the mouth-parts of an insect indicate concerning its food } What adaptations have you noticed in insects you have observed } In Avhat 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 }'ou observed } Have you seen insects carrying pollen ? CHAPTER IX. A SPIDER'S ACTIVITIES. Place a li\ing 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 b}' 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 bod}' 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, {a) A spider seen from above X 3- (d) A front view of the mandibles X 5- (c) A view of the top of the head showing the ocelli. (d) 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 Fig. 85.— a Spider's Leg. which w^e 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 wqth 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. ^6). 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 somew^hat 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, of 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 tlieir beauty. Such a web is not a nest, or a house; it is a trap. 96 ANIM/IL ACTiyiTIES. Commonly the spider builds her home at one side of the trap, and, holding in one claw a thread which she Fig. ^6. — 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, t'iie pulling indicates a wasp or bee the movements are o\ 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 hopelessh' 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 chemistr}^ of breathing is the same in all animals. Reproduction. The spider deposits her eggs in a cocoon of silk which she makes w4th 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 9« MINIMAL ACTIVITIES. tiny thread. They moult often, and very soon, with- out any teaching, they know how to spin their tiny wheel-shaped webs. They eat other insects, as do their elders, and often dine on one another. For them the struggle for existence is a fierce one, and domestic relations count for little, the mother eating 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 large is the nerve-mass concealed in the cephalothorax of the spider. Several ganglia have grown together and produced a sort of second brain, considerably larger than the nerve-mass which lies above the throat. Not only is this brain large, but as it is made by the concentration of many smaller nerve-masses, or gan- 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. The spider then is extremely sensitive to any change in its surroundings. It sees, though not very clearly, by means of eight eyes 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 smells, we have no doubt; but its keenest sense is that of touch. Movements. The 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 sho^^'s 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 man}'-legged brown insects which disappear so hurriedly when one overturns a A SPIDER'S ACTIVITIES. 99 board or stone, in almost an\- field or garden. In some localities these animals are called "earwigs ", in other places they are 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. The}' 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. i. How do the breathing-organs of a spider differ from those of the insects previoush' 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-flies. 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 (experiments). Spider- webs. Water-spiders. Trap-door Spiders. Scorpions. Cheese-mites. Centipedes. Thousand-legs. Stings and Poisons. The Sense of Sight in Spiders. Where lOO ANIMAL ACTIVITIES. I Have Found Spiders. Are Spiders of Any Use ? The Mosquito's Boat. My Experience in Rearing Butterflies. Lightning-bugs. Injurious Insects. Some Insect Friends. Aphides as Cows of Ants. Valuable Substances Furnished by Insects. The First Paper- makers. Do Insects Talk 1 Insects I Dislike. VOCABULARY, A e'rial (Gr. aer, the air), inhabit- ing the air. A quat'ic (Lat. aqua, water), in- habiting the water. Ceph al 0 tho'rax (Gr. kephale, head, and thorax), 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. Habitat (Lat. habito, to dwell), the natural abode of an ani- mal. Ma line' (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. suo^ to sew), a seam or joint. Ter res'tri al ( Lat. tei-ra, the earth i, inhabiting or living on the land. CHAPTER X. HOMOLOGIES AMONG CRUSTACEA. Living crayfish can be bought in the markets of Lirge cities. One or two of these should be kept in an aquarium with several inches of water in a place where the class may study their structure and their move- FiG. 87. — Side View of Crayfish, ati. antenna; r. rostrum; cep. cephalic portion; tho, thoracic portion of cephalothorax; ab^ abdomen. ments before attempting the laboratory exercise on the shrimp. Feed the crayfish with pieces of meat or fish, and note the manner of seizing and eating food. Touch the antennae with various substances. See "Outline for Requirements in Zoolog}* " printed b)' Harvard University. Notice how the crayfish walks and how it swims backward when disturbed. I02 /iNIMAL 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. Fig. 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 szvimmercts. At the end of the abdomen is the tclson, which forms with the last pair of swimmerets the tail of the shrimp. The large claws used for grasping prey Fig. 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 obser\'e .^ 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 maxillipcdcs. In front of the maxilli- pedes are two pairs of maxilla:. In front of the maxillae are the mandibles. How many pairs of antennae do you find } Are they branched } How do the eyes differ from those of a grasshopper } I04 ANIMAL ACTiyiTIFS. 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 having pincers with those which do not have those organs. How much extra growth would be needed to produce a pair of pincers on the last pair of legs ? Examine all the jointed ap- pendages on one side of the How many do you find ? Counting a pair of appendages to each segment or somite, 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 Fig. 90. — Fourtli Ab- dominal Segment of Crayfish. /, tergum; st, sternum; //. pleu- rum; /r, protopodite; €71, endopodite; ex, ex- opodite. One append- age has been removed. body. HOMOLOGIES AMONG CRUSTACEA. 105 nervous system should be especially noted. In looking for the heart remove the top of the carapace where \-ou see the depression just behind the line between head and thorax. Summary of Drawings, {a) Side view of shrimp X 4 (omitting- appendages). B .^ Fig. 91. — Cra\ti^h Appendages. A, antennule; B, antenna; C. man- dible; D, second maxilla ; E, second maxillipede. [b) 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. {e) Large antenna x 6. (f) Small antenna X 6. i^g) First, second, and last X4. io6 ANIMAL ACTIVITIES. (/i) A swimmeret from the third abdominal segment seen from behind X 6. (i) Sixth swimmeret. Homologies. In the lobster, shrimp, and crayfish, the antennae, claws, legs, and swimmerefs are seen to Fig. 92. — Lx)ngitudinal Section of Crayfish. c7. anus; d.a., dorsal artery; /i.^^., intestine or hind- gut; ^, heart; »i.g., midgut; //, liver; s, stom- ach; k, kidney; /a, labrum or lip; s.a., sternal artery; n.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 Jioinologons. 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, the\' are said to be iDialogous. Thus the wing of a bird and the wing of a butterfly are analocfous but not homolo""ous. HOMOLOGIES AMONG CRUSTACEA. lO' 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 basipodite 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 similarit}' 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 ? {b') The number and form of swimmerets {c) The number of antennae ? Fig. 93. — Walking Appendage o f Crayfish with Gill, ^, Attached. id) W (/) (A) (0 The number of segments bodv The divisions of the The eyes ? The carapace .'' 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. io8 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 Fig. 94. — The Common Crab. yet appear very unlike. Parts which arise in the same way in the processes of development may become so Fig. 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- onh' slight external resemblance to one another in adult life are classified together because in embryological life they show so man\' 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- 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, }'et in the young the abdomen of this animal Fig. 96. Water-flea {Daphnia pulex). Fig. 97. — Cyclops. A. dorsal view; B, side view. is essentialh" like that of the }'oung crayfish and bears liomologous parts. no 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 Ento- nwstraca. 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 hatching from the ^^^ 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 Fig. 98. — A Barnacle. HOMOLOGIES AMONG CRUSTACEA. m 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 Qgg as free-swimming larvae, bearing a striking similarity to other Crustacea at this stage of growth. The common larval form is called the iiaupluis. (See first stage in Fig. 95. ) It has a single eye and three pairs of appendages. The higher Crus- tacea pass through this nauplius stage before hatching from the ^%g. 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. AX EXERCISE FOR THE XOTE-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 " b\' selecting the points of resemblance among them, W'e 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 ph}-lum because they constitute one of the large divisions of the 112 ANIMAL ACTIVITIES. Grass- hop.per. Spider. Lithobius. Shrimp. Bilateral ? Are appendages jointed ? Wings, antennae, legs, and swini- 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 Xymphalidae, 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: (i) 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. 114 ANIMAL ACTIVITIES. (5) 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, (i) 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. 1 1 VOCABULARY An al'o gOUS (Gr. ana. according to, znd ioffos.) Analogous organs are those having the same use but not necessarily the same structure or origin. Bas ip'O dite (Lat. basis, base, and Gr. pons, foot), part of a crus- tacean appendage. Car'a pace iLat. capara, a hood), the hard covering of the cephalo- thorax in Crustacea. Ceph al i za'tion (Gr. kephale, head), a tendency to aggregate nerves and organs of sense near the head. Cox op 'O dite (Lat. coxa^ hip, and Gr. pons), the joint of a crusta- cean appendage nearest the body. Cms ta'ce a, a class of arthropoda commonly having a hard shell. Decapod^Gr. deka. ten, and/f/^j-), an order of Crustacea having ten legs. Dif fer en ti a'tion (Lat. dis, apart, and fero, to carry), the setting apart of tissues and organs to perform special kinds of work. Em bry d'o gy ( Gr. embryon^ an I embryo, and logos), the study of I embryonic life. En dop' 0 dite ( Gr. e)i, in, and/^Kj), I the outer branch of a swim- meret. Ex u'vi um (Lat. exuo, to strip off), the cast-off skin of an insect or crustacean. Fang, a hollow tooth emitting poison. Far til i za'tion (Lat./^r^?, 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. Homologous (Gr. homos, same, and h^gos), having the same rel- ative position and structure. I'sopod(Gr. isos, equal, Tindpous), an order of Crustacea having the legs of equal length. Maxil'liped {maxilla, 2ind pous), a foot-jaw. Os mo'sis iGr. osmose, pushing), an interchange of gases or liquids through a slightly porous substance. Pro top'o dite (Gr. protos, first, 2i\\d poiis), a part of a swimmeret consisting of the basipodite and coxopodite. Re'nal (Lat. reiialis, kidney), per- taining to the kidneys. Ros'tmm (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. sotna, 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. tango, to touch), having the sense of touch. Tel' son (Gr. t els on, a boundary), the posterior somite of a crus- tacean. Tet ra dec'a pod (Gr. tetra, four. deka and pons), an order of Crustacea having fourteen legs. CHAPTER XI. THE ACTIVITIES OF OXE-CELLED ANIMALS AND SPONGES. Thus 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 ma}- 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 wa\'s may be very well understood by studying descriptions of a few forms. The Amoeba. 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 Ii6 ONE-CELLED ANLMALS AND SPONGES. 117 under the microscope looks like a drop of moving jelly of irregular outline. The greater part of the Amoeba 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 Amoeba is made is called Fig. 99. — Forms of Amoebse {highly viagnified). 2 and 3 were drawn from the same specimen; 5, 6, 7, and 8 were drawn from another specimen; iV, 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 ever}' animal begins its life as a single cell of protoplasm. Within the Amoeba'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. Il8 ANIMAL ACTIVITIES. Taking Food. Not only is the Amoeba 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 Amoeba's body. The shell of the plant is thrust out through the Amoeba's covering at any point when all the nutritious matter has been taken from it. Dis- solving and chemically changing the food is digestio7i. Making it a part of the Amoeba's protoplasm is assimi- latio7i. 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 Amoeba has eaten and digested food until it has grown to be too large, the nucleus shows signs of divid- ing, the Amoeba assumes a dumbbell shape and finally ^, splits into two Amoebas, ' ^^"""■'^ each equally capable of Fig. ioo.— Amoeba 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 q';x\\^A fission. Discovery. If touched the Amoeba 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 Amoeba 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 Httle swelhng thus made is called a pscudopodiiini 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 Amoeba'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 ^^^ (a single cell) of one of the more specialized members of the series passes in its growth. Rhizopoda with Shells. Some of the Amceba-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, that is, they are yiq. formed from the protoplasm 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 RJiizopoda. Some of the Rhizopoda secrete shells of calcium car- I20 ANIMAL ACTIVITIES. bonate or limestone. When these shells are perforated with many holes the animals are called Foraniiiiifera. Fig. I02. — 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. Fig. 103. — The Origin of Chalk. A^ chalk {magnified); B, ooze {mag- nified). Chalk. At present there live near the surface of tlie ocean great numbers of these shelled Rhizopods. ONE- CELLED ANIMALS AND SPONGES. 121 When they die their sliells 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 tripolite, 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 Fig. 104. — Infusorial Earth {magnified). Fig. 105. — Infusorians {77iagnified). 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 cilia. One- celled animals which move by cilia are called Iiifusoria 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, hke the bell-animalcule, or vorticella, shown in the figure, and some are rapidly moving free animals like those found in infusions of hay. 132 /iNIMAL ACTiyiTIES. One of the Infusoria found in infusions of vegetable matter is the Paf-auieciiiui, or slipper-animalcule (Fig. 107). This ma}' be found and stud- ied very easily. W^here 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 definite shape '^. Is it bilateral .'' Is the Amoeba 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 } 3. Do you see the movement of cilia } On what part of the body are they situated ? 4. Do you find 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. the blue particles go ? Summary of Drawings, {a) A sketch animals as they appear when viewed with a of the microscope. (/;) Sketch of a single animal showing as many 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 Fig. 106. — Vorticella {magH{_fie(£). A, ex- tended ; B, contract- ed: C, in fission. a groove sur- Where do of several low power parts ONE-CELLED AMMALS AND SPONGES. 123 Do you find the cavity for the passage of the large blood-vessel "^ Call this the haemal arch, and the spine attached to it the haemal spine. This arch protects the dorsal aorta. Are there any ribs present } Using one of the vertebrae 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 \\'ith nerves. (/) End view of a vertebra from near the tail. {g) End view of a vertebra above the visceral cavity. (//) Longitudinal section of a vertebra. Vertebrates. The study of a fish introduces us to the class Vertcbrata of the sub-kingdom Chordata. The possession of a back-bone made up of vertebrae gives this class its name. This back-bone furnishes a THE STRUCTURE AND ACTIVITIES OF A FISH. I75 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 vertebrae. The soft substance extending through the centra of the vertebrae of the fish probabh' 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 ANIMAL ACTIVITIES. with the gullet. This bladder serves to vary the specific gravity of the fish in the water. Sometimes it is used in producing a noise. 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. The blood is then distributed to all parts of the body by arteries. See Fig. 132. Questions. What do you mean by saying that a fish is cold-blooded ^ 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 Nests of the Stickleback. The Migrations of Salmon. Bream. Trout. Sharks. Electric Eels. The Sea-serpent. Flying Fish. VOCABULARY. Aor'ta (Gr. aeiro, to raise), the i Chor da'ta (Gr. chorde, a chord), large artery of the body. The sub-kingdom including the Ar'te ry (Gr. arteria, windpipe), I back-boned animals. a tube carrying blood away ' Hae'mal (Gr. haitna, blood), per- from the heart. , taining to the blood. Sometimes Cau'dal (Lat. cauda, tail), pertain- ing to a tail. Cen'tnim (Lat. centru?n, a centre), the body of a vertebra. Cerebel'lum (Lat. dim. of cere- brum), the hind brain. It con- lobes. used with the same meaning as visceral. Het er 0 cer'cal (Gr. Iieteros, differ- ent, and kerkos, tailK applied to the tails of fishes having unequal trols comlnned muscular action. Cer'e brum (Lat. cerebnwi, brain), the front brain, the seat of the reasoning faculties. Ho mo cereal (Gr. homos, same, and kerkos), a word applied to the tails of fishes having equal lobes. THE STRUCTURE AND ACTIVITIES OF A FISH. i77 Im'bri ca ted (Lat. imbrex, gutter- tile), overlapping. Max'il la ry (Lat. macero, to s6ft- en), pertaining to the jaw; com- monly to the upper jaw. Mes'entery (Gr. mesos, middle, and ente?-on, intestine), in verte- brates the membrane holding the intestines in place. Neu'ral (Gr. neuron, a nerve), per- taining to the nerves. In verte- brates it is applied to the dorsal cavity of the body. No to chord (Gr. notos, back, and chorde, a cord), a rod of carti- lage from which the vertebral column develops in vertebrates. (E soph'a gus (Gr. oisd, will carry, and phagein, to eat), the tube connecting the throat with the stomach. 0 per'cu lum (Lat. operculum, a lid), the gill-cover in fishes. Pec'to ral (Lat. pectus, breast), pertaining to the breast. Tes'sel la ted (Lat. tessellatus, 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. 178 ANIMAL ACTIVITIES, O 4 02 •S E a G J3 (£3 to u •0 X c to 8 S < to c 1 0 C a 0 CHAPTER XVII. TADPOLES AND FROGS. Ix the study of the frog, aquaria are indispensable. The expense, howe\'er, 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 i8o /iNIMAL ACTIVITIES. In a specimen which has been hardened in alcohol do you find vertebrae ? Do you find a 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. (<^) 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 man}- 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 find a mem- brane covering the eye (nictitating membrane) } Frog Hardened in Alcohol. Look in the mouth. Do you find any teeth ^ How many ^ Where are the)' ? 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. l8l (Eustachian tube.) Cut open the membrane covering the ear and use a probe. Using a prepared specimen showing the internal organs, do you find the peritoneum ? the mesentery } the stomach ? the intestine ? the hver ? 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 fi-eshly 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 } In what ways does a frog resemble a fish .'' How does the frog differ from the fish } Summary of Drawings, {a) Outline of organs seen in the visceral cavity. [b) 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 l82 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 on the upper jaw and on the palate or roof of the mouth. Taking Oxygen. When the young frog emerges from the ^gg 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 da}'s these external gills disappear, and other gills grow under the opercular membrane. This Fig. 135. — Tongue of a Frog. Fig. 136. — A Young Tadpole Showing External Gills. membrane is joined to the bod}'-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 Fig. 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 AVA Fig. 138.— Heart of Adult Frog. a, auricles ; v, ven- tricle. Fig. 139. — Blood-cells of a Frog, a, red cor- puscle; ^, colorless cor- puscle. breathes by the entire surface of the body, the skin being especially rich in blood-vessels. i84 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 Fig. 140. — Blood -corpuscles of Man. j, r', r", red corpuscles ; p and g, white corpuscles; c^ 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 usc- FiG. 141. — Viscera of Frog. 5w./«., small intestine; Z./., large intes- tine; ^>.^/., bladder; /t'.r^., pericardial cavity; F, ventricle; T.A., large artery; Ao, aorta; /. pulmonary artery; Pn, 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 &gg. 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, 1^6 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 Fig. 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 cling in clusters to plants, or other objects; ife poles 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 confervae so common on the sides of aquaria. Growth is now rapid, and in a few months the legs appear and the tail is absorbed. Fig. 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. i88 ANIMAL ACTIVITIES. Fig. 144. — Growth of Frog's Egg. A muscle shortens because the cells of protoplasm of which it is composed all have the power of contrac- tility. The cells all contract in one direction, making the whole muscle shorter and thicker. These contractions are under the control of the nerves. A number of muscle-cells make one of the fibrillae. Several of these fibrill?e wrapped in a sheath form a fibre. The fibres are wrapped in bundles, and these bundles are covered by a thin la}'er of tough connective tissue. The sheaths or coverings of muscles, bundles, and fibres unite to form tendons by which the muscles are attached to the bones (Figs. 149 and 150). Muscles under the control of the will, like those in the leg of a frog or of a man, show peculiar cross-mark- ings. Muscles not under the control of the will, like those of the intestine or stomach, are commonly unstriped. The bony skeleton of the frog, on which the muscles act to cause the movements of the body, has an axis of nine movable bones, the vertebrae. Behind these a long bone, the urostyle, reaches to the hips, and in front is at- tached the head w^ith its broad skull and large jaws. On the base of the skull are two rounded prominences called condyles, which fit into corresponding de- pressions on the atlas-bone, the first bone of the vertebral axis (Fig. 151). The fore limbs are attached to the axial skeleton by muscles and ligaments. A shoulder, or pectoral girdle, consisting of several bones is present. The hinder Fig. 45. — Very Young Tadpoles. TADPOLES AND FROGS. 189 limbs are attached to the axial skeleton through the pelvic girdle. The bones of the arm consist of the Jnnnertis, or forearm, the radio-tihia, corresponding to <^^ ^^^ Fig. 146. — Various Stages of Tadpole. the two bones, the radius and tdna 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 tibia Fig. 147. — Young Frogs. diwd fibiila in man, the tarsal bones, two of which are much longer than the others, the metatarsal or ankle- bones and t\\Q phalanges (Fig. 152V 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 sharp as in 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, i 5 3 and 1 54). Fig. 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. 191 Sight. The optic lobes just mentioned are con- nected with a pair of eyes very much Hke 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 7'etina, which corresponds to the ground glass of a camera and is composed of nervous tissue forming the end of the optic nerve. The frog sees well, B f ■ " ■ ' ", km I . *^ /rsj ' # Fig. 149. — Striped Muscle-fibres. A. a fibre much magnified; B, a fibre breaking up into fibrillae. as is evidenced by the precision with which he strike? 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 eiistacJiian 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 hning the mouth. Touch. The skin is well supplied with nerves, and there are special tactile areas. Classification. The frog belongs to the division of Vertcbrata 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 toads, fro^s, and sala- belong the 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 resembles in 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 Fig. 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 CLAVICLE, Cif„jE_- Fig. 153. — Brain of Frog. 01. olfactory- lobes; CH, cerebral hemispheres ; OpL, optic lobes ; CI, cerebellum; MO, medulla oblongata. Fig. 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 MEDULLA OBLONGATA CEREBELLUM SPINAL CORD SP'NAL COLUMN CUT ENDS OF SPINAL NEIIVES Fig. 154. — Brain and Spinal Cord of Man. 196 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 XVni. BIRDS. Ix 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 ^vith this class of Vertcbrata. 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 7iictitating 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 t 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 Qgg compare with the size of its body ? How does the size of a frog's Qgg 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 man}' 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. {b) Sketch of a wing covered with feathers. {c) Side view of foot and leg, naming femur, fibula, tibia, tarsus, metatarsus, and phalanges. {d) Sketch of whole feather. {e) Sketch of a barb showing barbules (magnified). f IG. 155. — a, beak of snipe, fitted for probing in soft mud ; b, beak of sparrow, fitted for cracking seeds ; c. 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. Xoticeable., 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 ojt 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 miore than a hundred thousand canker-worm es^^s in Fig, 156. — The Digestive Organs of a Bird, a, oesophagus; b, crop; C, stomach; c. 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 i))iporta}icc of preserving bird life eannot be easily overestimated. BIRDS. 20I Fig. 157. — Diagram of the Heart of a Bird. 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 oesophagus 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. Respiration. Breathing 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 Ggg 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. i6o). At the elbow the arm is bent, and the space between the arm and forearm is filled with a strong web bearing feathers and Fig. [58.— The Skeleton of a Bird. BIRDS. 20^ 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- 59. — 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 ha\e 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. A B C Fig. i6o. — A, arm of man; B, fore leg of dog; C. wing of bird; /^, humerus; r, radius; u, ulna; c, carpus- m, metacarpus; /, phalanges. Fig. i6i. — A Bird's Wing, a, when flying; />, 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, ox}'gen 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. Not only can birds move from place to place in search of food, 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. Fig. 162. — The Sternum of a Shrike. 2o6 ANIMAL ACTIVITIES. Some fossil birds had teeth Hke reptiles, and at least one bird had a long reptilian tail (Fig. i66). Because of these resemblances birds and reptiles have sometimes been classed together as Saiiropsida. Classification of Birds. Birds have been most com- monly classed in accordance with their most easily Fig. 163. — Feathers, a, a quill-feather ; b, quill-feathers fastened to wing ; c, a shape-feather ; d, a down-feather. recognized points of external structure; this structure being dependent largely on the habits 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 The legs are long and lacking. I. The Running Birds (Struthii). the wings small. The keel of the sternum is 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. Fig. 164.— a Bird's Leg. short, duck. III. Swimming Birds (Xatatores). The legs are and there is a web between the front toes. Penguin, 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 (Columbinoe). These birds resemble the rasores but have weaker legs, pointed wings, and a fleshy membrane at the base of the beak. Pigeon. VII. Oimbing 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 I)ointing forward and one pointing backward, all on a level. Here belong almost all our common song birds. Fig. 165. -A, foot of a pelican; i?, foot of a perching bird; C, foot of a kinefisher. Qiicstions. What are some common birds of very rapid flight t 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' Xests. 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 ]\Ir. Bur- The Arch?eopteryx. roughs Bird says m Homes. ' ' Birds and Shapes and Length of Life among Birds. Bees and Sharp Eyes." Colors of Birds' Eggs. Falconry. VOCABULARY. Am phib'ia (Gr. amphi, around, or on both sides, and bios, life), a class of vertebrateanimalsbreath- ing by gills when young. Au'ricle (Lat. auris, ear), a cham- ber of the heart for receiving blood from the veins. Barb (Lat. barba, beard), one of the side branches of a feather. Barb'ule (Lat. dim. of barba), one of the projections along the edges of the barbs of a feather. Bat ra'chi a (Gr. bairichos, frog), another name for the Amphibia. Car'pus (Gr. karpos, wrist), the \vri. 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 dio-itiGrrade o o animals. The horse presents an extreme illustration of the digitigi-ade 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 /iNIM^L /ICTIVITIES. palms, toes, finger Thev we could hasten only by rising on fingers and Should we so rise it is easy to see that the little and the thumb would not touch the ground, 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 Fig. 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 mictacarpal 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. Hair, 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 t' J Fig. 192. — Growth of Hair. ^, hair- rudiment ; ^, 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 Hghter 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 1 Fig. 193. — I, 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 hi EAR 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 Fig. 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. QiiestioJis. Refer to Figs. 178, 195, and 196. Fig. 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 RELATiyES {MAMMALS). 233 In what respects are the monke}'s pecuHarly fitted for their environment ? How do monkevs differ from doc^s ? well In the struggle for existence what advantages do Fig. 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 ? MAN'S NEAR RELATIVES (MAMMALS). 235 ?8 0 U ■a ffi 6 3 E- . 1 1 J 1 1 > § 1 8 > en 1 ! 3 6 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 lar'^/'^ of dragon-flies and mos- quitoes live in the water, Avhile 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 habitat. Animals living mostly in the air are said to be aerial, those inhabiting the dry land terrestriaU and those dwelling in the water aqtiatic. Aquatic animals may be either fresh- water or marine form.s. 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, b}^ 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 ever}'- 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 \\.?, fauna /)M^X. as the plants inhabiting a locality consti- tute its flora. The entire region inliabited 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 oi 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 b\' 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 lars^e 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 Zoologists. 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 oi change of dwelling-place these questions 2 40 /iKIMAL 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 an insoluble 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 tracheae 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 tracheae 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. 242 ANIMAL ACTIVITIES. u •a ••• ^ S? , •c o 1— 1 1^ o Oi D 73 »— 1 03 ... . 1^ iJh M H > «H rv^ T ^ r-i w N CS ;zi o _. o Y u C/3 a u /-»> u Q >- «J" c J )— 1 rt c/: s < W ^ Z jj < 3 ^ ^ ^ c '^ ^ en "s < g u t ^ b O OJ H C/3 ►3 u < CHAPTER XXT. ANIMAL RELATIONSHIPS. Classification. In the earlier days of zoological 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, IMollusks, 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 3 • 3 3 3 Fig. 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 da}'. 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 archaeopteryx, a reptile-like bird. We do not know that any living birds or reptiles have descended directly from the archaeopteryx, but it — 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 careiul study of fossils. 246 ANIMAL ACTiyiTIES. Embryology. The sea-squirts, called also ascidians and tunicates, were once classified as belonging to the MoUusca, and later to the Vermes. Zoologists 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 Fig. 199. — The Archceopterj-x. 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. Fig. 200. — Diagram of a Sea-squirt, a, mouth; 3. vent; ^.gullet-open- ing; d, nerve-ganglion; mals, separating the thoracic and visceral cavities. Dig i ti grade (Lat. digitus, a fin- ger, -.wAgradiis. a step), walking on the toes without using the sole of the ibot. Gas'tru la i^Lat. dim. oi gaster, the belly), an embryonic lorm of animals belonging to the Meta- zoa. Mammal ;^Lat. mamma, breast), a vertebrate animal whose female has milk-producing glands. Mor'u la (Gr. moron, a mulberry), an early stage trom the growth of an egg. Plan'ti grade (Lat. planta, the sole of the loot, and gradus, a step;, applied to animals which walk on the sole of the foot. Pter 0 dac'tyl (Gr. pUron, a wing, and daktylos, a linger^, an ex- tinct liying reptile. INDEX. Abdomen of Crustacea, 102 " " grasshopper, 32 <' '' insects, 32 Aboral surface, 140 Acephala, 165 Actinozoa, 137 Activities of amoeba, 116 " " bird, 199 '< " butterfly, 47 " " earthworm, 150 " *' fresh. water mussel, 158 " '' frog, 181 '* *' grasshopper, 36 '< << hydra, 129 " " spider. 93 " " starfish, 142 Adaptations. 86 Adductor muscles, 156, 159 Air-sacs of birds, 205 " '* spiders, 97 Alimentary canal, 37 Alternation of generations, 133 Ambulacral areas, 141 '' feet, 140 Amoeba, 116 Amphibia, 192 Amphioxus, 247 Ampullse, 141, 143 Analogous organs, 106 Anatomy, 30 Angleworm, 148 Animal kingdom, 2 Animal relationships, 243 Annulata, 148 Anodon, 155, 157, 254 Anosia plexippus, 68 Antennae, 33 " of crayfish, 105 '' " grasshoppers, 33 Antennules, X05 Aorta of fish, 170 " " frog, 195 Apes, 232 Aphis, 72 Apparatus, 4 Appendicular skeleton of frog, 189 Aquaria, 8 Arachnida. 113 Archaeopteryx, 209 Argonaut, 166 Aristotle's lantern, 146 Arthropoda, 2, iii Ascidians, 246 Asellus, 86 Assimilation. 118 Asterias vulgaris, 140 Atlas bone, 188 Auditory nerves, 173 Auricle of fish, 170 Aves, 254 Axial skeleton, 220 *' " of frog, 188 B Balancer of fly, 58, 67 Barnacles, no 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 offish, 173 " " frog, 188 257 258 INDEX. Botany, 31 Branchial arches of fish, 170 Bream, 14 Breeding-cage, 6 Brittle starfish. 144 Butterflies. 5, 21, 45 Butterfly enemies, 50 Byssus, 167 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, loi Cerebellum, 173 Cerebral lobes. 173 Cerebrum, 173 Chalk animals, 120 Characteristics of actinozoa, 137 '< " amphibia, 192 ♦< *' arachnida, 113 " " birds, 205 " '* ccelenterata, 137 «' <* Crustacea, 113 " << echinodermata ** " hydrozoa. 147 « *' moUusca, 166 " *' pisces, 175 " '< protozoa, 123 «< <■' reptilia, 192 << " scyphozoa, 137 Chemistry of life, 24 Chimpanzee, 182 Chitin, 44 Chordata. 2. 174, 254 Chrysalids. 48 Cilia, 121 Circulation of birds, 201 '' " fish, 171 " '• fi-og, 185 <' " man, 221 Classes. 112 Classification of animal kingdom, 2, 243, 253. 254, 255 " *' arthropoda, iii '< '' birds, 207 " " 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, 1 17 Coracoid bones, 203 Coral, 2, 135 Cornea, 214 Corpuscles, 184 Costal, 56 Coxa of insects, 34 Coxopodite, 104, 107 Crayfish. 2. 13. lOl Cricket, 5, 41, 42 Crinoids, 146 Cross-fertilization, 131 ' Crow, 23 Crustacea, loi Ctenophora, 253 Cyclops, II, 109 Danais archippus, 68 Daphnia pulex, 109 INDEX. 259 Decomposition of water. 26 Definitions : see vocabularies Degeneration, no Dental formulae, 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 Earthworm, 7, 148 Echinodermata, 142 Ectoderm. 123 Eggs of birds, 201 '• '' 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 Facets, 33 Families, 112 Fauna, 237 Feathers. 198 Feet of birds, 198 Femur of insects, 34 " " man, 194 Fertilization of plants by insects, 89 Fibula, 167 Fingers and toes of mammals, 224 Fins of fish, 159 Fishes, 169 Fission. 118 Flies. 6, 57 Flight of birds, 202, 203, 204 " insects, 42 Food of amoeba, 118 " " butterfly, 5, 49 " '' caterpillar, 6, 48 '• " crayfish, 13 *' " earthworm, 150 " " fish. 169 " " fly, 6, 57 " '^ frog, 7, 179 " " grasshopper, 36 " " hydra, 1 1, 128. 129 *' '• leech, 13 *' " mussel, 8, 166 " " slug, 7 " *' snail, 8 " " spider, 6, 94 " " starfish, 142 ♦' " tadpole, 13 " " txirtle, 7 " '• ^^'^isp, 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 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 26o INDEX. H Habitat, 236. 240 Habits and organs, 88 Haemal 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 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 " 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 Larvae 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 " viscera, 223 Mandibles, 33 Mantle of mollusca. 156, 161, 166 Mask of dragon-fly larva, 77 Materials for study, 4 Matter, 24 Maxillae, 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 INDEX, 261 N Names of insects, 66 Natatores, 208 Natural selection, 54 Nauplius. Ill 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 " of grasshopper, 37 Ocelli, 33 Olfactory lobes of fish, 173 Oosperms, 131 Operculum of snail, 164 Optic lobes offish, 173 Oral surface of starfish. 140 Orders, 112 *• of insects, 64 Orthoptera, 65 Oscula of sponge, 124 Osmosis, 38 Ovipositor, 33 Oxidation, 27 Pallial line, 156 Palpi, 34 Paramecium, 122 Parthenogenesis, 73 Passeres, 208 Pearls, 161 Pectoral fins, 169 Pectoral girdle, 175 Pedal ganglia, 162 PediceUariae, 140 Pelecypoda, 165 Pelvic girdle, 175 Peritoneum, 181 Phalanges, 189, 199 Phosphorescence, 114 Phylum, I, 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, 1 19 Pterodactyl, 245 Pupation, 70 Radiate symmetry, 2 Range of animals, 237 Raptores, 208 Reference-books, vi Repair. 26 Reproduction, 30 " of amoeba, 118 *' '■ grasshopper, 37 Reptilia, 192 Resemblances, 61, iii Respiration of grasshopper, 3> Rhizopoda, 119 Sand-wasp. 74 Sarcoda, 123 Sauropsida, 207 Scansores, 208 Scyphozoa, 134. Sea-anemone, 15 " cucumber, 146 *' squirt, 246 " urchin, 145 Sedentary, 115 37 262 INDEX. Slugs, Smelt, Snails. 174, 195 Senses of grasshopper, 40 Septa of coral, 135 Serial homology, 107 Shrimp. loi Silicious sponge. 125 Siphon of mussel, 158 Skeleton of bat, 222 '• " bird. 193 " *' chimpanzee, 223 " fish, 173 " frog, 193 " " horse, 215 *' *' man, 194 7, 162 169 5. 163 Snakes, 7 Somite, 104 Sow-bug, 5 Species, 112 Sperms of hydra, 130 Spicules of sponge, 125 Spider, 93 Spinal cord, 17;; Spinal nerve, 173 Spinnerets, 94 Spiracles, 32 Sponges, 123 Squash-bug, 61 Squid, 166 Starfish, 140 Sternum, 104 Stone-lilies, 2 Stridulating, 4] Structure and habitat, Struthii, 207 Stylets, 43 Supraoesophageal ganglia, 167 Survival of fittest, 35 Swimmerets, 103 Sympathetic system of nerves, 181 Synapta, 146 Tadpoles, 179 Tanning worms, 148 Tarsus of insect, 34 " *' man, 197 Teeth of mammals, 231 Tel son, 115 Tergum, 32, 104 42 240 Thecse, 138 Thorax of insects, 33 Thysaneura, 65 Tibia of insect, 34 " •' man. 194 Tongue of frog. 182 Trachea of an in^ect, 38 Trochanter of insects, 34 Turtles, 7 Tympanum, 33 U Unio, 155 Urostyle, 198 Urea. 29 Usefulness of earthworms, 153 \' 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, 115 echinodermata, 147 insects, 44, 56, 67, 85 mollusca, 167 vertebrate animals. 176, 177, 210, 255 Vocabularies of general terms fre-= quently used, 31, 100. 255 W Wasps, 5 Waste, 26 Water-boatman, 80, 81 •' fleas, 109 '• spider, 95 Web of spider, 95 Wing of birds, 198 *' " insect, 42 Winglet, 58 Z Zooids, 132 Zoology, 30 34332 590 sPSQ