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Full text of "Principles of zoology : touching the structure, development, distribution, and natural arrangement of the races of animals, living and extinct, with numerous illustrations : part I, Comparative physiology, for the use of schools and colleges"

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IV. Modern Age. 
III. Tertiary Age. 

II. Secondary Age. 

I. Palaeozoic Age. 
Metamorphic Rocks.. 

;T 0>F TOI IA&TO Ai 




Upper Tertiary Formation. 

Lower Tertiary " 

Cretaceous " 

Oolitic " 

Trias " 

Carboniferous " 

Devonian " 

Upper Silurian " 

Lower Silurian " 



TO 



PRINCIPLES OF ZOOLOGY: 

TOUCHING 

THE STRUCTURE, DEVELOPMENT, DISTRIBUTION, 
AND NATURAL ARRANGEMENT 

OF THE 

RACES OF ANIMALS, LIVING AND EXTINCT 

WITH NUMEROUS ILLUSTRATIONS. 
PART I. 

COMPARATIVE PHYSIOLOGY. 

FOR THE USE OF SCHOOLS AND COLLEGES. 



BY 



LOUIS AGASSIZ AND A. A. GOULD. 



REVISED EDITION. 



BOSTON: 
GOULD AND LINCOLN, 

59 WASHINGTON STREET. 

1851. 



Entered, according to Act of Congress, in the year 1851, 

BY GOULD AND LINCOLN, 
In the Clerk's Office of the District Court for the District of Massachusetts. 



STEREOTYPED AT THE 
BOSTON STEREOTYPE FOUNDRY. 



G. C. Rand & Co., Printers, Cornhill. 



PREFACE. 



THE design of this work is to furnish, an epitome of the leading 
principles of the science of Zoology, as deduced from the present 
state of knowledge, so illustrated as to be intelligible to the begin- 
ner. No similar treatise now exists in this country, and, indeed, 
some of the topics have not been touched upon in the English lan- 
guage, unless in a strictly technical form, and in scattered articles. 
On this account, some of the chapters, like those on Embryology 
and Metamorphosis, may, at first, seem too abstruse for scholars in 
\ our common schools. This may be the case, until teachers shall have 
made themselves somewhat familiar with subjects comparatively new 
to them. But so essential have these subjects now become to a correct 
interpretation of philosophical zoology, that the study of them will 
hereafter be indispensable. They furnish a key to many phenomena 
; ' / which have been heretofore locked in mystery. 

Being intended for American students, the illustrations have been 
drawn, as far as possible, from American objects : some of them are 
presented merely as ideal outlines, which convey a more definite 
idea than accurate sketches from nature ; others have been left ira- 

', perfect, except as to the parts especially in. question ; a large propor- 
^ tion of them, however, are accurate portraits from original drawings. 

~ Popular names have been employed as far as possible, and to the 

^scientific names an English termination has generally been given; 

: but the technical terms have been added, in brackets, whenever mis- 
understanding was apprehended. Definitions of those least likely 
to be understood, may be found in the Index. 

The principles of Zoology developed by Professor Agassiz in his 
published works have been generally adopted in this, and the results 
of many new researches have been added. 

The authors gratefully acknowledge the aid they have received, 
in preparing the illustrations and working out the details, from Mr. 

1* 



6 PREFACE. 

E. Desor, for many years an associate of Professor Agassiz, from Count 
Pourtales and E. C. Cabot, Esq., and also from Professor Asa Gray, 
by valuable suggestions in the revision of the letter-press. 

The first part is devoted to Comparative Anatomy, Physiology, 
and Embryology, as the basis of Classification, and also to the illus- 
tration of the geographical distribution and the geological succession 
of Animals ; the second to Systematic Zoology, in which the prin- 
ciples of Classification will be applied, and the principal groups of 
animals will be briefly characterized. 

Should our aim be attained, this work will produce more enlarged 
ideas of man's relations to Nature, and more exalted conceptions of 
the Plan of Creation and its Great Author. 

BOSTON, June 1, 1848. 



PREFACE TO THE REVISED EDITION. 

IN revising the present work, the authors have endeavored to 
render more precise those passages which admitted of too broad a 
signification or of a double interpretation ; and to correct such errors 
as had arisen from inadvertence, or such as the rapid progress of Sci- 
ence has disclosed. They are indebted for many suggestions on 
these points to several distinguished teachers who have used the work 
as a text book, and more especially to Professor Wyman, of Harvard 
University. Several entirely new paragraphs have also been added. 

A list of some of the principal authors who have made original 
researches, or of treatises which enter more into detail than was ad- 
missible in an elementary work, has been given at the close of the 
volume, for the use of those who would pursue the subject of 
Zoology in a more extended manner. 

The work having thus been revised and enlarged, the authors sub- 
mit it to the public with increased confidence in its accuracy and 
usefulness. 

BOSTON, February 1, 1851. 



TABLE OF CONTENTS. 



Page 

INTRODUCTION . . 17 



CHAPTER FIRST. 

THE SPHERE AND FUNDAMENTAL PRINCIPLES OF ZOOLOGY . 25 

CHAPTER SECOND. 

GENERAL PROPERTIES OF ORGANIZED BODIES .... 35 

SECTION I. 
Organized and Unorganized Bodies 35 

SECTION II. 
Elementary Structure of Organized Bodies 36 

SECTION III. 
Differences between Animals and Plants 41 

CHAPTER THIRD. 

FUNCTIONS AND ORGANS OF ANIMAL LIFE . . . 44 

SECTION I. 
Of the Nervous System and General Sensation 44 



8 TABLE OF CONTENTS. 

SECTION II. 

Page 

Of the Special Senses 48 

1. Of Sight 48 

2. Of Hearing 55 

3. Of Smell 60 

4. Of Taste 62 

5. OfTouch 63 

6. Of the Voice 64 

CHAPTER FOURTH. 

OF INTELLIGENCE AND INSTINCT . ... 67 

CHAPTER FIFTH. 

OF MOTION 73 

SECTION I. 

Apparatus of Motion 73 

SECTION II. 

Of Locomotion 79 

1. Plan of the Organs of Locomotion 82 

2. Of Standing, and the Modes of Progression ... 88 

Walking 90 

Running 91 

Leaping 91 

Climbing 92 

Flying 92 

Swimming 93 

CHAPTER SIXTH. 

OF NUTRITION 96 

SECTION I. 

Of Digestion 97 

Digestive Tube 97 

Chymification 100 

Chylification 100 

Mastication 101 

Insalivation 108 

Deglutition 108 



TABLE OF CONTENTS. 



CHAPTER SEVENTH. 

Page 

OF THE BLOOD AND CIRCULATION Ill 



CHAPTER EIGHTH. 

I 

Or RESPIRATION . . . 118 

CHAPTER NINTH. 

OF THE SECRETIONS . . 126 

CHAPTER TENTH. 
EMBRYOLOGY 131 

SECTION I. 

Of the Egg . 131 

Form of the Egg .... 

Formation of the Egg ... . . 133 

Ovulation ... . . 134 

Laying ........... 135 

Composition of the Egg 137 

SECTION II. 

Development of the Young icithin the Egg . . 139 

SECTION III. 
Zoological Importance of Embryology . 153 

CHAPTER ELEVENTH. 

PECULIAR MODES OF REPRODUCTION 156 



SECTION I. 

Gemmiparous and Fissiparous Reproduction .... 156 

SECTION II. 
Alternate and Equivocal Reproduction ... . 158 



i 



10 TABLE OF CONTENTS. 

SECTION III. 

Page 

Consequences of Alternate Generation 167 

CHAPTER TWELFTH. 

METAMORPHOSES OP ANIMALS 174 



" CHAPTER THIRTEENTH. 

GEOGRAPHICAL DISTRIBUTION OF ANIMALS .... 186 

SECTION I. 
General Laws of Distribution 186 

SECTION II. 

Distribution of the Faunas 194 

I. Arctic Fauna 197 

II. Temperate Faunas 198 

III. Tropical Faunas 204 

SECTION III. 
Conclusions 207 

CHAPTER FOURTEENTH. 

GEOLOGICAL SUCCESSION OF ANIMALS ; OR, THEIR DISTRIBUTION 

IN TIME 214 

SECTION I. 
Structure of the Earth's Crust 214 

SECTION II. 

Ages of Nature 221 

Palaeozoic Age 223 

Secondary Age . . . 227 

Tertiary Age 233 

Modern Age 235 

Conclusions 237 



EXPLANATION OF THE FIGURES. 



FRONTISPIECE. The diagram opposite the title page is intended to 
present, at one view, the distribution of the principal types of animals, 
and the order of their successive appearance in the layers of the earth's 
crust. The four Ages of Nature, mentioned at page 221, are represented 
by four zones, of different shades, each of which is subdivided by circles, 
indicating the number of formations of which they are composed. The 
whole disk is divided by radiating lines into four segments, to include the 
four great departments of the Animal Kingdom ; the Vertebrates, with 
Man at their head, are placed in the upper compartment, the Articulates 
at the left, the Mollusks at the right, and the Radiates below, as being 
the lowest in rank. Each of these compartments is again subdivided to 
include the different classes belonging to it, which are named at the outer 
circle. At the centre is placed a figure to represent the primitive egg, 
with its germinative vesicle and germinative dot, (278,) indicative of the 
universal origin of all animals, and the epoch of life when all are appar- 
ently alike, (275, 276.) Surrounding this, at the point from which each 
department radiates, are placed the symbols of the several departments, 
as explained on page 155. The zones are traversed by rays which repre- 
sent the principal types of animals, and their origin and termination in- 
dicates the age at which they first appeared or disappeared, all those which 
reach the circumference being still in existence. The width of the ray in- 
dicates the greater or less prevalence of the type at different geological 
ages. Thus, in the class of Crustaceans, the Trilobites appear to com- 
mence in the earliest strata, and to disappear with the carboniferous for- 
mation. The Ammonites also appeared in the Silurian formation, and 
did not become extinct before the deposition of the Cretaceous rocks. 
The Belemnites appear in the lower Oolitic beds ; many forms commence 
in the Tertiary ; a great number of types make their appearance only in 
the Modern age ; while only a few have continued from the Silurian, 
through every period to the present. Thus, the Crinoids were very nu- 
merous in the Primary Age, and are but slightly developed in the Tertiary 
and Modern Age. It is seen, at a glance, that the Animal Kingdom is 
much more diversified in the later than in the earlier Ages. 

Below the circle is a section, intended to show more distinctly the rel- 
ative position of the ten principal formations of stratified rocks (461) 
composing the four great geological ages ; the numerals corresponding to 
those on the ray leading to Man, in the circular figure. See also figure 154. 



12 EXPLANATION OF THE FIGURES. 

THE CHART OF ZOOLOGICAL REGIONS, page 195, is intended to show 
the limits of the several Faunas of the American Continent, correspond- 
ing to the climatal regions. And as the higher regions of the mountains 
correspond in temperature to the climate of higher latitudes, it will be 
seen that the northern temperate fauna extends, along the mountains of 
Mexico and Central America, much farther towards the Equator than it 
does on the lower levels. In the same manner, the southern warm fauna 
extends northward, along the Andes. 

FIG. 

1. Simple cell, magnified, as seen in the house-leek. 

2. Cells when altered by pressure upon each other ; from the pith of elder. 

3. Nucleated cells, (a,) magnified; b, nucleolated cells. 

4. Cartilaginous tissue from a horse, magnified 120 diameters. 

5. Osseous tissue from a horse, magnified 450 diameters. 

6. Nervous fibres, showing the loops as they terminate in the skin of a 

frog. 

7. Gray substance of the brain, magnified. 

8. Head of an embryo fish, to show its cellular structure throughout. 

9. Diagram, to show the nervous system of the Vertebrates, as found 

in a monkey. 

10. Diagram of the nervous system of the Articulates, as seen in a lobster. 

11. Diagram of the nervous system of the Mollusks, as found in Natica 

heros. 

12. Diagram of the nervous system of the Radiates, as found in Scutella, 

( Echinarachnius parma. ) 

13. Section of the eye. a, optic nerve ; b, sclerotic coat ; c, choroid coat; 

d, retina ; e, crystalline lens ; f t cornea ; g, iris ; h, vitreous body ; 
i, chamber, divided by the iris. 

14. Diagram, showing the effect of the eye on rays of light. 

15. Position of the eye of the snail. 

16. Eyes (ocelli) of the spider. 

17. Eye-spots of a star-fish, (Echinaster sanguinolentus.) 

18. Compound eyes, showing the arrangement of the faoettes, and their 

connection with the optic nerve, as seen in a crab's eye. 

19. Diagram of the human ear, to show the different chambers, canals, 

and bones. 

20. Tympanum and small bones of the ear, twice the natural size ; c t 

tympanum ; m, malleus ; n, incus ; o, orbiculare : s, stapes. 

21. Section of the brain of a crow, showing the origin of the nerves of 

the special senses. 

22. Diagram of the larynx, in man. 

23. Larynx of the merganser, (Mergus merganser.) 

24. Nests of Ploceus Philippinus, male and female. 

25. Distribution of nerves to the muscular fibres* 

26. Test, or crust-like covering of an Echinoderm, (Cidaris.) 



EXPLANATION OF THE FIGURES. 13 

FIG. 

27. Muscular ribbons of the willow-moth, (Cossits ligniperda.) 

28. Vertebra of a cod-fish. 

29. Disposition of the muscles of the trout, (Salmo trutta.) 

30. Disposition of the muscles of an owl, (Strix brachyotis.) 

31. Jelly-fishes, (Stomobrachium cruciatum, Hippocrene Bougainvillii.) 

32. Leech, showing the terminal cups. 

33. Portion of a Nereis, showing the gills as organs of motion. 
34-43. Modifications of the fore-arm. 

34. Monkey. 35. Deer. 36. Tiger. 37. Whale. 38. Bat. 
39. Pigeon. 40. Turtle. 41. Sloth. 42. Mole. 43. Whale. 

44. Leg of a beetle. 

45. Leg of a lizard. 

46. Skeleton of a tiger. 

47. Cuttle-fish, (Loligo illecebrosa.) 

48. Sea-anemone, (Actinia marginata ;) a, mouth ; b, stomach ; c, general 

cavity of the body. 

49. Planaria, showing the mouth, stomach, and its branches. 

50. Jaws, stomach, and intestine of a sea-urchin, (Echinus lividus.) 

51. Plan of the digestive organs of an insect. 

52. Plan of the digestive organs of a land-slug, ( Tebennophorus Carolini- 

ensis. ) 

53. Globules of chyle. 

54. Portion of intestine, showing the lacteals of man, and their entrance 

into a vein. 

55. Jaws of an Echinoderm, (Echinarachnhts parma.} 

56. Jaws of a sea-ur.chin, (Echinus granulatus.} 

57. Beak of a cuttle-.fish. 

58. Portion of the tongue of a mollusk, (Natica heros,) magnified. 

59. Jaws of an Annelide, (Nereis.) 

60. Trophi (organs for taking food) of a beetle. 

61. " of a bee. 

62. 63. " of a squash-bug. 

64. " of a butterfly. 

65. " of a Rotifer, (Brackiomts.) 

66. Jaws of ditto, magnified. 

67. Skull of a tiger, showing the muscles for mastication. 

68. Head of a snapping-turtle, (Emysaurus serpentina.} 

69. Head of a Whale, showing the whalebone. 

70. Head of an ant-eater. 

71. Head of an alligator. 

72. Head of a skate-fish, (Myliobatis,) showing the palate bone. 

73. Head of a monkey, showing the three different kinds of teeth. 

74. Teeth of an insectivorous animal, the mole. 

75. Teeth of a carnivorous animal, the tiger. 

76. Teeth of a rodent. 



14 EXPLANATION OF THE FIGURES. 

FlG. 

77. A polyp, (Tiibularia indivisa ) m, mouth ; o, ovaries ; p, tentacles. 

78. Blood disks in man, magnified. 

79. " " in birds, " 

80. " " in reptiles, " 

81. " " in fishes, " 

82. Portion of a vein opened, to show the valves. 

83. Network of capillary vessels. 

84. Dorsal vessel of an insect, with its valves. 

85. Cavities of the heart of mammals and birds. 

86. " " " of a reptile. 

87. " " " of a fish. 

88. Heart and bloodvessels of a gasteropod mollusk, (Natica.) 

89. Tracheae, or air tubes of an insect ; s, stigmata ; t, trachea. 

90. Relative position of the heart and lungs in man. 

91. Respiratory organs of a naked mollusk, (Polycera illuminata.) 

92. Respiratory organs (gills) of a fish. 

93. Vesicles and canals of the salivary glands. 

94. Section of the skin, magnified, to show the sweat glands ; a, the cutis ; 

b, blood-layer ; c, epidermis ; g, gland imbedded in the fat-layer^/.) 

95. Egg of a skate-fish, (Myliobatis.) 

96. Egg of hydra. 

97. Ege of snow-flea, (Podurella.) 

98. Section of an ovarian egg ; d, germinative dot ; g, germinative vesi- 

cle ; s, shell membrane ; v, vitelline membrane. 

99. Egg cases of Pyrula. 

100. Monoculus bearing its eggs, a a. 

101. Section of a bird's egg ; a, albumen ; c, chalaza ; e, embryo ; s, shell ; 

y, yolk. 

102. Cell-layer of the germ. 

103. Separation of the cell-layer into three layers ; s, serous or nervous 

layer; m, mucous or vegetative layer; v, vascular or blood layer. 

104. Embryo of a crab, showing its incipient rings. 

105. Embryo of a vertebrate, showing the dorsal furrow. 

106-8. Sections of the embryo, showing the formation of the dorsal canal. 

109. Section, showing the position of the embryo of a vertebrate, in re- 

lation to the yolk. 

110. Section, showing the same in an articulate, (Podurella.) 
111-22. Sections, showing the successive stages of development of the 

embryo of the white-fish, magnified. 
123. Young white-fish just escaped from the egg, with the yolk not yet 

fully taken in. 
124, 125. Sections of the embryo of a bird, showing the formation of the 

allantois ; e, embryo ; x x, membrane rising to form the amnios ; 

a, allantois ; y, yolk. 
126. The same more fully developed. The allantois (a) is further de- 



EXPLANATION OF THE FIGURES. 15 

FlG. 

veloped, and bent upwards. The upper part of the yolk (d d ) is 
nearly separated from the yolk sphere, and is to become the in- 
testine. The heart (A) is already distinct, and connected by 
threads with the blood-layer of the body. 

127. Section of the egg of a mammal ; v, the thick vitelline membrane, 

or chorion ; y, yolk ; s, germinative dot ; g, germinative vesicle. 

128. The same, showing the empty space (k) between the vitelline sphere 

and chorion. 

129. Shows the first indications of the germ already divided in two layers, 

the serous layer, (s,) and the mucous layer, (m.) 

130. The mucous layer (m) expands over nearly half of the yolk, and be- 

comes covered with many little fringes. 

131. The embryo (e) is seen surrounded by the amnios, (6,) and covered 

by a large allantois, (a;) p e, fringes of the chorion ; p m, fringes 
of the matrix. 

132. Hydra, showing its reproduction by buds. 

133. Vorticella, showing its reproduction by division. 

134. Polyps, showing the same. 

135. A chain of Salpse. 

136. An individual salpa ; m, the mouth ; a, embryos. 

137. Cercaria, or early form of the Distoma. 

138. Distoma, with its two suckers. 

139. Nurse of the Cercaria. 

140. The same, magnified, showing the included young. 

141. Grand nurses of the Cercaria, enclosing the young nurses. 

142. Stages of development of a jelly-fish, (Medusa ;) a, the embryo in 

its first stage, much magnified ; b, summit, showing the mouth ; 
c tfi ff> tentacles shooting forth ; e, embryo adhering, and form- 
ing a pedicle ; h, i, separation into segments ; d, a segment be- 
come free ; k, form of the adult. 

143. Portion of a plant-like polyp, (Campanularia ;) a, the cup which 

bears tentacles ; b, the female cup, containing eggs ; c, the cups 
in which the young are nursed, and from which they issue. 

144. Young of the same, with its ciliated margin, magnified. 

145. Eye of the perch, containing parasitic worms, (Distoma.) 

146. One of the worms magnified. 

147. Transformations of the canker-worm, (Geometra vemalis ) a, the 

canker worm ; 6, its chrysalis ; c, female moth ; d, male moth. 

148. Metamorphoses of the duck -barnacle, (Anatifa;) a, eggs, magnified ; 

b, the animal as it escapes from the egg ; c, the stem and eye ap- 
pearing, and the shell enclosing them ; d, animal removed from 
the shell, and further magnified ; e,f, the mature barnacle, affixed. 

149. Metamorphoses of a star-fish, (Echinaster sanguinolentits,) showing 

the changes of the yolk, (e ;) the formation of the pedicle, (p;) 
and the gradual change into the pentagonal and rayed form. 



16 EXPLANATION OF THE FIGURES. 

FIG. 

150. Comatula, a West India species, in its early stage, with its stem. 

151. The same detached, and swimming free. 

152. Longitudinal section of the sturgeon, to show its cartilaginous ver- 

tebral column. 

153. Amphioxus, natural size, showing its imperfect organization. 

154. Section of the earth's crust, to show the relative positions of the 

rocks composing it ; E, plutonic or massive rocks ; M, metamor- 
phic rocks ; T, trap rocks ; L, lava. 1. Lower Silurian forma- 
tion ; 2. Upper Silurian ; 3. Devonian ; 4. Carboniferous ; 5. 
Trias, or Saliferous ; 6. Oolitic ; 7. Cretaceous ; 8. Lower Terti- 
ary or Eocene ; 9. Upper Tertiary, or Miocene, and Pleiocene ; 
10. Drift. 

155. Fossils of the Paleozoic age ; a, Lingula prima ; b, Lepteena alter- 

nata ; c, Euomphalus hemisphericus ; d, Trocholites ammonius ; 
e, Avicula decussata ; f, Bucania expansa ; g, Orthoceras fusi- 
forme ; i, Cyathocrinus ornatissimus, Hall ; j, Cariocrinus orna- 
tus, Say ; k, Melocrinus amphora, Goldf. ; I, Columnaria alveo- 
lata ; m, Cyathophyllum quadrigeminum, Goldf. ; n, o, Caninia 
fiexuosa ; p, Chseietes lycoperdon. 

156. Articulata of the Palaeozoic age ; a, Harpes ; b, Arges ; c, Brontes ; 

d, Platynotus ; e, Eurypterus remipes. 

157- Fishes of the Palaeozoic age ; a, Pterichthys ; b, Coccosteus ; c, 
Dipterus ; d, palatal bone of a shark ; e, spine of a shark. 

158. Representations of the tracks of supposed birds and reptiles in the 

sandstone rocks. 

159. Supposed outlines of Ichthyosaurus, (a,) and Plesiosaurus, (6.) 

160. Supposed outline of Pterodactyle. 

161. Shells of the Secondary age ; a, Terebratula ; b, Goniomya ; c, 

Trigonia ; d, Ammonite. 

162. Supposed outline of the cuttle-fish, (a,) furnishing the Belemnite. 

163. Radiata from the Secondary age ; a, Lobophyllia flabellum ; b, Litho- 

dendron pseudostylina ; c, Pentacrinus briareus ; d, Pterocoma 
pinnata ; e, Cidaris ; f, Dysaster ; ff, Nucleolites. 

164. Shells of the Cretaceous formation ; a, Ammonites ; b, Crioceras ; 

c, Scaphites ; d, Ancyloceras ; e, Karaites ; f, Baculites ; g, 
Turrilites. 

165. Shells of the Cretaceous formation ; a, Magas ; b, Inoceramus ; c, 

Hippurites ; d, Spondylus ; e, Pleurotomaria. 

166. Radiata from the Cretaceous formation; a, Diploctenium cordatum; 

b, Marsupites ; d, Galerites ; c, Salenia ; e, Micraster cor- 
anguinum. 
167- Nummulite. 

168. Supposed outline of Paleotherium. 

169. Supposed outline of Anoplotherium. 

170. Skeleton of the Mastodon, in the cabinet of Dr. J. C. Warren. 



INTRODUCTION, 



EVERY art and science has a language of technical terms 
peculiar to itself. With those terms every student must 
make himself familiarly acquainted at the outset ; and, first 
of all, he will desire to know the names of the objects about 
which he is to be engaged. 

The names of objects in Natural History are double ; that 
is to say, they are composed of two terms. Thus, we speak 
of the white-bear, the black-bear, the hen-hawk, the sparrow- 
hawk ; or, in strictly scientific terms, we have Felis leo, the 
lion, Felis tigris, the tiger, Felis catus, the cat, Canis lupus^ 
the wolf, Canis vulpes, the fox, Canis familiaris, the dog, 
&c. They are always in the Latin form, and consequently 
the adjective name is placed last. The first is called the 
generic name ; the second is called the trivial, or specific 
name. 

These two terms are inseparably associated in every 
object of which we treat. It is very important, therefore, 
to have a clear idea of what is meant by the terms genus and 
species ; and although the most common of all others, they 
are not the easiest to be clearly understood. The Genus is 

2* 



18 INTHODUCTION. 

founded upon some of the minor peculiarities of anatomical 
structure, such as the number, disposition, or proportions 
of the teeth, claws, fins, dec., and usually includes several 
kinds. Thus, the lion, tiger, leopard, cat, &c., agree in the 
structure of their feet, claws, and teeth, and they belong to 
the genus Felis ; while the dog, fox, jackal, wolf, &c., have 
another and a different peculiarity of the feet, claws, and 
teeth, and are arranged in the genus Canis. 

The Species is founded upon less important distinctions, 
such as color, size, proportions, sculpture, &c. Thus we 
have different kinds, or species, of duck, different species 
of squirrel, different species of monkey, &c., varying from 
each other in some trivial circumstance, while those of each 
group agree in all their general structure. The specific 
name is the lowest term to which we descend, if we except 
certain peculiarities, generally induced by some modification 
of native habits, such as are seen in domestic animals. 
These are called varieties, and seldom endure beyond the 
causes which occasion them. 

Several genera which have certain traits in common are 
combined to form a family. Thus, the ale wives, herrings, 
shad, &c., form a family called Clupeidas ; the crows, black- 
birds, jays, &c., form the family Corvidse. Families are 
combined to form orders, and orders form classes, and finally, 
classes are combined to form the four primary divisions, or 
departments, of the Animal Kingdom. 

For each of these groups, whether larger or smaller, we 
involuntarily picture in our minds an image, made up of the 
traits which characterize the group. This ideal image is 
called a TYPE, a term which there will be frequent occasion 
to employ in our general remarks on the Animal Kingdom. 
This image may correspond to some one member of the 
group ; but it is rare that, any one species embodies all our 
ideas of the class, family, or genus to which it belongs. 



INTRODUCTION. 19 

Thus, we have a general idea of a bird ; but this idea does 
not correspond to any particular bird, or any particular 
character of a bird. It is not precisely an ostrich, an owl, 
a hen, or a sparrow ; it is not because it has wings, or 
feathers, or two legs ; or because it has the power of flight, 
or builds nests. Any, or all, of these characters would not 
fully represent our idea of a bird ; and yet every one has a 
distinct ideal notion of a bird, a fish, a quadruped, &c. It is 
common, however, to speak of the animal which embodies 
most fully the characters of a group, as the type of that 
group. Thus we might, perhaps, regard an eagle as the 
type of a bird, the duck as the type of a swimming-bird, and 
the mallard as the type of a duck, and so on. 

As we must necessarily make frequent allusions to ani- 
mals, with reference to their systematic arrangement, it seems 
requisite to give a sketch of their classification in as popular 
terms as may be, before entering fully upon that subject, and 
with particular reference to the diagram fronting the title- 
page. 

The Animal Kingdom consists of four great divisions, 
which we call DEPARTMENTS, namely : 

I. The department of Vertebrates. 
II. The department of Articulates. 

III. The department of Mollusks. 

IV. The department of Radiates. 



I. The department of VERTEBRATES includes all animals 
which have an internal skeleton, with a back-bone for its 
axis. It is divided into four classes : 

1. Mammals, (animals which nurse their young.) 

2. Birds. 



20 INTRODUCTION. 

3. Reptiles. 

4. Fishes. 



The class of MAMMALS is subdivided into three orders : 

a. Beasts of prey, (Carnivora.) 

b. Those which feed on vegetables, (Herbivora.) 

c. Animals of the whale kind, (Cetaceans.) 

The class of BIRDS is div.ided into four orders, namely, 

a. Perching Birds, (Insessores.) 

b. Climbers, (Scansores.) 

c. Waders, (Grallatores.) 

d. Swimmers, (Natatores.) 

The class of REPTILES is divided into five orders : 

a. Large reptiles with hollow teeth, most of which are 

now extinct, (Rhizodonts.) 

b. Lizards, (Lacertians.) 

c. Snakes, (Ophidians.) 

d. Turtles, (Chelonians.) 

e. Frogs and Salamanders, (Batrachians.) 

The class of FISHES is divided into four orders : 

a. Those with enamelled scales, like the gar-pike, 

(Ganoids,') fig. 157. c. 

b. Those with the skin like shagreen, as the sharks and 

skates, (Placoids.} 

c. Those which have the edge of the scales toothed, 

and usually with some bony rays to the fins, as the 
perch, (Ctenoids.) 



INTRODUCTION. 21 

d. Those whose scales are entire, and whose fin rays 
are soft, like the salmon, (Cycloids.) 

II. Department of ARTICULATES. Animals whose body is 
composed of rings or joints. It embraces three classes : 

1. Insects. 

2. Crustaceans, like the crab, lobster, &c. 

3. Worms. 

The class of INSECTS includes three orders : 

a. Those with a trunk for sucking fluids, like the butter- 

fly, (Suctoria,) fig. 62-64. 

b. Those which have jaws for dividing their food, (Man- 

ducata,) fig. 60. 

c. Those destitute of wings, like spiders, fleas, millipedes, 

&c., (Aptera.) 

The class CRUSTACEANS may be divided as follows : 

a. Those furnished with a shield, like the crab and lob- 
ster, (Malacostraca.) 

~b. Such as are not thus protected, (Entomostraca.) 

c. An extinct race, intermediate between these two, 
(Trilobites,) fig. 156. 

The class of WORMS comprises three orders : 

a. Those which have thread-like gills about the head, 

( Tubulibranchiates.) 

b. Those whose gills are placed along the sides, (Dor- 

sibranchiates.) 

c. Those who have no exterior gills, like the earth-worm, 

(Abranchiates,) and also the Intestinal Worms. 



22 INTRODUCTION. 

III. The department of MOLLUSKS is divided into three 
classes, namely : 

1. Those which have arms about the mouth, like the 

cuttle-fish, (Cephalopods,) fig. 47. 

2. Those which creep on a flattened disk or foot, like 

snails, (Gasteropods,} fig. 88. 

3. Those which have no distinct head, and are inclosed 

in a bivalve shell, like the clams, (Acephals.) 

The CEPHALOPODS may be divided into 

a. The cuttle-fishes, properly so called, ( Teuthideans,) 

fig. 47. 

1). Those having a shell, divided by sinuous partitions 
into numerous chambers, (Am?nonites^) fig. 164. 

c. Those having a chambered shell with simple par- 
titions, (Nautilus.} 

The GASTEROPODS contain four orders : 

a. The land snails which breathe air, (Pulmonates.) 

I. The aquatic snails which breathe water, (Branch- 
ifers,} fig. 88. 

c. Those which have wing-like appendages about the 

head, for swimming, (Pteropods.) 

d. A still lower form allied to the Polyps by their gen- 

eral appearance, (Rhizopods or Fora?ninifera.) 

The class of ACEPHALS contains three orders : 

a. Those having shells of two valves, (bivalves,) like the 

clam and oyster, (Lamellibrancliiates.} 

b. Those having two unequal valves, and furnished with 

peculiar arms, (Brachiopods.) 



INTRODUCTION. 23 

c. Mollusks living in chains or clusters, like the Salpa, fig. 
135 ; or upon plant-like stems, like Flustra, (Bryo- 
zoa.) 

IV. The department of RADIATES is divided into three 
classes : 

1. Sea-urchins, bearing spines upon the surface, (Echin- 

oderms,) figs. 12, 26. 

2. Jelly-fishes, (Acalephs,) fig. 31. 

3. Polyps, fixed like plants, and with a series of flexible 

arms around the mouth, figs. 48, 77, 143. 

The ECHINODERMS are divided into four orders : 
a. Sea-slugs, like biche-le-mar, (Holothurians.) 
T). Sea-urchins, (Echini,) fig. 26. 

c. Free star-fishes, (Asterida,') fig. 17. 

d. Star-fishes mostly attached by a stem, (Crinoids,) 

figs. 150, 151. 

The ACALEPHS include the following orders : 

a. Those furnished with vibrating hairs, by which they 
move, (Ctenophorce.) 

1. The Medusas, or common jelly-fishes, (Discophora,) 

figs. 31, 142. 
c. Those provided with aerial vesicles, (Siphonophora.) 

The class of POLYPS includes two orders. 

a. The so-called fresh-water polyps, and similar marine 

forms, with lobed tentacles, (Hydroids,) fig. 143. 

b. Common polyps, like the sea-anemone and coral- 

polyp, (Actinoids,) fig. 48. 

In addition to these, there are numberless kinds of micro- 



24 INTRODUCTION. 

scopic animalcules, commonly united under the name of 
infusory animals, (Infusoria,) from their being found specially 
abundant in water infused with vegetable matter. These 
minute beings do not, however, constitute a natural group in 
the Animal Kingdom. Indeed, a great many that were for- 
merly supposed to be animals are now found to be vegetables. 
Others are ascertained to be crustaceans, mollusks, worms 
of microscopic size, or the earliest stages of development of 
larger species. In general, however, they are exceedingly 
minute, and exhibit the simplest forms of animal life, and 
are now grouped together, under the title of Protozoa. But, 
as they are still very imperfectly understood, notwithstand- 
ing the beautiful researches already published on this sub- 
ject, and as many of them are likely to be finally distributed 
among vegetables, and the legitimate classes in the Animal 
Kingdom to which they belong, we have not assigned any 
special place for them. 



PHYSIOLOGICAL ZOOLOGY. 



CHAPTER FIRST. 

THE SPHERE AND FUNDAMENTAL PRINCIPLES OF 

ZOOLOGY. 

1. ZOOLOGY is that department of Natural History which 
relates to animals. 

2. To enumerate and name the animals which are found 
on the globe, to describe their forms, and investigate then- 
habits and modes of life, are the principal, but by no means 
the only objects of this science. Animals are worthy of our 
regard, not merely when considered as to the variety and ele- 
gance of their forms, or their adaptation to the supply of our 
wants ; but the Animal Kingdom, as a whole, has a still 
higher signification. It is the exhibition of the divine thought, 
as carried out in one department of that grand whole which 
we call Nature ; and considered as such, it teaches us most 
important lessons. 

3. Man, in virtue of his twofold constitution, the spiritual 
and the material, is qualified to comprehend Nature. 

3 



26 SPHERE AND FUNDAMENTAL 

Being made in the spiritual image of God, he is competent to 
rise to the conception of His plan and purpose in the works 
of Creation. Having also a material body, like that of 
other animals, he is also in a condition to understand the 
mechanism of organs, and to appreciate the necessities of 
matter, as well as the influence which it exerts over the in- 
tellectual element throughout the domain of Nature. 

4. The spirit and preparation we bring to the study of 
Nature, is a matter of no little consequence. When we would 
study with profit a work of literature, we first endeavor to 
make ourselves acquainted with the genius of the author ; 
and in order to know what end he had in view, we must 
have regard to his previous labors, and to the circumstances 
under which the work was executed. Without this, although 
we may perhaps enjoy its perfection as a whole, and ad- 
mire the beauty of its details, yet the spirit which pervades 
it will escape us, and many passages may even remain un- 
intelligible. 

5. So, in the study of Nature, we may be astonished at 
the infinite variety of her products ; we may even study 
some portion of her works with enthusiasm, and neverthe- 
less remain strangers to the spirit of the whole, ignorant of 
the plan on which it is based, and fail to acquire a proper 
conception of the varied affinities which combine beings 
together, so as to make of them that vast picture in which 
each animal, each plant, each group, each class, has its 
place, and from which nothing could be removed without 
destroying the proper meaning of the whole, 

6. Besides the beings which inhabit the earth at the pres- 
ent time, this picture also embraces the extinct races which 
are now known to us by their fossil remains only. And 
these are of the greatest importance, since they furnish us 
with the means of ascertaining the changes and modifica- 
tions which the Animal Kingdom has undergone in the sue- 



PRINCIPLES OF ZOOLOGY. 27 

cessive creations, since the first appearance of living 
beings. 

7. It is but a short time since it was not difficult for a 
man to -possess himself of the whole domain of positive 
knowledge in Zoology. A century ago, the number of 
known animals did not exceed 8000 ; that is to say, from 
the whole Animal Kingdom, fewer species were then 
known than are now contained in many private collections 
of certain families of insects merely. At the present 
day, the number of living species which have been satisfac- 
torily made out and described, is more than 50,000.* The 
fossils already described exceed 6000 species ; and if we 

* The number of vertebrate animals may be estimated at 20,000. 
About 1500 species of mammals are pretty precisely known, and the num- 
ber may probably be carried to about 2000. 

The number of Birds well known is 4 or 5000 species, and the probable 
number is 6000. 

The Reptiles number about the same as the Mammals, 1500 described 
species, and they will probably reach the number of 2000. 

The Fishes are more numerous : there are from 5 to 6000 species in the 
museums of Europe, and the number may probably amount to 8 or 10,000. 

The number of Mollusks already in collections probably reaches 8 or 
10,000. There are collections of marine shells, bivalve and univalve, which 
amount to 5 or 6000 ; and collections of land and fluviatile shells, which 
count as many as 2000. The total number of mollusks would, therefore, 
probably exceed 15,000 species. 

Among the articulated animals it is difficult to estimate the number of 
species. There are collections of coleopterous insects which number 20 to 
25,000 species ; and it is quite probable, that by uniting the principal col- 
lections of insects, 60 or 80,000 species might now be counted ; for the 
whole department of articulata, comprising the Crustacea, the cirrhipeda, 
the insects, the red-blooded worms, the intestinal worms, and the infuso- 
ria so far as they belong to this department, the number would already 
amount to 100,000 ; and we might safely compute the probable number of 
species actually existing at double that sum. 

Add to these about 10,000 for radiata, including echini, star-fishes, me- 
dusae, and polypi, and we have about 250,000 species of living animals ; and 
supposing the number of fossil species only to equal them, we have, at a 
very moderate computation, half a million of species. 



28 SPHERE AND FUNDAMENTAL 

consider that wherever any one stratum of the earth has 
been well explored, the number of species discovered has 
not fallen below that of the living species which now inhabit 
any particular locality of equal extent, and then bear in 
mind that there is a great number of geological strata, we 
may anticipate the day when the ascertained fossil species 
will far exceed the living species.* 

8. These numbers, far from discouraging, should, on the 
contrary, encourage those who study Natural History. 
Each new species is, in some respects, a radiating point 
which throws additional light on all around it ; so that, as 
the picture is enlarged, it at the same time becomes more 
intelligible to those who are competent to seize its promi- 
nent traits. 

9. To give a detailed account of each and all of these 
animals, and to show their relations to each other, is the 
task of the Naturalist. The number and extent of the vol- 
umes already published upon the various departments of 
Natural History show, that only a mere outline of a domain 
so vast could be fully sketched in an elementary work, and 
that none but those who make it their special study can be 
expected to survey its individual parts. 

10. Every well-educated person, however, is expected to 
have a general acquaintance with the great natural phe- 
nomena constantly displayed before his eyes. There is a 
general knowledge of man and the subordinate animals? 
embracing their structure, races, habits, distribution, mutual 
relations, &c., which is not only calculated to conduce es- 

* In a separate work, entitled " Nomenclator Zoologicus," by L. AGAS- 
siz, the principles of nomenclature are discussed, and a list of the names 
of genera and families proposed by authors is given. To this work those 
are referred who may desire to become more familiar with nomenclature, 
and to know in detail the genera and families in each class of the Animal 
Kingdom. 



PRINCIPLES OF ZOOLOGY. 29 

sentially to our happiness, but which it would be quite inex- 
cusable to neglect. This general view of Zoology, it is the 
purpose of this work to afford. 

11. A sketch of this nature should render prominent the 
more general features of animal life, and delineate the ar- 
rangement of the species according to their most natural 
relations and their .rank in the scale of being ; thus giving 
a panorama, as it were, of the entire Animal Kingdom. 
To accomplish this, we are at once involved in the question, 
What is it that gives an animal precedence in rank ? 

12. In one sense, all animals are equally perfect. Each 
species has its definite sphere of action, whether more or 
less extended, its own peculiar office in the economy of 
nature ; and a complete adaptation to fulfil all the purposes 
of its creation, beyond the possibility of improvement. In 
this sense, every animal is perfect. But there is a wide 
difference among them, in respect to their organization. In 
some it is very simple, and very limited in its operation ; in 
others, extremely complicated, and capable of exercising a 
great variety of functions. 

13. In this physiological point of view, an animal may be 
said to be more perfect in proportion as its relations with the 
external world are more varied ; in other words, the more 
numerous its functions are. Thus, an animal, like a quad- 
ruped, or a .bird, which has the five senses fully developed, 
and which has, moreover, the faculty of readily trans- 
porting itself from place to place, is more perfect than a 
snail, whose senses are very obtuse, and whose motion is 
very sluggish. 

14. In like manner, each of the organs, when separately 
considered, is found to have every degree of complication, 
and, consequently, every degree of nicety in the perform- 
ance of its function. Thus, the eye-spots of the star-fis-h 
and jelly-fish are probably endowed with merely the fac- 



30 SPHERE AND FUNDAMENTAL 

ulty of perceiving light, without the power of distinguishing 
objects. The keen eye of the bird, on the contrary, dis- 
cerns minute objects at a great distance, and when compared 
with the eye of a fly, is found to be not only more perfect, 
but constructed on an entirely different plan. It is the 
same with every other organ. 

15. We understand the faculties of animals, and appre- 
ciate their value, just in proportion as we become acquainted 
with the instruments which execute them. The study of 
the functions or uses of organs, therefore, requires an exam- 
ination of their structure ; they must never be disjoined, 
and must precede the systematic distribution of animals into 
classes, families, genera, and species. 

16. In this general view of organization, we must ever 
bear in mind the necessity of carefully distinguishing be- 
tween affinities and analogies, a fundamental principle re- 
cognized even by Aristotle, the founder of scientific Zoology. 
Affinity or homology is the relation between organs or parts 
of the body which are constructed on the same plan, how- 
ever much they vary in form, or even serve for very dif- 
ferent uses. Analogy, on the contrary, indicates the simi- 
larity of purposes or functions performed by organs of dif- 
ferent structure. 

17. Thus, there is an analogy between the wing of a bird 
and that of a butterfly, since botli of them serve for flight. 
But there is no affinity between them, since, as we shall 
hereafter see, they differ totally in their anatomical relations. 
On the other hand, there is an affinity between the bird's 
wing and the hand of a monkey ; since, although they serve 
for different purposes, the one for flight, and the other 
for climbing, they are both constructed on the same plan. 
Accordingly, the bird is more nearly allied to the monkey 
than to the butterfly, though they both have in common 
the faculty of flight. Affinities, and not analogies, therefore, 
must guide us in the arrangement of animals. 



PRINCIPLES OF ZOOLOGY. 31 

18. Our investigations should not be limited to adult 
animals, but should also include the changes which they 
undergo during the whole course of their development. 
Otherwise, we shall be liable to exaggerate the importance 
of certain peculiarities of structure which have a predomi- 
nant character in the full-;rown animal, but which are shaded 

O ' 

off, and vanish, as we revert to the earlier periods of life. 

19. Thus, for example, by regarding only adult individu- 
als, we might be induced to divide all animals into two 
groups, according to their mode of respiration ; uniting, on 
the one hand, all those which breathe by gills, and, on the 
other, those which breathe by lungs. But this distinction 
loses its importance, when we consider that various animals, 
for example, frogs, which respire by lungs in the adult 
state, have only gills when young. It is thence evident that 
the respiratory organs cannot be taken as a satisfactory 
basis of our fundamental classification. They are, as we 
shall see, subordinate to a more important system, namely, 
the nervous system. 

20. Again, we have a means of appreciating the relative 
grade of animals by the comparative study of their devel- 
opment. It is evident that the caterpillar, in becoming a 
butterfly, passes from a lower to a higher state. Clearly, 
therefore, animals resembling the caterpillar, the worms, for 
instance, must occupy a lower rank than those approaching 
the butterfly, like most insects. There is no animal which 
does not undergo a series of changes similar to those of the 

o o 

caterpillar or the chicken ; only, in many of them, the most 
important ones occur before birth, during what is called the 
embryonic period. 

21. The life of the chicken has not just commenced when 
it issues from the egg ; for if we break the egg some days 
previous to the time of hatching, we find in it a living ani- 
mal, which, although imperfect, is nevertheless a chicken : 



32 SPHERE AND FUNDAMENTAL 

it has been developed from a hen's egg, and we know that, 
should it continue to live, it would infallibly display all the 
characteristics of the parent bird. Now, if there existed in 
Nature an adult bird as imperfectly organized as the chicken 
on the day, or the day before it was hatched, we should 
assign to it an inferior rank. 

22. In studying the embryonic states of the mollusks or 
worms, we observe in them points of resemblance to many 
animals of a lower grade, to which they at length be- 
come entirely dissimilar. For example, the myriads of 
minute aquatic animals embraced under the name of Infu- 
soria, generally very simple in their organization, remind 
us of the embryonic forms of other animals. We shall have 
occasion to show that the Infusoria are not to be considered 
as a distinct class of animals, but that among them are found 
members of all the lower classes of animals, mollusks, 
crustaceans, worms, &c. ; and many of them are even found 
to belong to the Vegetable Kingdom. 

23. Not less striking are the relations that exist between 
animals and the regions they inhabit. Every animal has its 
home. Animals of the cold regions are not the same as 
those of temperate climates ; and these latter, in their turn, 
differ from those of tropical regions. Certainly, no one will 
maintain it to be the effect of accident that the monkeys, 
the most perfect of all brute animals, are found only in hot 
countries ; or that by chance merely the white bear and 
reindeer inhabit only cold regions. 

24. Nor is it by chance that most of the largest animals, 
of every class, the whales, the aquatic birds, the sea-turtles, 
the crocodiles, dwell in the water rather than on the land. 
And while the water affords freedom of motion to the largest, 
it is also the home of the smallest of living beings, allow- 
ing a degree of liberty to their motion, which they could not 
enjoy elsewhere. 



PRINCIPLES OF ZOOLOGY. 33 

25. Nor are our researches to be limited to the animals 
now living. There are buried in the crust of the earth the 
remains of a great number of animals belonging to species 
which do not exist at the present day. Many of these 
remains present forms so extraordinary that it is almost im- 
possible to trace their alliance with any animal now 
living. In general, they bear a striking analogy to the em- 
bryonic forms of existing species. For example, the curi- 
ous fossils known under the name of Trilobites (Fig. 156) 
have a shape so singular that it might well be doubted to 
what group of articulated animals they belong. But if we 
compare them with the embryo crab, we find so remarkable 
a resemblance that we do not hesitate to refer them to the 
crustaceans. We shall also see that some of the Fishes 
of ancient epochs present shapes altogether peculiar to them- 
selves, (Fig. 157,) but resembling, in a striking manner, the 
embryonic forms of our common fishes. A determination 
of the successive appearance of animals in the order of time 
is, therefore, of much importance in assisting to decide the 
relative rank of animals. 

26. Besides the distinctions to be derived from the varied 
structure of organs, there are others less subject to rigid 
analysis, but no less decisive, to be drawn from the imma- 
terial principle with which every animal is endowed. It is 
this which determines the constancy of species from genera- 
tion to generation, and which is the source of all the varied 
exhibitions of instinct and intelligence which we see dis- 
played, from the simple impulse to receive the food which is 
brought within their reach, as observed in the polyps, through 
the higher manifestations, in the cunning fox, the sagacious 
elephant, the faithful dog, to the exalted intellect of man, 
which is capable of indefinite expansion. 

27. Such are some of the general aspects in which we 
are to contemplate the animal creation. Two points of 



34 FUNDAMENTAL PRINCIPLES OF ZOOLOGY. 

view should never be lost sight of, nor disconnected, namely, 
the animal in respect to its own organism, and the animal 
in its relations to creation as a whole. By adopting too 
exclusively either of these points of view, we are in danger 
of falling either into gross materialism, or into vague and 
profitless pantheism. He who beholds in Nature nothing 
besides organs and their functions, may persuade himself 
that the animal is merely a combination of chemical and 
mechanical actions and reactions, and thus becomes a mate- 
rialist. 

28. On the contrary, he who considers only the manifes- 
tations of intelligence and of creative will, without taking 
into account the means by which they are executed, and the 
physical laws by virtue of which all beings preserve their 
characteristics, will be very likely to confound the Creator 
with the creature. 

29. It is only as it contemplates, at the same time, matter 
and mind, that Natural History rises to its true character 
and dignity, and leads to its worthiest end, by indicating to 
us, in Creation, the execution of a plan fully matured in the 
beginning, and undeviatingly pursued ; the work of a God 
infinitely wise, regulating Nature according to immutable 
laws, which He has himself imposed on her. 



CHAPTER SECOND. 

GENERAL PROPERTIES OF ORGANIZED BODIES. 

SECTION I. 

ORGANIZED AND UNORGANIZED BODIES. 

30. NATURAL HISTORY, in its broadest sense, embraces 
the study of all the bodies which compose the crust of the 
earth, or which are dispersed over its surface. 

31. These bodies may be divided into two great groups ; 
inorganic bodies, (minerals and rocks,) and living or organ- 
ized bodies, (vegetables and animals.) These two groups 
have nothing in common, save the universal properties of 
matter, such as weight, extension, &c. They differ at the 
same time as to their form, their structure, their chemical 
composition, and their mode of existence. 

32. The distinctive characteristic of inorganic bodies is 
rest ; the distinctive trait of organized bodies is independent 
motion, LIFE. The rock or the crystal, once formed, never 
changes from internal causes ; its constituent parts or mole- 
cules invariably preserve the position which they have once 
taken in respect to each other. Organized bodies, on the 
contrary, are continually in action. The sap circulates in 



36 ELEMENTARY STRUCTURE OF ORGANIZED BODIES. 

the tree, the blood flows through the animal, and in both 
there is, besides, the incessant movement of growth, decom- 
position, and renovation. 

33. Their mode of formation is also entirely different. 
Unorganized bodies are either simple or made up of ele- 
ments unlike themselves ; and when a mineral is en- 
larged, it is simply by the outward addition of particles 
constituted like itself. Organized bodies are not formed 
in this manner. They always, and necessarily, are derived 
from beings similar to themselves ; and once formed, they 
always increase interstitially, by the successive assimilation 
of new particles, derived from various sources. 

34. Finally, organized bodies are limited in their duration. 
Animals and plants are constantly losing some of their parts 
by decomposition during life, which at length cease to be 
supplied, and they die, after having lived for a longer or 
shorter period. Inorganic bodies, on the contrary, contain 
within themselves no principle of destruction ; and unless 
subjected to some foreign influence, a crystal or a rock would 
never change. The limestone and granite of our mountains 
remain just as they were formed in ancient geological 
epochs ; while numberless generations of plants and ani- 
mals have lived and perished upon their surface. 



SECTION II. 

ELEMENTARY STRUCTURE OF ORGANIZED BODIES. 

35. The exercise of the functions of life, which is the 
essential characteristic of organized bodies, (32,) requires a 
degree of flexibility of the organs. This is secured by 
means of a certain quantity of watery fluid, which pene- 



ELEMENTARY STRUCTURE OF ORGANIZED BODIES. 37 

trates all parts of the body, and forms one of its principal 
constituents. 

36. All living bodies, without exception, are made up of 
tissues so constructed as to be permeable to liquids. There 
is no part of the body, no organ, however hard and compact 
it may appear, which has not this peculiar structure. It ex- 
ists in the bones of animals, as well as in their flesh and fat ; 
in the wood, however solid, as well as in the bark and flowers 
of plants. It is to this general structure that the term or- 
ganism is now applied. Hence the collective name of 
organized beings,* which includes both the animal and the 
vegetable kingdoms. 

37. The vegetable tissues and most of the organic struc- 
tures, when examined by the microscope 

in their early states of growth, are found 
to be composed of hollow vesicles or cells. 
The natural form of the cells is that of a 
sphere or of an ellipsoid, as may be easily 
seen in many plants ; for example, in the 
tissue of the house-leek, (Fig. 1.) The 
intervals which sometimes separate them Fig. 1. 

from each other are called intercellular passages or spaces, 
(m.} When the cellules are very numerous, and crowd 
each other, their outlines become angular, and the intercel- 
lular spaces disappear, as seen in figure 2, which represents 



* Formerly, animals and plants were said to Reorganized, because they 
are furnished with definite parts, called organs, which execute particular 
functions. Thus, animals have a stomach, a heart, lungs, &c. ; plants 
have leaves, petals, stamens, pistils, roots, &c., which are indispensable 
to the maintenance of life and the perpetuation of the species. Since 
the discovery of the fundamental identity of structure of animal and 
vegetable tissues, a common denomination for this uniformity of texture 
has been justly preferred ; and the existence of tissues is now regarded 
as the basis of organization. 

4 







38 ELEMENTARY STRUCTURE OF ORGANIZED BODIES. 

the pith of the elder. They then 
have the form of a honey-comb ; 
whence they have derived their 
name of cellules. 

38. All the organic tissues, whether 
animal or vegetable, originate from 

cells. The cell is to the organ- Fig. 2. 

ized body what the primary form of the crystal is to the 

secondary, in minerals. As a general fact, it may be stated 

that animal cells are smaller than vegetable 
a o 

cells ; but they alike contain a central dot or 
vesicle, called nucleus. Hence such cells are 
called nucleated cells, (Fig. 3, a.) Sometimes 
the nucleus itself contains a still smaller 
dot, called nucleolus, (b.) 

39. The elementary structure of vegetables may be ob- 
served in every part of a plant, and its cellular character 
has been long known. But with the animal tissues there is 
far greater difficulty. Their variations are so great, and 
their transformations so diverse, that after the embryonic 
period it is sometimes impossible, even by the closest exam- 
ination, to detect their original cellular structure. 

40. Several kinds of tissues have been designated in the 
animal structure ; but their differences are not always well 
marked, and they pass into each other by insensible shades. 
Their modifications are still the subject of investigation, and 
we refer only to the most important distinctions. 

41. The areolar tissue consists of a network of delicate 
fibres, intricately interwoven so as to leave numberless 
communicating interstices, filled with fluid. It is inter- 
posed in layers of various thickness, between all parts of 
the body, and frequently accompanied by clusters of fat 
cells. The fibrous and the serous membranes are mere 
modifications of this tissue. 

42. The cartilaginous tissue is composed of nucleated 



ELEMENTARY STRUCTURE OF ORGANIZED BODIES. 



39 




Fig. 4. 




Fig. 5. 



cells, the intercellular spaces being filled with a more com- 
pact substance, called the hyaline matter. Figure 4 repre- 
sents a slip of cartilage from the horse, under 
a magnifying power of one hundred and twen- 
ty diameters. 

43. The osseous or bony tissue differs from 
the cartilaginous tissue, in having its meshes 
filled with salts of lime, instead of hyaline sub- 
stance, whence its compact and solid appear- 
ance. It contains, besides, minute, rounded, 
or star-like points, improperly called bone- 
corpuscles, which are found to be cavities or 
canals, sometimes radiated and branched, as 
is seen in figure 5, representing a section of a 
bone of a horse, magnified four hundred times. 

44. The muscular tissue, which forms the flesh of ani- 
mals, is composed of bundles of parallel fibres, which pos- 
sess the peculiar property of contracting or shortening them- 
selves, under the influence of the nerves. In the muscles 
under the control of the will, the fibres are commonly 
crossed by very fine lines or wrinkles ; but not so in the 
involuntary muscles. Every one is sufficiently familiar with 
this tissue, in the form of lean meat. 

45. The nervous tissue is of different kinds. In the 

nerves proper, it is composed of 

very delicate fibres, which return 

back at their extremities, and 

form loops, as shown in figure 6, 

representing nervous threads as 

they terminate in the skin of a 

frog. The same fibrous structure 

is found in the white portion of the brain. But 

the gray substance of the brain is composed of 
very minute granulations, interspersed with clusters of larger 
cells, as seen in figure 7. 





Fig. 7. 



Fig. 6. 



40 ELEMENTARY STRUCTURE OF ORGANIZED BODIES. 

46. The tissues above enumerated differ from each other 
more widely, in proportion as they are examined in animals 
of a higher rank. As we descend in the scale of being, 
the differences become gradually effaced. The soft body 
of a snail is much more uniform in its composition than 
the body of a bird or a quadruped. Indeed, multitudes 
of animals are known to be made up of nothing but cells 
in contact with each other. Such is the case with the 
polyps; yet they contract, secrete, absorb, and repro- 
duce; and most of the Infusoria move freely, by means of 
little fringes on their surface, arising from a peculiar kind 
of cells. 

47. A no less remarkable uniformity of structure is to be 
observed in the higher animals, in the earlier periods of 
their existence, before the body has arrived at its definite 
form. The head of the adult salmon, for instance, con- 
tains not only all the tissues we have mentioned, namely, 

bone, cartilage, muscle, nerve, brain, 
and membranes, but also bloodves- 
sels, glands, pigments, &c. Let 
us, however, examine it during the 
embryonic state, while it is yet in 
Fig. 8. the egg, and we find that the whole 

head is made up of cells which differ merely in their dimen- 
sions ; those at the top of the head being very small, those sur- 
rounding the eye a little larger, and those beneath being still 
larger, (Fig. 8.) It is only at a later period, after still further 
development, that these cellules become transformed, some 
of them into bone, others into blood, others into flesh, &c. 

48. Again : the growth of the body, the introduction of 
various tissues, the change of form and structure, proceed in 
such a manner as to give rise to several cavities, variously 
combined among themselves, and each containing, at the 
end of these transformations, peculiar organs, or peculiar 
systems of organs. 




DIFFERENCES BETWEEN ANIMALS AND PLANTS. 41 



SECTION III. 

DIFFERENCES BETWEEN ANIMALS AND PLANTS. 

49. At first glance, nothing would seem more widely 
different than animals and plants. What is there in com- 
mon, for instance, between an oak or an elm, and the bird 
which seeks shelter amid their foliage ? 

50. The differences are usually so obvious, that this 
question would be superfluous if applied only to the higher 
forms of the two kingdoms. But this contrast diminishes, 
in proportion as their structure is simplified ; and as we 
descend to the lower forms, the distinctions are so few 
and so feebly characterized, that it becomes at length dif- 
ficult to pronounce whether the object we have before us is 
an animal or a plant. Thus, the sponges have so great a 
resemblance to some of the polypi, that they have generally 
been classed among animals, although in reality they be- 
long to the vegetable kingdom. 

51. Animals and plants differ in the relative predomi- 
nance of the elements, oxygen, carbon, hydrogen and nitro- 
gen, of which they are composed. In vegetables, only a 
small proportion of nitrogen is found ; while it enters largely 
into the composition of the animal tissues. 

52. Another peculiarity of the Animal Kingdom is, the 
presence of large, distinctly limited cavities, usually intended 
for the lodgment of certain organs ; such is the skull and 
the chest in the higher animals, the cavity of the gills in 
fishes, and of the abdomen, or general cavity of the body, 
which exists in all animals, without exception, for the pur- 
pose of digestion, or the reception of the digestive organs. 

53. The well-defined and compact forms of the organs 

4* 



42 DIFFERENCES BETWEEN ANIMALS AND PLANTS. 

lodged in these cavities, is a peculiarity belonging to animals 
only. In plants, the organs designed for special purposes 
are never embodied into one mass, but are distributed over 
various parts of the individual. Thus, the leaves, which 
answer to the lungs, instead of being condensed into one 
organ, are scattered independently in countless numbers over 
the branches. Nor is there any organ corresponding to the 
brain, the heart, the liver, or the stomach. 

54. Moreover, the presence of a proper digestive cavity 
involves marked differences between the two kingdoms, in 
respect to alimentation or the use of food. In plants, the 
fluids absorbed by the roots are carried, through the trunk 
and all the branches, to the whole plant, before they arrive 
at the leaves, where they are to be digested. In animals, 
on the contrary, the food is at once received into the diges- 
tive cavity, where it is elaborated ; and it is only after it has 
been thus dissolved and prepared, that it is introduced into 
the other parts of the body. The food of animals consists 
of organized substances, while that of vegetables is derived 
from inorganic substances ; and they produce albumen, 
sugar, starch, &c., while animals consume them. 

55. Plants commence their development from a single 
point, the seed, and, in like manner, all animals are devel- 
oped from the egg. But the animal germ is the result of 
successive transformations of the yolk, while nothing similar 
takes place in the plant. The subsequent development of 
individuals is for the most part different in the two kingdoms. 
No limit is usually placed to the increase of plants ; trees 
put out new branches and new roots as long as they live. 
Animals, on the contrary, generally have a limited size and 
figure ; and these once attained, the subsequent changes are 
accomplished without any increase of volume, or essential 
alteration of form ; while the appearance of most vegetables 
is repeatedly modified, in a notable manner, by the develop- 



DIFFERENCES BETWEEN ANIMALS AND PLANTS. 43 

ment of new branches. Some of the lowest animals, how- 
ever, the polyps for instance, increase in a somewhat analo- 
gous manner, ( 329, 330.) 

56. In the effects they produce upon the air by respira- 
tion, there is an important difference. Animals consume 
the oxygen, and give out carbonic acid gas, which is de- 
structive to animal life ; while plants, by respiration, which 
they in most instances perform by means of the leaves, 
reverse the process, and thus furnish oxygen, which is so 
essential to animals. If an animal be confined in a small 
portion of air, or water containing air, this soon becomes so 
vitiated by respiration, as to be unfit to sustain life ; but if 
living plants are enclosed with the animal at the same time, 
the air is maintained pure, and no difficulty is experienced. 
The practical effect of this compensation, in the economy of 
Nature, is obviously most important ; vegetation restoring 
to the atmosphere what is consumed by animal respiration, 
combustion, &c., and vice versa. 

57. But there are two things which, more than all others, 
distinguish the animal from the plant, namely, the power of 
moving itself or its parts at will, and the power of perceiv- 
ing other objects or their influences ; in other words, volun- 
tary motion and sensation. 

58. All animals are susceptible of undergoing pleasure 
and pain. Plants have also a certain sensibility. They 
wither and fade under a burning sun, or when deprived of 
moisture ; and they die when subjected to too great a de- 
gree of cold, or to the action of poisons. But they have no 
consciousness of these influences, and suffer no pain ; while 
animals under similar circumstances suffer. Hence they 
have been called animate beings, in opposition to plants, 
which are inanimate beings. 



CHAPTER THIRD. 

FUNCTIONS AND ORGANS OF ANIMAL LIFE. 
SECTION I. 

OF THE NERVOUS SYSTEM AND GENERAL SENSATION. 

59. LIFE, in animals, is manifested by two sorts of func- 
tions, viz. : First, the peculiar functions of animal life, or 
those of relation, which include the functions of sensation 
and voluntary motion ; those which enable us to approach, 
and perceive our fellow beings and the objects about us, and 
to bring us into relation with them : Second, the functions 
of vegetative life, which are nutrition in its widest sense, 
and reproduction ; * those indeed which are essential to the 
maintenance and perpetuation of life. 

60. The two distinguishing characteristics of animals, 
namely, sensation and motion, (57,) depend upon special 
systems of organs, which are wanting in plants, the nervous 
system and the muscular system under its influence. The 
nervous system, therefore, is the grand characteristic of the 
animal body. It is the centre from which all the commands 
of the will issue, and to which all sensations tend. 



* This distinction is the more important, inasmuch as the organs of 
animal life, and those of vegetative life, spring from very distinct layers 
of the embryonic membrane. The first are developed from the upper 
layer, and the second from the lower layer of the germ of the animal. 
See Chapter on Embryology, p. 112. 



NERVOUS SYSTEM AND GENERAL SENSATION. 



45 



61. Greatly as the form, the arrangement, and the vol- 
ume of the nervous system 

va.ry in different animals, 
they may all be reduced to 
four principal types, which 
correspond, moreover, to the 
four great departments of the 
Animal Kingdom. In the 
vertebrate animals, namely, 
the fishes, reptiles, birds, and 

mammals, the nervous svs- 

j 

tern is composed of two prin- 
cipal masses, the spinal mar- 
row, (Fig. 9, c,) which runs 
along the back, and the 
brain, contained within the 
skull.* The volume of the 
brain is proportionally larger 
as the animal occupies a 
more elevated rank in the 
scale of being. Man, who 
stands at the head of Crea- 
tion, is in this respect also the 
most highly endowed being. Fig. 9. 

62. With the brain and spinal marrow are connected the 
nerves, which are distributed, in the form of branching 
threads, through every part of the body. The branches 
which unite with the brain are twelve pairs, called the cere- 




* The brain is composed of several distinct parts which vary greatly, in 
their relative proportions, in different animals, as will appear hereafter. 
They arc 1. The medulla oblongata ; 2. Cerebellum; 3. Optic lobes; 
4. Cerebral hemispheres ; 5. Olfactory lobes ; 6. the pituitary body ; 7- 
the pineal body. (See figures 9 and 21.) The spinal marrow is made up 
by the union of four nervous columns. 



46 NERVOUS SYSTEM AND GENERAL SENSATION. 

bral nerves, and are designed chiefly for the organs of 
sense located in the head. Those which join the spinal 
marrow are also in pairs, one pair for each vertebra or 
joint of the back. The number of pairs varies, therefore, in 
different classes and families, according to the number of 
vertebrae. Each nerve is double, in fact, being composed 
of two threads, which at their junction with the spinal mar- 
row are separate, and afterwards accompany each other 
throughout their whole course. The anterior thread trans- 
mits the commands of the will which induce motion ; the 
other receives and conveys impressions to the brain, to pro- 
duce sensations. 

63. In the Articulated animals, comprising the crabs, 

barnacles, worms, spi- 
ders, insects, and oth- 
er animals formed of 
rings, the nervous sys- 
10. tern consists of a se- 

ries of small centres or swellings, called ganglions, (Fig. 10,) 
placed beneath the alimentary canal, on the floor of the gen- 
eral cavity of the body, and connected by threads ; and of a 
more considerable mass placed above the oesophagus or 
throat, connected with the lower ganglions by threads which 
form a collar around the alimentary canal. The number of 
ganglions generally corresponds to the number of rings. 

64. In the Mollusks, (Fig. 11,) the nervous system con- 

sists of a single ganglionic 
circle, the principal swell- 
ings of which are placed 
symmetrically above and 
below the oesophagus, and 
from whence the filaments, 
Fig- 11- which supply the organs 

in different directions, take their origin. 





NERVOUS SYSTEM AND GENERAL SENSATION. 



47 




Fijr. 12. 



65. In the Radiata, (Fig. 12,) the nervous system is re- 
duced to a single ring, encircling 

the mouth, and giving off threads 
towards the circumference. It dif- 
fers essentially from that of the 
Mollusks, by being disposed in a 
horizontal position, and by its star- 
like form. 

66. The nerves branch off and 
diffuse sensibility to every portion 
of the body, and thereby men and 

the higher animals are enabled to gain a knowledge of the 
general properties of the objects which surround them ; every 
point of the body being made capable of determining whether 
an object is hot or cold, dry or moist, hard or soft, &c. There 
are some parts, however, the ends of the fingers, for exam- 
ple, in which this sensibility is especially acute, and these 
also receive a larger supply of nerves. 

67. On the contrary, those parts which are destitute of 
sensibility, such as the feathers of birds, the wool of ani- 
mals, or the hair of man, are likewise destitute of nerves. 
But the conclusive proof that sensibility resides in the nerves 
is, that when the nerve which supplies any member of the 
body is severed, that member at once becomes insensible. 

68. There are animals in which the faculty of percep- 
tion is limited to this general sense ; but their number is 
small, and, in general, they occupy the lowest place in the 
series. Most animals, in addition to the general sensibility, 
are endowed with peculiar organs for certain kinds of per- 
ceptions, which are acted upon by certain kinds of stimuli, 
as light, sound and odor, and which are called the SENSES. 
These are five in number, namely : sight, hearing, smell, 
taste, and touch. 



48 SPECIAL SENSES. 

SECTION II. 

OF THE SPECIAL SENSES. 

1. Of Sight. 

69. Sight is the sense by which light is perceived, and 
by means of which the outlines, dimensions, relative posi- 
tion, color and brilliancy of objects are discerned. Some 
of these properties may be also ascertained, though in a less 
perfect manner, by the sense of touch. We may obtain an 
idea of the size and shape of an object, by handling it ; but 
the properties that have a relation to light, such as color and 
brilliancy, and also the form and size of bodies that are be- 
yond our reach, can be recognized by sight only. 

70. The EYE is the organ of vision. The number, struc- 
ture, and position of the eyes in the body is considerably 
varied in the different classes. But whatever may be their 
position, these organs in all the higher animals are in connec- 
tion with particular nerves, called the optic nerves, (Fig. 13, 
a.) In the vertebrates, these are the second pair of the cer- 
ebral nerves, and arise directly from the middle mass of the 
brain, (Fig. 21, &,) which, in the embryo, is the most con- 
siderable of all. 

71. Throughout the whole series of vertebrate animals, 

the eyes are only two in num- 
ber, and occup)' bony cavities 
of the skull, called the orbits. 
The organ is a globe or hollow 
sphere formed by three princi- 
pal membranes, enclosed one 
within the other, and filled with 

transparent matter. Figure 13 
^i.. U i UU .iu> u . ! y.. uu ...n,. u , represents a vertical section 




OF SIGHT. 49 

through the eye, from before backwards, and will give an 
idea of the relative position of these different parts. 

72. The outer coat is called the sclerotic, (o ;) it is a 
thick, firm, white membrane, having its anterior portion 
transparent. This transparent segment, which seems set in 
the opaque portion, like a watch-glass in its rim, is called the 
cornea, (f.) 

73. The inside of the sclerotic is lined by a thin, dark- 
colored membrane, the cJioroid, (c.) It becomes detached 
from the sclerotic when it reaches the edge of the cornea, 
and forms a curtain behind it. This curtain gives to the eye 
its peculiar color, and is called the iris, (g.) The iris read- 
ily contracts and dilates, so as to enlarge or diminish an open- 
ing at its centre, the pupil, according as more or less light 
is desired. Sometimes the pupil is circular, as in man, the 
dog, the monkey ; sometimes in the form of a vertical ellipse, 
as in the cat ; or it is elongated sidewise, as in the sheep. 

74. The third membrane is the retina, (fZ.) It is formed 
by the optic nerve, which enters the back part of the eye, by 
an opening through both the sclerotic and choroid coats, and 
expands upon the interior into a whitish and most delicate 
membrane. It is upon the retina that the images of objects 
are received, and produce impressions, which are conveyed 
by the nerve to the brain. 

75. The fluids which occupy the cavity of the eye are of 
different densities. Behind, arid directly opposite to the pupil, 
is placed a spheroidal body, called the crystalline lens, (e.) 
It is tolerably firm, perfectly transparent, and composed of 
layers of unequal density, the interior being always more 
compact than the exterior. Its form varies in different classes 
of animals. In general, it is more convex in aquatic than in 
land animals ; whilst with the cornea it is directly the con- 
trary, being flat in the former, and convex in the latter. 

76. By means of the iris, the cavity, (i,) in front of the crys- 

5 



50 SPECIAL SENSES. 

talline lens is divided into two compartments, called the an- 
terior and posterior chambers. The fluid which fills these 
chambers is a clear watery liquid, called the aqueous humor. 
The portion of the globe behind the lens, which is much the 
largest, is filled by a gelatinous liquid, perfectly transparent, 
like that of the chambers, but somewhat more dense. This 
is called the vitreous humor, (h.} 

77. The object of this apparatus is to receive the rays of 
light, which diverge from all points of bodies placed before 
it, and to bring them again to a point upon the retina. It is 
a well-known fact, that when a ray of light passes obliquely 
from one medium to another of different density, it will be 
refracted or turned out of its course more or less, according 
to the difference of this density, and the obliquity at which 
the ray strikes the surface. This may be illustrated by the 
following figure, (Fig. 14.) 

A/ E 




Fig. 14. 

The ray a c, which strikes the cornea A B perpendicularly, 
continues without deviation, until it reaches the bottom of 
the eye at c. But the rays a m and a n, which strike the eye 
obliquely, change their direction, and instead of proceeding 
onward to m g and n d, take the direction m i and n f. A. 
still further refraction, though less considerable, is occasioned 
by passing through the crystalline lens C D, and the vitreous 
humor, so that the two rays, m i and nf, will at last meet in 
a point. This point is called the focus, (c,) and in distinct 
vision is always precisely at the retina, E F. 

78. From this arrangement, the image found upon the 



OF SIGHT. 51 

retina will be inverted. We may satisfy ourselves of this 
by direct observation. The eye of the white rabbit being 
destitute of the black pigment of the choroid, is quite trans- 
parent. Take the eye, soon after the death of the animal, 
and arrange it in one end of a tube, so that the cornea will 
face outwards ; then if we look in at the other end of 
the tube, we may see objects to which it is directed exactly 
pictured upon the retina, but in a reversed position. 

79. The mechanical structure of the eye may be per- 
fectly imitated by art. Indeed, the camera obscura is an 
instrument constructed on the very same plan. By it, exter- 
nal objects are pictured upon a screen, placed at the bottom 
of the instrument, behind a magnifying lens. The screen 
represents the retina ; the dark walls of the instrument 
represent the choroid ; and the cornea, the crystalline lens 
and the vitreous humor combined, are represented by the 
magnifying lens. But there is this important difference, that 
the eye has the power of changing its form, and of adapt- 
ing itself so as to discern with equal precision very remote, 
as well as very near, objects. 

80. By means of muscles which are attached to the ball, 
the eyes may be rolled in every direction, so as to view ob- 
jects on all sides, without moving the head. The eyes are 
usually protected by lids, which are two in the mammals, 
and generally furnished with a range of hairs at their edges, 
called eye-lashes. Birds have a third lid, which is vertical ; 
this is also found in most of the reptiles and a few mam- 
mals. In fishes, the lids are wanting, or immovable. 

81. The eye constructed as above described is called a 
simple eye, and belongs more especially to the vertebrate 
animals. In man, it arrives at its highest perfection. In 
him, the eye also performs a more exalted office than mere 
vision. It is a mirror, in which the inner man is reflected. 
His passions, his joys, and his sorrows, his inmost self, are 



52 SPECIAL SENSES. 

revealed, with the utmost fidelity, in the expression of his 
eye, and it has been rightly called " the window of the 
soul." 

82. Many of the invertebrate animals have the eye 
constructed upon the same plan as that of the vertebrate 
animals, but with this essential difference, that the optic 
nerve which forms the retina is not derived from a ner- 
vous centre, analogous to the brain, but arises from one 
of the ganglions. Thus, the eye of the cuttle-fish contains 
all the essential parts of the eye of the superior animals, 
and, what is no less important, they are only two in number, 
placed upon the sides of the head. 

83. The snail and kindred animals have, in like manner, 

only two eyes, mounted on the tip 
of a long stalk, (the tentacle,} or 
situated at its base, or on a short 
pedestal by its side. Their struc- 
ture is less perfect than in the cuttle- 
Fig. 15. fish? but still there is a crystalline lens, 
and more or less distinct traces of the vitreous body. Some 
bivalve mollusks, the scollops for example, have likewise 
a crystalline lens, but instead of two eyes, they are furnished 
with numerous eye-spots, which are arranged like a border 
around the lower margin of the animal. 

84. In spiders, the eyes are likewise simple, and usually 

eight in number. These 
little organs, usually called 
ocelli, instead of being 
placed on the sides of 
the body or of the head, 
occupy the anterior part 
of the back. All the essen- 
. 16. tial parts of a simple eye, 

the cornea, the crystalline lens, the vitreous body, are found in 





OF SIGHT. 53 

them, and even the choroid, which presents itself in the 
form of a black ring around the crystalline lens. Many in 
sects, in their caterpillar state, also have simple eyes. 
1 85. Rudiments of eyes have been observed in very 
many of the worms. They generally appear as small 
black spots on the head ; such as are seen on the head 
of the Leech, the Planaria and the Nereis. In these latter 
animals there are four spots. According to Muller, they 
are small bodies, rounded behind, and flattened in front, 
composed of a black, cup-shaped membrane, containing a 
small white, opaque body, which seems to be a continuation 
of the optic nerve. It cannot be doubted, therefore, that 
these are eyes ; but as they lack the optical apparatus 
which produces images, we must suppose that they can 
only receive a general impression of light, without the power 
of discerning objects. 

86. Eye-spots, very similar 
to those of the Nereis, are 
found at the extremity of the 
rays of some of the star-fishes, ^ 
in the sea-urchins, at the mar- 
gin of many Medusae, and in 
some Polypi. Ehrenberg has 
shown that similar spots also 
exist in a large number of the 

Infusoria. Fig. 17. 

87. In all the above-mentioned animals, the eyes, what- 
ever their number, are apart from each other. But there is 
still another type of simple eyes, known as aggregate eyes. 
In some of the millipedes, the pill-bugs, for instance, the eyes 
are collected into groups, like those of spiders ; each eye 
inclosing a crystalline lens and a vitreous body, surrounded 
by a retina and choroid. Such eyes consequently form a 

5* 




54 



SPECIAL SENSES. 



natural transition to the compound eyes of insects, to which 
we now give our attention. 

88. Compound eyes have the same general form as 
simple eyes ; they are placed either on the sides of the head, 
as in insects, or supported on pedestals, as in the crabs. 
But if we examine an eye of this kind by a magnifying lens, 
we find its surface to be composed of an infinite number of 
angular, usually six-sided faces. If these fafettes are re- 
moved, we find beneath a corresponding number of cones, (c,) 
side by side, five or six times as long as they are broad, 
and arranged like rays around the optic nerve, from 
which each one receives a little filament, so as to 
present, according to Miiller, the following disposition. 

(Fig. 18.) The cones are per- 
fectly transparent, but sepa- 
rated from each other by 
walls of pigment, in such a 
manner that only those rays 
which are parallel to the 
axes can reach the retina A ; 
all those which enter ob- 
liquely are lost ; so that of 
all the rays which proceed 
from the points a and Z>, only the central ones in each 
pencil will act upon the optic nerve, (d ;) the others will 
strike against the walls of the cones. To compensate 
for the disadvantage of such an arrangement, and for the 
want of motion, the number of facettes is greatly multi- 
plied, so that no less than 25,000 have been counted in 
a single eye. The image on the retina, in this case, may 
be compared to a mosaic, composed of a great number of 
small images, each of them representing a portion of the 
figure. The entire picture is, of course, more perfect, 




- 18 - 



OF HEARING. 55 

in proportion as the pieces are smaller and more nu- 
merous. 

89. Compound eyes are destitute of the optical apparatus 
necessary to concentrate the rays of light, and cannot adapt 
themselves to the distance of objects ; they see at a certain 
distance, but cannot look at pleasure. The perfection of 
their sight depends on the number of facettes or cones, 
and the manner in which they are placed. Their field of 
vision is wide, when the eye is prominent ; it is very limited, 
on the contrary, when the eye is flat. Thus the dragon-flies, 
on account of the great prominency of their eyes, see equally 
well in all directions, before, behind, or laterally ; whilst 
the water-bugs, which have the eyes nearly on a level with 
the head, can see to only a very short distance before them. 

90. If there be animals destitute of eyes, they are either 
of a very inferior rank, such as most of the polypi, or else 
they are animals which live under unusual circumstan- 
ces, such as the intestinal worms. Even among the ver- 
tebrates, there are some that lack the faculty of sight, as 
the Myxine glutinosa^ which has merely a rudimentary eye 
concealed under the skin, and destitute of a crystalline lens. 
Others, which live in darkness, have not even rudimentary 
eyes, as, for example, that curious fish (Aniblyopsis spelceiis,} 
which lives in the Mammoth Cave, and which appears to 
want even the orbital cavity. The craw-fishes, (Astacus 
pettucidus,) of this same cave, are also blind ; having 
merely the pedicle for the eyes, without any traces of 
fa9ettes. 

2. Hearing. 

91. To hear, is to perceive sounds. The faculty of per- 
ceiving sounds is seated in a peculiar apparatus, the EAR, 
which is constructed with a view to collect and augment the 
sonorous vibrations of the atmosphere, and convey them to 



56 



SPECIAL SENSES. 



the acoustic or auditory nerve, which arises from the poste- 
rior part of the brain. (Fig. 21, c.) 

92. The ears never exceed two in number, and are 
placed, in all the vertebrates, at the hinder part of the head. 
In a large proportion of animals, as the dog, horse, rabbit, 
and most of the mammals, the external parts of the ear 
are generally quite conspicuous ; and as they are, at the 
same time, quite movable, they become one of the promi- 
nent features of physiognomy. 

93. These external appendages, however, do not consti- 
tute the organ of hearing, properly speaking. The true seat 
of hearing is deeper, quite in the interior of the head. It is 
usually a very complicated apparatus, especially in the supe- 
rior animals. In mammals it is composed of three parts, the 
external ear, the middle ear, and the internal ear ; and its 
structure is as follows : (Fig. 19.) 



./f 




Fig. 19. 

94. The external ear, which is popularly regarded as the 
ear, consists of the conch, (a,) and the canal which leads 
from it the external auditory passage, (&.) The first is a 



OF HEARING 57 

gristly expansion, in the form of a horn or a funnel, the 
object of which is to collect the waves of sound ; for this 
reason, animals prick up their ears when they listen. The 
ear of man is remarkable for being nearly immovable. 
Therefore, persons, whose hearing is deficient, employ an 
artificial trumpet, by which the vibrations from a much 
more extended surface may be collected. The external 
ear is peculiar to mammals, and is wanting even in some 
aquatic species of these, such as the seals and the Orni- 
thorhyncus. 

95. The middle ear has received the name of the tym- 
panic cavity, (&.) It is separated from the auditory passage 
by a membranous partition, the tymj)anum or drum, (c ;) 
though it still communicates with the open air by means 
of a narrow canal, called the Eustachian tube, (i,) which 
opens at the back part of the mouth. 

In the interior of the chamber are 
four little bones, of singular forms, 
which anatomists have distinguished 
by the names of malleus, (Fig. 20, c,) 
incus, (n,] stapes, (s,) and os orbicu- 
lare, (o ;) which are articulated to- 
gether, so as to form a continuous 
chain, as here represented, magnified. 

96. The internal ear, which is 

also denominated the labyrinth, is an irregular cavity formed 
in the most solid part of the temporal bone, beyond the 
chamber of the middle ear, from which it is separated by a 
bony partition, which is perforated by two small holes, called, 
from their form, the round and the oval apertures, the fora- 
men rotundum, (Fig. 19, g,) and the foramen ovale, (h.) The 
first is closed by a membrane, similar to that of the tympa- 
num, while the latter is closed by the stapes, one of the little 
bones in the chamber. 




58 SPECIAL SENSES. 

97. Three parts are to be distinguished in the labyrinth, 
namely, the vestibule, which is the part at the entrance of the 
cavity ; the semicircular canals, (c/,) which occupy its upper 
part, in the form of three arched tubes ; and the cochlea, 
which is a narrow canal placed beneath, at the lower part 
of the vestibule, having exactly the form of a snail-shell, (e.) 
The entire labyrinth is filled with a watery fluid, in which 
membranous sacs or pouches float. Within these sacs, the 
auditory nerve (f) terminates. These pouches, therefore, 
are the actual seat of hearing, and the most essential parts 
of the ear. The auditory nerve is admitted to them by a 
long passage, the internal auditory canal. 

98. By this mechanism, the vibrations of the air are first 
collected by the external ear, whence they are conveyed 
along the auditory passage, at the bottom of which is the 
tympanum. The tympanum, by its delicate elasticity, aug- 
ments the vibrations, and transmits them to the internal ear, 
partly by means of the little bones in the chamber, which are 
disposed in such a manner that the stapes exactly fits the oval 
aperture, (foramen ovale;] and partly by means of the air 
which strikes the membrane covering the round aperture, (g,} 
and produces vibrations there, corresponding to those of the 
tympanum. After all these modifications, the sonorous 
vibrations at last arrive at the labyrinth and the auditory 
nerve, which transmits the impression to the brain. 

99. But the mechanism of hearing is not so complicated 
in all classes of animals, and is found to be more and more 
simplified as we descend the series. In birds, the middle 
and interior ears are constructed on the same plans as in the 
mammals ; but the outer ear no longer exists, and the audi- 
tory passage, opening on a level with the surface of the head 
behind the eyes, is merely surrounded by a circle of peculi- 
arly formed feathers. The bones of the middle ear are also 
lessjiumerous, there being generally but one. 



OF HEARING. 59 

100. In reptiles, the whole exterior ear disappears ; the 
auditory passage is always wanting, and the tympanum be- 
comes external. In some toads, even the middle ear also is 
completely wanting. The fluid of the vestibule is charged 
with salts of lime, which frequently give it a milky appear- 
ance, and which, when examined by the microscope, are 
found to be composed of an infinite number of crystals. 

101. In fishes, the middle and external ear are both 
wanting; and the organ of hearing is reduced to a mem- 
branous vestibule, situated in the cavity of the skull, and 
surmounted by semicircular canals, from one to three in 
number. The liquid of the vestibule contains chalky con- 
cretions of irregular forms, which are called Otolites, the 
use of which is doubtless to render the vibration of sounds 
more sensible. 

102. In crabs, the organ of hearing is found on the lower 
face of the head, at the base of the large antennae. It is a 
bony chamber closed by a membrane, in the interior of 
which is suspended a membranous sac filled with water. On 
this sac, the auditory nerve is expanded. In the cuttlefish, 
the vestibule is a simple excavation of the cartilage of the 
head, containing a little membranous sac, in which the audi- 
tory nerve terminates. 

103. Finally, some insects, the grasshopper for instance, 
have an auditory apparatus, no longer situated in the head, 
as with other animals, but in the legs ; and from this fact, we 
may be allowed to suppose, that if no organ of hearing has 
yet been found in most insects, it is because it has been 
sought for in the head only. 

104. It appears from these examples, that the part of the 
organ of hearing which is uniformly present in all animals 
furnished with ears, is precisely that in which the auditory 
nerve ends. This, therefore, is the essential part of the or- 
gan. The other parts of the apparatus, the tympanum, 
auditory passage, and even the semicircular canals, have for 



60 



SPECIAL SENSES. 



their object merely to aid the perception of sound with more 
precision and accuracy. Hence we may conclude that the 
sense of hearing is dull in animals where the organ is re- 

o o 

duced to its most simple form ; and that animals which have 
merely a simple membranous sac, without tympanum and 
auditory passage, as the fishes, or without semicircular 
canals, as the crabs, perceive sounds in but a very imper- 
fect manner. 

3. Of Smell. 

105. SMELL is the faculty of perceiving odors, and is 

a highly important 
sense to many ani- 
mals. Like sight 
and hearing, smell 
depends upon special 
nerves, the olfacto- 
n/i ( a ?) which are 
the first pair of cer- 
ebral nerves, and 
which, in the em- 
bryo, are direct pro- 
longations of the 
brain. 

106. The organ of smell is the NOSE. Throughout the 
series of vertebrates, it makes a part of the face, and in 
man, by reason of its prominent form, it becomes one of the 
dominant traits of his countenance ; in other mammals, the 
nose loses this prominency by degrees, and the nostrils no 
longer open downwards, but forwards. In birds, the position 
of the nostrils is a little different ; they open farther back 
and higher, at the origin of the beak, (/.) 

107. The nostrils are usually two in number. Some fishes 
have four. They are similar openings, separated by a par- 
tition upon the middle line of the body. In man and the 




Fig. 21. 

a, olfactory nerve ; b, optic nerve ; c, audi- 
tory nerve ; d, cerebrum ; e, cerebellum ; 
f, nostril. 



OF SMELL. 61 

mammals, the outer walls of the nose are composed of carti- 
lage ; but internally, the nostrils communicate with bony cav- 
ities situated in the bones of the face and forehead. These 
cavities are lined by a thick membrane, the pituitary mem- 
brane, on which are expanded the nerves of smell, namely, 
the olfactory nerves, and some filaments of the nerve which 
goes to the face. 

108. The process of smelling is as follows. Odors are 
particles of extreme delicacy which escape from very many 
bodies, and are diffused through the air. These particles 
excite the nerves of smell, which transmit the impressions 
made on them to the brain. To facilitate the perception of 
odors, the nostrils are placed in the course of the respiratory 
passages, so that all the odors which are diffused in the air 
inspired, pass over the pituitary membrane. 

109. The acuteness of the sense of smell depends on the 
extent to which the membrane is developed. Man is not so 
well endowed in this respect as many animals, which have 
the internal surface of the nostrils extremely complicated, as 
it is especially among the beasts of prey. 

110. The sense of smell in Reptiles is less delicate than 
in the mammals ; the pituitary membrane, also, is less de- 
veloped. Fishes are probably still less favored in this 
respect. As they perceive odors through the medium of 
water, we should anticipate that the structure of their 
apparatus would be different from that of animals which 
breathe in the air. Their nostrils are mere superficial pouch- 
es, lined with a membrane gathered into folds which gen- 
erally radiate from a centre, but are sometimes arranged 
in parallel ridges on each side of a central band. As the 
perfection of smell depends on the amount of surface 
exposed, it follows that those fishes which have these 
folds most multiplied are also those in which this sense is 
most acute. 

6 



62 SPECIAL SENSES. 

111. No special apparatus for smell has yet been found in 
Invertebrates. And yet there can be no doubt that insects, 
crabs, and some mollusks perceive odors, since they are 
attracted from a long distance by the odor of objects. Some 
of these animals may be deceived by odors similar to those 
of their prey ; which clearly shows that they are led to it by 
this sense. The carrion fly will deposit its eggs on plants 
which have the smell of tainted flesh. 

4. Of Taste. 

112. TASTE is the sense by which the flavor of bodies is 
perceived. That the flavor of a body may be perceived, it 
must come into immediate contact with the nerves of taste ; 
these nerves are distributed at the entrance to the digestive 
tube, on the surface of the tongue and the palate. By this 
sense, animals are guided in the choice of their food, and 
warned to abstain from what is noxious. There is an inti- 
mate connection between the taste and the smell, so that 
both these senses are called into requisition in the selection 
of food. 

113. The nerves of taste are not so strictly special as 
those of sight and hearing. They do not proceed from one 
single trunk, and, in the embryo, do not correspond to an 
isolated part of the brain. The tongue, in particular, receives 
nerves from several trunks ; and taste is perfect in proportion 
as the nerves which go to the tongue are more minutely dis- 
tributed. The extremities of the nerves generally terminate 
in little asperities of the surface, called papilla. Sometimes 
these papillae are very harsh, as in the cat and the ox ; and 
again they are very delicate, as in the human tongue, in that 
of the dog, horse, &c. 

114. Birds have the tongue cartilaginous, sometimes be- 
set with little stiff points; sometimes fibrous or fringed 
at the edges. In the parrots, it is thick and fleshy ; 



OF TOUCH. 63 

or it is even barbed at its point, as in the woodpeckers. 
In some reptiles, the crocodile for example, the tongue 
is adherent ; in others, on the contrary, it is capable of 
extensive motion, and serves as an organ of touch, as in the 
serpents, or it may be thrust out to a great length to take 
prey, like that of the chameleon, toad, and frog. In fishes, 
it is usually cartilaginous, as in birds, generally adherent, and 
its surface is frequently covered with teeth. 

115. It is to be presumed, that in animals which have a 
cartilaginous tongue, the taste must be very obtuse, especial- 
ly in those which, like most fishes, and many granivorous 
birds, swallow their prey without mastication. In fishes, 
especially, the taste is very imperfect, as is proved by then 
readily swallowing artificial bait. It is probable that they 
are guided in the choice of their prey by sight, rather 
than by taste or smell. 

116. Some of the inferior animals select their food with 
no little discernment. Thus, flies will select the sugary 
portions of bodies. Some of the mollusks, as the snails 
for example, are particularly dainty in the choice of their 
food. In general, the taste is but imperfectly developed, 
except in the mammals, and they are the only animals 
which enjoy the flavor of their food. With man, this 
sense, like others, may be greatly improved by exercise ; 
and it is even capable of being brought to a high degree 
of delicacy. 

5. Of Touch. 

117. The sense of TOUCH is merely a peculiar manifesta- 
tion of the general sensibility, seated in the skin, and 
dependent upon the nerves of sensation, which expand over 
the surface of the body. By the aid of this general sensi- 
bility, we learn whether a body is hot or cold, wet or dry. 
We may also, by simple contact, gain an idea, to a certain 



64 SPECIAL SENSES. 

extent, of the form and consistence of a body, as, for exam- 
ple, whether it be sharp or blunt, soft or hard. 

118. This faculty resides more especially in the hand, 
which is not only endowed with a more delicate tact, but, 
owing to the disposition of the ringers, and the opposition of 
the thumb to the other fingers, is capable of so moulding 
itself around objects, as to multiply the points of contact. 
Hence, touch is an attribute of man, rather than of other 
animals ; for among these latter, scarcely any, except the 
monkeys, have the faculty of touch in their hands, or, as it 
is technically termed, of palpation. 

119. In some animals, this faculty is exercised by other 
organs. Thus the trunk of the elephant is a most perfect 
organ of touch ; and probably the mastodon, whose numer- 
ous relics are found scattered in the superficial layers of 
the earth's crust, was furnished with a similar organ. 
Serpents make use of their tongue for touch ; insects 
employ their palpi, and snails their tentacles, for the same 
purpose. 

6. The Voice. 

120. Animals have not only the power of perceiving, 
but many of them have also the faculty of producing 
sounds of every variety, from the roaring of the lion to the 
song of the bird as it salutes the rising sun. It is moreover 
to be remarked that those which are endowed with a voice, 
likewise have the organ of hearing well developed. 

121. Animals employ their voice either for communica- 
tion with each other, or to express their sensations, their en- 
joyments, their sufferings. Nevertheless, this faculty is en- 
joyed by but a small minority of animals; with but very 
few exceptions, only the mammals, the birds, and a few 
reptiles are endowed with it. All others are dumb. 
Worms and insects have no true voice ; for we must not 



OF THE VOICE. 65 

mistake for it the buzzing of the bee, which is merely a 
noise created by the vibration of the wings ; nor the grating 
shriek of the Locust, (grasshopper,) caused by the friction of 
his legs against his wings ; nor the shrill noises of the cricket, 
or the tell-tale call of the katydid, produced by the friction 
of the wing covers upon each other, and in numerous similar 
cases which might he cited. 

122. Consequently, were the mammals, the birds, and the 
frogs to be struck out of existence, the whole Animal King- 
dom would be dumb. It is difficult for us, living in the midst 
of the thousand various sounds which strike our ear from all 
sides, to conceive of such a state. Yet such a state did 
doubtless prevail for thousands of ages, on the surface of our 
globe, when the watery w r orld alone was inhabited, and be- 
fore man, the birds, and the mammals were called into being. 

123. In man and the mammals, the voice is formed in an 
organ called the larynx, situated at the upper part of the 
windpipe, below the bone of the tongue, (a.) a \\ 

The human larynx, the part called Adam's 
apple, is composed of several cartilaginous b~\ 
pieces, called the thyroid cartilage, (&,) the I 
cricoid cartilage, (c,) and the small arytenoid ^_ 
cartilages. Within these are found two large 
folds of elastic substance, known by the name Fig. 22. 
of the vocal cords, (m.) Two other analogous folds, the 
superior ligaments of the glottis , (n,} are situated a little 
above the preceding. The glottis (o) is the space between 
these four folds. The arrangement of the vocal cords, and 
of the interior of the glottis in man, is indicated by dotted 
lines, in Fig. 22. 

124. The mechanism of the voice is as follows : the air, 
on its way to the lungs, passes the vocal cords. So long as 
these are in repose, no sound is produced ; but the moment 
they are made tense they narrow the aperture, and oppose 

6* 




66 



OF THE VOICE. 



an obstacle to the current of air, and it cannot pass without 
causing them to vibrate. These vibrations produce the 
voice ; and as the vocal cords are susceptible of different 
degrees of tension, these tensions determine different sounds ; 
giving an acute tone when the tension is great, but a grave 
and dull one when the tension is feeble. 

125. Some mammals have, in addition, large cavities 
which communicate with the glottis, and into which the air 
reverberates, as it passes the larynx. This arrangement is 
especially remarkable in the howling monkeys, which are dis- 
tinguished above all other animals for their deafening howls. 

126. In birds, the proper larynx is very simple, destitute 
of vocal cords, and incapable of producing sounds ; but at 
the lower end of the windpipe there is a second or inferior 
larynx, which is very complicated in structure. It is a kind 

of bony drum, (a,) having with- 
in it two glottides, formed at the 
top of the two branches (bb) of 
the windpipe, (c,) each provided 
with two vocal cords. The dif- 
ferent pieces of this apparatus 
are moved by peculiar muscles, 
the number of which varies in 
different families. In birds which 
have a very monotonous cry, 
such as the gulls, the herons, 
the cuckoos, and the mergansers, 

(Fig. 23,) there is but one or two pairs ; parrots have three ; 

and the birds of song have five. 

127. Man alone, of all the animal creation, has the power 
of giving to the tones he utters a variety of definite or ar- 
ticulate sounds ; in other words, he alone has the gift of 
speech. 




Fig. 23. 



CHAPTER FOURTH. 

OF INTELLIGENCE AND INSTINCT. 

128. BESIDES the material substance of which the body is 
constructed, there is also an immaterial principle, which, 
though it eludes detection, is none the less real, and to 
which we are constantly obliged to recur in considering the 
phenomena of life. It originates with the body, and is de- 
veloped with it, while yet it is totally apart from it. The 
study of this inscrutable principle belongs to one of the 
highesj branches of Philosophy ; and we shall here merely 
allude to some of its phenomena which elucidate the devel- 
opment and rank of animals. 

129. The constancy of species is a phenomenon depend- 
ing on the immaterial nature. Animals, and plants also, 
produce their kind, generation after generation. We shall 
hereafter show that all animals may be traced back, in the 
embryo, to a mere point in the yolk of the egg, bearing 
no resemblance whatever to the future animal ; and no in- 
spection would enable us to declare with certainty what that 
animal is to be. But even here an immaterial principle 
is present, which no external influence can essentially modify, 
and determines the growth of the future being. The egg of 
the hen, for instance, cannot be made to produce any other 
animal than a chicken, and the egg of the codfish produces 
only the cod. It may therefore be said with truth, that the 
chicken and the cod existed in the egg before their formation 
as such. 

130. PERCEPTION is a faculty springing from this princi- 
ple. The organs of sense are the instruments for receiving 



68 INTELLIGENCE AND INSTINCT. 

sensations, but they are not the faculty itself, without 
which they would be useless. We all know that the 
eye and ear may be open to the sights and sounds about 
us ; but if the mind happens to be preoccupied, we perceive 
them not. We may even be searching for something which 
actually lies within the compass of our vision; the light 
enters the eye as usual, and the image is formed on the 
retina ; but, to use a common expression, we look without 
seeing, unless the mind that perceives is directed to the object. 

131. In addition to the faculty of perceiving sensations, 
the higher animals have also the faculty of recalling past 
impressions, or the power of memory. Many animals retain 
a recollection of the pleasure or pain they have experi- 
enced, and seek or avoid the objects which may have pro- 
duced these sensations ; and, in doing so, they give proof 
of judgment. 

132. This fact proves that animals have the faculty of 
comparing their sensations and of deriving conclusions from 
them ; in other words, that they carry on a process of 



reasoning. 



133. These different faculties, taken together, constitute 
intelligence. In man, this superior principle, which is an 
emanation of the divine nature, manifests itself in all its 
splendor. God " breathed into him the breath of life, and 
man became a living soul." It is man's prerogative, and his 
alone, to regulate his conduct by the deductions of reason ; 
he has the faculty of exercising his judgment not only 
upon the objects which surround him, and of apprehending 
the many relations which exist between himself and the ex- 
ternal world ; he may also apply his reason to immaterial 
things, observe the operations of his own intellect, and, by 
the analysis of his faculties, may arrive at the conscious- 
ness of his own nature, and even conceive of that Infinite 
Spirit, " whom none by searching can find out." 



INTELLIGENCE AND INSTINCT. 69 

134. Other animals cannot aspire to conceptions of this 
kind ; they perceive only such objects as immediately strike 
their senses, and are incapable of continuous efforts of the 
reasoning faculty in regard to them. But their conduct is 
frequently regulated by another principle of inferior order, 
still derived from the immaterial principle, called INSTINCT. 

135. Under the guidance of Instinct, animals are enabled 
to perform certain operations, without instruction, in one 
imdeviating manner. When man chooses wood and stone, 
as the materials for his dwelling, in preference to straw and 
leaves, it is because he has learned by experience, or be- 
cause his associates have informed him, that these materials 
are more suitable for the purpose. But the bee requires no 
instructions in building her comb. She selects at once the 
fittest materials, and employs them with the greatest econo- 
my ; and the young bee exhibits, in this respect, as much 
discernment as those who have had the benefit of long 
experience. She performs her task without previous study, 
and, to all appearances, without the consciousness of its 
utility, being in some sense impelled to it by a blind impulse. 

136. If, however, we judge of the instinctive acts of ani- 
mals when compared with acts of intelligence, by the relative 
perfection of their products, we may be led into gross errors, 
as a single example will show. No one will deny that the 
honey-comb is constructed with more art and care than the 
huts of many tribes of men. And vet, who would presume 
to conclude from this that the bee is superior in intelligence 
to the inhabitant of the desert or of the primitive forest? 
It is evident, on the contrary, that in this particular case we 
are not to judge of the artisan by his work. As a work of 
man, a structure as perfect in all respects as the honey-comb 
would indicate very complicated mental operations, and 
probably would require numerous preliminary experiments. 

137. The instinctive actions of animals relate either to 



70 INTELLIGENCE AND INSTINCT. 

the procuring of food, or to the rearing of their young ; in 
other words, they have for their end the preservation of the 
individual and of the species. It is by instinct that the 
leopard conceals himself and awaits the approach of his 
prey. It is equally by instinct that the spider spreads his 
web to entangle the flies which approach it. 

138. Some animals go beyond these immediate precau- 
tions ; their instinct leads them to make provision for the 
future. Thus the squirrel lays in his store of nuts and 
acorns during autumn, and deposits them in cavities of 
trees, which he readily finds again in winter. The hamster 
digs, by the side of his burrow, compartments for magazines, 
which he arranges with much art. Finally, the bee, more 
than any other animal, labors in view of the future ; and 
she has become the emblem of order and domestic economy. 

139. Instinct exhibits itself, in a no less striking manner, 
in the anxiety which animals manifest for the welfare of 
their anticipated progeny. All birds build nests for the 
shelter and nurture of their young, and in some cases these 
nests are made exceedingly comfortable. Others show very 
great ingenuity in concealing their nests from the eyes of 
their enemies, or in placing them beyond their reach. 
There is a small bird in the East Indies, the tailor bird, 
(Sylvia sutoria,) which works wool or cotton into threads, 
with its feet and beak, and uses it to sew together the leaves 
of trees for its nest. 

140. The nest of the fiery hang-bird, (Icterus Baltimore,) 
dangling from the extremity of some slender, inaccessible 
twig, is familiar to all. The beautiful nest of the humming- 
bird, seated on a mossy bough, and itself coated with lichen 
and lined with the softest down from the cotton-grass or the 
mullein leaf, is calculated equally for comfort and for es- 
caping observation. An East Indian bird, (PloceusPhilippi- 
nus,) not only exhibits wonderful devices in the construction, 



INTELLIGENCE AND INSTINCT. 



71 




security, and comfort of its nest, but displays a still further 
advance towards intelligence. The nest is built at the tips 
of long pendulous twigs, usually hanging over the water. It 
is composed of grass, in such a manner as to form a com- 
plete thatch. The entrance 
is through a long tube, run- 
ning downwards from the 
edge of the nest ; and its 
lower end is so loosely woven, 
that any serpent or squirrel, 
attempting to enter the aper- 
ture, would detach the fibres, 
and fall to the ground. The 
male, however, who has no 
occasion for such protection, 
builds his thatched dome, sim- 
ilar to that of the female, and 
by its side ; but makes simply a perch across the base of 
the dome, without the nest-pouch or tube. 

141. But it is among insects that this instinctive solici- 
tude for the welfare of the progeny is every where exhibited 
in the most striking manner. Bees and wasps not only 
prepare cells for each of their eggs, but take care, before 
closing the cells, to deposit in each of them something ap- 
propriate for the nourishment of the future young. 

142. It is by the dictate of instinct, also, that vast numbers 
of animals of the same species associate, at certain periods 
of the year, for migration from one region to another ; as 
the swallows and passenger pigeons, which are sometimes 
met with in countless flocks. 

143. Other animals live naturally in large societies, and 
labor in common. This is the case with the ants and bees. 
Among the latter, even the kind of labor for each member 
of the community is determined beforehand, by instinct. 



72 INTELLIGENCE AND INSTINCT 

Some of them collect only honey and wax ; while others 
are charged with the care and education of the young ; and 
still others are the natural chiefs of the colony. 

144. Finally, there are certain animals so guided by their 
instinct as to live like pirates, on the avails of others' 
labor. The Lestris or Jager will not take the trouble to 
catch fish for itself, but pursues the gulls, until, worn out 
by the pursuit, they eject their prey from their crop. Some 
ants make war upon others less powerful, take their young 
away to their nests, and oblige them to labor in slavery. 

145. There is a striking relation between the volume of 
the brain compared with the body, and the degree of intelli- 
gence which an animal may attain. The brain of man is 
the most voluminous of all, and among other animals there is 
every gradation in this respect. In general, an animal is the 
more intelligent, in proportion as its brain bears a greater 
resemblance to that of man. 

146. The relation between instinct and the nervous 
system does not present so intimate a correspondence as 
exists between the intellect and the brain. Animals which 
have a most striking development of instinct, as the ants and 
bees, belong to a division of the Animal Kingdom where the 
nervous system is much less developed than that of the ver- 
tebrates, since they have only ganglions, without a proper 
brain. There is even a certain antagonism between instinct 
and intelligence, so that instinct loses its force and peculiar 
character, whenever intelligence becomes developed. 

147. Instinct plays but a secondary part in man. He is 
not, however, entirely devoid of it. Some of his actions are 
entirely prompted by instinct, as, for instance, the attempts of 
the infant to nurse. The fact, again, that these instinctive 
actions mostly belong to infancy, when intelligence is but 
slightly developed, goes to confirm the two last propositions. 



CHAPTER FIFTH. 

OF MOTION. 
SECTION I. 

APPARATUS OF MOTION. 

148. THE power of voluntary motion is the second grand 
characteristic of animals, (57.) Though they may not all 
have the means of transporting themselves from place to 
place, there is no one which has not the power of executing 
some motions. The oyster, although fixed to the ground, 
opens and closes its shell at pleasure ; and the little coral 
animal protrudes itself from its cell, and retires again at 
its will. 

149. The movements of animals are effected by means of 
muscles, which are organs designed expressly for this pur- 
pose, and which make up that portion of the body which 
is commonly called flesh. They are composed of threads, 
which are readily seen in boiled meat. These threads 
are again composed of still more delicate fibres, called mus- 
cular fibres, (45,) which have the property of elongating 
and contracting. 

150. The motions of animals and plants depend, therefore, 
upon causes essentially different. The expansion and closing 
of the leaves and blossoms of plants, which are their most 

7 



74 



APPARATUS OF MOTION. 



obvious motions, are due to the influence of light, heat, 
moisture, cold, and similar external agents ; but all the mo- 
tions peculiar to animals are produced by a cause residing 
within themselves, namely, the contractility of muscular 
fibres. 

151. The cause which excites contractility resides in the 
nerves, although its nature is not precisely understood. 

We only know that each 
muscular bundle receives 
one or more nerves, whose 
filaments pass at intervals 
across the muscular fibres, 
as seen in Fig. 25. It has 



also been shown, by experi- 
ment, that when a nerve 
entering a muscle is sev- 




Fig. 25. 



erecl, the muscle instantly loses its power of contracting 
under the stimulus of the will, or, in other words, is par- 
alyzed. 

152. The muscles may be classified, according as they 
are more or less under the control of the will. The con- 
tractions of some of them are entirely dependent on the will, 
as in the muscles of the limbs used for locomotion. Others 
are quite independent of it, like the contractions of the heart 
and stomach. The muscles of respiration ordinarily act inde- 
pendently of the will, but are partially subject to it : thus, 
when we attempt to hold the breath, we arrest, for the mo- 
ment, the action of the diaphragm. 

153. In the great majority of animals, motion is greatly 
aided by the presence of solid parts, of a bony or horny 
structure, which either serve as firm attachments to the 
muscles, or, being arranged so as to act as levers, to in- 
crease the precision and sometimes the force of movements. 
The solid parts are usually so arranged as to form a sub- 



APPARATUS OF MOTION. 75 

stantial framework for the body, which has been variously 
designated in the several classes of animals, as the test, shell, 

O 

carapace, skeleton, fyc. The study of these parts is one of the 
most important tranches of comparative anatomy. Their 
characters are the most constant and enduring of all others. 
Indeed, these solid parts are nearly all that remains of 
the numerous extinct races of animals of past geological 
eras ; and from these alone are we to determine the struc- 
ture and character of the ancient fauna. 

154. Most of the Radiata have a calcareous test or crusty 
shell. In the Polypi, this structure, when it exists, is usually 
very solid, sometimes assuming the form of a simple inter- 
nal skeleton, or forming extensively branched stems, as 
in the sea-fans ; or giving rise to solid masses, furnished 
with numerous cavities opening at the surface, from which 
the movable parts of the animals are protruded, with the 
power, however, of retracting themselves at pleasure, as in 
the corals. In the Echinoderms, the test is intimately con- 
nected with the structure of the soft 

parts. It is composed of numer- 
ous little plates, sometimes con- 
solidated and immovable, as in 
the sea-urchins, (Fig. 26,) and 
sometimes so combined, as to -p io . 2 

allow of various motions, as in 
the star-fishes, (Fig. 17,) which use their projecting rays, 
both for crawling and swimming. 

155. In the Mollusks, the solid parts are secreted by the 
skin, .most frequently in the form of a calcareous shell of 
one, two, or many pieces, serving for the protection of the 
soft parts which they cover. These shells are generally so 
constructed as to afford complete protection to the animal 
within their cavities. In a few, the shell is too small for this 
purpose ; and in some it exists only at a very early period, 




76 APPARATUS OF MOTION. 

and is lost as the animal is developed, so that at last there is 
no other covering than a slimy skin. In others, the skin 
becomes so thick and firm as to have the consistence of 
elastic leather ; or it is gelatinous or transparent, and, what is 
very curious, these tissues may be the same as those of woody 
fibre, as, for example, in the Ascidia. As a general thing, 
the solid parts do not aid in locomotion, so that the mol- 
lusks are mostly sluggish animals. It is only in a few rare 
cases that the shell becomes a true lever, as in the Scollops, 
(Pecten,) which use their shells to propel themselves in 



swimming. 



156. The muscles of mollusks either form a flat disk un- 
der the body, or large bundles across its mass, or are dis- 
tributed in the skin so as to dilate and contract it, or are 
arranged about the mouth and tentacles, which they put 
in motion. However varied the disposition may be, they 
always form very considerable masses, in proportion to the 
size of the body, and have a soft and mucous appearance, 
such as is not seen in the contractile fibres of other animals. 
This peculiar aspect no doubt arises from the numerous 
small cavities extending between the muscles, and the secre- 
tion of mucus which takes place in them. 

157. In the Articulated animals, the solid parts are ex- 
ternal, in the form of rings, generally of a horny structure, 
but sometimes calcareous, and successively fitting into each 
other at their edges. The tail of a lobster gives a good 
idea of this structure. The rings differ in the several 
classes of this department, merely as to volume, form, solid- 
ity, number of pieces, and the degree of motion which one 
has upon another. In some groups they are consolidated, so 
as to form a shield or carapace, such as we see in the 
crabs. In others, they are membranous, and the body is 
capable of assuming various forms, as in the leeches and 
worms generally. 



APPARATUS OF MOTION. 



77 



158. A variety of appendages are attached to these 
rings, such as jointed legs, or in place of them stiff bristles, 
oars fringed with silken threads, wings either firm or mem- 
branous, antennae, movable pieces which perform the office 
of jaws, &c. But however diversified this solid apparatus 
may be, it is universally the case that the rings, to which 
every segment of the body may be referred as to a type, com- 
bine to form but a single internal cavity, in which all the or- 
gans are enclosed, the nervous system, as well as the organs 
of vegetative life, (63.) 

159. The muscles which move 
all these parts have this peculiar- 
ity, that they are all enclosed with- 
in the more solid framework, and 
not external to it, as in the verte- 
brates ; and also that the muscular 
bundles, which are very consider- 
able in number, have the form of 
ribbons, or fleshy strips, with par- 
allel fibres of remarkable white- 
Figure 27 represents the 




Fig. 27. 



ness. 

disposition of the muscles of the caterpillar which destroys 
the willow, (Cossus ligniperda.] The right side represents 
the superficial layer of muscles, and the left side the deep- 
seated layer. 

160. The Vertebrata, like the articulated animals, have 
solid parts at the surface, as the hairs and horns of mam- 
mals, the coat of mail of the armadillo, the feathers and claws 
of birds, the bucklers and scales of reptiles and fishes, &c. 
But they have besides this, along the interior of the whole 
body, a solid framework not found in the invertebrates, well 
known as the SKELETON. 

161. The skeleton is composed of a series of separate 
bones, called vertebrae, united to each other by ligaments. 

7* 



78 



APPARATUS OF MOTION. 



a 



Each vertebra has a solid centre with four branches, two of 

which ascend and form an arch above, 
and two descend, forming an arch below 
the body of the vertebra. The upper 
arches form a continuous cavity (a) along 
the region of the trunk, which encloses 
the spinal marrow, and in the head re- 
ceives the brain, (61.) The lower arches 
(Z>) form another cavity, similar to the 
superior one, which contains the organs of 
nutrition and reproduction ; their branch- 
es generally meet below, and when dis- 
joined, the deficiency is supplied by 
fleshy walls. Every part of the skeleton 
may be reduced to this fundamental type, 
the vertebra, as will be shown, when treating specially of the 
vertebrate animals ; so that between the pieces composing 
the head, the trunk, or the tail, we have only differences 
in the degree of development of the body of the ver- 
tebra, or of its branches, and not in reality different plans 
of organization. 

162. The muscles which move this solid framework of 
the vertebrata are disposed around the vertebrae, as is 




Fig. 28. 




Fig. 29. 

well exemplified among the fishes, where there is a band 
of muscles for each vertebra. In proportion as limbs 



LOCOMOTION. 



79 



are developed, this intimate relation between the muscles 
and the vertebrae diminish- 
The muscles are un- 



es. 

equally distributed and are 
concentrated about the 
limbs, where the greatest 
amount of muscular force 
is required. For this rea- 
son, the largest masses of 
flesh in the higher verte- 
brates are found about the 
shoulders and hips ; while 
in fishes they are concen- 
trated about the base of the 




Fig. 30. 



tail, which is the part principally employed in locomotion. 



SECTION II. 

OF LOCOMOTION. 

163. One of the most curious and important applications 
of this apparatus of bones and muscles is for LOCOMO- 
TION. By this is understood the movement which an animal 
makes in passing from place to place, in the pursuit of pleas- 
ure, sustenance, or safety, in distinction from those motions 
which are performed equally well while stationary, such as 
the acts of respiration, mastication, &c. 

164. The means which nature has brought into action to 
effect locomotion under all the various circumstances in 
which animals are placed, are very diversified ; and the 
study of their adaptation to the necessities of animals is highly 
interesting in a mechanical, as well as in a zoological point 
of view. Two general plans may be noticed, under which 
these varieties may be arranged. Either the whole body is 




80 LOCOMOTION. 

equally concerned in effecting locomotion, or only some of 

its parts are employed for the purpose. 

165. The jelly-fishes (Medusae) swim 
by contracting their umbrella-shaped 
bodies upon the water below, and its 
resistance urges them forwards. Other 
animals are provided with a sac or 
siphon, which they may fill with water, 
and suddenly force out, producing a jet, 
which is resisted by the surrounding 
water, and the animal is thus propelled. 

The Biche-le-mar, (Holothuria,) the cuttle-fishes, the Salpse, 

&c., move in this way. 

166. Others contract small portions of the body in suc- 
cession, which being thereby rendered firmer, serve as 
points of resistance, against which the animal may strive, 
in urging the body onwards. The earth-worm, whose body 
is composed of a series of rings united by muscles, and 
shutting more or less into each other, has only to close up 
the rings at one or more points, to form a sort of fulcrum, 
against which the rest of the body exerts itself in extending 
forwards. 

167. Some have, at the extremities of the body, a cup or 
some other organ for maintaining a firm hold, each extremity 
acting in turn as a fixed point. Thus the Leech has a cup 
or sucker at its tail, by which it fixes itself ; the body is then 

elongated by the contraction 
of the muscular fibres which 
encircle the animal ; the mouth 
is next fixed by a similar suck- 
Fig. 32. er and by the contraction of 
muscles running lengthwise the body is shortened, and the 
tail, losing its hold, is brought forwards to repeat the same 
process. Most of the bivalve mollusks, such as the clams, 




LOCOMOTION. 81 

move from place to place, in a similar way. A fleshy organ, 
called the foot, is thrust forward, and its extremity fixed 
in the mud, or to some firm object, when it contracts, 
and thus draws along the body and the shell enclosing 
it. Snails, and many similar animals, have the fleshy under 
surface of their body composed of an infinitude of very short 
muscles, which, by successive contractions, so minute, indeed, 
as scarcely to be detected, enable them to glide along 
smoothly and silently, without any apparent muscular effort. 

168. In the majority of animals, however, locomotion is 
effected by means of organs specially designed for the pur- 
pose. The most simple are the minute, hair-like cilia,) 
which fringe the body of most of the microscopic infu- 
sory animalcules, and which, by their incessant vibrations, 
cause rapid movements. The sea-urchins and star-fishes 
have little thread-like tubes issuing from every side of the 
body, furnished with a sucker at the end. By attaching 
these to some fixed object, they are enabled to draw or roll 
themselves along ; but their progress is always slow. Insects 
are distinguished for the number and great perfection of their 
organs of motion. They have at least three pairs of legs, 
and usually wings also. But those that have numerous 
feet, like the centipedes, are not distinguished for agility. 
The Crustacea generally have at least five pairs of legs, 
which are used for both 

swimming and crawling. 
The Worms are much less 
active ; some of them have 
only short bristles at their 
sides. Some of the marine 
species use their fringe-like gills for paddles. (Fig. 33.) 

169. Among the Vertebrata, we find the greatest diversity 
in the organs of locomotion and the modes of their applica- 
tion, as well as the greatest perfection, in whatever element 




82 ORGANS OF LOCOMOTION. 

they may be employed. The sailing of the eagle, the bound- 
ing of the antelope, the swimming of the shark, are not 
equalled by any movements of insects, This superiority is 
due to the internal skeleton, which, while it admits a great 
display of force, gives to the motions, at the same time, a 
great degree of precision. 

1. Plan of the Organs of Locomotion. 

170. The organs of progression in vertebrated animals 
never exceed four in number, and to them the term limbs is 
more particularly applied. The study of these organs, as 
characteristic of the different groups of vertebrate animals, 
is most interesting, especially when prosecuted with a view 
to trace them all back to one fundamental plan, and to ob- 
serve the modifications, oftentimes very slight, by which a 
very simple organ is adapted to every variety of move- 
ment. No part of the animal structure more fully illustrates 
the unity of design, or the skill of the Intellect which has 
so adapted a single organ to such multiplied ends. On this 
account, we shall illustrate this subject somewhat in detail. 

171. It is easy to see that the wing which is to sustain 
the bird in the air must be different from the leg of the stag, 
which is to serve for running, or the fins of the fish that 
swims. But, notwithstanding their dissimilarity, the wing of 
the bird, the leg of the stag, and the shoulder fin of the fish, 
may still be traced to the same plan of structure ; and if 
we examine their skeletons, we find the same fundamental 
parts. In order to show this, it is necessary to give a short de- 
scription of the composition of the arm or anterior extremity. 

172. The anterior member, in the vertebrates, is invaria- 
bly composed of the following bones: 1. The shoulder- 
llade, or scapula, (a,) a broad and flat bone, applied upon 
the bones of the trunk ; 2. The arwi, (,) formed of a single 



OKGANS OF LOCOMOTION. 



83 



A 



a 



long cylindrical bone, the humerus ; 3. The fore-arm, com- 
posed of two long bones, the radius, (c,) and ulna, (d,) 
which are often fused into one ; 4. The hand, which is 
composed of a series of bones, more .0 

or less numerous in different classes, 
and which is divided into three parts, 
namely, the carpus, or wrist, (e,] the 
metacarpus, or palm, (/",) and the pha- 
langes, or fingers, (g.} The clavicle or 
collar-bone, (o,) when it exists, belongs 
also to the anterior member. It is a 
bone of a cylindrical form, fixed as 
a brace between the breast-bone and 
shoulder-blade. Its use is to keep the c 
shoulders separated ; to this end, we 
find it fully developed in all animals 
which raise the limbs from the sides, as 
the birds and the bats. On the other 
hand, it is rudimentary, or entirely want- 
ing in animals which move them back- 
wards and forwards only, as with most 
quadrupeds. 

173. The following outlines, in which corresponding bones 
are indicated by the same letters, will give an idea of the 
modifications which these bones present in different classes. 
In the arm of man, (Fig. 34,) the shoulder-blade is flat 
and triangular ; the bone of the arm is cylindrical, and en- 
larged at its extremities ; the bones of the fore-arm are 
somewhat shorter than the humerus, but more slender ; the 
hand is composed of the following pieces, namely, eight 
small bones of the carpus, arranged in two rows, five meta- 
carpal bones, which are elongated, and succeed those of the 
wrist ; five fingers of unequal length, one of which, the 
thumb, is opposed to the four others. 




f j 



Fig. 34. 



Fig. 35. 



84 



ORGANS OF LOCOMOTION. 



174. In the stag, (Fig. 35,) the bones of the fore-arm 
are rather longer than that of the arm, and the radius no 
longer turns upon the ulna, but is blended with it; the meta- 
carpal, or cannon bone, is greatly developed ; and, being 
quite as long as the fore-arm, it is apt to be mistaken for it. 
The fingers are reduced to two, each of which is surrounded 
by a hoof, at its extremity. 

175. In the arm of the lion, (Fig. 36,) the arm bone is 





Fig. 36. 

stouter, the carpal bones are less numerous, and the fingers 
are short, and armed with strong, retractile claws. In the 
whale, (Fig. 37,) the bones of the arm and fore-arm are 
much shortened, and very massive ; the hand is broad, the 
fingers strong, and distant from each other. 




Fig. 38. Fig. 39. 

In the bat, the thumb, which is represented by a small 
hook, is entirely free, (Fig. 38 ;) but the fingers are elon- 
gated in a disproportionate manner, and the skin is stretched 



ORGANS OF LOCOMOTION. 



85 



across them, so as to serve the purpose of a wing. In birds, 
the pigeon for example, (Fig. 39,) there are but two fingers, 
which are soldered together, and destitute of nails ; and the 
thumb is rudimentary. 

176. The arm of the turtle (Fig. 40) is peculiar in having, 





Fig. 41. 




Fig. 42. 

besides the shoulder-blade, two clavicles ; the arm-bone is 
twisted outwards, as well as the bones of the fore-arm, so 
that the elbow, instead of being behind, is turned forwards ; 
the fingers are long, and widely separated. In the Sloth, 
(Fig. 41,) the bones of the arm and fore-arm are very greatly 
elongated, and at the same time very slender ; the hand is 
likewise very long, and the fingers are terminated by enor- 
mous non-retractile nails. The arm of the Mole (Fig. 42) 
is still more extraordinary. The shoulder-blade, which is 
usually a broad and flat bone, becomes very narrow ; the 
arm-bone, on the contrary, is contracted so much as to seem 
nearly square ; the elbow projects backwards, and the hand 
is excessively large and stout. 

177. In fishes, the form and arrangement of the bones is 
so peculiar, that it is often difficult to trace their correspond- 
ence to all the parts found in other animals ; nevertheless, 
the bones of the fore-arm are readily recognized. In the Cod 
8 



86 ORGANS OF LOCOMOTION. 

(Fig. 43) there are two flat and broad bones, one of which, 
the ulna, (d,) presents a long point, anteriorly. The bones of 




c 






9 c - C_x~ 

Fig. 43. 

the carpus are represented by four nearly square little bones. 
But in these again there are considerable variations in dif- 
ferent fishes, and in some genera they are much more irreg- 
ular in form. The fingers are but imperfectly represented 
by the rays of the fin, (g,) which are composed of an infini- 
tude of minute bones, articulated with each other. As to 
the humerus and shoulder, their analogies are variously in- 
terpreted by different anatomists. 

178. The form of the members is so admirably adapted to 
the special offices which they are designed to perform, that 
by a single inspection of the bones of the arm, as repre- 
sented in the preceding sketches, one might infer the uses to 
which they are to be put. The arm of man, with its 
radius turning upon its ulna, the delicate and pliable fingers, 
and the thumb opposed to them, bespeak an organ for the 
purpose of handling. The slender and long arm of the 
sloth, with his monstrous claws, would be extremely incon- 
venient for walking on the ground, but appropriate for seizing 
upon the branches of the trees, on which these animals live. 
The short fingers, armed with retractile nails, indicate the 
lion, at first glance, to be a carnivorous animal. The arm 
of the stag, with his very long cannon-bone, and that of the 
horse, also, with its solitary finger enveloped in a hoof, are 
organs especially adapted for running. The very slender 
and greatly elongated fingers of the bat are admirably con- 



ORGANS OF LOCOMOTION. 87 

trived for the spread of a wing, without increasing the 
weight of the body. The more firm and solid arm of the 
bird indicates a more sustained flight. The short arm of the 
whale, with his spreading fingers, resembles a strong oar. 
The enormous hand of the mole, with its long elbow, is con- 
structed for the difficult and prolonged efforts requisite in bur- 
rowing. The twisted arm of the tortoise can be applied to no 
other movement than creeping. And finally, the arm of the 
fish, completely enveloped in the mass of the flesh, presents, 
externally, a mere delicate balancer, the pectoral fin. 

179. The posterior members are identical in their structure 
with the anterior ones. The bones of which they are 
composed, are, 1. The pelvis, (Fig. 46,) which corresponds 
to the shoulder blade ; 2. The thigh bone, or femur-) which 
is a single bone, like the humerus ; 3. The bones of the leg, 
the tibia and fibula, which, like the radius and ulna, some- 
times coalesce into one bone ; and lastly, the bones of the 
foot, which are divided, like those of the hand, into three 
parts, the tarsus or ankle, the metatarsus or instep, and the 
toes. The modifications are generally less marked than in 
the arm, inasmuch as there is less diversity of function ; for 
in all animals, without exception, the posterior extremities 
are used exclusively for support or locomotion. 

180. The anterior extremity of the vertebrates, however 
varied in form, whether it be an 

arm, a wing, or a fin, is thus 
shown to be composed of essen- 
tially the same parts, and con- 
structed upon the same general 
plan. This affinity does not ex- 
tend to the invertebrates ; for al- 
though in many instances their Fig. 44. Fig: 45. 
limbs bear a certain resemblance to those of the vertebrates, 
and are even used for similar purposes, yet they have no real 




88 OF STANDING AND PROGRESSION. 

affinity. Thus the leg of an insect, (Fig. 44,) and that 
of a lizard, (Fig. 45 ;) the wing of a butterfly and the 
wing of a bat. are quite similar in form, position, and use; 
but in the bat and the lizard, the organ has an internal bony 
support, which is a part of the skeleton ; while the leg of 
the insect has merely a horny covering, proceeding from one 
of the rings of the body, and the wing of the butterfly is 
merely a fold of the skin, showing that the limbs of the 
Articulata are constructed upon a different plan, (157.) It 
is by ascertaining and regarding these real affinities, or 
the fundamental differences, existing between similar organs, 
that the true natural grouping of animals is to be attained. 

2. Of Standing, and the Modes of Progression. 

181. Standing, or the natural attitude of an animal, de- 
pends on the form and functions of the limbs. Most of the 
terrestrial mammals, and the reptiles, both of which employ 
all four limbs in walking, have the back-bone horizontal, and 
resting at the same time upon both the anterior and poste- 
rior extremities. Birds, whose anterior limbs are intended 
for a purpose very different from the posterior, stand upon 
the latter, when at rest, although the back-bone is still very 
nearly horizontal. Man alone is designed to stand upright, 
with his head supported on the summit of the vertebral col- 
umn. Some monkeys can rise upon the hind legs into the 
erect posture ; but it is evidently a constrained one, and not 
their habitual attitude. 

182. That an animal may stand, it is requisite that the 
limbs should be so disposed that the centre of gravity, in 
other words, the point about which the body balances itself, 
should fall within the space included by the feet. If the 
centre of gravity is outside of these limits, the animal falls 
to the side to which the centre of gravity inclines. On 
this account, the albatross, and some other aquatic birds 



OF STANDING. 89 

which have the feet placed very far back, cannot use them 
for walking;. 

O 

183. The more numerous and the more widely separated 
are the points of support, the firmer an animal stands. On 
this account, quadrupeds are less liable to lose their balance 
than birds. If an animal has four legs, it is not necessary 
that thev should have a broad base. Thus we see that 

/ 

most quadrupeds have slender legs, touching the earth by 
only a small surface. Broad feet would interfere with each 
other, and only increase the weight of the limbs, without 
adding to their stability. Birds are furnished with long toes, 
which, as they spread out, subserve the purpose of tripods. 
Moreover, the muscles of the toes are so disposed that the 
weight of the bird causes them to grasp firmly ; hence it 
is enabled to sleep standing in perfect security upon the roost, 
without effort. 




Fig. 46. 

184. In quadrupeds, the joints at the junction of the limbs 
with the body bend freely in only one direction, that is, to- 
wards the centre of gravity ; so that if one limb yields, the 
tendency to fall is counteracted by the resistance of the 
limbs at the other extremity of the body. The same antag- 
onism is observed in the joints of the separate limbs, which 
are flexed alternately in opposite directions. Thus the thigh 
bends forwards, and the leg backwards ; while the arm bends 

8* 



90 MODES OF PROGRESSION. 

backwards, and the fore-arm forwards. Different terms have 
been employed to express the various modes of progression, 
according to the rapidity or the succession in which the 
limbs are advanced. 

185. PROGRESSION is a forward movement of the body, 
effected by successively bending and extending the limbs. 
WALKING is the ordinary and natural gait, and other paces 
are only occasionally employed. When walking' is accom- 
plished by two limbs only, as in man, the body is inclined 
forwards, carrying the centre of gravity in that direction ; 
and while one leg sustains the body, the other is thrown 
forwards to prevent it from falling, and to sustain it in turn. 
For this reason, walking has been defined to be a continual 
falling forwards, continually interrupted by the projection of 
the legs. 

186. The throwing forwards of the leg, which would 
require a very considerable effort, were the muscles obliged 
to sustain the weight of the limbs also, is facilitated by a very 
peculiar arrangement ; that is, the joints are perfectly closed 
up ; so that the external pressure of the atmosphere is suffi- 
cient of itself to maintain the limbs in place, without the as- 
sistance of the muscles. This may be proved by experi- 
ment. If we cut away all the muscles around the hip joint, the 
thigh bone still adheres firmly to the pelvis, but separates the 
moment a hole is pierced, so as to admit air into the socket. 

187. In ordinary walking, the advancing leg touches the 
ground just before the other is raised ; so that there is a 
moment when the body rests on both limbs. It is only when 
the speed is very much accelerated, that the two actions 
become simultaneous. The walking of quadrupeds is a 
similar process, but with this difference, that the body always 
rests on at least two legs. The limbs are raised in a deter- 
minate order, usually in such a manner that the hind-leg of 
one side succeeds the fore-leg of the opposite side. Some 



MODES OF PROGRESSION. 91 

animals, as the giraffe, the lama, and the bear, raise both 
legs of one side at the same moment. This is called am- 
bling, or pacing. 

188. RUNNING consists in the same succession of motions 
as walking, so accelerated that there is a moment be- 
tween two steps when none of the limbs touch the ground. 
In the horse and dog, and in most mammals, a distinction is 
made between the walk, the trot, the canter, and the gallop, 
all of which have different positions or measures. The trot 
has but two measures. The animal raises a leg on each 
side, in a cross direction, that is to say, the right fore-leg 
with the left hind-leg, and so on. The canter has three 
measures. After advancing the two fore-legs, one after the 
other, the animal raises and brings forward the two hind-legs, 
simultaneously. When this movement is greatly urged, 
there are but two measures; the fore-limbs are raised to- 
gether as well as the hind-legs ; it is then termed a gallop. 

189. LEAPING consists in a bending of all the limbs, fol- 
lowed by a sudden extension of them, which throws the 
body forwards with so much force as to raise it from the 
ground, for an instant, to strike again at a certain distance in 
advance. For this purpose, the animal always crouches 
before leaping. Most animals make only an occasional use 
of this mode of progression, when some obstacle is to be 
surmounted ; but in a few instances, this is the habitual 
mode. As the hind-legs are especially used in leaping, we 
observe that all leaping animals have the posterior members 
very much more robust than the anterior, as the frog, the 
kangaroo, jerboa, and even the hare. Leaping is also com- 
mon among certain birds, especially among the sparrows, 
the thrushes, &c. Finally, there is also a large number of 
leaping insects, such as the flea, the large tribe of grass- 
hoppers and crickets, in which we find that pair of legs 
with which leaping is accomplished much more developed 
than the others. 



92 MODES OF PROGRESSION. 

190. CLIMBING is merely walking upon an inclined or 
even upright surface. It is usually accomplished by means of 
sharp nails ; and hence many carnivorous animals climb 
with great facility, such as the cat tribe, the lizards ; and 
many birds, the woodpecker, for instance. Others employ 
their arms for this purpose, like the bears when they climb 
a tree ; or their hands, and even their tails, like the mon- 
keys ; or their beaks, like the parrots. Lastly, there are some 
whose natural mode of progression is climbing. Such are 
the sloths, with their arms so long, that, when placed upon 
the ground, they move very awkwardly ; and yet their struc- 
ture is by no means defective, for in their accustomed move- 
ments upon trees they can use their limbs with very great 
adroitness. 

191. Most quadrupeds can both walk, trot, gallop, and 
leap ; birds walk and leap ; lizards neither leap nor gallop, 
but only walk and run, and some of them with great rapidity. 
No insect either trots or gallops, but many of them leap. 
Yet their leaping is not always the effect of the muscular 
force of their legs, as with the flea and grasshopper ; but 
some of them leap by means of a spring, in the form of a 
hook, attached to the tail, which they bend beneath the 
body, and which, when let loose, propels them to a great 
distance, as in the Podurella3. Still others leap by means of 
a spring, attached beneath the breast, which strikes against 
the abdomen when the body is bent ; as the spring-beetles, 
(Elaters.) 

192. FLIGHT is accomplished by the simultaneous action 
of the two anterior limbs, the wings, as leaping is by that of 
the two hinder limbs. The wings being expanded, strike 
and compress the air, which thus becomes a support, for the 
moment, upon which the bird is sustained. But as this 
support very soon yields, owing to the slight density of the 
air, it follows that the bird must make the greater and more 



MODES OF PROGRESSION. 93 

rapid efforts to compensate for this disadvantage. Hence it 
requires a much greater expenditure of strength to fly than 
to walk ; and, therefore, we find the great mass of muscles 
in birds concentrated about the breast, (Fig. 30.) To facili- 
tate its progress, the bird, after each flap of the wings, brings 
them against the body, so as to present as little surface as 
possible to the air ; for a still further diminution of resistance, 
all birds have the anterior part of the body very slender. 
Their flight would be much more difficult if they had large 
heads and short necks. 

193. Some quadrupeds, such as the flying-squirrel and 
Galeopithecus, have a fold of the skin at the sides, which 
may be extended by the legs, and which enables them to 
leap from branch to branch with more security. But this 
is not flight, properly speaking, since none of the peculiar 
operations of flight are performed. There are also some 
fishes, whose pectoral fins are so extended as to enable them 
to dart from the water, and sustain themselves for a consider- 
able time in the air ; and hence they are called flying-fish. 
But this is not truly flight. 

194. SWIMMING is the mode of locomotion employed by 
the greater part of the aquatic animals. Most animals which 
live in the water swim with more or less facility. Swimming 
has this in common with flight, that the medium in which it 
is performed, the water, becomes also the support, and read- 
ily yields also to the impulse of the fins. Only, as water is 
much more dense than air, and as the body of most aquatic 
animals is of very nearly the same specific gravity as water, 
it follows that, in swimming, very little effort is requisite to 
keep the body from sinking. The whole power of the mus- 
cles is consequently employed in progression, and hence 
swimming requires vastly less muscular force than flying. 

195. Swimming is accomplished by means of various or- 
gans designated under the general term, fins, although in an 



94 MODES OF PROGRESSION. 

anatomical point of view these may represent very different 
parts. In the Whales, the anterior extremities and the tail 
are transformed into fins. In Fishes, the pectoral fins, which 
represent the arms, and the ventral fins, which represent the 
legs, are employed for swimming, but they are not the prin- 
cipal organs ; for it is by the tail, or caudal fin, that pro- 
gression is principally effected. Hence the progression of 
the fish is precisely that of a boat under the sole guidance 
of the scull ing-oar. In the same manner as a succes- 
sion of strokes alternately right and left propels the boat 
straight forwards, so the fish advances by striking alternately 
right and left. To advance obliquely, it has only to strike 
a little more strongly in the direction opposite to that which 
he wishes to take. The Whales, on the contrary, swim by 
striking the water up and down ; and it is the same with a 
few fishes also, such as the rays and the soles. The air- 
bladder facilitates the rising and sinking of the fish, by ena- 
bling it to vary the specific weight of the body. 

196. Most land animals swim with more or less ease, by 
simply employing the ordinary motions of walking or leaping. 
Those which frequent the water, like the beaver, or which 
feed on marine animals, as the otter and duck, have webbed 
feet ; that, is to say, the fingers are united by a membrane, 
which, when expanded, acts as a paddle. 

197. There is also a large number of invertebrate animals 
in which swimming is the principal or the only mode of 
progression. Lobsters swim by means of their tail, and, like 
the Whales, strike the water up and down. Other Crustacea 
have a pair of legs fashioned like oars ; as the posterior legs 
in sea-crabs, for example. Many insects, likewise, swim 
with their legs, which are abundantly fringed with hairs to 
give them surface ; as the little water boatmen, (Gyrinus, 
Dytiscus,) whose mazy dances on the summer streams every 
one must have observed. The cuttle-fish uses its long ten- 









MODES OF PROGRESSION. 95 

tacles as oars, (Fig. 47 ;) and some star-fishes (Comatula, 
Euryale) use their arms with great adroitness, (Fig. 151.) 
Finally, there are some insects which have their limbs con- 
structed for running on the surface of water, as the water- 
spiders, (Ranatra, Hydrometra.) 




Fig. 47. 

198. A large number of animals have the faculty of mov- 
ing both in the air and on land, as is the case with most birds, 
and a great proportion of insects. Others move with equal 
facility, and by the same members, on land and in water, as 
some of the aquatic birds and most of the reptiles, which latter 
have even received the name Amphibia, on this account. 
There are some which both walk, fly, and swim, as the ducks 
and water-hens ; but they do not excel in either mode of 
progression. 

199. However different the movements and offices per- 
formed by the limbs may appear to us, according to the ele- 
ment in which they act, we see that they are none the less 
the effect of the same mechanism. The contraction of the 
same set of muscles causes the leg of the stag to bend for 
leaping, the wing of the bird to flap in the air, the arm of 
the mole to excavate the earth, and the fin of the whale to 
strike the water. 



CHAPTER SIXTH. 

NUTRITION. 

200. THE second class of the functions of animals are 
those which relate to the maintenance of life and the per- 
petuation of the species ; the functions of vegetative life, (59.) 

201. The increase of the volume of the body must re- 
quire additional materials. There is also an incessant waste 
of particles which, having become unfit for further use, are 
carried out of the system. Every contraction of a muscle 
expands the energy of some particles, whose place must be 
supplied. These supplies are derived from every natural 
source, the animal, vegetable, and even the mineral king- 
doms ; and are received under every variety of solid, liquid, 
and gaseous form. Thus, there is a perpetual interchange 
of substance between the animal body and the world around. 
The conversion of these supplies into a suitable material, its 
distribution to all parts, and the appropriation of it to the 
growth and sustenance of the body, is called NUTRITION in 
the widest sense of that term. 

202. In early life, during the period of growth, the amount 
of substances appropriated is greater than that which is lost. 
At a later period, when growth is completed, an equilibrium 
between the matters received and those rejected is established. 
At a still later period, the equilibrium is again disturbed, 
more is rejected than is retained, decrepitude begins, and at 
last the organism becomes exhausted, the functions cease, and 
death ensues. 

203. The solids and fluids taken into the body as food are 



OF DIGESTION. 



97 



subjected to a process called Digestion, by which the solid 
portions are reduced to a fluid state also, the nutritive sepa- 
rated from the excrementitious, and the whole prepared to 
become blood, bone, muscle, &c. The residue is afterwards 
expelled, together with those particles of the body which 
require to be renewed, and those which have been derived 
from the blood by several processes, termed Secretions. 
Matters in a gaseous form are also received and expelled with 
the air we breathe, by a process called Respiration. The 
nutritive fluids are conveyed to every part of the body by 
currents, usually confined in vessels, and which, as they 
return, bring back the particles which are to be either reno- 
vated or expelled. This circuit is what is termed the Circu- 
lation. The function of Nutrition, therefore, combines sev- 
eral distinct processes. 

SECTION I. 

OF DIGESTION. 

204. Digestion, or the process by which the nutritive parts 
of food are elaborated and pre- 
pared to become part of the body, 

is effected in certain cavities, the 
stomach and intestines, or alimen- 
tary canal. This canal is more or 
less complicated in the various 
classes of animals ; but there is no 
animal, however low its organiza- 
tion, without it, in some form, (54.) 

205. In the polypi, the digestive 
apparatus is limited to a single 
cavity. In the Sea Anemone, (Ac- 
tinia,) for example, it is a pouch, (Fig. 48, 5,) suspended in 

9 




Fig. 48. 




98 



NUTRITION. 




the interior of the body. When the food has been sufficiently 
digested there, it passes, by imbibition, into the general cav- 
ity of the body, (c,) which is filled with water, and mingling 

with it, flows thence into all parts of the an- 
imal. The jelly-fishes, (Medusas,) and 
some Worms, have a distinct stomach, with 
appendages branching off in every direction, 
(Fig. 31,) in which a more complete elabo- 
ration takes place. The little worms known 
by the name of Planaria, present a striking 
example of these ramifications of the intes- 
tine, (Fig. 49, e.) But here, likewise, the 
product of digestion mingles with the fluids 
of the cavity of the body which surround 
the intestine (d) and its branches, and cir- 
culation is not yet distinct from diges- 
Fig. 49. tion. 
206. As we rise in the scale of animals, the functions 
concerned in nutrition become more and more distinct from 
each other. Digestion and circulation, no longer confounded, 
are accomplished separately, in distinct cavities. The most 

important organs concerned in di- 
gestion are the stomach, and the 
small and large intestine. The 
first indications of such a distinc- 
tion are perceived in the higher 
Radiata, such as the sea-urchins, 
(Fig. 50,) in which the stomach (s) 
is broader than either extremity of 
the intestine. The dimensions and 
form of the cavities of the intestine 
vary considerably, according to the mode of life of the ani- 
mal ; but the special functions assigned to them are invaria- 
ble ; and the three principal cavities succeed each other, in 




Fig. 50. 




OF DIGESTION. 



99 




every animal where they are found, in an invariable order ; 
first, the stomach, (s,) then the intestine, which is small at 
first, but often enlarged 
towards its termination. 
This arrangement may 
be seen by the follow- 
ing diagrams from a bee- 
tle and a land mollusk, 
where the same letters 
indicate corresponding 
parts, (Figs. 51, 52.) 

207. From the mouth, 
(m,) the food passes into 
the stomach through a 
narrow tube in the neck, 
called the (Esophagus or 

gullet, (o.) This is not Fig. 51. Fig. 52. 

always a direct passage of uniform size ; but there is some- 
times a pouch, the crop, (c,) into which the food is first intro- 
duced, and which sometimes acquires considerable dimen- 
sions, especially in birds, and in some insects and mollusks, 
(Fig. 51.) In the stomach, the true digestive process is be- 
gun. The food no sooner arrives there than changes com- 
mence, under the influence of a peculiar fluid called the gas- 
tric juice, which is secreted by glands lining the interior of 
the stomach. The digestive action is sometimes aided by the 
movements of the stomach itself, which, by its strong contrac- 
tions, triturates the food. This is especially the case in the 
gizzard of some birds, which, in the hens and ducks, for in- 
stance, is a powerful muscular organ. In some of the Crus- 
tacea and Mollusks, as the Lobster and Aplysia, there are 
even solid organs for breaking down the food within the 
stomach itself. 

208. The result of this process is the reduction of the food 



100 NUTRITION. 

to a pulpy fluid, called chyme, which varies in its nature with 
the food. Hence the function of .the stomach has been 
named chymification. With this, the function of digestion is 
complete in many of the lower animals, and chyme is circu- 
lated throughout the body ; this is the case in Polypi and Jelly- 
fishes, and some Worms and Mollusks. In other animals, 
however, the chyme thus formed is transferred to the intes- 
tine, by a peculiar movement, like that of a worm in creep- 
ing, which has accordingly received the name of vermicular 
or peristaltic motion. 

209. The form of the small intestine (i) is less variable 
than that of the stomach. It is a narrow tube, with thin walls, 
coiled in various directions in the vertebrate animals, but 
more simple in the invertebrates, especially the insects. Its 
length varies, according to the nature of the food, being in 
general longer in herbivorous than in carnivorous animals. 
In this portion of the canal, the aliment undergoes its com- 
plete elaboration, through the agency of certain juices which 
here mingle with the chyme, such as the bile secreted by the 
liver, and the pancreatic juice, secreted by the pancreas. 
The result of this elaboration is to produce a complete sepa- 
ration of the truly nutritious parts, in the form of a milky 
liquid called chyle. The process is called chylification ; and 
there are great numbers of animals, such as the Insects, 
Crabs, and Loosters, some Worms, and most of the Mollusks, 
in which the product of digestion is not further modified by 
respiration, but circulates throughout the body as chyle. 

210. The chyle is composed of minute, colorless globules, 

of a somewhat flattened form, (Fig. 53.) In 
the higher animals, the Vertebrates, it is taken 
up and carried into the blood by means of very 
minute vessels, called lymphatic vessels or 
lacteah, which are distributed every where in 
the walls of the intestine, and communicate 








OF DIGESTION. 101 

with the veins, forming also in their course several glandular 

masses, as seen in a portion of intestine connected with a vein, 

in Fig. 54 ; and it is not until thus 

taken up, and mingled with the 

circulating blood, that any of our 

food really becomes a part of the 

living body. Thus freed of the 

nutritive portion of the food, the 

residue of the product of digestion 

passes on to the large intestine, 

from whence it is expelled in the 

form of excrement. Fl S- 54> 

211. The organs above described constitute the most es- 
sential for the process of digestion, and are found more or less 
developed in all but some of the radiated animals ; but there 
are, in the higher animals, several additional ones for aiding 
in the reduction of the food to chyme and chyle, which render 
their digestive apparatus quite complicated. In the first place, 
hard parts, of a horny or bony texture, are usually placed about 
the moutii of those animals that feed on solid substances, which 
serve for cutting or bruising the food into small fragments 
before it is swallowed ; and, in many of the lower animals, 
these organs are the only hard portions of the body. This 
process of subdividing or chewing the food is termed jnasti- 
cation. 

212. Beginning with the Radiata, we find the apparatus 
for mastication partaking of the star-like arrangment which 
characterizes those animals. Thus in Scutella, (Fig. 55,) 
we have a pentagon composed of five triangular jaws, con- 
verging at their summits towards a central aperture which 
corresponds to the mouth, each one bearing a cutting plate or 
tooth, like a knife-blade, fitted by one edge into a cleft. The 
five jaws move towards the centre, and pierce or cut the ob- 
jects which come between them. In some of the sea-urchins, 

9* 






102 NUTRITION. 

(Echinus,) this apparatus, which has been called Aristotle's 





Fig. 55. Fig. 56. 

lantern, (Fig. 56,) consists of numerous pieces, and is much 
more complicated. Still, the five fundamental pieces or jaws, 
each of them bearing a tooth at its point, may be recognized, 
as in Scutella; only instead of being placed horizontally, 
they form an inverted pyramid. 

213. Among the Mollusks, a few, like the cuttle-fishes, 
have solid jaws or beaks closely resembling 

the beak of a parrot, (Fig. 

57,) which move up and 

down as in birds. But a 

much larger number rasp 

their food bv means of a flat 

tf 

Fig. 57. blade coiled up like a watch- Fig. 58. 

spring, the surface of which is covered with innumerable 
minute tooth-like points of a horny consistence, as seen in a 
highly magnified portion of the so-called tongue of Natica, 
(Fig. 58, a,) which, however, is only a modification of the 
beaks of cuttle-fishes. 

214. The Articulata are remarkable, as 
a class, for the diversity and complication 
of their apparatus for taking and dividing 
their food. In some marine worms, Nereis, 
for example, the jaws consist of a pair of 
Fig. 59. curved, horny instruments, lodged in a 

sheath, (Fig. 59.) In spiders, these jaws are external, and 









OF DIGESTION. 



103 



sometimes mounted on long, jointed stems. Insects which 
masticate their food have, for the most part, at least two pairs 
of horny jaws, (Figs. 60, 61, m,j,) besides several additional 
pieces which serve for seizing and holding their food. 
Those which live on the fluids which they extract either from 
plants or from other animals, have the masticatory organs 
transformed into a trunk or tube for that purpose. This 
trunk is sometimes rolled up in a spiral manner, as in the 
butterfly, (Fig. 64;) or it is stiff, and folded beneath the 






V 




Fig. 61. 



Fig. 62. Fig. 63. Fig. 64. 

chest, as in the squash-bugs, (Fig. 62,) containing several 
piercers of extreme delicacy, (Fig. 63,) adapted to penetrate 
the skin of animals or other objects whose juices they extract ; 
or they are prolonged so as to shield the tongue when thrust 
out in search of food, as in the bees, (Fig. 61, t.) The crabs 
have their anterior feet transformed into a kind of jaws, and 
several other pairs of articulated appendages performing ex- 





o' 



65. 



Fig. 66. 



clusively masticatory functions. Even in the microscopic 
Rotifers, we find very complicated jaws, as seen in a Brachi- 
onus, (Fig. 65,) and still more magnified in Fig. 66. But 



104 



NUTKITION. 




amidst this diversity of apparatus, there is one thing which 
characterizes all the Articulata, namely, the jaws always 
move sideways ; while those of the Vertebrates and Mollusks 
move up and down, and those of the Radiata concentrically. 

215. In the Vertebrates, the jaws form a part of the bony 

skeleton. In most of them the 
lower jaw only is movable, and 
is brought up against the upper 
jaw by means of very strong mus- 
cles, the temporal and masseter 
Fig. 67. muscles, (Fig. 67, t, i,) which 

perform the principal motions requisite for seizing and mas- 
ticating food. 

216. The jaws are usually armed with solid cutting 

instruments, the TEETH, or else are 
enveloped in a horny covering, the 
beak, as in the birds and tortoises, 
(Fig. 68.) In some of the whales, 
the true teeth remain concealed in the 
Fig. 68. jaw-bone, and we have instead a range 

of long, flexible, horny plates or fans, fringed at the margin, 
which serve as strainers to separate the minute marine ani- 
mals on which they feed 
from the water drawn in 
with them, (Fig. 69.) 
A few are entirely des- 
titute of teeth, as the 
ant-eater, (Fig. 70.) 

217. Though all the 
vertebrates possess jaws, 
Fig. 69. it must not be inferred 

that they all chew their food. Many swallow their prey 
whole ; as most birds, tortoises, and whales. Even many of 
those which are furnished with teeth do not masticate their , 





OF DIGESTION. 



105 



food ; some using them merely for seizing and securing their 
prey, as the lizards, frogs, crocodiles, and the great majority 
of fishes. In such animals, the teeth are nearly all alike in 
form and structure, as for instance, in the alligator, (Fig. 71,) 
the porpoises, and many fishes. A few of the latter, some of 




Fig. 70. 





Fig. 71. Fig. 72. 

the Rays, for example, have a sort of bony pavement, (Fig. 
72,) composed of a peculiar kind of teeth, with which they 
crush the shells of the mollusks and crabs on which they 
feed. 

218. The Mammals, however, are almost the only verte- 
brates which can properly be said to masticate their food. 
Their teeth are well 
developed, and pre- 
sent great diversity 
in form, arrangement 
and mode of inser- 
tion. Three kinds 
of teeth are usually 
distinguished in most 
of these animals, 
whatever may be Fig. 73. 

their mode of life ; namely, the cutting teeth, incisors ; the 




106 NUTRITION. 

tusks or carnivorous teeth, canines ; and the grinders, molars, 
(Fig. 73.) The incisors (a) occupy the front of the mouth, 
the upper ones being set in the intermaxillary bones ; they 
are the most simple and the least varied, have generally 
a thin cutting summit, and are employed almost exclusively 
for seizing food, except in the elephant, in which they assume 
the form of large tusks. The canines (b) are conical, more 
elongated than the others, more or less curved, and only two 
in each jaw. They have but a single root, like the incisors, 
and in the carnivora become very formidable weapons. In 
the herbivora, they are wanting, or when existing they are 
usually so enlarged and modified as also to become powerful 
organs of offence and defence, although useless for mastica- 
tion ; as in the babyroussa, &c. The molars (c) are the most 
important for indicating the habits and internal structure of 
the animal ; they are, at the same time, most varied in 
shape. Among them we find every transition, from those of 
a sharp and pointed form, as in the cat tribe, to those with 
broad and level summits, as in the ruminants and rodents. 
Still, when most diversified in the same animal, they have 
one character in common, their roots being never simple, 
but double or triple, a peculiarity which not only fixes them 
more firmly, but prevents them from being driven into the 
jaw in the efforts of mastication. 

219. The harmony of organs already spoken of (22-24) 
is illustrated, in a most striking manner, by the study of the 
teeth of the mammals, and especially of their molar teeth. 
So constantly do they correspond with the structure of the 
other parts of the body, that a single molar is sufficient not 
only to indicate the mode of life of the animal to which it 
belongs, and show whether it feeds on flesh or vegetables, or 
both, but also to determine the particular group to which it is 
related. Thus, those beasts of prey which feed on insects, 
and which on that account have been called Insectivora, such 



OF DIGESTION. 



107 



as the moles and bats, have the molars terminated by several 




Fig. 74. 





Fig. 76- Fig. 75. 

sharp, conical points, (Fig. 74,) so arranged that the eleva- 
tions of one tooth fit exactly into the depressions of the tooth 
opposite to it. In the true Carnivora, (Fig. 75,) on the con- 
trary, the molars are compressed laterally, so as to have 
sharp, cutting edges, as in the bats ; and they shut by the 
side of each other, like the blades of scissors, thereby di- 
viding the food with great facility. 

220. The same adaptation is observed in the teeth of her- 
bivorous animals. Those which chew the cud, (ruminants,) 
many of the thick-skinned animals, (pachydermata,) like the 
elephant, and some of the gnawers, (rodentia,) like the hare, 
(Fig. 76,) have the summits of the molars flat, like mill-stones, 
with more or less prominent ridges, for grinding the grass 
and leaves on which they subsist. Finally, the omnivora, 
those which feed on both flesh and fruit, like man and the 
monkeys, have the molars terminating in several rounded 
tubercles, being thus adapted to the mixed nature of their 
food. 

221. Again, the mode in which the molars are combined 
with the canines and incisors furnishes excellent means of 
characterizing families and genera. Even the internal struc- 
ture of the teeth is so peculiar in each group of animals, and 
yet subject to such invariable rules, that it is possible to 
determine with precision the general structure of an animal, 



108 NUTRITION. 

merely by investigating the fragment of a tooth under a mi- 
croscope. 

222. Another process, subsidiary to digestion, is called 
insalivation. Animals which masticate their food have 
glands, in the neighborhood of the mouth, which secrete a 
fluid called saliva. This fluid mingles with the food as it is 
chewed, and prepares it also to be more readily swallowed. 
The salivary glands are generally wanting, or rudimentary, 

r otherwise modified, in animals which swallow their food 
without mastication. After it has been masticated and min- 
gled with saliva, it is moved backwards by the tongue, and 
passes down through the oesophagus, into the stomach. This 
act is called deglutition or swallowing. 

223. The wisdom and skill of the Creator is strikingly 
illustrated in the means he has afforded to every creature for 
securing the means for subsistence. Some animals have 
no ability to move from place to place, but are fixed to the 
soil ; as the oyster, the polyp, &c. These are dependent for 
subsistence upon such food as may stray or float near, and 
they have the means of securing it when it comes within 
their reach. The oyster closes its shell, and thus entraps its 
prey ; the polyp has flexible arms, (Fig. 77,) capable of 

great extension, which it throws instantly 
around any minute animal that comes in con- 
tact with it. The cuttle-fish, also, has elongated 
arms about the mouth, furnished with ranges 
of suckers, by which it secures its prey, 
(Fig. 47.) 

224. Some are provided with instruments 
Fig. 77. f or extracting food from places which would 
be otherwise inaccessible. Some of the mollusks, with their 
rasp-like tongue, (Fig. 58,) perforate the shells of other ani- 
mals, and thus reach and extract the inhabitant. Insects 
have various piercers, suckers, or a protractile tongue for the 




OF DIGESTION. 109 

same purpose, (Figs. 61-64.) Many Annelides, the leeches 
for example, have a sucker, which enables them to produce 
a vacuum, and thereby draw out blood from the perforations 
they make in other animals. Many microscopic animals are 
provided with hairs or cilia around the mouth, (Fig. 65,) 
which by their incessant motion produce currents that bring 
within reach the still more minute creatures or particles on 
which they feed. 

225. Among the Vertebrata, the herbivora generally em- 
ploy their lips or their tongue, or both together, for seizing 
the grass or leaves they feed upon. The carnivora use their 
jaws, teeth, and especially their claws, which are long, sharp, 
even movable, and admirably adapted for the purpose. The 
woodpeckers have long, bony tongues, barbed at the tip, 
with which they draw out insects from deep holes and crevi- 
ces in the befrk of trees. Some reptiles also use their tongue 
to take their prey. Thus, the chameleon obtains flies at a 
distance of three or four inches, by darting out his tongue, 
the enlarged end of which is covered with a glutinous sub- 
stance to which they adhere. The elephant, whose tusks 
and short neck prevent him from bringing his mouth to the 
ground, has the nose prolonged into a trunk, which he uses 
with great dexterity for bringing food and drink to his mouth. 
Doubtless the mastodon, once so abundant in this country, 
was furnished with a similar organ. Man and the monkeys 
employ the hand exclusively, for prehension. 

226. Some animals drink by suction, like the ox, others 
by lapping, like the dog. Birds simply fill the beak with 
water, then, raising the head, allow it to run down into the 
crop. It is difficult to say how far aquatic animals re- 
quire water with their food ; it seems, however, impossible 
that they should swallow their prey without introducing at 
the same time some water into their stomach. Of many 
among the lowest animals, such as the Polyps, it is well 

10 



110 OF DIGESTION. 

known that they frequently fill the whole cavity of their body 
with water, through the mouth, the tentacles, and pores 
upon the sides, and empty it at intervals through the same 
openings. And thus the aquatic mollusks introduce water 
into special cavities of the body, or between their tissues, 
through various openings, while others pump it into their 
blood vessels, through pores at the surface of their body. 
This is the case with most fishes. 

226 a. Besides the more conspicuous organs above de- 
scribed, there are among the lower animals various micro- 
scopic apparatus for securing their prey. The lassos of polypi 
have been already mentioned incidentally, (223.) They are 
minute cells, each containing a thin thread coiled up in its 
cavity, which may be thrown out by inversion, and extend to 
a considerable length beyond the sac to which it is at- 
tached. Such lassos are grouped in clusters upon the ten- 
tacles, or scattered upon the sides of the Actinia and of 
most polypi. They occur also in similar clusters upon the 
tentacles and the disk of jelly-fishes. The nettling sensa- 
tion produced by the contact of many of these animals is 
undoubtedly owing to the lasso cells. Upon most of the 
smaller animals, they act as a sudden, deadly poison. In 
Echinoderms, such as star-fishes, and sea-urchins, we find 
other microscopic organs in the form of clasps, placed upon 
a movable stalk. The clasps, which may open and shut al- 
ternately, are composed of serrated or hooked branches, 
generally three in number, closing concentrically upon each 
other. With these weapons, star-fishes not more than two 
inches in diameter may seize and retain shrimps of half 
that length, notwithstanding their efforts to disentangle them- 
selves. 



CHAPTER SEVENTH. 



OF THE BLOOD AND CIRCULATION. 



227. THE nutritive portions of the food are poured into 
the general mass of fluid which pervades every part of the 
body, out of which every tissue is originally constructed, 
and from time to time renewed. This fluid, in the general 
acceptation of the term, is called blood ; but it differs greatly 
in its essential constitution in the different groups of the 
Animal Kingdom. In polypi and medusse, it is merely 
chyme, (208 ;) in most mollusks and articulates it is chyle, 
(209 ;) but in vertebrates it is more highly organized, and 
constitutes what is properly called BLOOD. 

228. The BLOOD, when examined by the microscope, is 
found to consist of a transparent fluid, the serum, consisting 
chiefly of albumen, fibrin, and water, in which float many 
rounded, somewhat compressed bodies, called blood disks. 




Fig. 78. 



These vary in number with the natural heat of the animal 
from which the blood is taken. Thus, they are more nu- 



112 OF THE BLOOD 

merous in birds than in mammals, and more abundant in the 
latter than in fishes. In man and other mammals they are 
very small and nearly circular, (Fig. 78 ;) they are some- 
what larger, and of an oval form, in birds and fishes, (Figs. 
79, 81 ;) and still larger in reptiles, (Fig. 80.) 

229. The color of the blood in the vertebrates is bright 
red ; but in some invertebrates, as the crabs and mollusks, 
the nutritive fluid is nearly or quite colorless ; while in the 
worms and some echinoderms, it is variously colored yellow, 
orange, red, violet, lilac, and even green. 

230. The presence of this fluid in every part of the body 
is one of the essential conditions of animal life. A per- 
petual current flows from the digestive organs towards the 
remotest parts of the surface ; and such portions as are not 
required for nutriment and secretions return to the centre of 
circulation, mingled with fluids which need to be assimilated 
to the blood, and with particles of the body which are to be 
expelled, or, before returning to the heart, are distributed in 
the liver. The blood is kept in an incessant CIRCULATION 
for this purpose. 

231. In the lowest animals, such as the polypi, the nutri- 
tive fluid is simply the product of digestion (chyme) mingled 
with water in the common cavity of the viscera, with which 
it comes in immediate contact, as well as with the whole 
interior of the body. In the jelly-fishes, which occupy a 
somewhat higher rank, a similar liquid is distributed by pro- 
longations of the principal cavity to different parts of the 
body, (Fig. 31.) Currents are produced in these, partly by 
the general movements of the animal, and partly by means 
of the incessant vibrations of microscopic fringes, called 
vibratile cilia, which overspread the interior. In most of 
the mollusks and articulates, the blood (chyle) is also in 
immediate contact with the viscera, water being mixed with 
it in mollusks ; the vessels, if there are any, not forming a 



AND CIRCULATION. 



113 



complete circuit, but emptying into various cavities which 
interrupt their course. 

232. In animals of still higher organization, as the verte- 
brates, we find the vital fluid enclosed in an appropriate set 
of vessels, by which it is successively conveyed throughout 
the system to supply nutriment and secretions, and to the 
respiratory organs, where it absorbs oxygen, or, in other 
words, becomes oxygenated. 

233. The vessels in which the blood circulates are of two 
kinds : 1. The arteries, of a firm, elastic structure, which 
may be distended or contracted, according to the volume of 
their contents, and which convey the blood from the centre 
towards the surface, distributing it to every point of the 
body. 2. The veins, of a thin, membranous 
structure, furnished within with valves, (Fig. 

82, v,) which aid in sustaining the column of 
blood, only allowing it to flow from the peri- 
phery towards the centre. The arteries con- 
stantly subdivide into smaller and smaller 
branches ; while the veins commence in minute 
twigs, and are gathered into branches and larger 
trunks, to unite finally into a few stems, near the J 

Ig. 

centre of circulation. 

234. The extremities of the arteries and veins are con- 
nected by a net-work of extremely 

delicate vessels, called capillary ves- 
sels, (Fig. 83.) They pervade eveiy 
portion of the body, so that almost 
no point can be pricked without 
drawing blood. Their office is to 

o 

distribute the nutritive fluid to the 
organic cells, where all the important processes of nutrition 
are performed, such as the alimentation and growth of all 
organs and tissues, the elaboration of bile, milk, saliva, and 

10* 










Fig. 83. 




114 OF THE BLOOD 

other important products derived from blood, the removal of 
effete particles and the substitution of new ones, and all 
those changes by which the bright blood of the arteries be- 
comes the dark blood of the veins ; and again, in the cells 
of the respiratory organs which the capillaries supply, the 
dark venous blood is oxygenated and restored to the bright 
scarlet hue of the arterial blood. 

235. Where there are blood-vessels in the lowest animals, 

the blood is kept in motion by 
the occasional contraction of 
some of the principal vessels, 
as in the worms. Insects have 
a large vessel running along 
the back, furnished with valves, 
-p. CT 8 , so arranged that, when the ves- 

sel contracts, the blood can 

flow only towards the head, and, being thence distributed to 
the body, is returned again into the dorsal vessel, (Fig. 84,) 
by fissures at its sides. 

236. In all the higher animals there is a central organ, 
the hearty which forces the blood through the arteries to- 
wards the periphery, and receives it again on its return. 
The HEART is a hollow, muscular organ, of a conical form, 
which dilates and contracts at regular intervals, independ- 
ently of the will. It is either a single cavity, or is divided 
by walls into two, three, or four compartments, as seen in 
the following diagrams. These modifications are important 
in their connection with the respiratory organs, and indicate 
the higher or lower rank of an animal, as determined by the 
quality of the blood distributed in those organs. 

237. In the mammals and birds the heart is divided by a 
vertical partition into two cavities, each of which is again 
divided into two compartments, one above the other, as seen 
in the diagram, (Fig. 85.) The two upper cavities are called 



AND CIRCULATION. 



115 



auricles, and the two lower ventricles. Reptiles have two 




Fig. 85. 



Fig. 86. 



Fig. 87. 



auricles and one ventricle, (Fig. 86.) Fishes have one auri- 
cle and one ventricle only, (Fig. 87.) 

238. The auricles do not communicate with each other, 
in adult animals, nor do the ventricles. The former receive 
the blood from the body and the respiratory organs, through 
veins, and each auricle sends it into the ventricle beneath, 
through an opening guarded by a valve, to prevent its reflux ; 
while the ventricles, by their contractions, force the blood 
through arteries into the lungs, and through the body gen- 
erally. 

239. The two auricles dilate at the same instant, and also 
contract simultaneously ; so also do the ventricles. These 
successive contractions and dilatations constitute the pulsa- 
tions of the heart. The contraction is called systole, and the 
dilatation is called diastole. Each pulsation consists of two 
movements, the diastole or dilatation of the ventricles, 
during which the auricles contract, and the systole or con- 
traction of the ventricles, while the auricles dilate. The 
frequency of the pulse varies in different animals, and even 
in the same animal, according to its age, sex, and the degree 
of health. In adult man, they are commonly about seventy 
beats per minute. 

240. The course of the blood in those animals which have 
four cavities to the heart is as follows, beginning with the 
left ventricle, (Fig. 85, I. v.) By the contraction of this 



116 OF THE BLOOD 

ventricle, the blood is driven through the main arterial trunk, 
called the aorta, (Fig. 90, a,) and is distributed by its 
branches throughout the body ; it is then collected by the 
veins, carried back to the heart, and poured into the right 
auricle, (Fig. 85, r a,) which sends it into the right ventricle 
rv.) The right ventricle propels it through another set of 
arteries, the pulmonary arteries, (Fig. 90, >,) to the lungs, 
(/ ; ) it is there collected by the pulmonary veins, and con- 
veyed to the left auricle, (Fig. 85, I a,) by which it is returned 
to the left ventricle, thus completing the circuit. 

241. Hence the blood in performing its whole circuit 
passes twice through the heart. The first part of this cir- 
cuit, the passage of the blood through the body, is called 
the great circulation ; and the second part, the passage of 
the blood through the lungs, is the lesser or pulmonary cir- 
culation : this double circuit is said to be a complete circu- 
lation. In this case the heart may be justly regarded as 
two hearts conjoined, and in fact the whole of the lesser cir- 
culation intervenes in the passage of the blood from one side 
of the heart to the other ; except that during the embryonic 
period there is an opening between the two auricles, which 
closes as soon as respiration commences. 

242. In reptiles, (Fig. 86,) the venous blood from the 
body is received into one auricle, and the oxygenated blood 
from the lungs into the other. These throw their contents 
into the single ventricle below, which propels the mixture in 
part to the body, and in part to the lungs ; but as only the 
smaller portion of the whole quantity is sent to the luno-s in 
a single circuit, the circulation is said to be incomplete. In 
the Crocodiles, the ventricle has a partition which keeps sep- 
arate the two kinds of blood received from the auricles ; but 
the mixture soon takes place by means of a special artery, 
which passes from the pulmonary artery to the aorta. 

243. In fishes, (Fig. 87,) the blood is carried directly 



AND CIRCULATION. 117 

from the ventricle to the gills, which are their chief respir- 
atory organs ; thence it passes into arteries for distribution 
to the system in general, and returns by the veins to the 
auricle. Here the blood, in its circuit, passes but once 
through the heart ; but the heart of a fish corresponds nev- 
ertheless to the heart of a mammal, and not to one half of 
it, as has often been maintained, for the gills are not lungs. 

244. Crabs and other Crustacea have but a single ventri- 
cle, without an auricle. 
In the mollusks, there is 
likewise but a sinsjle ven- 

O 

tricle, as in Natica, (Fig. 
88, 7i.) Some have in 
addition one or two auri- 
cles. These auricles are 
sometimes so disioined 

I 

as to form so many isolated hearts, as in the cuttle-fish. 
Among Radiata, the sea-urchins are provided with a tubular 
heart. 




CHAPTER EIGHTH. 



OF RESPIRATION. 



245. FOR the maintenance of its vital properties, the blood 
must be submitted to the influence of the air. This is true 
of all animals, whether they live in the atmosphere or in the 
water. No animal can survive for any considerable period 
of time without air ; and the higher animals almost instantly 
die when deprived of it. It is the office of RESPIRATION to 
bring the blood into communication with the air. 

246. Among animals which breathe in the open air, 

some have a series of tubes branching 
through the interior of the body, called 
trachea, (Fig. 89, ^,) opening externally 
upon the sides of the body, by small aper- 
tures, called stigmata, (s ; ) as in insects 
and in some spiders. But the most com- 
mon mode of respiration is by means of 
LUNGS, a pair of peculiar spongy or cel- 
lular organs, in the form of large pouches, 
which are the more complicated in pro- 
portion to the quantity of air to be con- 
sumed. 

247. In the lower vertebrata, provided with lungs, they 
form a single organ ; but in the higher classes they are in pairs, 
placed in the cavity formed by the ribs, one on each side of 




Fig. 89. 



OF RESPIRATION. 



119 




Fig. 90. 



the vertebral column, and enclosing the heart (h) between 
them, (Fig. 90, Z Z.) The lungs communicate with the atmos- 
phere by means of a tube composed of cartilaginous rings 
which arises from the back part of the mouth, and divides 
below, first into a branch for each organ, and then into in- 
numerable branches penetrating their 
whole mass, and finally terminating in 
minute sacs. This tube is the trachea 
or windpipe, (w?,) and its branches are 
the bronchi. In the higher air-breath- 
ing animals the lungs and heart occupy 
an apartment by themselves, the chest, 
which is separated from the other con- 
tents of the lower arch of the vertebral 
column, (161,) by a fleshy partition, 
called the diaphragm, passing across 
the cavity of the body, and arching up into the chest. The 
only access to this apartment from without is by the glottis, 
(Fig. 22, 0,) through the trachea. 

248. The mechanism of respiration by lungs may be com- 
pared to the action of a bellows. The cavity of the chest is 
enlarged by raising the ribs, the arches of which naturally 
slope somewhat downward, but more especially by the con- 
traction of the diaphragm, whereby its intrusion into the 
chest is diminished. This enlargment causes the air to rush 
in through the trachea, distending the lung so as to fill the 
additional space. When the diaphragm is again relaxed, 
and the ribs are allowed to subside, the cavity is again dimin- 
ished, and the air expelled. These movements are termed 
inspiration or inhalation, and expiration. The spongy pul- 
monary substance being thus distended by air, the blood sent 
from the heart is brought into such contact with it as to allow 
the requisite interchange to take place, (235.) 

249. The respiration of animals breathing in water is ac- 



120 



OF RESPIRATION. 





complished by a different apparatus. The air is to be 
9 derived from the water, in which 

more or less is always diffused. 
The organs for this purpose are 
Fig. 91. called branchice or gills, and are 

either delicate tufts or plumes floating outside of the body, 

as in some of the marine worms, 
(Fig. 33,) and many mollusks, (Fig. 
91, g ;) or they consist of deli- 
cate combs and brushes, as in fishes, 
(Fig. 92,) crabs, and most mollusks, 
(Fig. 88, g.) These gills are al- 
Fig. 92. ways so situated that the water has 

free access to them. In the lower aquatic animals, such as 
the polypi, and some jelly-fishes and mollusks, respiration 
takes place by the incessant motions of vibratory cilia, which 
fringe both the outside and the cavities of the body ; the cur- 
rents they produce bringing constantly fresh supplies of water, 
containing air, into contact with the respiratory surface. 

250. Many animals living in water, however, rise to the 
surface and breathe the atmosphere there, or are furnished 
with the means of carrying away a temporary supply of air, 
whilst others are furnished with reservoirs in which the blood 
requiring oxygenation may be accumulated, and their stay 
under water prolonged. This is the case with the seals, 
whales, tortoises, frogs, many insects and mollusks, &c. 

251. The vivifying power of the air upon the blood is due 
to its oxygen. If an animal be confined for a time in a 
closed vessel, and the contained air be afterwards examined, 
a considerable portion of its oxygen will have disappeared, 
and another gas of a very different character, namely, car- 
bonic acid gas, will have taken its place. The essential 
office of respiration is to supply oxygen to the blood, at the 
same time that carbon is removed from' it. 



OF RESPIRATION. 121 

252. An immediately obvious effect of respiration in the 
red-blooded animals is a change of color ; the blood, in 
passing through the respiratory organs, being changed from 
a very dark purple to a bright scarlet. In the great circula- 
tion (241) the scarlet blood occupies the arteries, and is usu- 
ally called red blood, in contradistinction from the venous 
blood, which is called Hack blood. In the lesser circulation, 
on the contrary, the arteries carry the dark, and the veins 
the red blood. 

253. The quantity of oxygen consumed by various ani- 
mals in a given time has been accurately ascertained by ex- 
periment. It has been found, for instance, that a common- 
sized man consumes, on an average, about 150 cubic feet in 
twenty-four hours ; and as the oxygen constitutes but 21 per 
cent, of the atmosphere, it follows that he inhales, during a 
day, about 700 cubic feet of atmospheric air. In birds, the 
respiration is still more active, while in reptiles and fishes it 
is much more sluggish. 

254. The energy and activity of an animal is, therefore, 
somewhat dependent on the activity of its respiration. Thus 
the toad, whose movements are very sluggish, respires much 
more slowly than the mammals, birds, and even insects ; and 
it has been ascertained that a butterfly, notwithstanding its 
comparatively diminutive size, consumes more oxygen than 
a toad. 

255. The circulation and respiration have a reciprocal in- 
fluence upon each other. If the heart be powerful, or if 
on violent exercise a more rapid supply of blood to repair 
the consequent waste is demanded, (201,) respiration must be 
proportionally accelerated to supply air to the greater amount 
of blood sent to the lungs. Hence the panting occasioned by 
running or other unusual efforts of the muscles. On the 
other hand, if respiration be hurried, the blood is rendered 
more stimulating by greater oxygenation, and causes an ac- 

11 



122 OF RESPIRATION. 

celeration of the circulation. The quantity of air consumed 
varies, therefore, with the proportion of the blood which is 
sent to the lungs. 

256. The proper temperature of an animal, or what is 
termed ANIMAL HEAT, depends on the combined activity of 
the respiratory and circulating systems, and is in direct pro- 
portion to it. In many animals the heat is maintained at a 
uniform temperature, whatever may be the variations of the 
surrounding medium. Thus, birds maintain a temperature 
of about 108 Fahrenheit ; and in a large proportion of mam- 
mals it is generally from 95 to 105. These bear the 
general designation of warm-blooded animals. 

257. Reptiles, fishes, and most of the still lower animals, 
have not this power of maintaining a uniform temperature. 
The heat of their body is always as low as from 35 to 50, 
but varies perceptibly with the surrounding medium, being 
often, however, a little above it when the external tempera- 
ture is very low, though some may be frozen without the loss 
of life. For this reason, they are denominated cold-blooded 
animals ; and all animals which have such a structure of 
the heart that only a part of the blood which enters it is sent 
to the respiratory organs, are among them, (243.) 

258. The production of animal heat is obviously connected 
with the respiratory process. The oxygen of the respired 
air is diminished, and carbonic acid takes its place. The 
carbonic acid is formed in the body by the combination of 
the oxygen of the air with the carbon of the blood. The 
chemical combination attending this function is, therefore, 
essentially the same as that of combustion. It is thus easy 
to understand how the natural heat of an animal is greater, 
in proportion as respiration is more active. Flow far nutri- 
tion in general, and more particularly assimilation, by which 
the liquid parts are fixed and solidified, is connected with the 
maintenance of the proper temperature of animals, and the 



OF RESPIRATION. 123 

uniform distribution of heat through the body, has not yet 
been satisfactorily ascertained. 

259. Some of the higher warm-blooded animals do not 
maintain their elevated temperature during the whole year ; 
but pass the winter in a sort of lethargy called HIBERNATION, 
or the hibernating sleep. The marmot, the bear, the bat, 
the crocodile, and most reptiles, furnish examples. During 
this state the animal takes no food ; and as it respires only 
after very prolonged intervals, its heat is diminished, and its 
vital functions generally are much reduced. The structural 
cause of hibernation is not ascertained ; but the phenomena 
attending it fully illustrate the laws already stated, (254-8.) 

260. There is another point of view in which respiration 
should be considered, namely, with reference to the buoy- 
ancy of animals, or their power of rising in the atmosphere, 
and their ability to live at different depths in the water, under 
a diminished or increased pressure. The organs of res- 
piration of birds and insects are remarkably adapted for the 
purpose of admitting at will a greater quantity of air into 
their body, the birds being provided with large pouches ex- 
tending from the lungs into the abdominal cavity and into 
the bones of the wing. In insects the whole body is pene- 
trated by air tubes, the ramifications of their tracheae, which 
are enlarged at intervals into wider cells ; whilst most of the 
aquatic animals are provided with minute, almost micro- 
scopic tubes, penetrating from the surface into the substance, 
or the cavities of the body, admitting water into the interior, 
by which they thus adapt their whole system to pressures 
which would otherwise crush them. These tubes may with 
propriety be called water-tubes. In fishes, they penetrate 
through the bones of the head and shoulder, through skin 
and scales, and communicate with the blood vessels and 
heart, into which they pour water ; in mollusks they are 
more numerous in the fleshy parts, as, for example, in the 



124 OF RESPIRATION. 

foot, which they help to distend, and communicate with the 
main cavity of the body, supplying it also with liquid ; in 
echinoderms they pass through the skin, and even through 



260 a. In order fully to appreciate the homologies between the 
various respiratory apparatus observed in different animals, it is ne- 
cessary to resort to a strict comparison of the fundamental connec- 
tions of these organs with the whole system of organization, rather 
than to the consideration of their special adaptation to the elements 
in which they live. In Vertebrates, for instance, there are two sets 
of distinct respiratory organs, more or less developed at different pe- 
riods of life, or in different groups. All Vertebrates, at first, have 
gills arising from the sides of the head, and directly supplied with 
blood from the heart ; but these gills are the essential organs of res- 
piration only in fishes and some reptiles, and gradually disappear 
in the higher reptiles, as well as in birds and Mammalia, towards 
the close of their embryonic growth. Again, all Vertebrates have 
lungs, opening in or near the head ; but the lungs are fully devel- 
oped only in Mammalia, birds, and the higher reptiles, in propor- 
tion as the branchial respiration is reduced ; whilst in fishes the air- 
bladder constitutes a rudimentary lung. 

260 b. In Articulates, there are also two sorts of respiratory or- 
gans ; aerial, called tracheae in insects, and lungs in spiders ; and 
aquatic, in Crustacea and worms, called gills. But these trachea and 
lungs open separately upon the two sides of the body, (air never 
being admitted through the mouth or nostrils in Articulates ;) the 
gills are placed in pairs ; those which are like the trachea? occupying 
a similar position, so that there are nearly as many pairs of tracheae 
and gills as there are segments in these animals, (Figs. 89 and 33.) 
The different respiratory organs in Articulates are in reality mere 
modifications of the same apparatus, as their mode of formation and 
successive metamorphoses distinctly show, and cannot be compared 
with either the lungs or gills of Vertebrates ; they are special organs 
not found in other classes, though they perform the same functions. 
The same may be said of the gills and lungs of mollusks, which 
are essentially alike in structure, the lungs of snails and slugs being 
only a modification of the gills of aquatic mollusks ; but these two 
kinds of organs differ again in their structure and relations from the 
tracheae and gills of Articulates, as much as from the lungs and gills 



OF RESPIRATION. 125 

the hard shell, whilst in polyps they perforate the walls of 
the general cavity of the body, which they constantly fill 
with water. 



of Vertebrates. In those Radiates which are provided with distinct 
respiratory organs, such as the Echinoderms, we find still another 
typical structure, their gills forming bunches of fringes around the 
mouth, or rows of minute vesicles along the radiating segments of 
the body. 

11* 



CHAPTER NINTH. 

OF THE SECRETIONS. 

261. WHILE, by the process of digestion, a homogeneous 
fluid is prepared from the food, and supplies new material to 
the blood, another process is also going on, by which the 
blood is analyzed, as it were ; some of its constituents being 
selected and so combined as to form products for useful 
purposes, while other portions of it which have become useless 
or injurious to the system are taken up by different organs, 
and expelled in different forms. This process is termed 
SECRETION. 

262. The organs by which these operations are per- 
formed are much varied, consisting either of flat surfaces or 
membranes, of minute simple sacs, or of delicate elongated 
tubes, all lined with minute cells, called epithelium cells, 
which latter are the real agents in the process. Every sur- 
face of the body is covered by them, and they either dis- 
charge their products directly upon the surface, as on the 
mucous membrane, or they unite in clusters and empty into 
a common duct, and discharge by a single orifice, as is the 
case with some of the intestinal glands, and of those from 
which the perspiration issues upon the skin, (Fig. 94.) 




OF THE SECRETIONS. 127 

263. In the higher animals, where 
separate organs for special purposes are 
multiplied, numerous sacs and tubes are 
assembled into compact masses, called 
glands. Some of these are of large size, 
such as the salivary glands, the kidneys, 

and the liver. In these, clusters of sacs "pv" "s" 

open into a common canal, and this canal 
unites with similar ones forming larger trunks, such as we 
find in the salivary glands, (Fig. 93,) and finally they all 
discharge by a single duct. 

264. By the organs of secretion, two somewhat different 
purposes are effected, namely, fluids of a peculiar character 
are selected from the blood, for important uses, such as the 
saliva, tears, milk, &c., some of which differ but little in 
their composition from that of the blood itself, and might 
be retained in the blood with impunity ; or, the fluids 
selected are such as are positively injurious, and cannot 
remain in the blood without soon destroying life. These 
latter are usually termed EXCRETIONS. 

tt 

265. As the weight of the body, except during its period 
of active growth, remains nearly uniform, it follows that it 
must daily lose as much as it receives ; in other words, the 
excretions must equal in amount the food and drink taken, 
with the exception of the small proportion discharged by the 
alimentary canal. Some of the most important of these 
outlets will be now indicated. 

266. We have already seen (37) that all animal tissues 
admit of being traversed by liquids and gases. This mutual 
transmission of fluids from one side of a membrane to the 
other is termed endosmosis and exosmosis, or imbibition and 
transudation, and is a mechanical, rather than a vital, phe- 
nomenon, inasmuch as it takes place in dead as well as in 



128 OF THE SECRETIONS. 

living tissues. The bloodvessels, especially the capillaries, 
share this property. Hence portions of the circulating fluids 
escape through the walls of the vessels and pass off at the 
surface. This superficial loss is termed exhalation. It is 
most active where the bloodvessels most abound, and accord- 
ingly is very copious from the air-tubes of the lungs and 
from the skin. The loss in this way is very considerable ; 
and it has been estimated that, under certain circumstances, 
the body loses, by exhalation, five eighths of the whole weight 
of the substances received into it. 

267. The skin, or outer envelop of the body, is otherwise 
largely concerned in the losses of the body. Its layers 
are constantly renewed by the tissues beneath, and the 
outer dead layers are thrown off. This removal is some- 
times gradual and continual, as in man. In fishes and many 
mollusks, it comes off in the form of slime, which is, in fact, 
composed of cells detached from the surface of the skin. 
Sometimes the loss is periodical, when it is termed moulting. 
Thus, the mammals cast their hair, and the deer their horns, 
the birds their feathers, the serpents their skins, the crabs 
their test, the caterpillars their outer envelop, with all the 
hairs growing from it. 

268. The skin presents such a variety of structure in the 
different groups of animals as to furnish excellent distinctive 
characters of species, genera, and even families, as will 
hereafter be shown. In the vertebrates we may recognize 
several distinct layers, of unequal thickness, as may be seen 
in figure 94, which represents a magnified section of the 
human skin, traversed by the sudoriferous canals. The 
lower and thickest layer, (a,) is the cut-is, or true skin, and 
is the part which is tanned into leather. Its surface presents 
numerous papillae, in which the nerves of general sensation 
terminate ; they also contain a fine network of bloodvessels, 



OF THE SECRETIONS. 



129 



usually termed the vascular layer. The 
superficial layer (c) is the epidermis, 
or cuticle. The cells of which it is com- 
posed are distinct at its inner portion, 
but become dried and flattened as they 
are pushed outwards. It is supplied with 
neither vessels nor nerves, and, conse- 
quently, is insensible. Between these 
two layers, and more especially con- 
nected with the cuticle, is the rete muco- 
sum, (&,) a very thin layer of cells, some 
of which contain the pigment which 
gives the complexion to the different 
races of men and animals. The scales 
of reptiles, the nails and claws of 




Fig. 94. 



mammals, and the solid coverings of the Crustacea, are 
merely modifications of the epidermis. On the other hand, 
the feathers of birds and the scales of fishes arise from the 
vascular layer. 

269. Of all the Excretions, if we except that from the 
Lungs, the bile seems to be the most extensive and im- 
portant ; and hence a liver, or some analogous organ, by 
which bile is secreted, is found in animals of every depart- 
ment ; while some, or all, of the other glands are want- 
ing in the lower classes of animals. In Vertebrates, the 
liver is the largest of all the organs of the body. In mol- 
lusks, it is no less preponderant. In the gasteropods, like the 
snail, it envelopes the intestine in its convolutions, (Fig. 52 ;) 
and in the acephala, like the clam and oyster, it generally 
surrounds the stomach. In insects it is found in the shape of 
long tubes, variously contorted and interlaced, (Fig. 51.) In 
the Radiata, this organ is largely developed, especially 
among the echinoderms. In the star-fishes it extends into 



130 OF THE SECRETIONS. 

all the recesses of the rays ; and, in color and structure, re- 
sembles the liver of mollusks. Even in polyps, we find pe- 
culiar brown cells lining the digestive cavity, which, proba- 
bly, perform functions similar to those of the liver in the 
higher animals. 

270. The great importance of the respiratory organs in 
discharging carbon from the blood has already been spoken 
of, (245, 251.) The substances removed by the liver and 
the lungs are of the same class, being those which are desti- 
tute of nitrogen. These organs seem, in some sense, sub- 
sidiary to each other ; and hence, in those animals where 
the respiratory organs are largely developed, the biliary 
organs are comparatively small, and vice versa. Another 
and opposite class of impurities, and no less pernicious if 
retained in the blood, is removed by the KIDNEYS ; and, 
consequently, organs answering to the kidneys are found 
very far down in the series of animals. Most of the peculiar 
ingredients of the urine are capable of assuming solid, crys- 
talline forms ; and, in some animals, as in reptiles and 
birds, the whole secretion of the kidneys is solid. In most 
cases, however, the urinary salts are largely diluted with 
water ; arid, as the lungs and liver are supplementary to 
each other in the removal of carbon, so the lungs, the kid- 
neys, and the skin mutually relieve each other in the removal 
of the watery portions of the blood. 



CHAPTER TENTH. 
EMBRYOLOGY. 

SECTION I. 

OF THE EGG. 

271. THE functions of vegetative life, of which we have 
treated in the preceding chapters, namely, digestion, circu- 
lation, respiration, and secretion, have for their end the pres- 
ervation of the individual. We have now to treat of the 
functions that serve for the perpetuation of the species, 
namely, those of reproduction, (200.) 

272. It has been generally admitted that animals as well 
as plants are the offspring of individuals of the same kind ; 
and vice versa^ that none of them can give birth to individ- 
uals differing from themselves : but recent investigations 

o * o 

have modified to a considerable extent this view, as we shall 
see hereafter. 

273. Reproduction in animals is almost universally accom- 
plished by the association of individuals of two kinds, males 
and females, living commonly in pairs or in flocks, each of 
them characterized by peculiarities of structure and external 
appearance. As this distinction prevails throughout the ani- 
mal kingdom, it is always necessary, if we would obtain a 
correct and complete idea of a species, to take into account 
the peculiarities of both sexes. Every one is familiar with the 
differences between the cock and the hen, the lion and the 
lioness, &c. Less prominent peculiarities are observed in 



132 EMBRYOLOGY. 

most Vertebrates. Among Articulata, the differences are no 
less striking, the males being often of a different shape and 
color, as in crabs, or having even more complete organs, as 
in many tribes of insects, where the males have wings, while 
the females are destitute of them, (Fig. 147.) Among mol- 
lusks, the females have often a wider shell. 

274. Even higher distinctions than specific ones are based 
upon peculiarities of the sexes ; for example, the whole 
class of Mammalia is characterized by the fact that the 
female is furnished with organs for nourishing her young 
with a peculiar liquid, the milk, secreted by herself. Again, 
the Marsupial, such as the opossum and kangaroo, are dis- 
tinguished by the circumstance that the female has a pouch 
into which the young are received in their immature con- 
dition at birth. 

275. That all animals are produced from eggs, (Omne 
vivum ex 000,) is an old adage in Zoology, which modern 
researches have fully confirmed. In tracing back the phases 
of animal life, we invariably arrive at an epoch when the 
incipient animal is enclosed within an egg. It is then called 
an embryo, and the period passed in this condition is called 
the embryonic period. 

276. Before the various classes of the animal kingdom 
had been attentively studied during the embryonic period, 
all animals were divided into two great divisions : the ovip- 
arous, comprising those which lay eggs, such as birds, 
reptiles, fishes, insects, mollusks, &c., and the viviparous^ 
which bring forth their young alive, like the mammalia, and 
a few from other orders, as the sharks, vipers, &c. This 
distinction lost much of its importance when it was shown 
that viviparous animals are produced from eggs, as well as 
the oviparous ; only that their eggs, instead of being laid 
before the development of the embryo begins, undergo their 
early changes in the body of the mother. Production from 



OF THE EGG. 



133 




Fig. 95. 



eggs should, therefore, be considered as a universal charac- 
teristic of the Animal Kingdom. 

277. Form of the Egg. The general form of the egg 
is more or less spherical. The eggs of birds have the form 
of an elongated spheroid, narrow at one end ; and this 
form is so constant, that the term oval has been universally 
adopted to designate it. But this is by no means the usual 
form of the eggs of other animals. 

In most instances, on the contra- 
ry, they are spherical, especially 
among the lower animals. Some 
have singular appendages, as those 
of the skates and sharks, (Fig. 95,) which are shaped like 
a hand-barrow, with four hooked horns at the corners. The 
eggs of the hydra, or fresh water 
polyp, are thickly covered with 
prickles, (Fig. 96.) Those of 
certain insects, the Podurella, for 
example, are furnished with fila- 
ments which give them a hairy 
aspect, (Fig. 97 ;) others are cylindrical or prismatic ; and 
frequently the surface is sculptured. 

278. Formation of the Egg. The egg originates within 
peculiar organs, called ovaries, which are glandular bodies, 
usually situated in the abdominal cavity. So long as the 
eggs remain in the ovary, they are very minute in size. In 
this condition they are called ovarian, or primitive eggs. 
They are identical in all animals, being, in 

fact, merely little cells (u) containing yolk, 
(?/,) and including other smaller cells, the 
germinative vesicle, (g,) and the germinative 
dot, (tZ.) The yolk itself, with its membrane, 
(y,) is formed while the egg remains in the 
ovary. It is afterwards enclosed in another 
envelope, the shell membrane, which may remain soft, (s,) 

12 




Fig. 96. 




Fig. 97. 




Fig. 98. 



134 EMBRYOLOGY. 

or be further surrounded by calcareous deposits, the shell 
proper, (Fig. 101, s.) The number of these eggs is large, in 
proportion as the animal stands lower in the class to which 
it belongs. The ovary of a herring contains more than 
25,000 eggs ; while that of birds contains a much smaller 

oJD f 

number, perhaps one or two hundred only. 

279. Ovulation. Having attained a certain degree of 
maturity, which varies in different classes, the eggs leave 
the ovary. This is called ovulation, and must not be con- 
founded with the laying of the eggs, which is the subsequent 
expulsion of them from the abdominal cavity, either imme- 
diately, or through a special canal, the oviduct. Ovulation 
takes place at certain seasons of the year, and never be- 
fore the animal has reached a particular age, which is 
commonly that of its full growth. In a majority of species, 
ovulation is repeated for a number of years consecutively, 
generally in the spring in terrestrial animals, and frequently 
several times a year ; most of the lower aquatic animals, how- 
ever, lay their eggs in the fall, or during winter. In others, 
on the contrary, it occurs but once during life, at the period of 
maturity, and the animal soon afterwards dies. Thus the but- 
terfly and most insects die, shortly after having laid their eggs. 

280. The period of ovulation is one of no less interest to 
the zoologist than to the physiologist, since the peculiar 
characteristics of each species are then most clearly marked. 
Ovulation is to animals what flowering is to plants ; and, 
indeed, few phenomena are more interesting to the student 
of nature than those exhibited by animals at the pairing 
season. Then their physiognomy is the most animated, 
their song the most melodious, and their attire the most 
brilliant. Some birds appear so different at this time, that 
zoologists are always careful to indicate whether or not a 
bird is represented at the breeding season. Fishes, and 
many other animals, are ornamented with much brighter 
colors at this period. 



OF THE EGG. 



135 



281. Laying. After leaving the ovary, the eggs are 
either discharged from the animal, that is, laid ; or they 
continue their development within the parent animal, as is 
the case in some fishes and reptiles, as sharks and vipers, 
which, for that reason, have been named ovo -viviparous 
animals. The eggs of the mammalia are not only developed 
within the mother, but become intimately united to her ; this 
peculiar mode of development has received the name of 
gestation. 

282. Eggs are sometimes laid one by one, as in birds ; 
sometimes collectively and in great numbers, as in 

the frogs, the fishes, and most of the invertebrates. 
The queen ant of the African termites lays 80,000 
eggs in twenty-four hours ; and the common hair- 
worm, (Gordius,) as many as 8,000,000 in less than 
one day. In some instances they are united in 
clusters by a gelatinous envelop ; in others they are -pig. 99. 
enclosed in cases or between membranous disks, 
forming long strings, as in the eggs of the Pyrula shell, (Fig. 
99.) The conditions under which the eggs 
of different animals are placed, on being laid, 
are very different. The eggs of birds, and of 
some insects, are deposited in nests constructed 
for that purpose by the parent. Other animals 
carry their eggs attached to their bodies ; 
sometimes under the tail, as in the lobsters 
and crabs, sometimes hanging in large bun- 
dles on both sides of the tail, as in the Mo- 
noculus, (Fig. 100, .) 





Fig. 100. 



283. Some toads carry them on the back, and, what is 
most extraordinary, it is the male which undertakes this 
office. Many mollusks, the Unio for example, have them 
enclosed between the folds of the gills during incubation. 
In the jelly fishes and polyps, they hang in clusters, either 



136 EMBRYOLOGY. 

outside, (Fig. 77, o,) or inside, at the bottom of the cavity 
of the body. Some insects, such as the gad-flies, deposit 
their eggs on other animals. Finally, many abandon their 
eggs to the elements, taking no further care of them after 
they have been laid ; such is the case with most fishes, some 
insects, and many mollusks. As a general rule, it may be 
said that animals take the more care of their eggs and brood 
as they occupy a higher rank in their respective classes. 

284. The development of the embryo does not always 
take place immediately after the egg is laid. A considera- 
ble time, even, may elapse before it commences. Thus, the 
first eggs laid by the hen do not begin to develop until the 
whole number which is to constitute the brood is deposited. 
The eggs of most butterflies, and of insects in general, are 
laid in autumn, in temperate climates, and remain unchanged 
until the following spring. During this time, the principle 
of life in the egg is not extinct, but is simply inactive, or in 
a latent state. This tenacity of life is displayed in a still 
more striking manner in plants. The seeds, which are 
equivalent to eggs, preserve for years, and even for ages, 
their power to germinate. Thus, there are some well- 
authenticated cases in which wheat taken from the ancient 
catacombs of Egypt has been made to sprout and grow. 

285. A certain degree of warmth is requisite for the 
hatching of eggs. Those of birds, especially, require to be 
submitted, for a certain length of time, to a uniform tem- 
perature, corresponding to the natural heat of the future 
chicken, which is naturally supplied by the body of the 
parent. In other words, incubation is necessary for their 
growth. Incubation, however, is not a purely vital phenom- 
enon, but may be easily imitated artificially. Some birds 
of warm climates dispense with this task ; for example, the 
ostrich often contents herself with depositing her eggs in the 
sand of the desert, leaving them to be hatched by the sun. In 



OF THE EGG. 



137 



like manner, the eggs of most birds may be hatched by main- 
taining them at the proper temperature by artificial means. 
Some fishes are also known to build nests and to sit upon 
their eggs, as the sticklebacks, sun-fishes, and cat-fishes ; but 
whether they impart heat to them or not, is doubtful. 

Before entering into the details of embryonic transfor- 
mations, a few words are necessary respecting the composi- 
tion of the egg. 

286. Composition of the Egg. The egg is composed 
of several substances, varying in structure, as well as in 
appearance. Thus, in a hen's egg, (Fig. 101,) we have first 
a calcareous shell, (s,) lined by a double membrane, the shell 
membrane, (m ;) then an albuminous substance, the white, 
(a,} in which several layers may be distinguished ; within 
this we find the yolk, (y,) enclosed in its membrane ; and 
before it was laid, there was in the midst of the latter a mi- 
nute vesicle, the germinative vesicle, (Fig. 98, g,) containing 
a still smaller one, the germinative dot* (d.) These different 
parts are not equally important in a 

physiological point of view. The 
most conspicuous of them, namely, m i 
the shell and the white, are not es- 
sential parts, and therefore are often 
wanting ; while the yolk, the ger- 
minative vesicle, and the germina- 
tive dot are found in the eggs of 

all animals ; and out of these, and of these only, the germ is 
formed, in the position shown by Fig. 101, e. 

287. The vitellus or yolk (Fig. 101, y) is the most essen- 
tial part of the egg. It is a liquid of variable consistence, 
sometimes opaque, as in the eggs of birds, sometimes trans- 
parent and colorless, as in the eggs of some fishes and 
mollusks. On examination under the microscope, it appears 
to be composed of an accumulation of granules and oil-drops. 

12* 




Fig. 101. 



138 EMBRYOLOGY. 

The yolk is surrounded by a very thin skin, the vitelline 
membrane, (Fig. 98, v.) In some insects, when the albumen 
is wanting, this membrane, surrounded by a layer of pecu- 
liar cells, forms the exterior covering of the egg, which, in 
such cases, is generally of a firm consistence, and sometimes 
even horny. 

288. The germinative vesicle (Fig. 98, g) is a cell of ex- 
treme delicacy, situated, in the young egg, near the middle 
of the yolk, and easily recognized by the greater transpar- 
ency of its contents when the yolk is in some degree opaque, 
as in the hen's egg, or by its outline, when the yolk itself is 
transparent, as in eggs of fishes and mollusks. It contains 
one or more little spots, somewhat opaque, appearing as 
small dots, the germinal dots, (d.) On closer examination, 
these dots are themselves found to contain smaller nucleoli. 

289. The albumen, or white of the egg, (Fig. 101, a,) is 
a viscous substance, generally colorless, but becoming 
opaque white on coagulation. Voluminous as it is in birds' 
eggs, it nevertheless plays but a secondary part in the histo- 
ry of their development. It is not formed in the ovary, like 
the yolk, but is secreted by the oviduct, and deposited around 
the yolk, during the passage of the egg through that canal. 
On this account, the eggs of those animals in which the ovi- 
duct is wanting, are generally without the albumen. In 
birds, the albumen consists of several layers, one of which, 
the clialazcB, (c,) is twisted. Like the yolk, the albumen is 
surrounded by a membrane, the shell membrane, (w,) which 
is either single or double, and in birds, as also in some 
reptiles and mollusks, is again protected by a calcareous 
covering, forming a true shell, (s.) In most cases, how- 
ever, this envelop continues membranous, particularly in the 
eggs of the mollusks, most crustaceans and fishes, salaman- 
ders, frogs, &c. Sometimes it is horny, as in the sharks 
and skates. 



DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 139 



SECTION II. 

DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 

290. The formation and development of the young ani- 
mal within the egg is a most mysterious phenomenon. From 
a hen's egg, for example, surrounded by a shell, and com- 
posed, as we have seen, (Fig. 101,) of albumen and yolk, 
with a minute vesicle in its interior, there is produced, at the 
end of a certain time, a living animal, composed apparently 
of elements entirely different from those of the egg, en- 
dowed with organs perfectly adapted to the exercise of all 
the functions of animal and vegetative life, having a pul- 
sating heart, a digestive apparatus, organs of sense for the 
reception of outward impressions, and having, moreover, the 
faculty of performing voluntary motions, and of experi- 
encing pain and pleasure. These phenomena are certainly 
sufficient to excite the curiosity of every intelligent person. 

291. By opening eggs which have been subjected to incu- 
bation during different periods of time, we may easily satisfy 
ourselves that these changes are effected gradually. We 
thus find that those which have undergone but a short incu- 
bation exhibit only faint indications of the future animal ; 
while those upon which the hen has been sitting for a 
longer period include an embryo chicken proportionally 
more developed. Modern researches have taught us that 
these gradual changes, although complicated, and at first 
sight so mysterious, follow a constant law in each great 
division of the Animal Kingdom. 

292. The study of these changes constitutes that peculiar 
branch of Physiology called EMBRYOLOGY. As there are 
differences in the four great departments of the Animal 



140 EMBRYOLOGY. 

Kingdom perceptible at an early stage of embryonic life, 
quite as obvious as those found at maturity, and as the 
phases of embryonic development furnish important indi- 
cations for the natural classification of animals, we propose 
to give the outlines of Embryology, so far as it may have 
reference to Zoology. 

293. In order to understand the successive steps of em- 
bryonic development, we must bear in mind that the whole 
animal body is formed of tissues, the elements of which are 
cells, (39.) These cells, however, are more or less diversi- 
fied and modified, or even completely metamorphosed in the 
full grown animal ; but, at the commencement of embry- 
onic life, the whole embryo is composed of minute cells of 
nearly the same form and consistence, originating within the 
yolk, and constantly undergoing changes under the influence 
of life. New cells are successively formed, while others 
disappear, or are modified and so transformed as to become 
bones, muscles, nerves, &c. 

294. We may form some idea of this singular process, 
by noticing how, in the healing of a wound, new substance 
is supplied by the transformation of blood. Similar changes 
take place in the embryo, during its early life ; only, instead 
of being limited to some part of the body, they pervade the 
whole animal. 

295. The changes commence, in most animals, soon after 
the eggs are laid, and are continued without interruption 
until the development of the young is completed ; in others, 
birds for example, they proceed only to a certain extent, and 
are then suspended until incubation takes place. The yolk, 
which at first consists of a mass of uniform appearance, grad- 
ually assumes a diversified aspect. Some portions become 
more opaque, and others more transparent ; the germinal 
vesicle, which was in the midst of the yolk, rises to its upper 
part where the germ is to be formed. These early changes 



DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 141 

are accompanied, in some animals, by a rotation of the yolk 
within the egg, as may be distinctly seen in some of the 
mollusks, especially in the snails. 

296. At the same time, the yolk undergoes a peculiar 
process of segmentation. It is first divided into halves, 
forming distinct spheres, which are again regularly sub- 
divided into two more, and so on, till the whole yolk as- 
sumes the appearance of a mulberry, each of the spheres of 
which it is composed having in its interior a transparent 
vesicle. This is the case in mammalia, most mollusks, 
worms, &c. In many animals, however, as in the naked 
reptiles and fishes,* this segmentation is only partial, the 
divisions of the yolk not extending across its whole mass. 

297. But whether complete or partial, this process leads 
to the formation of a germ comprising the whole yolk, or 
rising above it as a disk-shaped protuberance, composed of 
little cells, which has been variously designated under the 
names of germinative disk, proligerous disk, blastoderma, 
germinal membrane. In this case, however, that portion of 
the yolk which has undergone less obvious changes forms, 
nevertheless, part of the growing germ. The disk again 
gradually enlarges, until it embraces the whole, or nearly 
the whole, of the yolk. 

298. At this early epoch, namely, a few days, and some- 
times a few hours, 

after development 
has begun, the 
germ proper con- 
sists of a single 
layer composed Fig. 102. Fig. 103. 



* In the Birds and higher reptiles we find, in the mature egg, a peculiar 
organ, called cicatricula, which may, nevertheless, have been formed by 
a similar process before it was laid. 




142 



EMBRYOLOGY. 



of very minute cells, all of which are alike in appearance 
and form, (Fig. 102, g.) But soon after, as the germ increases 
in thickness, several layers may be discerned, in vertebrated 
animals, (Fig. 103,) which become more and more distinct. 

299. The upper layer, (s,) in which are subsequently 
formed the organs of animal life, namely, the nervous sys- 
tem, the muscles, the skeleton, &c., (59,) has received the 
name of serous or nervous layer. The lower layer, (m,) 
which gives origin to the organs of vegetative life, and espe- 
cially to the intestines, is called the mucous or vegetative 
layer, and is generally composed of larger cells than those 
of the upper or serous layer. Finally, there is a third 
layer, (v,) interposed between the two others, giving rise to 
the formation of blood and the organs of circulation ; whence 
it has been called blood layer, or vascular layer. 

300. From the manner in which the germ is modified, we 
can generally distinguish, at a very early epoch, to what de- 
partment of the animal kingdom an individual is to belong. 
Thus, in the Articulata, the germ is divided into segments, 

indicating the transverse divisions 
of the body, as, for example, in the 
embryo of the crabs, (Fig. 104.) 
The germ of the vertebrated ani- 
mals, on the other hand, displays 
a longitudinal furrow, which marks 
the position the future back-bone 
is to occupy, (Fig. 105.) 

301. The development of this furrow is highly important, 
as indicating the plan of structure of vertebrated animals in 
general, as will be shown by the following figures, which 
represent vertical sections of the embryo at different epochs.* 





Fig. 104. 



Fig. 105. 



* In these figures, the egg is supposed to be cut down through the mid- 
dle, so that only the cut edge of the embryo is seen ; -whereas, if viewed 



DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 143 

At first the furrow (Fig. 106, 1} is very shallow, and a lit- 




Fig. 106. Fig. 107. Fig. 108. 

tie transparent, narrow band appears under it, called the 
primitive stripe, (a.) The walls of the furrow consist of two 
raised edges formed by a swelling of the germ along both sides 
of the primitive stripe. Gradually, these walls grow higher, 
and we perceive that their summits have a tendency to ap- 
proach each other, as seen in Fig. 107 ; at last they meet 
and unite completely, so that the furrow is now changed 
into a closed canal, (Fig. 108, Z>.) This canal is soon filled 
with a peculiar liquid, from which the spinal marrow and 
brain are formed at a later period. 

302. The primitive stripe is gradually obliterated by a 
peculiar organ of a cartilaginous nature, the dorsal cord, 
formed in the lower wall of the dorsal canal. This is found 
in the embryos of all vertebrates, and is the representative 
of the back-bone. In the mean time, the margin of the 
germ gradually extends farther and farther over the yolk, so 
as finally to enclose it entirely, and form another cavity in 
which the organs of vegetative life are to be developed. 
Thus the embryo of vertebrates has two cavities, namely, 
the upper one, which is very small, containing the nervous 
system, and the lower, which is much larger, for the intes- 
tines, (161.) 

303. In all classes of the Animal Kingdom, the embryo 
proper rests upon the yolk, and covers it like a cap. But 
the direction by which its edges approach each other, and 



from above, it would extend over the yolk in every direction, and the 
furrow at b, of Fig. 106, would appear as in Fig. 105. 



144 



EMBRYOLOGY. 




Fig. 109. 



unite to form the cavity of the body, is very unlike in dif- 
ferent animals ; and these several modes 

are of high importance in classification. 
Among the Vertebrates, the embryo lies 
with its face or ventral surface towards 
the yolk, (Fig. 109,) and thus the suture, 
or line at which the edges of the germ 
unite to enclose the yolk, and which in 
the mammals forms the navel, is found 
in front. Another suture is found along 
the back, arising from the actual folding upwards of the 
upper surface of the germ, to form the dorsal cavity. 

304. The embryo in the Articulata, on the contrary, lies 
with its back upon the yolk, as seen in the following figure, 

which represents an embryo of Podurella ; 
consequently the yolk enters the body on 
that side ; and the suture, which in the 
vertebrates is found on the belly, is here 
found on the back. In the Cephalopoda 
the yolk communicates with the lower 
side of the body, as in Vertebrates, but 
there is no dorsal cavity formed in them. 
In the other Mollusks, as also in the Worms, there is this 
peculiarity, that the whole yolk is changed at the beginning 
into the substance of the embryo ; whilst in Vertebrates, and 
the higher Articulates and Mollusks, a part of it is reserved, 
till a later period, to be used for the nourishment of the em- 
bryo. Among Radiata, the germ is formed around the yolk, 
and seems to surround the whole of it, from the first.* 

305. The development of the embryo of the vertebrated 
animals may be best observed in the eggs of fishes. Being 




Fig. 110. 



* These facts show plainly that the circumstance of embryos arising 
from the whole or a part of the yolk is of no systematic importance. 



DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 145 

transparent, they do not require to be cut open, and, by 
sufficient caution, the whole series of embryonic changes 
may be observed upon the same individual, and thus the suc- 
cession in which the organs appear be ascertained with pre- 
cision ; whereas, if we employ the eggs of birds, which are 
opaque, we are obliged to sacrifice an egg for each obser- 
vation. 

306. To illustrate these general views as to the develop- 
ment of the embryo, we will briefly describe the principal 
phases, as they have been observed in the White-fish of Eu- 
rope, which belongs to the salmon family. The following 
magnified sections will illustrate this development, and show 
the period at which the different organs successively appear. 






Fig. 111. Fig. 112. Fig. 113. 

307. The egg, when laid, (Fig. ill,) is spherical, about the 
size of a small pea, and nearly transparent. It has no albu- 
men, and the shell membrane is so closely attached to the 
membrane of the yolk, that they cannot be distinguished. 
Oil-like globules are scattered through the mass of the yolk, 
or grouped into a sort of disk, under which lies the germina- 
tive vesicle. The first change in such an egg occurs a few 
hours after it has been laid, when the shell membrane sepa- 
rates from the yolk membrane, in consequence of the ab- 
sorption of a quantity of water, (Fig. 112,) by which the 
egg increases in size. Between the shell membrane (s m) 
and the yolk, (?/,) there is now a considerable transparent 
space, which corresponds, in some respects, to the albumen 
found in the eggs of birds. 

308. Soon afterwards we see, in the midst of the oil-like 

13 



146 



EMBRYOLOGY. 



globules, a swelling in the shape of a transparent vesicle, 
(Fig. 113, g,) composed of very delicate cells. This is the 
first indication of the germ. This swelling rapidly enlarges 
until it envelops a great part of the yolk, when a depression 






Fig. 114. 



Fig. 115. 



Fig. 116. 



is formed upon it, (Fig. 114.) This depression becomes by 
degrees a deep furrow, and soon after a second furrow ap- 
pears at right angles with the former, so that the germ now 
presents four elevations, (Fig. 115.) The subdivision goes 
on in this way, during the second and third days, until the 
germ is divided into numerous little spheres, giving the sur- 
face the appearance of a mulberry, (Fig. 116.) This ap- 
pearance, however, does not long continue ; at the end of 
the third day, the fissures again disappear, and leave no 
visible traces. After this, the germ continues to extend 
as an envelop around the yolk, which it at last entirely 
encloses. 

309. On the tenth day, the first outlines of the embryo 
begin to appear, and we soon distinguish in it a depression 
between two little ridges, whose edges constantly approach 





Fig. 117. Fig. 118. Fig. 119. 

each other until they unite and form a canal, (Fig. 117, Z>, 



DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 147 

as has been before shown, (Fig. 107.) At the same time, 
an enlargement at one end of the furrow is observed. This 
is the rudiment of the head, (Fig. 118,) in which may soon 
be distinguished traces of the three divisions of the brain, 
(Fig. 119,) corresponding to the senses of sight, (m,) hear- 
ing, (e,) and smell, (p.] 

310. Towards the thirteenth day, we see a transparent, 
cartilaginous cord, in the place afterwards occupied by the 
back-bone, composed of large cells, on which transverse 




Fig. 120. 



Fig. 121. 



Fig. 122. 



divisions are successively forming, (Figs. 120, 121, c.) This 
is the dorsal cord, a part of which, as we have before seen, is 
common to all embryos of vertebrated animals. It always 
precedes the formation of the back-bone ; and in some 
fishes, as the sturgeon, this cartilaginous or embryonic state 
is permanent through life, and no true back-bone is ever 
formed. Soon after, the first rudiments of the eye appear, 
in the form of a fold in the external membrane of the germ, 
in which the crystalline lens (Fig. 121, a;) is afterwards 
formed. At the same time we see, at the posterior part 
of the head, an elliptical vesicle, which is the rudiment of the 
ear. At this period, the distinction between the upper and 
the lower layer of the germ is best traced ; all the changes 
mentioned above appertaining to the upper layer. 

311. After the seventeenth day, the lower layer divides 
into two sheets, the inferior of which becomes the intestine. 



148 EMBRYOLOGY. 

The heart shows itself about the same time, under the form 
of a simple cavity, (Fig. 121, /,) in the midst of a mass 
of cells belonging to the middle or vascular layer. As soon 
as the cavity of the heart is closed in, regular motions of 
contraction and expansion are perceived, and the globules 
of blood are seen to rise and fall in conformity with these 
motions. 

312. There is as yet, however, no circulation. It is not 
until the thirtieth day that its first traces are manifest in the 
existence of two currents, one running towards the head, the 
other towards the trunk, (Fig. 122,) with similar returning 
currents. At this time the liver begins to be formed. Mean- 
while, the embryo gradually disengages itself, at both ends, 
from its adherence to the yolk ; the tail becomes free, and 
the young animal moves it in violent jerks. 

313. The embryo, although still enclosed in the egg, now 
unites all the essential conditions for the exercise of the 
functions of animal life. It has a brain, an intestine, a pul- 
sating heart and circulating blood, and it moves its tail spon- 
taneously. But the forms of the organs are not yet complete ; 
nor have they yet acquired the precise shape that character- 
izes the class, the family, the genus, and the species. The 
young White-fish is as yet only a vertebrate animal in gen- 
eral, and might as well be taken for the embryo of a frog. 

314. Towards the close of the embryonic period, after the 
fortieth day, the embryo acquires a more definite shape. 
The head is more completely separated from the yolk, the 
jaws protrude, and the nostrils approach nearer and nearer to 
the end of the snout ; divisions are formed in the fin which 
surrounds the body ; the anterior limbs, which were indicated 
only by a small protuberance, assume the shape of fins ; and 
finally, the openings of the gills appear, one after the other, 
so that we cannot now fail to recognize the type of fishes. 

315. In this state, the young white-fish escapes from the 




Fig. 123. 



DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 149 

egg, about the sixtieth day after it is laid, (Fig. 123,) but 
its development is still 
incomplete. The out- 
lines are yet too indis- 
tinct to indicate the 
genus and the species 
to which the fish be- 
longs ; at most we distinguish its order only. The opercula 
or gill-covers are not formed ; the teeth are wanting ; the 
fins have as yet no rays ; the mouth is underneath, and it 
is some time before it assumes its final position at the most 
projecting point of the head. The remainder of the yolk is 
suspended from the belly, in the form of a large bladder, but 
it daily diminishes in size, until it is at length completely taken 
into the animal, (304.) The duration of these metamorphoses 
varies extremely in different fishes ; some accomplish it in the 
course of a few days, while in others, months are required. 



315 a. In frogs and all the naked reptiles, the development is very 
similar to that of fishes. It is somewhat different in the scaly rep- 
tiles, (snakes, lizards, and turtles,) which have peculiar membranes 
surrounding and protecting the embryo during its growth. From 
one of these envelopes, the allantois, (Fig. 125, ,) is derived their 
common name of Allantotdian Vertebrates, in opposition to the naked 
reptiles and fishes, which are called Anattantotdian. 

315 b. The AllantoTdian Vertebrates differ from each other in 
several essential peculiarities. Among Birds, as well as in the scaly 




Fig. 124. 



Fig. 125. 



reptiles, we find at a certain epoch, when the embryo is already dis- 

13* 



150 



EMBRYOLOGY. 



316. As a general fact, it should be further stated, that 
the envelopes which protect the egg, and also the embryo, 
are the more numerous and complicated as animals belong 
to a higher class, and produce a smaller number of eggs. 
This is particularly evident when contrasting the innumer- 
able eggs of fishes, discharged almost without protection 



engaging itself from the yolk, a fold rising around the body from the 
upper layer of the germ, so as to present, in a longitudinal section, 
two prominent walls, (Fig. 124, xx.') These walls, converging from 
all sides upwards, rise gradually till they unite abo.ve the middle of 
the back, (Fig. 125.) When the junction is effected, which in the 
hen's egg takes place in the course of the fourth day, a cavity is 
formed between the back of the embryo (Fig. 126, e) and the new 
membrane, whose walls are called the amnios. This cavity becomes 
filled with a peculiar liquid, the amniotic water. 

315 c. Soon after the embryo has been enclosed in the amnios, a 
shallow pouch forms from the mucous layer, below the posterior ex- 
tremity of the embryo, between the tail and the vitelline mass. This 
pouch, at first a simple little sinus, (Fig. 125, a,) grows larger and 
larger, till it forms an extensive sac, the allaniois, turning backwards 
and upwards, so as completely to separate the two plates of the am- 
nios, (Fig. 126, a,) and finally enclosing the whole embryo, with its 




Fig. 123. 

amnios, in another largo sac. The tubular part of this sac, which is 
nearest the embryo, is at last transformed into the urinary bladder. 
The heart (A) is already very large, with mniute arterial threads 



DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 151 

into the water, with the well-protected eggs of birds, and 
still more with the growth of young mammals within the 
body of the mother. 

317. But neither in fishes, nor in reptiles, nor in birds, 
does the vitelline membrane, or any other envelope of the egg, 
take any part in the growth of the embryo ; while on the 




Fig. 127. 



Fig. 128. 



passing off from it. At this period there exist true gills upon the 
sides of the neck, and a branchial respiration goes on. 

315 d. The development of 
mammals exhibits the following 
peculiarities. The egg is ex- 
ceedingly minute, almost micro- 
scopic, although composed of the 
same essential elements as those 
of the lower animals. The vitel- 
line membrane, called chorion, in 

this class of animals, is comparatively thicker, (Fig. 127, v,) always 
soft, surrounded by peculiar cells, being a kind of albumen. The 
chorion soon grows proportionally larger than the vitelline sphere 
itself, (Fig. 128, y,) so as no longer to invest it directly, being sepa- 
rated from it by an empty space, (&.) The germ is formed in the 
same position as in the other classes of Vertebrates, namely, at the top 
of the vitellus, (Fig. 
129 ;) and here also 
two layers may be 
distinguished, the up- 
per or serous layer, (s,) 
and the lower or mu- 
cous layer, (m.) As 
it gradually enlarges, 
the surface of the 
chorion becomes cov- 
ered with little fringes, which, at a later epoch, will be attached to 
the mother by means of similar fringes arising from the walls of 
the matrix, or organ which contains the embryo. 

315 e. The embryo itself undergoes, within the chorion, changes 




Fig. 129. 



Fig. 130. 



152 EMBRYOLOGY. 



contrary, in the mammals, the chorion, which corresponds 
to the vitelline membrane, is vivified, and finally becomes 
attached to the maternal body, thus establishing a direct con- 
nection between the young and the mother ; a connection 
which is again renewed in another mode, after birth, by the 
process of nursing. 



similar to those described in birds : its body and its organs are 
formed in the same way ; an amnios encloses it, and an allantols 
grows out of the lower extremity of the little animal. As soon as the 
allantoTs has surrounded the embryo, its blood vessels become more 
and more numerous, so as to extend into the 
fringes of the chorion, (Fig. 1 3 1, p e ;) while, 
on the other hand, similar vessels from the 
mother extend into tlfc corresponding 
fringes of the matrix, (p m,} but without 
directly communicating with those of the 
chorion. These two sorts of fringes soon 
become interwoven, so as to form an intri- 
cate organ filled with blood, called the pla- Fig. 131. 
centa, to which the embryo remains sus- 
pended until birth. 

315 f. From the fact above stated, it is clear that there are three 
modifications of embryonic development among vertebrated animals, 
namely, that of fishes and naked reptiles, that of scaly reptiles and 
birds, and that of the mammals, which display a gradation of more and 
more complicated adaptation. In fishes and the naked reptiles, the 
germ simply encloses the yolk, and the embryo rises and grows from 
its upper part. In the scaly reptiles and birds there is, besides, an 
amnios arising from the peripheric part of the embryo and an allantols 
growing out of the lower cavity, both enclosing and protecting the 
germ. 




ITS ZOOLOGICAL IMPORTANCE. 153 

SECTION III. 

ZOOLOGICAL IMPORTANCE OF EMBRYOLOGY. 

318. As a general result of the observations which have 
been made, up to this time, on the embryology of the various 
classes of the Animal Kingdom, especially of the verte- 
brates, it may be said, that the organs of the body are suc- 
cessively formed in the order of their organic importance, 
the most essential being always the earliest to appear. In 
accordance with this law, the organs of vegetative life, the 
intestines and their appurtenances, make their appearance 
subsequently to those of animal life, such as the nervous 
system, the skeleton, &c. ; and these, in turn, are preceded 
by the more general phenomena belonging to the animal as 
such. 

319. Thus we have seen that, in the fish, the first changes 
relate to the segmentation of the yolk and the formation of 
the germ, which is a process common to all classes of ani- 
mals. It is not until a subsequent period that we trace the 
dorsal furrow, which indicates that the forming animal will 
have a double cavity, and consequently belong to the division 
of the vertebrates ; an indication afterwards fully confirmed 
by the successive appearance of the brain and the organs 
of sense. Later still, the intestine is formed, the limbs be- 
come evident, and the organs of respiration acquire their 
definite form, thus enabling us to distinguish with certainty 
the class to which the animal belongs. Finally, after the 
egg is hatched, the peculiarities of the teeth, and the shape 
of the extremities, mark the genus and species. 

320. Hence, the embryos of different animals resemble 
each other more strongly when examined in the earlier 
stages of their growth. We have already stated that, during 



154 EMBRYOLOGY. 

almost the whole period of embryonic life, the young fish 
and the young frog scarcely differ at all, (313 :) so it is also 
with the young snake compared with the embryo bird. The 
embryo of the crab, again, is scarcely to be distinguished 
from that of the insect ; and if we go still further back in 
the history of development, we come to a period when no 
appreciable difference whatever is to be discovered between 
the embryos of the various departments. The embryo of 
the snail, when the germ begins to show itself, is nearly the 
same as that of a fish or a crab. All that can be predicted 
at this period is, that the germ which is unfolding itself 
will become an animal ; the class and the group are not yet 
indicated. 

321. After this account of the history of the development 
of the egg, the importance of Embryology to the study of 
systematic Zoology cannot be questioned. For evidently, if 
the formation of the organs in the embryo takes place in an 
order corresponding to their importance, this succession must 
of itself furnish a criterion of their relative value in classifi- 
cation. Thus, those peculiarities that first appear should be 
considered of higher value than those that appear later. In 
this respect, the division of the Animal Kingdom into four 
types, the Vertebrates, the Articulates, the Mollusks, and the 
Radiates, corresponds perfectly with the gradations displayed 
by Embryology. 

322. This classification, as has been already shown, (61,) 
is founded essentially on the organs of animal life, the ner- 
vous system and the parts belonging thereto, as found in the 
perfect animal. Now, it results from the above account, 
that in most animals the organs of animal life are precisely 
those that are earliest formed in the embryo ; whereas those 
of vegetative life, on which is founded the division into 
classes, orders, and families, such as the heart, the respiratory 
apparatus, and the jaws, are not distinctly formed until after- 



ITS ZOOLOGICAL IMPORTANCE. 155 

wards. Therefore a classification, to be true and natural, 
must accord with the succession of organs in the embryonic 
development. This coincidence, while it corroborates the 
anatomical principles of Cuvier's classification of the Animal 
Kingdom, furnishes us with new proof that there is a general 
plan displayed in every kind of development. 

323. Combining these two points of view, that of Embry- 
ology with that of Anatomy, the four divisions of the Animal 
Kingdom may be represented by the four figures which are 
to be found, at the centre of the diagram, at the beginning 
of the volume. 

324. The type of Vertebrates, having two cavities, one 
above the other, the former destined to receive the nervous 
system, and the latter, which is of a larger size, for the intes- 
tines, is represented by a double crescent united at the cen- 
tre, and closing above, as well as below. 

325. The type of Articulata, having but one cavity, grow- 
ing from below upwards, and the nervous system forming 
a series of ganglions, placed below the intestine, is repre- 
sented by a single crescent, with the horns directed up- 
wards. 

326. The type of Mollusks having also but one cavity, the 
nervous system being a simple ring around the oesophagus, 
with ganglions above and below, from which threads go off 
to all parts, is represented by a single crescent with the 
horns turned downwards. 

327. Finally, the type of Radiata, the radiating form of 
which is seen even in the youngest individuals, is represented 
by a star. 



CHAPTER ELEVENTH. 

PECULIAR MODES OF REPRODUCTION. 
SECTION I. 

GEMMIPAROITS AND FISSIPAROUS REPRODUCTION. 

328. WE have shown in the preceding chapter, that ovula- 
tion, and the development of embryos from eggs, is common 
to all classes of animals, and must be considered as the great 
process for the reproduction of species. Two other modes 
of propagation, applying, however, to only a limited number 
of animals, remain to be mentioned, namely, gemmiparous 
reproduction, or multiplication by means of buds, and fissip- 
arous reproduction, or propagation by division ; and also 
some still more extraordinary modifications yet involved in 
much obscurity. 

329. Reproduction by buds occurs among the polyps, me- 

dusse, and some of the infusoria. On the stalk, 
or even on the body of the Hydra, (Fig. 132,) 
and of many infusoria, there are formed 
buds, like those of plants. On close exam- 
ination they are found to be young animals, 
at first very imperfectly formed, and commu- 
nicating at the base with the parent body, 

from which they derive their nourishment. By 
Fig. 132. . 

degrees, the animal is developed ; in most 

cases, the tube by which it is connected with the parent 




GEMMIPAROUS AND FISSIPAROtTS REPRODUCTION. 157 



withers away, and the animal is thus detached and becomes 
independent. Others remain through life united to the parent 
stalk, and, in this respect, present a more striking analogy to 
the buds of plants. But in the polyps, as in trees, budding 
is only an accessory mode of reproduction, which pre- 
supposes a trunk already existing, originally the product of 
ovulation. 

330. Reproduction by division, or fissiparous reproduction, 
is still more extraordinary ; it takes place only in polyps and 
some infusoria. A cleft or fissure at some part of the body 
takes place, very slight at first, 
but constantly increasing in 
depth, so as to become a deep 
furrow, like that observed in the 
yolk, at the beginning of embry- 
onic development ; at the same 
time the contained organs are di- 
vided and become double, and thus two individuals are formed 
of one, so similar to each other that it is impossible to say which 
is the parent and which the offspring. The division takes place 
sometimes vertically, as, for example, in Vpjticella, (Fig. 
133,) and in some Polyps, (Fig. 134,) and sometimes trans- 




Fig. 133. 






Fig. 134. 

versely. In some Infusoria, the Paramecia, for instance, 
this division occurs as often as three or four times in a day. 
331. In consequence of this same faculty, many animals 
are able to reproduce various parts of their bodies when 
accidentally lost. It is well known that crabs and spiders, 
on losing a limb, acquire a new one. The same happens 
with the arms of the star-fishes. The tail of a lizard is also 

14 



158 REPRODUCTION. 

readily reproduced. Salamanders even possess the faculty 
of reproducing parts of the head, including the eye with all 
its complicated structure. Something similar takes place in 
our own bodies, when a new skin is formed over a wound, 
or when a broken bone is reunited. 

332. In some of the lower animals, this power of repara- 
tion is carried much farther, and applies to the whole body, 
so as closely to imitate fissiparous reproduction. If an earth- 
worm, or a fresh-water polyp, be divided into several pieces, 
the injury is soon repaired, each fragment speedily becoming 
a perfect animal. Something like this reparative faculty is 
seen in the vegetable kingdom, as well as the animal. A 
willow branch, planted in a moist soil, throws out roots below 
and branches above ; and thus, after a time, assumes the 
shape of a perfect tree. 

333. These various modes of reproduction do not exclude 
each other. All animals which propagate by gemmiparous 
or fissiparous reproduction also lay eggs. Thus the fresh- 
water polyps (Hydra) propagate both by eggs and by buds. 
In Vorticella, according to Ehrenberg, all three modes are 
found ; it is propagated by eggs, by buds, and by division. 
Ovulation, however, is the most common mode of reproduc- 
tion ; the other modes, and also alternate reproduction, are 
only additional means employed by Nature to secure the per- 
petuation of the species. 



SECTION II. 

ALTERNATE AND EQUIVOCAL REPRODUCTION. 

334. It is a matter of common observation, that individuals 
of the same species have the same general appearance, by 
which their peculiar organization is indicated. The trans- 



ALTERNATE AND EQUIVOCAL REPRODUCTION. 159 

mission of these characteristics, from one generation to the 
next, is justly considered as one of the great laws of the 
Animal and Vegetable Kingdoms. It is, indeed, one of the 

^j <u ' 

points on which the definition of species is generally founded. 
We would, however, unhesitatingly adopt the new definition 
of Dr. S. G. Morton, who defines species to be '* primordial 
organic forms." 

335. But it does not follow that animals must resemble 
their parents in every condition, and at every epoch of their 
existence. On the contrary, as we have seen, this resem- 
blance is very faint, in most species, at birth ; and some, 
such as the caterpillar and the tadpole, undergo com- 
plete metamorphoses before attaining their final shape as the 
butterfly and frog. Nevertheless, we do not hesitate to refer 
the tadpole and the frog to the same species ; and so with the 
caterpillar and the butterfly ; because we know that there is the 
same individual observed in different stages of development. 

336. There is, also, another series of cases, in which the 
offspring not only do not resemble the parent at birth, but, 
moreover, remain different during their whole life, so that 
their relationship is not apparent until a succeeding genera- 
tion. The son does not resemble the father, but the grand- 
father ; and in some cases the resemblance reappears only 
at the fourth or fifth generation, and even later. This sin- 
gular mode of reproduction has received the name of alter- 
nate generation. The phenomena attending it have been 
of late the object of numerous scientific researches, which 
are the more deserving of our attention, as they furnish a 
solution to several problems alike interesting in a zoological 
and in a philosophical point of view. 

337. Alternate generation was first observed among the 
Salpse. These are marine mollusks, without shells, belong- 
ing to the family Tunicata. They are distinguished by the 
curious peculiarity of being united together in considerable 
numbers, so as to form long chains, which float in the sea, 



160 REPRODUCTION. 

the mouth, (m,) however, being free in each, (Fig. 135.) 




Fig. 135. 



Fig. 136. 



The individuals thus joined in floating colonies produce eggs ; 
but in each animal there is generally but one egg formed, 
which is developed in the body of the parent, and from 
which is hatched a little mollusk, (Fig. 136,) which remains 
solitary, and differs in many respects from the parent. This 
little animal, on the other hand, does not produce eggs, but 
propagates by a kind of budding, which gives rise to chains 
already seen within the body of their parent, (a,) and these 
again bring forth solitary individuals, &c. 

338. In some parasitic worms, alternate generation is 
accompanied by still more extraordinary phenomena, as is 
shown by the late discoveries of the Danish naturalist, Steen- 
strup. Among the numerous animals which inhabit stagnant 
pools, in which fresh-water shells, particularly Lymnea and 

Paludina, are found, there is a small worm, 
know to naturalists under the name of Cer- 
caria, (Fig. 137.) When examined with 
a lens, it looks much like a tadpole, with a 
long tail, a triangular head, and a large 
sucker (a) in the middle of the body. Va- 
rious viscera appear within, and, among 
others, a very distinct forked cord, (c,) 
which embraces the sucker, and which is 
thought to be the liver. 

339. If we watch these worms, which 
always abound in company with the shells 
mentioned, we find them after a while attaching themselves, 
by means of their sucker, to the bodies of the mollusks. When 




Fig. 137. 



ALTERNATE AND EQUIVOCAL REPRODUCTION. 



161 




Fig. 138. 



fixed, they soon undergo considerable alteration. The tail, 
which was previously employed for locomotion, is now use- 
less, falls off, and the animal surrounds itself with a mucous 
substance, in which it remains nearly motionless, 
like the caterpillar on its transformation into the 
Pupa. If, however, after some time, we remove 
the little animal from its retreat, we find it to be 
no longer a Cercaria, but an intestinal worm, 
called Distoma, having the shape of Fig. 138, 
with two suckers. The Distoma, therefore, is 
only a particular state of the Cercaria, or, rather, 
the Cercaria is only the larva of the Distoma. 

340. What now is the origin of the Cercaria ? The fol- 
lowing are the results of the latest researches on this point. 
At certain periods of the year, we find in the viscera of the 
Limnea (one of the most common fresh-water mollusks) a 
quantity of little worms of an elongated form, 
with a well marked head, and two posterior 
projections like limbs, (Fig. 139.) On examin- 
ing these worms attentively, under the micro- 
scope, we discover that the cavity of their 
body is filled by a mass of other little worms, 
which a practised eye easily recognizes as 
young Cercarise, the tail and the characteristic 
furcated organ (a) within it being distinctly visible, (Fig. 
140.) These little embryos 
increase in size, distending 
the worm which contains 
them, and. which seemingly 
has no other office than to 
protect and forward the de- Fig. 140. 

velopment of the young 

Cercaria. It is, as it were, their living envelop. On this 
account, it has been called the nurse. 

14* 




Fig. 139. 





162 REPRODUCTION. 

341. When they have reached a certain size, the young 
Cercariae leave the body of the nurse, and move freely in 
the abdominal cavity of the mollusks, or escape from it into 
the water, to fix themselves, in their turn, to the body of 
another rnollusk, and begin their transformations anew. 
312. But this is not the end of the series. The nurses of 
the Cercaria are themselves the offspring of little 
worms of yet another kind. At certain seasons, 
we find in the viscera of the Limnea, worms 
somewhat like the nurses of Cercaria in shape, 
(Fig. 141,) but rather longer, more slender, and 
having a much more elongated stomach, (s.) 
These worms contain, in the hinder part of the 
body, little embryos, (,) which are the young 
nurses, like Figures 139, 140. This generation 

TTl 1 *| 1 ^^ ^^ 

has received the name of grand-nurses. 

343. Supposing these grand-nurses to be the immediate 
offspring of the Distoma, (Fig. 138,) as is probable, we have 
thus a quadruple series of generation. Four generations 
and one metamorphosis are required to evolve the perfect 
animal ; in other words, the parent finds no resemblance to 
himself in any of his progeny, until he comes down to the 
great-grandson. 

344. Among the Aphides, or plant-lice, the number of 
generations is still greater. The first generation, which is 
produced from eggs, soon undergoes metamorphoses, and 
then gives birth to a second generation, which is followed by 
a third, and so on ; so that it is sometimes the eighth or 
ninth generation before the perfect animals appear as males 
and females, the sexes being then for the first time distinct, 
and the males provided with wings. The females lay eggs, 
which are hatched the following year, to repeat the same 
succession. Each generation is an additional step towards 
the perfect state : and, as each member of the succession is 



ALTERNATE AND EQUIVOCAL REPRODUCTION. 163 

an incomplete animal, we cannot better explain their office, 
than by considering them analogous to the larvae of the 
Cercaria, that is, as nurses.* 

345. The development of the Medusa? is not less instruc- 
tive. According to the observations of Sars, a Norwegian 
naturalist, the Medusa brings forth living young, which, 
after having burst the covering of the egg, swim about 
freely for some time in the body of the mother. When 
born, these animals have no resemblance whatever to the 
perfect Medusa. They are little cylindrical bodies, (Fig. 
142, ,) much resembling infusoria, and, like them, covered 
with minute cilia, by means of which they swim with much 
activity. 

V 

346. After swimming about freely in the water for some 
days, the little animal fixes itself by one extremity, (Fig. 
142, e.) At the opposite extremity a depression is gradu- 

* There is a certain analogy between the larvae of the plant-louse 
(Aphis) and the neuters or working ants and bees. This analogy has 
given rise to various speculations, and, among others, to the following 
theory, which is not without interest. The end and aim of all alternate 
generation, it is said, is to favor the development of the species in its 
progress towards the perfect state. Among the plant-lice, as among all 
the nurses, this end is accomplished by means of the body of the nurse. 
Now, a similar end is accomplished by the working ants and bees, only, 
instead of being performed as an organic function, it is turned into an 
outward activity, which makes them instinctively watch over the new gen- 
eration, nurse and take care of it. It is no longer the body of the nurse, 
but its own instincts, which become the instrument of the development. 
This seems to receive confirmation from the fact that the working bees, 
like the plant-lice, are barren females. The attributes of their sex, in 
both, seem to consist only in their solicitude for the welfare of the new 
generation, of which they are the natural guardians, but not the parents. 
The task of bringing forth young is confided to other individuals, to the 
queen among the bees, and to the female of the last generation among 
the plant-lice. Thus the barrenness of the working bees, which seems 
an anomaly as long as we consider them complete animals, receives 
a very natural explanation so soon as we look upon them, merely as 
nurses. 



164 



REPRODUCTION. 



ally formed, the four corners (bf) become elongated, and, 
by degrees, are transformed into tentacles, (c.) These 



a 







01 






Fig. 142. 



tentacles rapidly multiply, until the whole of the upper 
margin is covered with them, (g.] Then transverse 
wrinkles are seen on the body, at regular distances, ap- 
pearing first above and extending downwards. These 
wrinkles, which are at first very slight, grow deeper and 
deeper, and, at the same time, the edge of each segment 
begins to be serrated, so that the animal presents the ap- 
pearance of a pine cone, surmounted by a tuft of tentacles, 
(h ;) whence the name of Strobila, which was originally 
given to it, before it was known to be only a transient state 
of the jelly-fish. The separation constantly goes on, until at 
last the divisions are united by only a very slender axis, and 
resemble a pile of cups placed within each other, (i.) 
The divisions are now ready for separation ; the upper ring 
first disengages itself, and then the others in succession.* 
Each segment (d) then continues its development by itself, 
until it becomes a complete Medusa, (k ;) while, according 
to recent researches, the basis or stalk .remains and pro- 
duces a new colony. 

347. It is thus, by a series of metamorphoses, that the 
little animal which, on leaving the egg, has the form of the 

* These free segments have been described as peculiar animals, under 
the name of Ephyra. 



ALTERNATE AND EQUIVOCAL REPRODUCTION. 165 

Infusoria, passes in succession through all the phases we 
have described. But the remarkable point in these meta- 
morphoses is, that what was at first a single individual is 
thus transformed, by transverse division, into a number of 
entirely distinct animals, which is not the case in ordinary 
metamorphoses. Moreover, the upper segment does not 
follow the others in their development. Its office seems to 
be accomplished so soon as the other segments begin to be 
independent, being intended merely to favor their develop- 
ment, by securing and preparing the substances necessary 
to their growth. In this respect, it resembles the nurse of 
the Cere aria. 

348. The Hydroid Polyps present phenomena no less 
numerous and strange. The Campanularia has a branching, 
plant-like form, with little cup-shaped cells on the ends and in 
the axils of the branches, each of which contains a little 
animal. These cups have not all the same 
organization. Those at the extremity of 

the branches, (,) and which appear first, 
are furnished with long tentacles, where- 
with they seize their food, (Fig. 143.) 
Those in the axils of the branches, and 
which appear late, are females, (,) and 
have no such tentacles. Inside of the lat- 
ter, little spherical bodies are found, each 
having several spots in the middle ; these 
are the eggs. Finally, there is a third 
form, different from the two preceding, 
produced by budding from the female polyp, to which it in 
some sort belongs, (c.) It is within this that the eggs ar- 
rive, after having remained some time within the female. 
Their office seems to be to complete the incubation, for it is 
always within them that the eggs are hatched. 

349. The little animal, on becoming free, has not the 





166 REPRODUCTION. 

slightest resemblance to the adult polyp. As in the young 
Medusa, the body is cylindrical, covered with 
delicate cilia. After having remained free for 
some time, the young animal fixes itself and as- 
sumes a flattened form. By degrees, a little swell- 
ing rises from the centre, which elongates, and at 
last forms a stalk. This stalk ramifies, and we 
soon recognize in it the animal of figure 143, 
with the three kinds of buds, which we may 
consider as three distinct forms of the same animal. 

350. The development of Campanularia presents, in 
some respects, an analogy to what takes place in the re- 
production of plants, and especially of trees. They should 
be considered as groups of individuals, and not as single 
individuals. The seed, which corresponds to the embryo 
of the Hydroid, puts forth a little stalk. This stalk soon 
ramifies by gemmiparous reproduction, that is, by throwing 
out buds which become branches. But ovulation, or repro- 
duction by means of seeds, does not take place until an ad- 
vanced period, and requires that the tree should have attained 
a considerable growth. It then produces flowers with pistils 
and stamens, that is, males and females, which are com- 
monly united in one flower, but which in some instances are 
separated, as in the hickories, the elders, the willows, &c.* 

* Several plants are endowed with organs similar to the third form of 
buds, as seen in the Campanularia ; for example, the liverwort, (Marchan- 
tia polymorpha,) which has at the base of the cup a little receptacle, from 
the bottom of which little disk-like bodies are constantly forming, which, 
when detached, send out roots, and gradually become complete individu- 
als. Besides that, we find in these animals, as in plants, the important 
peculiarity, that all the individuals are united in a common trunk, which 
is attached to the soil ; and that all are intimately dependent on each 
other, as long as they remain united. And if we compare, in this point 
of view, the various species in which alternate reproduction has been 
observed, we find that the progress displayed in each type consists pre- 
cisely in the increasing freedom of the individual in its various forms. At 



CONSEQUENCES OF ALTERNATE GENERATION. 167 



SECTION III. 

CONSEQUENCES OF ALTERNATE GENERATION. 

351. These various examples of alternate generation ren- 
der it evident, that this phenomenon ought not to be consid- 
ered as an anomaly in Nature ; but as the special plan of de- 
velopment, leading those animals in which it occurs to the 
highest degree of perfection of which they are susceptible. 
Moreover, it has been noticed among all types of inverte- 
brated animals ; while among the Vertebrates it is as yet 
unknown. It would seem that individual life in the lower 
animals is not defined within so precise limits as in the 
higher types ; owing, perhaps, to the greater uniformity and 
independence of their constituent elements, the cells, and 
that, instead of passing at one stride as it were, through all 
the phases of their development, in order to accomplish it, 
they must either be born in a new form, as in the case of 
alternate generation, or undergo metamorphoses, which are 
a sort of second birth. 

352. Many analogies may be discovered between alternate 
reproduction and metamorphosis. They are parallel lines 
that lead to the same end, namely, the development of the 
species. Nor is it rare to see them coexisting in the same 

first, we have all the generations united in a common trunk, as in the 
lower Polyps and in plants ; then in the Medusae and in some of the 
Hydroid Polyps the third generation begins to disengage itself. Among 
some of the intestinal worms, (the Distoma,) the third generation is 
enclosed within its nurse, and this, in its turn, is contained in the body 
of the grand-nurse, while the complete Distoma lives as a parasitic worm 
in the body of other animals, or even swims freely about in the larva 
state, as Cercaria. Finally, in the Plant-lice, all the generations, the 
nurses as well as the perfect animals, are separate individuals. 



168 REPRODUCTION. 

animal. Thus, in the Cercaria, we have seen an animal pro- 
duced from a nurse afterwards transformed into a Distoma, 
by undergoing a regular metamorphosis. 

353. In each new generation, as in each new metamor- 
phosis, a real progress is made, and the form which results 
is more perfect than its predecessor. The nurse that pro- 
duces the Cercaria is manifestly an inferior state, just as the 
chrysalis is inferior to the butterfly. 

354. But there is this essential difference between the 
metamorphoses of the caterpillar and alternate reproduction, 
that, in the former case, the same individual passes through 
all the phases of development ; whereas, in the latter, the 
individual disappears, and makes way for another, which 
carries out what its predecessors had begun. It would give 
a correct idea of this difference to suppose that the tadpole, 
instead of being itself transformed into a frog, should die, 
having first brought forth young frogs ; or that the chrysalis 
should, in the same way, produce young butterflies. In 
either case, the young would still belong to the same species, 
but the cycle of development, instead of being accomplished 
in a single individual, would involve two or more acts of 
generation. 

355. It follows, therefore, that the general practice of de- 
riving the character of a species from the sexual forms alone, 
namely, the male and the female, is not applicable to all 
classes of animals ; since there are large numbers whose 
various phases are represented by distinct individuals, en- 
dowed with peculiarities of their own. Thus, while in the 
stag the species is represented by two individuals only, stag 
and hind, the Medusa, on the other hand, is represented 
under the form of three different types of animals ; the first 
is free, like the Infusoria, the second is fixed on a stalk, like 
a polyp, and the third again is free, consisting in its turn 
of male and female. In the Distoma, also, there are four 



CONSEQUENCES OF ALTERNATE GENERATION. 169 

separate individuals, the grand-nurse, the nurse, the larva or 
Cercaria, and the Distoma, in which the sexes are not sepa- 
rate. Among the Aphides, the number is much greater 
still. 

356. The study of alternate generation, besides making 
us better acquainted with the organization of the lower ani- 
mals, greatly simplifies our nomenclature. Thus, in future, 
instead of enumerating the Distoma and the Cercaria, or the 
Strobila, the Ephyra, and the Medusa, as distinct animals, 
belonging to different classes and families, only the name 
first given to one of these forms will be retained, and the 
rest be struck from the pages of Zoology, as representing 
only the transitory phases of the same species. 

357. Alternate generation always presupposes several 
modes of reproduction, of which the primary is invariably 
by ovulation. Thus, we have seen that the Polyps, the 
Medusa, the Salpa, &c., produce eggs, which are generally 
hatched within the mother. The subsequent generation, on 
the contrary, is produced in a different manner, as we have 
shown in the preceding paragraphs ; as among the Medusas, 
by transverse division ; among the Polyps and Salpee, by 
buds, &c. 

358. The subsequent generations are, moreover, not to be 
regarded in the same light as those which first spring directly 
from eggs. In fact, they are rather phases of development, 
than generations properly so called ; they are either without 
sex, or females whose sex is imperfectly developed. The 
nurses of the Distoma, the Medusa, and the Campanularia, 
are barren, and have none of the attributes of maternity, 
except that of watching over the development of the species, 
being themselves incapable of producing young. 

359. Another important result follows from the above ob- 
servations, namely, that the differences between animals 
which are produced by alternate generation are less, the 

15 



170 REPRODUCTION. 

earlier the epoch at which we examine them. No two ani- 
mals can be more unlike than an adult Medusa (Fig. 31) 
and an adult Campanularia, (Fig. 143;) they even seem to 
belong to different classes of the Animal Kingdom, the for- 
mer being considered as an Acaleph, the latter as a Polyp. 
On the other hand, if we compare them when first hatched 
from the egg, they appear so much alike that it is with the 
greatest difficulty they can be distinguished. They are 
then little Infusoria, without any very distinct shape, and 
moving with the greatest freedom. The larvse of certain 
intestinal worms, though they belong to a different depart- 
ment, have nearly the same form, at one period of their life. 
Farther still, this resemblance extends to plants. The 
spores of certain sea-weeds have nearly the same appear- 
ance as the young Polyp, or the young Medusa ; and what 
is yet more remarkable, they are also furnished with cilia, 
and move about in a similar manner. But this is only a 
transient state. Like the young Campanularia and the young 
Medusa, the spore of the sea-weed is free for only a short 
time ; soon it becomes fixed, and from that moment the 
resemblance ceases. 

360. Are we to conclude, then, from this resemblance of 
the different types of animals at the outset of life, that there 
is no real difference between them ; or that the two King- 
doms, the Animal and the Vegetable, actually blend, be- 
cause their germs are similar ? On the contrary, we think 
nothing is better calculated to strengthen the idea of the 
original separation of the various groups, as distinct and 
independent types, than the study of their different phases. 
In fact, a difference so wide as that between the adult 
Medusa and the adult Campanularia must have existed even 
in the young ; only it does not show itself in a manner 
appreciable by our senses ; the character by which they 
subsequently differ so much being not. yet developed. To 



CONSEQUENCES OF ALTERNATE GENERATION. 171 

deny the reality of natural groups, because of these early 
resemblances, would be to take the semblance for the 
reality. It would be the same as saying that the frog and 
the fish are one, because at one stage of embryonic life it is 
impossible, with the means at our command, to distinguish 
them. 

361. The account we have above given of the develop- 
ment, the metamorphoses, and the alternate reproduction of 
the tower animals, is sufficient to undermine the old theory 
of Spontaneous Generation, which was proposed to account 
for the presence of worms in the bodies of animals, for the 
sudden appearance of myriads of animalcules in stagnant 
water, and under other circumstances rendering their occur- 
rence mysterious. We need only to recollect how the 
Cercaria insinuates itself into the 

skin and the viscera of mollusks, 
(339, 342,) to understand how 
admission may be gained to the 
most inaccessible parts. Such be- 
ings occur even in the eye of many Fig. 145. Fig. 146. 
animals, especially of fishes ; they 

are numerous in the eye of the common fresh-water perch 
of Europe. To the naked eye they seem like little white 
spots, (Fig. 145;) but when magnified, they have the form 
of Fig. 146. 

362. As to the larger intestinal worms found in other 
animals, the mystery of their origin has been entirely solved 
by recent researches. A single instance will illustrate their 
history. At certain periods of the year, the Sculpins of the 
Baltic are infested by a particular species of Tsenia or tape- 
worm, from which they are free at other seasons. Mr. Esch- 
richt found that, at certain seasons, the worms lose a great 
portion of the long chain of rings of which they are com- 
posed. On a careful examination, he found that each ring 





172 KEPRODUCTION. 

contained several hundred eggs, which, on being freed from 
their envelop, float in the water. As these eggs are innu- 
merable, it is not astonishing that the Sculpins should occa- 
sionally swallow some of them with their prey. The eggs, 
being thus introduced into the stomach of the fish, find con- 
ditions favorable to their development ; and thus the species 
is propagated, and at the same time transmitted from one 
generation of the fish to another. The eggs which are not 
swallowed are probably lost. 

363. All animals swallow, in the same manner, with their 
food, and in the water they drink, numerous eggs of such 
parasites, any one of which, finding in the intestine of the 
animal favorable conditions, may be hatched. It is probable 
that each animal affords the proper conditions for some par- 
ticular species of worm ; and thus we may explain how it is 
that most animals have parasites peculiar to themselves. 

364. As respects the Infusoria, we also know that most 
of them, the Rotifera especially, lay eggs. These eggs, 
which are extremely minute, (some of them only y]jtTo^ ^ 
an inch in diameter,) are scattered every where in great 
profusion, in water, in the air, in mist, and even in snow. 
Assiduous observers have not only seen the eggs laid, but 
moreover, have followed their development, and have seen 
the young animal forming in the egg, then escaping from it, 
increasing in size, and, in its turn, laying eggs. They have 
been able, in some instances, to follow them even to the fifth 
and sixth generation. 

365. This being the case, it is much more natural to 
suppose that the Infusoria * are products of like germs, than 



* In this connection, it ought to be remembered that a large proportion 
of the so-called Infusoria are not independent animals, but immature 
germs, belonging to different classes of the Animal Kingdom, and that 
many must be referred to the Vegetable Kingdom. 



SPONTANEOUS GENERATION. 173 

to assign to them a spontaneous origin altogether incompati- 
ble with what we know of organic development. Their 
rapid appearance is not at all astonishing, when we reflect 
that some mushrooms attain a considerable size in a few 
hours, but yet pass through all the phases of regular growth ; 
and, indeed, since we have ascertained the different modes of 
generation among the lower animals, no substantial difficul- 
ties to the axiom, " omne vivum ex ovo," (275,) any longer 
exist. 

15* 



CHAPTER TWELFTH. 

METAMORPHOSES OF ANIMALS. 

366. UNDER the name of metamorphoses are included 
those changes which the body of an animal undergoes after 
its birth, and which are modifications, in various degrees, of 
its organization, form, and its mode of life. Such changes 
are not peculiar to certain classes, as has been so long sup- 
posed, but are common to all animals, without exception. 

367. Vegetables also undergo metamorphoses, but with 
this essential difference, that in vegetables the process con- 
sists in an addition of new parts to the old ones. A succession 
of leaves, differing from those which preceded them, comes 
on each season ; new branches and roots are added to the 
old stem, and woody layers to the trunk. In animals, the 
whole body is transformed, in such a manner that all the 
existing parts contribute to the formation of the modified 
body. The chrysalis becomes a butterfly ; the frog, after 
having been herbivorous during its tadpole state, becomes 
carnivorous, and its stomach is adapted to this new mode of 
life ; at the same time, instead of breathing by gills, it be- 
comes an air-breathing animal ; its tail and the gills disap- 
pear ; lungs and legs are being developed, and, finally, it is 
to live and move on land. 

368. The nature, the duration, and importance of meta- 
morphoses, as also the epoch at which they take place, are 
infinitely varied. The most striking changes which naturally 
present themselves to the mind when we speak of metamor- 



METAMORPHOSES OF ANIMALS. 175 

phoses, are those occurring in insects. Not merely is there 
a change of physiognomy and form observable, or an organ 
more or less formed, but their whole organization is modified. 
The animal enters into new relations with the external world, 
while, at the same time, new instincts are imparted to it. It 
has lived in water, and respired by gills ; it is now furnished 
with air-tubes, and breathes in the atmosphere. It passes by, 
with indifference, objects which before were attractive, and 
its new instincts prompt it to seek conditions which would 
have been most pernicious during its former period of life. 
All these changes are brought about without destroying the 
individuality of the animal. The mosquito, which to-day 
haunts us with its shrill trumpet, and pierces us for our 
blood, is the same animal that, a few days ago, lived obscure 
and unregarded in stagnant water, under the guise of a little 
worm. 

369. Every one is familiar with the metamorphoses of the 
silk-worm. On escaping from the egg, the little worm or 
caterpillar grows with great rapidity for twenty days, when 
it ceases to feed, spins its silken cocoon, casts its skin, and 
remains enclosed in its chrysalis state.* During this period 
of its existence, most extraordinary changes take place. The 
jaws with which it masticated mulberry leaves are trans- 
formed into a coiled tongue ; the spinning organs are reduced ; 
the gullet is lengthened and more slender; the stomach, 
which was nearly as long as the body, is now contracted into 
a short bag ; the intestine, on the contrary, becomes elon- 
gated and narrow. The dorsal vessel is shortened. The 
ganglions of the thoracic region approach each other, and 
unite into a single mass. Antennas and palpi are developed on 
the head, and instead of simple eyes appear compound ones. 



* In the raising of silk-worms this period is not waited for, but the ani- 
mal is killed as soon as it has spun its cocoon. 



176 METAMORPHOSES OF ANIMALS. 

The muscles, which before were uniformly distributed, (159,) 
are now gathered into masses. The limbs are elongated, 
and wings spring forth from the thorax. More active motions 
then reappear in the digestive organs, and the animal, burst- 
ing the envelop of its chrysalis, issues in the form of a winged 
moth. 

370. The different external forms which an insect may 
assume is well illustrated by one which is unfortunately too 
well known in this country, namely, the canker-worm. Its 
eggs are laid on posts and fences, or upon the branches of our 
apple-trees, elms, and other trees. They are hatched about 
the time the tender leaves of these trees begin to unfold. 

a b c d 






Fig. 147. 

The caterpillar (a) feeds on the leaves, and attains its full 
growth at the end of about four weeks, being then not quite 
an inch in length. It then descends to the ground, and en- 
ters the earth to the depth of four or five inches, and having 
excavated a sort of cell, is soon changed into a chrysalis or 
nymph, (5.) At the usual time in the spring, it bursts the 
skin, and appears in its perfect state, under the form of a 
moth, (d.) In this species, however, only the male has 
wings. The perfect insects soon pair, the female (c) crawls 
up a tree, and, having deposited her eggs, dies. 

371. Transformations no less remarkable are observed 
among the Crustacea. The metamorphoses in the family of 
Cirrhipedes are especially striking. It is now known that 
the barnacles, (Balanus,) which have been arranged among 
the mollusks, are truly crustaceans ; and this result of modern 
researches has been deduced in the clearest manner from the 



METAMORPHOSES OF ANIMALS. 



J77 



study of their transformations. The following figures repre- 
sent the different phases of the duck-barnacle, (Anatifa.) 



a 




Fig. 148. 



372. The Anatifa, like all Crustacea, is reproduced by 
eggs, specimens of which, magnified ninety diameters, are 
represented in figure 148, a. From these eggs little ani- 
mals issue, which have not the slightest resemblance to the 
parent. They have an elongated form, (&,) a pair of ten- 
tacles, and four legs, with which they swim freely in the 
water. 

373. Their freedom, however, is of but short duration. 
The little animal soon attaches itself by means of its tenta- 
cles, having previously become covered with a transparent 
shell, through which the outlines of the body, and also a very 
distinct eye, are easily distinguished, (Fig. 148, c.) Figure 
148, d, shows the animal taken out of its shell. It is plainly 
seen that the anterior portion has become considerably en- 
larged. Subsequently, the shell becomes completed, and 
the animal casts its skin, losing with it both its eyes and its 
tentacles. On the other hand, a thick membrane lines the 
interior of the shell, which pushes out and forms a stem, 
(e,) by means of which the animal fixes itself to immersed 
bodies, after the loss of its tentacles. This stem gradually 
enlarges, and the animal soon acquires a definite shape, such 



178 



METAMORPHOSES OF ANIMALS. 



as it is represented in figure 148, /, attached to a piece of 
floating wood. 

374. There is, consequently, not only a change of organi- 
zation in the course of the metamorphoses, but also a change 
of faculties and mode of life. The animal, at first free, 
becomes fixed ; and its adhesion is effected by totally 
different organs at different periods of life, first by means of 
tentacles, which were temporary organs, and afterwards 
by means of a fleshy stem developed especially for that 
purpose. 

375. The Radiata also furnish us with examples of vari- 
ous metamorphoses, especially among the star-fishes. A 
small species living on the coast of New England (Echi- 
naster sanguinolentus) undergoes the following phases, 
(Fig. 149.) 




376. If the eggs are examined by the microscope, each 
one is found to contain a small, pear-shaped body, which 
is the embryo, (e,) surrounded by a transparent envelop. 
On escaping from the egg, the little animal has an oblong 
form, with a constriction at the base. This constriction 
becoming deeper and deeper forms a pedicle, (p,) which 
soon divides into three lobes. The disk also assumes a pen- 
tagonal form, with five double series of vesicles. The first 
rudiments of the rays are seen to form in the interior of the 
pentagon. At the same time, the peduncle contracts still 
more, being at last entirely absorbed into the cavity of the 
body, and the animal soon acquires its final form, (m.) 



METAMORPHOSES OF ANIMALS. 



179 





Fig. 151. 



377. Analogous transformations take place in the Comat- 

ula. In early life 
(Fig. 150) it is 
fixed to the ground 
by a stem, but be- 
comes detached at 
a certain epoch, 
and then floats 
freely in the sea, 
(Fig. 151.) On 
the other hand, 

the Polypi seem to follow a reverse 
course, many of them becoming fixed to 
the ground after having been previously 
Fig. 150. free. 

378. The metamorphoses of mollusks, though less 
striking, are not less worthy of notice. Thus, the oyster, 
with which we are familiar in its adhering shell, is free 
when young, like the clam (Mya) and most other shell- 
fishes. Others, which are at first attached or suspended to 
the gills of the mother, afterwards become free, as the Unio. 
Some naked Gasteropods, the Acteon or the Eolis, for ex- 
ample, are born with a shell, which they part with shortly 
after leaving the egg. 

379. The study of metamorphoses is, therefore, of the 
utmost importance for understanding the real affinities of 
animals very different in appearance, as is readily shown by 
the following instances. The butterfly and the earth-worm 
seem, at the first glance, to have no relation whatever. 
They differ in their organization, no less than in their out- 
ward appearance. But, on comparing the caterpillar and 
the worm, these two animals closely resemble each other. 
The analogy, however, is only transient ; it lasts only 
during the larva state of the caterpillar, and is effaced as it 



180 METAMORPHOSES OF ANIMALS. 

passes to the chrysalis and butterfly states. The latter be- 
comes a more and more perfect animal, whilst the worm 
remains in its inferior state. 

380. Similar instances are furnished by animals belong- 
ing to all the types of the Animal Kingdom. Who would 
think, at first glance, that a Barnacle or an Anatifa were 
more nearly allied to the crab than to the oyster ? And, 
nevertheless, we have seen, (372,) in tracing back the Anat- 
ifa to its early stages, that it then bears a near resemblance 
to a little Crustacean, (Fig. 148, d.] It is only when full 
grown that it assumes its peculiar moliusk-like covering. 

381. Among the Cuttle-fishes there are several, the 
Loligo, (Fig. 47,) for example, which are characterized by 
the form of their tentacles, the two interior being much 
longer than the others, and of a different form ; whilst in 
others, as the Octopus, they are all equal. But if we com- 
pare the young, we find that in both animals the tentacles 
are all equal, though they differ in number. The inequality 
in the tentacles is the result of a further development. 

382. Among the Radiata, the Pentacrinus and the Comat- 
ula exemplify the same point. The two are very different 
when full grown, the latter being a free-swimming star-fish, 
(Fig. 151,) while the former is attached to the soil, like a 
Polyp. But we have seen (377) that the same is the case 
with Comatula in its early period ; and that, in consequence 
of a further metamorphosis, it becomes disengaged from its 
stem, and floats freely in the water. 

383. In the type of Vertebrates, the considerations drawn 
from metamorphoses acquire still greater importance in ref- 
erence to classification. The Sturgeon and the White-fish, 
before mentioned, (306,) are two very different fishes ; yet, 
taking into consideration their external form and bearing 
merely, it might be questioned which of the two should 
take the highest rank ; whereas the doubt is very easily 



METAMORPHOSES OF ANIMALS. 



181 



resolved by an examination of their anatomical structure. 
The White-fish has a skeleton, and, moreover, a vertebral 
column, composed of firm bone. The Sturgeon, (Fig. 152,) 




Fig. 152. 

on the contrary, has no bone in the vertebral column, except 
the spines or apophyses of the vertebras. The middle part, 
or body of the vertebra, is cartilaginous ; the mouth is trans- 
verse, and underneath the head ; and the caudal fin is un- 
equally forked, while in the White-fish it is equally forked. 

384. If, however, we observe the young W T hite-fish just 
after it has issued from the egg, (Fig. 123,) the contrast will 
be less striking. At this period the vertebras are cartilagi- 
nous, like those of the Sturgeon ; its mouth, also, is trans- 
verse and inferior, and its tail undivided ; at that period the 
White-fish and the Sturgeon are, therefore, much more alike. 
But this similarity is only transient ; as the White-fish grows, 
its vertebras become ossified, and its resemblance to the 
Sturgeon is comparatively slight. As the Sturgeon has no 
such transformation of the vertebras, and is, in some sense, 
arrested in its development, while the White-fish undergoes 
subsequent transformation, we conclude that, compared with 
the White-fish, it is really inferior in rank. 

385. This relative inferiority and superiority strikes us 
still more when we compare with our most perfect fishes 
(the Salmon, the Cod) some of those worm-like animals, so 
different from ordinary fishes that they were formerly placed 
among the worms. The Am- 



phioxus, represented of its nat- 
ural size, (Fig. 153,) not only Fig. 153. 
16 



182 METAMORPHOSES OF ANIMALS. 

has no bony skeleton, but not even a head, properly speak- 
ing. Yet the fact that it possesses a dorsal cord, extending 
from one extremity of the body to the other, proves that it 
belongs to the type of Vertebrates. But as this peculiar 
structure is found only at a very early period of embryonic 
development, in other fishes, we conclude that the Amphi- 
oxus holds the very lowest rank in this class. 

386. Nevertheless, the metamorphoses of animals after 
birth, will, in many instances, present but trifling modifica- 
tions of the relative rank of animals, compared with those 
which may be derived from the study of changes previous 
to that period, as there are many animals which undergo no 
changes of great importance after their escape from the egg, 
and occupy, nevertheless, a high rank in the Zoological 
series, as, for example, Birds and Mammals. The question 
is, whether such animals are developed according to differ- 
ent plans, or whether their peculiarity in that respect is 
merely apparent. To answer this question, let us go back 
to the period anterior to birth, and see if some parallel may 
not be made out between the embryonic changes of these 
animals and the metamorphoses which take place subse- 
quently to birth in others. 

387. We have already shown that embryonic develop- 
ment consists in a series of transformations ; the young ani- 
mal enclosed in the egg differing at each period of its de- 
velopment, from what it was before. But because these 
transformations precede birth, and are, therefore, not generally 
observed, they are not less important. To be satisfied that 
these transformations are in every respect similar to those 
which follow birth, we have only to compare the changes 
which immediately precede birth with those which immediate- 
ly follow it, and we shall readily perceive that the latter are 
simply a continuation of the former, till all are completed. 

388. Let us recur to the development of fishes for illus- 



METAMORPHOSES OF ANIMALS. 183 

tration. The young White-fish, as we have seen, (315,) is 
far from having acquired its complete development when 
born. The vertical fins are not yet separate ; the mouth has 
not yet its proper position ; the yolk has not yet retreated 
within the cavity of the body, but hangs below the chest in 
the form of a large bag. Much, therefore, remains to be 
changed before its development is complete. But the fact 
that it has been born does not prevent its future evolution, 
which goes on without interruption. 

389. Similar inferences may be drawn from the develop- 
ment of the chicken. The only difference is, that the young 
chicken is born in a more mature state, the most important 
transformations having taken place during the embryonic 
period, while those to be undergone after birth are less con- 
siderable, though they complete the process begun in the 
embryo. Thus we see it, shortly after birth, completely 
changing its covering, and clothed with feathers instead of 
down ; still later its crest appears, and its spurs begin to be 
developed. 

390. In certain Mammals, known under the name of 
Marsupials, (the Opossum and Kangaroo,) the link between 
the transformations which take place before birth, and those 
that occur at a later period, is especially remarkable, These 
animals are brought into the world so weak and undeveloped 
that they have to undergo a second gestation, in a pouch with 
which the mother is furnished, and in which the young remain, 
each one fixed to a teat, until they are entirely developed. 
Even those animals which are born nearest to the complete 
state, undergo, nevertheless, embryonic transformations. 
Ruminants acquire their horns ; and the lion his mane. Most 
mammals, at birth, are destitute of teeth, and incapable of 
using their limbs ; and all are dependent on the mother, and 
the milk secreted by her, until the stomach is capable of 
digesting other aliments. 



184 METAMORPHOSES OF ANIMALS. 

391. If it be thus shown that the transformations which 
take place in the embryo are of the same nature, and of the 
same importance, as those which occur afterwards, the cir- 
cumstance that some precede and others succeed birth can- 
not mark any radical distinction between them. Both are 
processes of the life of the individual. Now, as life does not 
commence at birth, but goes still farther back, it is quite clear 
that the modifications which supervene during the former 
period are essentially the same as, and continuous with, the 
later ones ; and hence, that metamorphoses, far from being 
exceptional in the case of Insects, are one of the general 
features of the Animal Kingdom. 

392. We are, therefore, perfectly entitled to say that all 
animals, without exception, undergo metamorphoses. Were 
it not so, we should be at a loss to conceive why animals 
of the same division present such wide differences; and that 
there should be, as in the class of Reptiles, some families 
that undergo important metamorphoses, (the frogs, for ex- 
ample,) and others in which nothing of the kind is observed 
after birth, (the Lizards and Tortoises.) 

393. It is only by connecting the two kinds of transforma- 
tions, namely, those which take place before, and those after 
birth, that we are furnished with the means of ascertaining 
the relative perfection of an animal ; in other words, these 
transformations become, under such circumstances, a natural 
key to the gradation of types. At the same time, they will 
force upon us the conviction that there is an immutable prin- 
ciple presiding over all these changes, and regulating them 
in a peculiar manner in each animal. 

394. These considerations are exceedingly important, not 
only from their bearing upon classification, but not less so from 
the application which may be made of them to the study of 
fossils. If we examine attentively the fishes that have been 
found in the different strata of the earth, we remark that 



METAMORPHOSES OF ANIMALS. 185 

those of the most ancient deposits have, in general, preserved 
only the apophyses of their vertebrse, whilst the vertebra? 
themselves are wanting. Were the Sturgeons of the Amer- 
ican rivers to become petrified, they would be found in a 
similar state of preservation. As the apophyses are the 
only bony portions of the vertebral column, they alone 
would be preserved. Indeed, fossil Sturgeons are known, 
which are in precisely this condition. 

395. From the fact above stated, we may conclude that 
the oldest fossil fishes did not pass through all the metamor- 
phoses which our osseous fishes undergo ; and, consequently, 
that they were inferior to analogous species of the present 
epoch which have bony vertebrae. Similar considerations 
apply to the fossil Crustacea and to the fossil Echinoderms, 
when compared with living ones, and will, probably, be 
true of all classes of the Animal Kingdom, when fully studied 
as to their geological succession. 

16* 



CHAPTER THIRTEENTH. 

GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 
SECTION I. 

GENERAL LAWS OF DISTRIBUTION. 

396. No animal, excepting man, inhabits every part of the 
surface of the earth. Each great geographical or climatal 
region is occupied by some species not found elsewhere ; 
and each animal dwells within certain limits, beyond which 
it does not range while left to its natural freedom, and within 
which it always inclines to return, when removed by acci- 
dent or design. Man alone is a cosmopolite. His domain is 
the whole earth. For him, and with a view to him, it was 
created. His right to it is based upon his organization and 
his relation to Nature, and is maintained by his intelligence 
and the perfectibility of his social condition. 

397. A group of animals which inhabits any particular 
region, embracing all the species, both aquatic and terrestrial, 
is called its FAUNA ; in the same manner as the plants of a 
country are called its Flora. To be entitled to this name, it 
is not necessary that none of the animals composing the 
group should be found in any other region ; it is sufficient 
that there should be peculiarities in the distribution of the 
families, genera, and species, and in the preponderance of 
certain types over others, sufficiently prominent to impress 
upon a region well-marked features. Thus, for example, in 
the islands of the Pacific are found terrestrial animals, alto- 



GENERAL LAWS OF DISTRIBUTION. 187 

gether peculiar, and not found on the nearest continents. 
There are numerous animals in New Holland differing from 
any found on the continent of Asia, or, indeed, on any other 
part of the earth. If, however, some species inhabiting both 
shores of a sea which separates two terrestrial regions are 
found to be alike, we are not to conclude that those regions 
have the same Fauna, any more than that the Flora of Lap- 
land and England are alike, because some of the sea-weeds 
found on both their shores are the same. 

398. There is an evident relation between the fauna of 
any locality and its temperature, although, as we shall here- 
after see, similar climates are not always inhabited by similar 
animals, (401, 402.) Hence the faunas of the two hemis- 
pheres have been distributed into three principal divisions, 
namely, the arctic, the temperate, and the tropical faunas ; 
in the same manner as we have arctic, temperate, and tropi- 
cal floras. Hence, also, animals dwelling at high elevations 
upon mountains, where the temperature is much reduced, 
resemble the animals of colder latitudes, rather than those of 
the surrounding plains. 

399. In some respects, the peculiarities of the fauna of a 
region depend upon its flora, at least so far as land animals 
are concerned ; for herbivorous animals will exist only 
where there is an adequate supply of vegetable food. But 
taking the terrestrial and aquatic animals together, the limi- 
tation of a fauna is less intimately dependent on climate 
than that of a flora. Plants, in truth, are for the most part 
terrestrial, (marine plants being relatively very few,) while 
animals are chiefly aquatic. The ocean is the true home of 
the Animal Kingdom ; and while plants, with the excep- 
tion of the lichens and mosses, become dwarfed, or perish 
under the influence of severe cold, the sea teems with 
animals of all classes, far beyond the extreme limit of flower- 
ing plants. 



188 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

400. The influence of climate, in the colder regions, acts 
merely to induce a greater uniformity in the species of 
animals. Thus the same animals inhabit the northern polar 
regions of the three continents. The polar bear is the same 
in Europe, Asia, and America, and so are also a great many 
birds. In the temperate regions, on the contrary, the 
species differ on each of the continents, but they still pre- 
serve the same general features. The types are the same, 
but they are represented by quite different species. In 
consequence of these general resemblances, the first colo- 
nists of New England erroneously applied the names of 
European species to American animals. Similar differences 
are observed in distant regions of the same continent, within 
the same parallels of latitude. The animals of Oregon and 
of California are not the same as those of New England. 
The difference, in certain respects, is even greater than 
between the animals of New England and Europe. In like 
manner, the animals of temperate Asia differ more from those 
of Europe than they do from those of America. 

401. Under the torrid zone, the Animal Kingdom, as well 
as the Vegetable, attains its highest development. The ani- 
mals of the tropics are not only different from those of the 
temperate zone, but, moreover, they present the greatest 
variety among themselves. The most gracefully propor- 
tioned forms are found by the side of the most grotesque, 
decked with every combination of brilliant coloring. At the 
same time, the contrast between the animals of different con- 
tinents is more marked ; and, in many respects, the animals 
of the different tropical faunas differ not less from each other 
than from those of the temperate or frozen zones. Thus, 
the fauna of Brazil varies as much from that of Central 
Africa as from that of the United States. 

402. This diversity upon different continents cannot de- 
pend simply on any influence of the climate of the tropics ; 



GENERAL LAWS OF DISTRIBUTION. 189 

if it were so, uniformity ought to be restored in proportion 
as we recede from the tropics towards the antarctic tem- 
perate regions. But, instead of this, the differences con- 
tinue to increase ; so much so, that no faunas are more in 
contrast than those of Cape Horn, the Cape of Good Hope, 
and New Holland. Hence, other influences must be in oper- 
ation besides those of climate; influences of a higher 
order, which are involved in a general plan, and intimately 
associated with the development of life on the surface of the 
^arth. 

403. Faunas are more or less distinctly limited, according 
to the natural features of the earth's surface. Sometimes 
two faunas are separated by an extensive chain of moun- 
tains, like the Rocky Mountains. Again, a desert may in- 
tervene, like the desert of Sahara, which separates the fauna 
of Central Africa from that of the Atlas and the Moorish 
coast, the latter being merely an appendage to the fauna 
of Europe. But the sea effects the most complete limita- 
tion. The depths of the ocean are quite as impassable for 
marine species as high mountains are for terrestrial animals. 
It would be quite as difficult for a fish or a mollusk to 
cross from the coast of Europe to the coast of America, as 
it would be for a reindeer to pass from the arctic to the 
antarctic regions, across the torrid zone. Experiments of 
dredging in very deep water have also taught us that the 
abyss of the ocean is nearly a desert. Not only are no 
materials found there for sustenance, but it is doubtful if ani- 
mals could sustain the pressure of so great a column of 
water, although many of them are provided with a system of 
pores, (260,) which enables them to sustain a much greater 
pressure than terrestrial animals. 

404. When there is no great natural limit, the transition 
from one fauna to another is made insensibly. Thus, in 
passing from the arctic to the temperate regions of North 



190 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

America, one species takes the place of another, a third suc- 
ceeds the second, and so on, until finally the fauna is found 
to be completely changed, though it is not always possible 
to mark the precise line which divides the one from the 
other. 

405. The range of species does not at all depend upon 
their powers of locomotion ; if it were so, animals which 
move slowly and with difficulty would have a narrow range, 
whilst those which are very active would be widely diffused. 
Precisely the reverse of this is actually the case. The com- 
mon oyster extends at least from the St. Lawrence to the 
Carolinas ; its range is consequently very great ; much more 
so than that of some of the fleet animals, as, for instance, the 
Moose. It is even probable that the very inability of the 
oyster to travel really contributes to its diffusion, inasmuch 
as, having once spread over extensive grounds, there is no 
chance of its return to a former limitation, inasmuch as, being 
fixed, and consequently unable to choose positions for its 
eggs, they must be left to the mercy of currents ; while 
Fishes, by depositing their eggs in the bays and inlets of the 
shore, undisturbed by currents and winds, secure them from 
too wide a dispersion. 

406. The nature of their food has an important bearing 
upon the grouping of animals, and upon the extent of their 
distribution. Carnivorous animals are generally less con- 
fined in their range than herbivorous ones ; because their 
food is almost every where to be found. The herbivora, on 
the contrary, are restricted to the more limited regions 
corresponding to the different zones of vegetation. The 
same remark may be made with respect to Birds. Birds of 
prey, such as the eagle and vulture, have a much wider range 
than the granivorous and gallinaceous birds. Still, notwith- 
standing the facilities they have for change of place, even 
the birds that wander widest recognize limits which they do 



GENERAL LAWS OF DISTRIBUTION. 191 

not overstep. The Condor of the Cordilleras does not de- 
scend into the temperate regions of the United States ; and yet 
it is not that he fears the cold, since he is frequently known 
to ascend even above the highest summits of the Andes, and 
disappears from view where the cold is most intense. Nor 
can it be from lack of prey. 

407. Again, the peculiar configuration of a country some- 
times determines a peculiar grouping of animals, into what 
may be called local faunas. Such, for example, are the 
prairies of the West, the Pampas of South America, the 
Steppes of Asia, the Deserts of Africa ; and, for marine 
animals, the basin of the Caspian. In all these localities, 
animals are met with which exist only there, and are not 
found except under those particular conditions. 

408. Finally, to obtain a true picture of the zoological 
distribution of animals, not the terrestrial types alone, but 
the marine species, must also be included. Notwithstanding 
the uniform nature of the watery element, the animals which 
dwell in it are not dispersed at random ; and though the 
limits of the marine may be less easily defined than those of 
the terrestrial faunas, still, marked differences between the 
animals of great basins are not less observable. Properly 
to apprehend how marine animals may be distributed into 
local faunas, it must be remembered that their residence is 
not in the high sea, but along the coasts of continents and 

O ' O 

on soundings. It is on the 'Banks of Newfoundland, and not 
in the deep sea, that the great cod-fishery is carried on ; and 
it is well known that when fishes migrate, they run along the 
shores. The range of marine species being, therefore, con- 
fined to the vicinity of the shores, their distribution must be 
subjected to laws similar to those which regulate the terres- 
trial faunas. As to the fresh-water fishes, not only do the 
species vary in the different zones, but even the different 
rivers of the same region have species peculiar to them, and 



192 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

not found in neighboring streams. The garpikes (Lepi- 
dosteus) of the American rivers afford a striking example of 
this kind. 

409. A very influential cause in the distribution of aquatic 
animals is the depth of the water ; so that several zoological 
zones, receding from the shore, may be defined, according 
to the depth of water ; much in the same manner as we mark 
different zones at different elevations in ascending moun- 
tains, (398.) The Mollusks, and even the Fishes found near 
the shore in shallow water, differ, in general, from those 
living at the depth of twenty or thirty feet, and these again 
are found to be different from those which are met with at 
a greater depth. Their coloring, in particular, varies, ac- 
cording to the quantity of light they receive, as has also 
been shown to be the case with the marine plants. 

410. It is sometimes the case that one or more animals 
are found upon a certain chain of mountains, and not else- 
where ; as, for instance, the Mountain Sheep ( Ouis montana) 
upon the Rocky Mountains, or the Chamois and the Ibex 
upon the Alps. The same is also the case on some of the 
wide plains or prairies. This, however, does not entitle 
such regions to be considered as having an independent 
fauna, any more than a lake is to be regarded as having a 
peculiar fauna, exclusive of the animals of the surrounding 
country, merely because some of the species found in the 
lake may not ascend the rivers emptying into it. It is only 
when the whole group of animals inhabiting such a region 
has such peculiarities as to give it a distinct character, when 
contrasted with animals found in surrounding regions, that 
it is to be regarded as a separate fauna. Such, for exam- 
ple, is the fauna of the great steppe, or plain of Gobi, in 
Asia ; and such indeed that of the chain of the Rocky Moun- 
tains may prove to be, when the animals inhabiting them shall 
be better known. 



GENERAL LAWS OF DISTRIBUTION. 193 

411. The migration of animals might at first seem to pre- 
sent a serious difficulty in determining the character or the 
limits of a fauna ; but this difficulty ceases, if we regard the 
country of an animal to be the place where it makes its 
habitual abode. As to Birds, which of all animals wander 
farthest, it may be laid down as a rule, that they belong 
to the zone in which they breed. Thus, the gulls, many of 
the ducks, mergansers, and divers, belong to the boreal 
regions, though they pass a portion of the year with us. On 
the other hand, the swallows and martins, and many of the 
gallinaceous birds belong to the temperate faunas, notwith- 
standing their migration during winter to the confines of the 
torrid zone. This rule does not apply to the fishes who an- 
nually leave their proper home, and migrate to a distant 
region merely for the purpose of spawning. The Salmon, 
for example, comes down from the North, to spawn on the 
coast of Maine and Nova Scotia. 

412. Few of the Mammals, and these mostly of the tribe 
of Rodents, make extensive migrations. Among the most 
remarkable of these are the Kamtschatka rats. In Spring 
they direct their course westward, in immense troops ; and, 
after a very long journey, return again in Autumn to their 
quarters, where their approach is anxiously awaited by the 
hunters, on account of the fine furs to be obtained from the 
numerous carnivora which always follow in their train. 
The migrations of the Lemmings are marked by the devas- 
tations they commit along their course, as they come down 
from the borders of the Frozen Ocean to the valleys of 
Lapland and Norway ; but their migrations are not period- 
ical. 

17 



194 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 



SECTION II. 

DISTRIBUTION OF THE FAUNAS. 

413. We have stated that all the faunas of the globe may 
be divided into three groups, corresponding to as many great 
climatal divisions, namely, the glacial or arctic, the temperate 
and the tropical faunas. These three divisions appertain to 
both hemispheres, as we recede from the equator towards the 
north or south poles. It will hereafter be shown that the 
tropical and temperate faunas may be again divided into 
several zoological provinces, depending on longitude or on 
the peculiar configuration of the continents. 

414. No continent is better calculated to give a correct 
idea of distribution into faunas, as determined by climate, 
than the continent of America ; extending as it does across 
both hemispheres, and embracing all latitudes, so that all 
climates are represented upon it, as shown by the chart on the 
following page. 

415. Let a traveller embark at Iceland, which is situated 
on the borders of the polar circle, with a view to observe, 
in a zoological aspect, the principal points along the eastern 
shore of America. The result of his observation will be 
very much as follows. Along the coast of Greenland and 
Iceland, and also along Baffin's Bay, he will meet with an 
unvaried fauna, composed throughout of the same animals, 
which are also for the most part identical with those of the 
arctic shores of Europe. It will be nearly the same along 
the coast of Labrador. 

416. As he approaches Newfoundland, he will see the 
landscape, and with it the fauna, assuming a somewhat more 
varied aspect. To the wide and naked or turfy plains of 
the boreal regions succeed forests, in which he will find 



EQUATOR 



FAUNAS. 

I. North Glacial or Arctic. 

II. Northern Temperate. 

III. Northern Warm. 

IV. Tropical. 

V. Southern "Warm. 

VI. Southern Temperate. 




196 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

various animals which dwell only in forests. Here the tem- 
perate fauna commences. Still the number of species is not 
yet very considerable ; but as he advances southward, along 
the coasts of Nova Scotia and New England, he finds new 
species gradually introduced, while those of the colder regions 
diminish, and at length entirely disappear, some few acci- 
dental or periodical visitors excepted, who wander, during 
winter, as far south as the Carolinas. 

417. But it is after having passed the boundaries of the 
United States, among the Antilles, and more especially on 
the southern continent, along the shores of the Orinoco and 
the Amazon, that our traveller will be forcibly struck with 
the astonishing variety of the animals which people the for- 
ests, the prairies, the rivers, and the sea-shores, most of which 
he will also find to be different from those of the northern 
continent. By this extraordinary richness of new forms, he 
will become sensible that he is now in the domain of the 
tropical fauna. 

418. Let him still travel on beyond the equator towards 
the tropic of Capricorn, and he will again find the scene 
change as he enters the regions where the sun casts his rays 
more obliquely, and where the contrast of the seasons is 
more marked. The vegetation will be less luxuriant; the 
palms will have disappeared to make place for other trees ; 
the animals will be less varied, and the whole picture will 
recall to him, in some measure, what he witnessed in the 
United States. He will again find himself in the temperate 
region, and this he will trace on, till he arrives at the ex- 
tremity of the continent, the fauna and the flora becoming 
more and more impoverished as he approaches Cape Horn. 

419. Finally, we know that there is a continent around 
the South Pole. Although we have as yet but very imper- 
fect notions respecting the animals of this inhospitable clime, 
still, the few which have already been observed there present 



DISTRIBUTION OF THE FAUNAS. 197 

a close analogy to those of the arctic region. It is another 
glacial fauna, namely, the antarctic. Having thus sketched 
the general divisions of the faunas, it remains to point out 
the principal features of each of them. 

420. I. ARCTIC FAUNA. The predominant feature of the 
Arctic Fauna is its uniformity. The species are few in num- 
ber ; but, on the other hand, the number of individuals is 
immense. We need only refer to the clouds of birds which 
hover upon the islands and shores of the North ; the shoals 
of fishes, the salmon among others, which throng the coasts 
of Greenland, Iceland, and Hudson's Bay. There is great 
uniformity, also, in the form and color of these animals. Not 

f ' 

a single bird of brilliant plumage is found, and few fishes 
with varied hues. Their forms are regular, and their tints 
as dusky as the northern heavens. The most conspicuous 
animals are the white-bear, the moose, the reindeer, the 
musk-ox, the white-fox, the polar-hare, the lemming, and 
various Seals ; but the most important are the Whales, which, 
it is to be remarked, rank lowest of all the Mammals. 
Among the Birds may be enumerated some sea-eagles and 
a few Waders, while the great majority are aquatic species, 
such as gulls, cormorants, divers, petrels, ducks, geese, gan- 
nets, &c., all belonging to the lowest orders of Birds. Rep- 
tiles are altogether wanting. The Articulate, are represented 
by numerous marine worms, and by minute crustaceans of 
the orders Isopoda and Amphipoda. Insects are rare, and 
*f inferior types. Of the type of Mollusks, there are 
Acephala, particularly Tunicata, fewer Gasteropods, and 
very few Cephalopods. Among the Radiata are a great 
number of jelly-fishes, particularly the Beroe ; and to con- 
clude with the Echinoderms, there are several star-fishes 
and Echini, but few Holothurise. The class of Polypi is 
very scantily represented, and those producing stony corals 
are entirely wanting. 

17* 



198 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

421. This assemblage of animals is evidently inferior to 
that of other faunas, especially to those of the tropics. Not 
that there is a deficiency of animal life ; for if the species 
arc less numerous, there is a compensation in the multitude 
of individuals, and, also, in this other very significant fact, 
that the largest of all animals, the whales, belong to this 
fauna. 

422. It has already been said, (400,) that the arctic fauna 
of the three continents is Jhe same ; its southern limit, how- 
ever, is not a regular line. It does not correspond precisely 
with the polar circle, but rather to the isothermal zero ; that 
is, the line where the average temperature of the year is at 
32 of Fahrenheit. The course of this line presents numer- 
ous undulations. In general, it may be said to coincide with 
the northern limit of trees, so that it terminates where forest 
vegetation succeeds the vast arid plains, the barrens of North 
America, or the tundras of the Samoyedes. The uniformity 
of these plains involves a corresponding uniformity of plants 
and animals. On the North American continent it extends 
much farther southward on the eastern shore than on the 
western. From the peninsula of Alashka, it bends north- 
wards towards the Mackenzie, then descends again towards 
the Bear Lake, and comes down nearly to the northern shore 
of Newfoundland. 

423. II. TEMPERATE FAUNAS. The faunas of the tem- 
perate regions of the northern hemisphere are much more 
varied than that of the arctic zone. Instead of consisting 
mainly of aquatic tribes, we have a considerable number of 
terrestrial animals, of graceful form, animated appearance, 
and varied colors, though less brilliant than those found in 
tropical regions. Those parts of the country covered with 
forests especially swarm with insects, which become the food 
of other animals ; worms and terrestrial and fluviatile mol- 
lusks are also abundant. 



DISTRIBUTION OF THE FAUNAS. 199 

424. Still, the climate is not sufficiently warm over the 
whole extent of this zone to allow the trees to retain their 
foliage throughout the year. At its northern margin, the 
leaves, excepting those of the pines and spruces, fall, on the 
approach of the cold season, and vegetation is arrested for a 
longer or shorter period. Insects retire, and the animals 
which live upon them no longer find nourishment, and are 
obliged to migrate to warmer regions, on the borders of the 
tropics, where, amid the ever-verdant vegetation, they find 
the means of subsistence. 

425. Some of the herbivorous Mammals, the Bats, and 
the reptiles which feed on insects, pass the winter in a state 
of torpor, from which they awake in spring. Others retire 
into dens, and live on the provisions they have stored up 
during the warm season. The Carnivora, the Ruminants, 
and the most active portion of the Rodents, are the only ani- 
mals that do not change either their abode or their habits. 
The fauna of the temperate zone thus presents an ever- 
changing picture, which may be considered as one of its 
most important features, since these changes recur with equal 
constancy in the Old and the New World. 

426. Taking the contrast of the vegetation as a basis, and 
the consequent changes of habit imposed upon the denizens 
of the forests, the temperate fauna has been divided into 
two regions ; a northern one, where the trees, except the 
pines, drop their leaves in winter, and a southern one, where 
t^ey are evergreen. Now, as the limit of the former, that 
of the deciduous trees, coincides, in general, with the limit 
of the pines, it may be said that the cold region of the tem- 
perate fauna extends as far as the pines. In the United 
States this coincidence is not so marked as in other regions, 
inasmuch as the pines along the Atlantic coast extend into 
Florida, while they do not prevail in the Western States ; 
but we may consider as belonging to the southern portion 



200 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

of the temperate region that part of the country south of 
the latitude where the Palmetto or Cabbage-tree ( Chamarops) 
commences, namely, all the States to the south of North 
Carolina ; while the States to the north of this limit belong 
to the northern portion of the temperate region. 

427. This division into two zones is supported by obser- 
vations made on the maritime faunas of the Atlantic coast. 
The line of separation between them, however, being influ- 
enced by the Gulf Stream, is considerably farther to the 
north, namely, at Cape Cod ; although there is also another 
decided limitation of the marine animals at a point nearly 
coinciding with the line of demarkation above mentioned, 
namely, at Cape Hatteras. It has been observed that of 
one hundred and ninety-seven Mollusks inhabiting the coast 
of New England, fifty do not pass to the north of Cape Cod, 
and eighty-three do not pass to the south of it ; only sixty- 
four being common to both sides of the Cape. A similar 
limitation of the range of Fishes has been noticed by Dr. 
Storer ; and Dr. Hoi brook has found the Fishes of South 
Carolina to be different from those of Florida and the West 
Indies. In Europe, the northern part of the temperate re- 
gion extends to the Pyrenees and the Alps ; and its south- 
ern portion consists of the basin of the Mediterranean, to- 
gether with the northern part of Africa, as far as the desert 
of Sahara. 

428. A peculiar characteristic of the faunas of the tem- 
perate regions in the northern hemisphere, when contrasted 
with those of the southern, is the great similarity of the pre- 
vailing types on both continents. Notwithstanding the im- 
mense extent of country embraced, the same stamp is every 
where exhibited. Generally, the same families, frequently 
the same genera, represented by different species, are 
found. There are even a few species of terrestrial animals 
regarded as identical on the continents of Europe and 



DISTRIBUTION OF THE FAUNAS. 201 

America ; but their supposed number is constantly dimin- 
ished, as more accurate observations are made. The pre- 
dominant types among the mammals are the bison, deer, ox, 
horse, hog, numerous rodents, especially squirrels and hares, 
nearly all the insectivora, weasels, martens, wolves, foxes, 
wildcats, &c. On the other hand, there are no Edentata 
and no Quadrumana, with the exception of some monkeys, 
on the two slopes of the Atlas and in Japan. Among Birds, 
there is a multitude of climbers, passerine, gallinaceous, and 
many rapacious birds. Of Reptiles, there are lizards and 
tortoises of small or medium size, serpents, and many ba- 
trachians, but no crocodiles. Of fishes, there is the trout 
family, the cyprinoids, the sturgeons, the pikes, the cod, and 
especially the great family of Herrings and Scomberoids, to 
which latter belong the mackerel and the tunny. All classes 
of the Mollusks are represented ; though the cephalopods are 
less numerous than in the torrid zone. There is an infinite 
number of Articulata of every type, as well as numerous 
Polyps, though the corals proper do not yet appear abun- 
dantly. 

429. On each of the two continents of Europe and Amer- 
ica there is a certain number of species, which extend from 
one extreme of the temperate zone to the other. Such, for 
example, are the deer, the bison, the cougar, the flying-squir- 
rel, numerous birds of prey, several tortoises, and the rattle- 
snake, in America. In Europe, the brown bear, wolf, 
swallow, and many birds of prey. Some species have a 
still wider range, like the ermine, which is found from Behr- 
ing's Straits to the Himalaya Mountains, that is to say, from 
the coldest regions of the arctic zone to the southern confines 
of the temperate zone. It is the same with the muskrat, 
which is found from the mouth of Mackenzie's River to 
Florida. The field-mouse has an equal range in Europe. 
Other species, on the contrary, are limited to one region. 



202 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

The Canadian elk is confined to the northern portion of the 
fauna ; while the prairie wolf, the fox-squirrel, the Bassaris, 
and numerous birds, never leave the southern portion.* 

430. In America, as in the Old World, the temperate 
fauna is further subdivided into several districts, which may 
be regarded as so many zoological provinces, in each of 
which there is a certain number of animals differing from 
those in the others, though very closely allied. Temperate 
America presents us with a striking example in this respect. 
We have, on the one hand : 

1st. The fauna of the United States properly so called, on 
this side of the Rocky Mountains. 

2d. The fauna of Oregon and California, beyond those 
mountains. 

Though there are some animals which traverse the chain 
of the Rocky Mountains, and are found in the prairies of 
the Missouri as well as on the banks of the Columbia, as, 
for example, the Rocky Mountain deer, (Antilope furcifer,) 
yet, if we regard the whole assemblage of animals, they are 
found to differ entirely. Thus, the rodents, part of the 
ruminants, the insects, and all the mollusks, belong to dis- 
tinct species. 

431. The faunas or zoological provinces of the Old World 
which correspond to these are : 

* The types which are peculiar to temperate America, and are not found 
in Europe, are the Opossum, several genera of Insectivora, among them 
the shrew-mole (Scalops aquaticus) and the star-nose mole, (Condylura 
cristata,) which replaces the Mygale of the Old World ; several genera 
of rodents, especially the muskrat. Among the types characteristic of 
America must also be reckoned the snapping-turtle among the tortoises ; 
the Menobranchus and Menopoma, among the Salamanders ; the Gar- 
pike and Amia among the fishes ; and finally, among the Crustacea, the 
Limulus. Among the types which are wanting in temperate America, 
and which are found in Europe, may be cited the horse, the wild boar, and 
the true mouse. All the species of domestic mice which live in America 
have been brought from the Old World. 



DISTRIBUTION OF THE FAUNAS. 203 

1st. The fauna of Europe, which is very closely related to 
that of the United States proper. 

2d. The fauna of Siberia, separated from the fauna of 
Europe by the Ural Mountains. 

3d. The fauna of the Asiatic table-land, which, from what 
is as yet known of it, appears to be quite distinct. 

4th. The fauna of China and Japan, which is analogous 
to that of Europe in the Birds, and to that of the United 
States in the Reptiles as it it also in the flora. 

Lastly, it is in the temperate zone of the northern hemi- 
sphere that we meet with the most striking example of 
those local faunas which have been mentioned above. 
Such, for example, is the fauna of the Caspian Sea, of the 
steppes of Tartary, and of the Western prairies. 

432. The faunas of the southern temperate regions differ 
from those of the tropics as much as the northern temperate 
faunas do ; and, like them also, may be distinguished into 
two provinces, the colder of which embraces Patagonia. 
But besides differing from the tropical faunas, they are also 
quite unlike each other on the different continents. Instead 
of that general resemblance, that family likeness which we 
have noticed between all the faunas of the temperate zone 
of the northern hemisphere, we find here the most complete 
contrasts. Each of the three continental peninsulas which 
jut out southerly into the ocean represents, in some sense, a 
separate world. The animals of South America, beyond the 
tropic of Capricorn, are in all respects different from those 
at the southern extremity of Africa. The hyenas, wild- 
boars, and rhinoceroses of the Cape of Good Hope have no 
analogues on the American continent ; and the difference is 
equally great between the birds, reptiles and fishes, insects 
and mollusks. Among the most characteristic animals of 
the southern extremity of America are peculiar species of 
seals, and especially, among aquatic birds, the penguins. 



< 

204 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

433. New Holland, with its marsupial mammals, with 
which are associated insects and mollusks no less singular, 
furnishes a fauna still more peculiar, and which has no simi- 
larity to those of any of the adjacent countries. In the seas 
of that continent, where every thing is so strange, we find 
the curious shark, with paved teeth and spines on the back, 
(Cestracion Pliilippii^) the only living representative of a 
family so numerous in former zoological ages. But a most 
remarkable feature of this fauna is, that the same types 
prevail over the whole continent, in its temperate as well as 
its tropical portions, the species only being different at dif- 
ferent localities. 

434. TROPICAL FAUNAS. The tropical faunas are dis- 
tinguished, on all the continents, by the immense variety of 
animals which they comprise, not less than by the brilliancy 
of their dress. All the principal types of animals are rep- 
resented, and all contain numerous genera and species. 
We need only refer to the tribe of humming-birds, which 
numbers not less than 300 species. It is very important to 
notice, that here are concentrated the most perfect, as well 
as the oddest, types of all the classes of the Animal King- 
dom. The tropical region is the only one occupied by the 
Quadrumana, the herbivorous bats, the great pachydermata, 
such as the elephant, the hippopotamus, and the tapir, and 
the whole family of Edentata. Here also are found the 
largest of the cat tribe, the lion and tiger. Among the Birds 
we may mention the parrots and toucans, as essentially 
tropical ; among the Reptiles, the largest crocodiles, and 
gigantic tortoises ; and finally, among the articulated animals, 
an immense variety of the most beautiful insects. The 
marine animals, as a whole, are equally superior to those of 
other regions ; the seas teem with crustaceans and numerous 
cephalopods, together with an infinite variety of gasteropods 
and acephala. The Echinoderms there attain a magnitude 



DISTRIBUTION OF THE FAUNAS. 205 

and variety elsewhere unknown ; and lastly, the Polyps there 
display an activity of which the other zones present no ex- 
" ample. Whole groups of islands are surrounded with coral 
reefs formed by those little animals. 

435. The variety of the tropical fauna is further enriched 
by the circumstance that each continent furnishes new and 
peculiar forms. Sometimes whole types are limited to one 
continent, as the sloth, the toucans, and the humming-birds to 
America, the giraffe and hippopotamus to Africa ; and again 
animals of the same group have different characteristics, ac- 
cording as they are found on different continents. Thus, 
the monkeys of America have flat and widely separated 
nostrils, thirty-six teeth, and generally a long, prehensile tail. 
The monkeys of the Old World, on the contrary, have nostrils 
close together, only thirty-two teeth, and not one of them has 
a prehensile tail. 

436. But these differences, however important they may 
appear at first glance, are subordinate to more important 
characters, which establish a certain general affinity between 
all the faunas of the tropics. Such, for example, is the fact 
that the quadrumana are limited, on all the continents, to 
the warmest regions ; and never, or but rarely, penetrate 
into the temperate zone. This limitation is a natural con- 
sequence of the distribution of the palms ; for as these trees, 
which constitute the ruling feature of the flora of the tropics, 
furnish, to a great extent, the food of the monkeys on both 
continents, we have only to trace the limits of the palms, to 
have a pretty accurate indication of the extent of the tropical 
faunas on all three continents. 

437. Several well-marked faunas may be distinguished in 
the tropical part of the American continent, namely : 

1. The fauna of Brazil, characterized by its gigantic rep- 
tiles, its monkeys, its Edentata, its tapir, its humming-birds, 
and its astonishing variety of insects. 

18 



206 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

2. The fauna of the western slope of the Andes, com- 
prising Chili and Peru; and distinguished by its Llamas, 
vicunas, and birds, which differ from those of the basin of 
the Amazon, as also do the insects and mollusks. 

3. The fauna of the Antilles and the Gulf of Mexico. 
This is especially characterized by its marine animals, among 
which the Manatee is particularly remarkable ; an infinite 
variety of singular fishes, embracing a large number of 
Plectognaths ; also Mollusks, and Radiata of peculiar species. 
It is in this zone that the Pentacrinus caput-medusa is found, 
the only representative, in the existing creation, of a family so 
numerous in ancient epochs, the Crinoidea with a jointed stem. 

The limits of the fauna of Central America cannot yet be 
well defined, from want of sufficient knowledge of the ani- 
mals which inhabit those regions. 

438. The tropical zone of Africa is distinguished by a 
striking uniformity in the distribution of the animals, which 
corresponds to the uniformity of the structure and contour 
of that continent. Its most characteristic species are spread 
over the whole extent of the tropics : thus, the giraffe is met 
with from Upper Egypt to the Cape of Good Hope. The 
hippopotamus is found at the same time in the Nile, the 
Niger, and Orange River. This wide range is the more 
significant as it also relates to herbivorous animals, and thus 
supposes conditions of vegetation very similar, over wide 
countries. Some forms are, nevertheless, circumscribed 
within narrow districts ; and there are marked differences 
between the animals of the eastern and western shores. 
Among the remarkable species of the African torrid region 
are the baboons, the African elephant, the crocodile of the 
Nile, a vast number of Antelopes, and especially two species 
of Orang-outang, the Chimpanzee and the Engeena, a large 
and remarkable animal, only recently described. The fishes 
of the Nile have a tropical character, as well as the animals 



CONCLUSIONS. 207 

of Arabia, which are more allied to those of Africa than to 
those of Asia. 

439. The tropical fauna of Asia, comprising the two 
peninsulas of India and the Isles of Sunda, is not less marked. 
It is the country of the gibbons, the red orang, the royal 
tiger, the gavial, and a multitude of peculiar birds. Among 
the fishes, the family of Chetodons is most numerously 
represented. Here also are found those curious spiny 
fishes, whose intricate gills' suggested the name Labyrinthici, 
by which they are known. Fishes with tufted gills are more 
numerous here than in other seas. The insects and mol- 
lusks are no less strongly characterized. Among others is 
the nautilus, the only living representative of the great fam- 
ily of large, chambered-shells which prevailed so extensively 
over other types, in former geological ages. 

440. The large Island of Madagascar has its peculiar 
fauna, characterized by its makis and its curious rodents. 
It is also the habitat of the Aya-aya. Polynesia, exclusive 
of New Holland, furnishes a number of very curious animals, 
which are not found on the Asiatic continent. Such are the 
herbivorous bats, and the Galeopithecus or flying Maki. The 
Galapago islands, only a few hundred miles from the coast 
of Peru, have a fauna exclusively their own, among which 
gigantic land-tortoises are particularly characteristic. 

SECTION III. 

CONCLUSIONS. 

441. From the survey we have thus made of the distribu- 
tion of the Animal Kingdom, it follows : 

1st. Each grand division of the globe has animals which 
are either wholly or for the most part peculiar to it. These 
groups of animals constitute the faunas of different regions. 



208 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

2d. The diversity of faunas is not in proportion to the 
distance which separates them. Very similar faunas are 
found at great distances apart ; as, for example, the fauna 
of Europe and that of the United States, which yet are 
separated by a wide ocean. Others, on the contrary, differ 
considerably, though at comparatively short distances ; as 
the fauna of the East Indies and the Sunda Islands, and that 
of New Holland ; or the fauna of Labrador and that of New 
England. 

3d. There is a direct relation between the richness of a 
fauna and the climate. The tropical faunas contain a much 
larger number of more perfect animals than those of the 
temperate and polar regions. 

4th. There is a no less striking relation between the fauna 
and flora, the limit of the former being oftentimes deter- 
mined, so far as terrestrial animals are concerned, by the 
extent of the latter. 

442. Animals are endowed with instincts and faculties 
corresponding to the physical character of the countries they 
inhabit, and which would be of no service to them under 
other circumstances. The monkey, which is a frugivorous 
animal, is organized for living on the trees from which he 
obtains his food. The reindeer, on the contrary, whose 
food consists of lichens, lives in cold regions. The latter 
would be quite out of place in the torrid zone, and the mon- 
key would perish with hunger in the polar regions. Animals 
which store up provisions are all peculiar to temperate or cold 
climates. Their instincts would be uncalled for in tropical 
regions, where the vegetation presents the herbivora with an 
abundant supply of food at all times. 

443. However intimately the climate of a country seems to 
be allied with the peculiar character of its fauna, we are not 
to conclude that the one is the consequence of the other. 
The differences which are observed between the animals of 



CONCLUSIONS. 209 

different faunas are no more to be ascribed to the influences 
of climate, than their organization is to the influence of the 
physical forces of nature. If it were so, we should necessa- 
rily find all animals precisely similar, when placed under 
the same circumstances. We shall find, by the study of the 
different groups in detail, that certain species, though very 
nearly alike, are nevertheless distinct in two different faunas. 
Between the animals of the temperate zone of Europe, and 
those of the United States, there is similarity but not iden- 
tity ; and the particulars in which they differ, though ap- 
parently trifling, are yet constant. 

444. Fully to appreciate the value of these differences, it 
is often requisite to know all the species of a genus or of a 
family. It is not uncommon to find, upon such an exam- 
ination, that there is the closest resemblance between spe- 
cies that dwell far apart from each other, while species of 
the same genus, that live side by side, are widely different. 
This may be illustrated by a single example. The Menopo- 
ma, Siren, Amphiuma, Axolotl, and the Menobranchus, are 
Batrachians which inhabit the rivers and lakes of the United 
States and Mexico. They are very similar in external 
form, yet differ in the fact that some of them have external 
gills at the sides of the head, in which others are deficient ; 
that some have five legs, while others are only provided 
with two ; and also in having either two or four legs. 
Hence we might be tempted to refer them to different types, 
did we not know intermediate animals, completing the series, 
namely, the Proteus and Megalobatrachus. Now, the for- 
mer exists only in the subterranean lakes of Austria, and 
the latter in Japan. The connection in this case is conse- 
quently established by means of species which inhabit con- 
tinents widely distant from each other. 

445. Neither the distribution of animals, therefore, any 
more than their organization, can be the effect of external 

18* 



210 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

influences. We must, on the contrary, see in it the realiza- 
tion of a plan wisely designed, the work of a Supreme Intel- 
ligence who created, at the beginning, each species of ani- 
mal at the place, and for the place, which it inhabits. To 
each species has been assigned a limit which it has no dis- 
position to overstep, so long as it remains in a wild state. 
Only those animals which have been subjected to the yoke 
of man, or whose subsistence is dependent on man's social 
habits, are exceptions to this rule. 

446. As the human race has extended over the surface 
of the earth, man has more or less modified the animal popu- 
lation of different regions, either by exterminating certain 
species, or by introducing others with which he desires to be 
more intimately associated the domestic animals. Thus, 
the dog is found wherever we know of the presence of man. 
The horse, originally from Asia, was introduced into Ameri- 
ca by the Spaniards ; where it has thriven so well, that it 
is found wild, in innumerable herds, over the Pampas of 
South America, and the prairies of the West. In like 
manner, the domestic ox became wild in South America. 
Many less welcome animals have followed man in his pere- 
grinations ; as, for example, the rat and the mouse, as well 
as a multitude of insects, such as the house-fly, the cock- 
roach, and others which are attached to certain species of 
plants, as the white butterfly, the Hessian fly, &c. The 
honey-bee, also, has been imported from Europe. 

447. Among the species which have disappeared, under 
the influence of man, we may mention the Dodo, a pecu- 
liar species of bird which once inhabited the Mauritius, 
some remains of which are preserved in the British and 
Ashmolean Museums ; also a large cetacean of the north, 
(Rytina Stelleri^ formerly inhabiting the coasts of Behring's 
Straits, and which has not been seen since 1768. Accord- 
ing to all appearances, we must also count among these the 



CONCLUSIONS. 211 

great stag, the skeleton and horns of which have been found 
buried in the peat-bogs of Ireland. There are also many 
species of animals whose numbers are daily diminishing, 
and whose extinction may be foreseen ; as the Canada deer, 
(Wapiti,) the Ibex of the Alps, the Lammergeyer, the 
bison, the beaver, the wild turkey, &c. 

448. Other causes may also contribute towards dispersing 
animals beyond their natural limits. Thus, the sea-weeds 
are carried about by marine currents, and are frequently 
met with far from shore, thronged with little crustaceans, 
which are in this manner transported to great distances from 
the place of their birth. The drift wood which the Gulf 
Stream floats from the Gulf of Mexico even to the western 
shores of Europe, is frequently perforated by the larvse of 
insects, and may, probably, serve as depositories for the eggs 
of fishes, Crustacea, and mollusks. It is possible, also, that 
aquatic birds may contribute in some measure to the diffu- 
sion of some species of fishes and mollusks, either by the 
eggs becoming attached to their feet, or by means of those 
which they evacuate undigested, after having transported 
them to considerable distances. Still, all these circum- 
stances exercise but a very feeble influence upon the dis- 
tribution of species in general ; and each country, none the 
less, preserves its peculiar physiognomy, so far as its animals 
are concerned. 

449. There is only one way to account for the distribu- 
tion of animals as we find them, namely, to suppose that 
they are autochthonoi, that is to say, that they originated 
like plants, on the soil where they are found. In order to 
explain the particular distribution of many animals, we are 
even led to admit that they must have been created at 
several points of the same zone ; an inference which we 
must make from the distribution of aquatic animals, especial- 
ly that of Fishes. If we examine the fishes of the different 



GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 

rivers of the United States, peculiar species will be found in 
each basin, associated with others which are common to 
several basins. Thus, the Delaware River contains species 
not found in the Hudson. But, on the other hand, the pick- 
erel is found in both. Now, if all animals originated at one 
point, and from a single stock, the pickerel must have passed 
from the Delaware to the Hudson, or vice versa, which it 
could only have done by passing along the sea-shore, or by 
leaping over large spaces of terra jlrma ; that is to say, in 
both cases it would be necessary to do violence to its organi- 
zation. Now, such a supposition is in direct opposition to 
the immutability of the laws of Nature. 

450. We shall hereafter see that the same laws of distri- 
bution are not limited to the actual creation only, but that 
they have also ruled the creations of former geological 
epochs, and that the fossil species have lived and died, most 
of them, at the place where their remains are found. 

451. Even Man, although a cosmopolite, is subject, in a 
certain sense, to this law of limitation. While he is every 
where the one identical species, yet several races, marked 
by certain peculiarities of features, are recognized : such as 
the Caucasian, Mongolian, and African races, of which we 
are hereafter to speak. And it is not a little remarkable, 
that the abiding places of these several races correspond 
very nearly with some of the great zoological regions. 
Thus we have a northern race, comprising the Samoyedes 
in Asia, the Laplanders in Europe, and the Esquimaux in 
America, corresponding to the arctic fauna, (400,) and, 
like it, identical on the three continents, having for its 
southern limit the region of trees, (422.) In Africa, we 
have the Hottentot and Negro races, in the south and central 
portions respectively, while the people of northern Africa 
are allied to their neighbors in Europe ; just as we have 
seen to be the case with the zoological fauna in general, 



CONCLUSIONS. 213 

(403.) The inhabitants of New Holland, like its animals, 
are the most grotesque and uncouth of all races, (433.) 

452. The same parallelism holds good elsewhere, though 
not always in so remarkable a degree. In America, espe- 
cially, while the aboriginal race is as well distinguished from 
other races as is its flora, the minor divisions are not so 
decided. Indeed, the facilities, or we might sometimes 
rather say necessities, arising from the varied supplies of 
animal and vegetable food in the several regions, might be 
expected to involve, with his corresponding customs and 
modes of life, a difference in the physical constitution of 
man, which would contribute to augment any primeval dif- 
ferences. It could not indeed be expected, that a people 
constantly subjected to cold, like the people of the North, 
and living almost exclusively on fish, which is not to be 
obtained without great toil and peril, should present the same 
characteristics, either bodily or mental, as those who idly 
regale on the spontaneous bounties of tropical vegetation. 



CHAPTER FOURTEENTH. 

GEOLOGICAL SUCCESSION OF ANIMALS; OR, THEIR 
DISTRIBUTION IN TIME. 

SECTION I. 

STRUCTURE OF THE EARTH'S CRUST. 

453. THE records of the Bible, as well as human tra- 
dition, teach us that man and the animals associated with 
him were created by the word of God ; " the Lord made 
heaven and earth, the sea, and all that in them is;' 1 ' and 
this truth is confirmed by the revelations of science, which 
unequivocally indicate the direct interventions of creative 
power. 

454. But man and the animals which now surround him 
are not the only kinds which have had a being. The sur- 
face of our planet, anterior to their appearance, was not a 
desert. There are, scattered through the crust of the earth, 
numerous animal and vegetable remains, which show that 
the earth had been repeatedly supplied with, and long in- 
habited by, animals and plants altogether different from those 
now living. 

455. In general, their hard parts are the only relics of 
them which have been preserved, such as the skeleton and 
teeth of Vertebrates ; the shells of the Mollusks and Radiata ; 
the shields of the Crustaceans, and sometimes the wing-cases 
of Insects. Most frequently they have lost their original 



STRUCTURE OF THE EARTH^S CRUST. 215 

chemical composition, and are changed into stone ; and 
hence the name of petrifactions or fossils, under which lat- 
ter term are comprehended all the organized bodies of 
former epochs, obtained from the earth's crust. Others have 
entirely disappeared, leaving only their forms and sculpture 
impressed upon the rocks. 

456. The study of these remains and of their position in 
the rocks constitutes PALEONTOLOGY ; one of the most essen- 
tial branches of Zoology. Their geological distribution, or 
the order of their successive appearance, namely, the distri- 
bution of animals in time, is of no less importance than the 
geographical distribution of living animals, their distribution 
in space, of which we have treated in the preceding chapter. 
To obtain an idea of the successive creations, and of the stu- 
pendous length of time they have required, it is necessary to 
sketch the principal outlines of Geology. 

457. The rocks* which compose the crust of our globe 
are of two kinds : 

1. The Massive Rocks, called also Plutonic or Igneous 
Rocks, which lie beneath all the others, or have sometimes 
been forced up through them, from beneath. They were 
once in a melted state, like the lava of the present epoch, 
and on cooling at the surface formed the original crust of the 
globe, the granite, and later porphyry, basalt, &c. 

2. The Sedimentary or Stratified Rocks, called also Nep- 
tunic Rocks, which have been deposited in water, in the same 
manner as modern seas and lakes deposit sand and mud on 
their shores, or at the bottom. 

458. These sediments have been derived partly from the 
disintegration of the older rocks, and partly from the decay 
of plants and animals. The materials being disposed in 



* Rocks, in a geological sense, include all the materials of the earth, 
the loose soil and gravel, as well as the firm rock. 



216 GEOLOGICAL SUCCESSION OF ANIMALS. 

layers or strata, have become, as they hardened, limestones, 
slates, marls, or grits, according to their chemical and me- 
chanical composition, and contain the remains of the animals 
and plants which were scattered through the waters.* 

459. The different strata, when undisturbed, are arranged 
one above the other in a horizontal manner, like the leaves 
of a book, the lowest being the oldest. In consequence of 
the commotions which the crust of the globe has undergone, 
the strata have been ruptured, and many points of the surface 
have been elevated to great heights, in the form of moun- 
tains ; and hence it is that fossils are sometimes found at the 
summit of the highest mountains, though the rocks contain- 
ing them were originally formed at the bottom of the sea. 
But even when folded, or partly broken, their relative age 
may still be determined by an examination of the ends of 
the upturned strata, where they appear or crop out in suc- 
cession, at the surface, or on the slopes of mountains, as seen 
in the diagram, (Fig. 154.) 

460. The sedimentary rocks are the only ones which have 
been found to contain animal and vegetable remains. These 
are found imbedded in the rock, just as we should find them 
in the mud now deposited at the bottom of the sea, if laid 
dry. The strata containing fossils are numerous. The com- 
parison and detailed study of them belongs to Geology, of 

* Underneath the deepest strata containing fossils, between these and 
the Plutonic rocks, are generally found very extensive layers of slates 
without fossils, (gneiss, mica-slate, talcose-slate,) though stratified, and 
known to the geologist under the name of Metamorphic Rocks, (Fig. 154, 
M,) being probably sedimentary rocks, which have undergone consider- 
able changes. The Plutonic rocks, as well as the metamorphic rocks, 
are not always confined to the lower levels, but they are often seen rising 
to considerable heights, and forming many of the loftiest peaks of the 
globe. The former also penetrate, in many cases, like veins, through the 
whole mass of the stratified and metamorphic layers, and expand at the 
surface ; as is the case with the trap dykes, and as lava streams actually 
do at the present era, (Fig. 154, T. L.} 



STRUCTURE OF THE EARTH'S CRUST. 



217 



which Paleontology forms an essential part. A group of 
strata extending over a certain geographical extent, all of 
which contain some fossils in common, no matter what may 
be the chemical character of the rock, whether it be lime- 
stone, sand, or clay, is termed a geological Formation. Thus, 
the coal beds, with the intervening slates and grits, and the 
masses of limestone, between which they often lie, constitute 
but one formation the carboniferous formation. 

461. Among the stratified rocks we distinguish ten prin- 
cipal Formations, each of which indicates an entirely new 
era in the earth's history ; while each of the layers which 
compose a formation indicates but some partial revolution. 
Proceeding from below upwards, they are as follows, as 
indicated in the cut, and also in the lower diagram on the 
Frontispiece. 




Fig. 154. 

1st. The Lower Silurian. This is a most extensive for- 
mation, no less than eight stages of which have been made 
out by Geologists in North America, composed of various 
limestones and sandstones.* 

* 1. Potsdam Sandstone ; 2. Calciferous Sandstone ; 3. Chazy Lime- 
stone ; 4. Bird's-eye Limestone ; o. Black River Limestone ; 6. Trenton. 
Limestone ; 7- Utica Slate ; 8. Hudson River Group ; being all found in 
the western parts of the United States. 

19 



218 GEOLOGICAL SUCCESSION OF ANIMALS. 

2d. The Upper Silurian. It is also a very extensive for- 
mation, since about ten stages of it are found in the State of 
New York.* 

3d. The Devonian, including in North America no less 
than eleven stages.t It occurs also in Russia and Scotland, 
where it was first made out as a peculiar formation. 

4th. The Carboniferous Formation, consisting of three 
grand divisions. I 

5th. The Trias, or Saliferous Formation, which, contain- 
ing the richest deposits of Salt on the continent of Europe, 
comprises three stages,^ to one of which the Sandstone of 
the Connecticut valley belongs. 

6th. The Oolitic Formation, only faint traces of which 
exist on the continent of America. It comprises at least four 
distinct stages. || 

7th. The Cretaceous, or Chalk Formation, of which three 
principal stages have been recognized, two of which are 
feebly represented in this country, in the Southern and Mid- 
dle States. 

8th. The Lower Tertiary, or Eocene, very abundant in the 
Southern States of the Union, and to which belong the 
coarse limestone of Paris, and the London clay in England. 

* 1. Oneida Conglomerate 5 2. Medina Sandstone; 3. Clinton Group ; 
4. Niagara Group ; 5. Onondaga Salt Group ; 6. Water Limestone ; 
7. Pentamerus Limestone ; 8. Delthyris Shaly Limestone ; 9. Encrinal 
Limestone ; 10. Upper Pentamerus Limestone. 

f 1. Oriskany Sandstone; 2. Cauda-Galli Grit; 3. Onondaga Lime- 
stone ; 4. Corniferous Limestone ; 5. Marcellus Shale ; 6. Hamilton 
Group ; 7. Tully Limestone ; 8. Genesee Slate ; 9. Portage Group ; 
10. Chemung Group ; 11. Old Red Sandstone. 

J 1. The Permian, extensively developed in Russia, especially in the 
government of Perm ; 2. The coal measures, containing the rich deposits 
of coal in the Old and New World ; 3. The Magnesian Limestone of 
England. 

1. New Red Sandstone ; 2. Muschelkalk ; 3. Keuper. 

|| 1. The Lias ; 2. The Lower Oolite ; 3. The Middle Oolite ; 4. The 
Upper Oolite. 



STRUCTURE OF THE EARTH'S CRUST. 219 

9th. The Upper Tertiary, or Miocene and Pleiocene, 
found also in the United States, as far north as Martha's 
Vineyard and Nantucket, and very extensive in Southern 
Europe, as well as in South America. 

10th. The Drift, forming the most superficial deposits, 
and extending over a large portion of the northern countries 
in both hemispheres. 

We have thus more than forty distinct layers already 
made out, each of which marks a distinct epoch in the earth's 
history, indicating a more or less extensive and important 
change in the condition of its surface. 

462. All the formations are not every where found, or are 
not developed to the same extent, in all places. So it is 
with the several strata of which they are composed. In 
other words, the layers of the earth's crust are not continuous 
throughout, like the coats of an onion. There is no place on 
the globe where, if it were possible to bore down to its 
centre, all the strata would be found. It is easy to under- 
stand how this must be so. Since irregularities in the 
distribution of water upon the solid crust have, necessarily, 
always existed to a certain extent, portions of the earth's 
surface must have been left dry at every epoch of its 
history, gradually forming large islands and continents, as 
the changes were multiplied. And since the rocks were 
formed by the subsidence of sediment in water, no rocks 
would be formed except in regions covered by water ; they 
.would be thickest at the parts where most sediment was 
deposited, and gradually thin out towards their circumference. 
We may therefore infer, that all those portions of the earth's 
surface which are destitute of a certain formation were dry 
land, during that epoch of the earth's history to which such 
formation relates, excepting, indeed, where the rocks have 
been subsequently removed by the denuding action of water 
or other causes. 



220 GEOLOGICAL SUCCESSION OF ANIMALS. 

463. Each formation represents an immense period of 
time, during which the earth was inhabited by successive 
races of animals and plants, whose remains are often found, 
in their natural position, in the places where they lived and 
died, not scattered at random, though sometimes mingled to- 
gether by currents of water, or other influences, subsequent 
to the time of their interment. From the manner in which 
the remains of various species are found associated in the 
rock, it is easy to determine whether the animals to which 
these remains belonged lived in the water, or on land, on the 
beach or in the depths of the ocean, in a warm or in a cold 
climate. They will be found associated in just the same 
way as animals are that live under similar influences at the 
present day. 

464. In most geological formations, the number of spe- 
cies of animals and plants found in any locality of given 
extent, is not below that of the species now living in an 
area of equal extent and of a similar character ; for though, 
in some deposits, the variety of the animals contained may 
be less, in others it is greater than that on the present surface. 
Thus, the coarse limestone in the neighborhood of Paris, 
which is only one stage of the lower tertiary, contains not 
less than 1200 species of shells ; whereas the species now 
living in the Mediterranean do not amount to half that num- 
ber. Similar relations may be pointed out in America. 
Mr. Hall, one of the geologists of the New York Survey, has 
described, from the Trenton limestone, (one of the ten stages 
of the lower Silurian,) 170 species of shells, a number almost 
equal to that of all the species found now living on the coast 
of Massachusetts. 

465. Nor was the number of individuals less than at 
present. Whole rocks are entirely formed of animal re- 
mains, particularly of corals and shells. So, also, coal is 
composed of the remains of plants. If we consider the slow- 



AGES OF NATURE. 221 

ness with which corals and shells are formed, it will give us 
some faint notion of the vast series of ages that must have 
elapsed in order to allow the formation of those rocks, and 
their regular deposition, under the water, to so great a thick- 
ness. If, as all things combine to prove, this deposition took 
place in a slow and gradual manner in each formation, we 
must conclude, that the successive species of animals found 
in them followed each other at long intervals, and are not the 
work of a single epoch. 

466. It was once believed that animals were successively 
created in the order of their relative perfection ; so that the 
most ancient formations contained only animals of the low- 
est grade, such as the Polyps, the Echinoderms, to which 
succeeded the Mollusks, then the Articulated Animals, and, 
last of all, the Vertebrates. This theory, however, is now 
untenable ; since fossils belonging to each of the four depart- 
ments have been found in the fossiliferous deposits of every 
age. Indeed, we shall see that even in the lower Silurian 
formation there exist not only Polyps and other Radiata, but 
also numerous Mollusks, Trilobites, (belonging to the Articu- 
lata,) and even Fishes. 



SECTION II. 

AGES OF NATURE. 

467. Each formation, as has been before stated, (460,) 
contains remains peculiar to itself, which do not extend into 
the neighboring deposits above or below it. Still there is a 
connection between the different formations, more strong in 
proportion to their proximity to each other. Thus, the ani- 
mal remains of the Chalk, while they differ from those of all 
other formations, are, nevertheless, much more nearly related 

19* 



222 GEOLOGICAL SUCCESSION OF ANIMALS. 

to those of the Oolitic formation, which immediately precedes, 
than to those of the carboniferous formation, which is much 
more ancient; and, in the same manner, the fossils of the 
carboniferous group approach more nearly to those of the 
Silurian formation than to those of the Tertiary. 

468. These relations could not escape the observation of 
naturalists, and indeed they are of great importance for the 
true understanding of the development of life at the surface 
of our earth. And, as in the history of man, several grand 
periods have been established, under the name of Ages, 
marked by peculiarities in his social and intellectual condi- 
tion, and illustrated by contemporaneous monuments, so, in 
the history of the earth, also, are distinguished several great 
periods, which may be designated as the various Ages of 
Nature, illustrated, in like manner, by their monuments, the 
fossil remains, which, by certain general traits stamped upon 
them, clearly indicate the eras to which they belong. 

469. We distinguish four Ages of Nature, corresponding 
to the great geological divisions, namely : 

1st. The Primary or Palceozoic Age, comprising the lower 
Silurian, the upper Silurian, and the Devonian. During this 
age there were no air-breathing animals. The fishes were 
the masters of creation. We may therefore call it the Reign 
of Fishes. 

2d. The Secondary Age, comprising the carboniferous for- 
mation, the Trias, the Oolitic, and the Cretaceous formations. 
This is the epoch in which air-breathing animals first appear. 
Reptiles predominate over the other classes, and we may 
therefore call it the Reign of Reptiles. 

3d. The Tertiary Age, comprising the tertiary formations. 
During this age, terrestrial mammals, of great size, abound. 
This is the Reign of Mammals. 

4th. The Modern Age, characterized by the appearance 
of the most perfect of all created beings. This is the Reign 
of Man. 



AGES OF NATURE. 



223 



Let us review each of these four Ages of Nature, with 
reference to the diagram at the beginning of the volume. 

470. THE PALEOZOIC AGE. Reign of Fishes. The 
palseozoic fauna, being the most remote from the present 
epoch, presents the least resemblance to the animals now 
existing, as will easily be perceived by a glance at the fol- 




Fig. 155. 

lowing sketches, (Fig. 155.) In no other case do we meet 
with animals of such extraordinary shapes, as in the strata 
of the Palseozoic age. 

471. We have already stated (466) that there are found, 
in each formation of the primary age, animal remains of all 
the four great departments, namely, vertebrates, articulata, 
mollusks, and radiata. We have now to examine to what 
peculiar classes and families of each department these re- 
mains belong, with a view to ascertain if any relation between 



224 GEOLOGICAL SUCCESSION OF ANIMALS. 

the structure of an animal, and the epoch of its first appear- 
ance on the earth's surface, may be traced. 

472. As a general result of the inquiries hitherto made, 
it may be stated that the palseozoic animals belong, for the 
most part, to the lower divisions of the different classes. 
Thus, of the class of Echinoderms, we find scarcely any 
but Crinoicls, which are the least perfect of the class. We 
have represented, in the above sketches, several of the most 
curious forms,* as well as of the Polyps, of which there are 
some quite peculiar types from the X renton limestone, and 
from the Black River limestone. 

473. Of the Mollusks, the bivalves or Acephala are nu- 
merous, but, for the most part, they belong to the Brachiopo- 
da, that is to say, to the lowest division of the class, including 
mollusks with unequal valves, having peculiar appendages 
in the interior. The Leptcena alternata, (&,) which is found 
very abundantly in the Trenton limestone, is one of these 
shells. The only fossils yet found in the Potsdam sandstone, 
the oldest of all fossiliferous deposits, belong, also, to this 
family, (Lingula prima, a.) Besides this, there are also 
found some bivalves of a less uncommon shape, (Avicula 
decussata, e.) 

474. The Gasteropods are less abundant ; some of them 
are of a peculiar shape and structure, (Bucania expansa,/; 
Euomphalus hemisphericm, c.) Those more similar to our 
common marine snails have all an entire aperture ; those 
with a canal being of a more recent epoch. 

475. Of the Cephalopods we find some genera not less 
curious, part of which disappear in the succeeding epochs ; 



* (i]Cyathocrinus ornatissimus, Hall; (j) Melocrinus Amphora, Goldf. ; 
(7c) Cariocrinus ornatus, Say ; (7) Columnaria alveolata ; (m) Cyatho- 
phylhim quadrigeminum, Goldf. ; (n, o) Caninia flexuosa ; (p~) Ch&tetes 
ty coper don. 



AGES OF NATURE. 



225 



such, in particular, as those of the straight, chambered shells 
called Orthoceratites, some of which are twelve feet in length, 
(Orthoceras fusiforme, g.) There are also found some of a 
coiled shape, like the Ammonites of the secondary age, but 
having less complicated partitions, ( Trocliolites ammonius,d.} 
The true cuttle-fishes, which are the highest of the class, 
are not yet found. On the contrary, the Bryozoa, which 
have long been considered as polyps, but which, according 
to all appearances, are mollusks of a very low order, are 
very numerous in this- epoch. 

476. The Articulata of the Palseozoic age are mostly 
Trilobites, animals which evidently belong to the lower 
order of the Crustaceans, (Fig. 156.) There is an incom- 
pleteness and want of development, in the form of their 
body, that strongly reminds us of the embryo among the 
crabs. A great many genera have already been discovered. 




Fig. 156. 

We may consider as belonging to the more extraordinary 
the forms here represented, (Harpes, a ; Argzs, 1) ; Bron- 
tes, c ; and Platynotus, d ;) the latter, as well as the Isotelus, 
the largest of all, being peculiar to the Palseozoic deposit of 
this country. Some others seem more allied to the crusta- 
ceans of the following ages, but are nevertheless of a very 
extraordinary form, as Eurypterus remipes, (e.) There are 
also found, in the Devonian, some very large Entomostraca. 
The class of Worms is represented only by a few Serpulse, 



226 



GEOLOGICAL SUCCESSION OF ANIMALS. 



which are marine worms, surrounded by a solid sheath. The 
class of Insects is entirely wanting. 

477. The inferiority of the earliest inhabitants of our 
earth appears most striking among the Vertebrates. There 
are as yet neither reptiles, birds, nor mammals. The fishes, 
as we have said, are the sole representatives of this division 
of animals. 

478. But the fishes of that early period were not like 
ours. Some of them had the most extraordinary forms, so 
that they have been often mistaken for quite different ani- 
mals ; for example, the Pterichthys, (a,) with its two wing- 



a 




Fig. 157. 

like appendages, and also the Coccosteus (I) of the same 
deposit, with its large plates covering the head and the ante- 
rior part of the body. There are also found remains of 
shark's spines, (e,) as well as palatal bories, (rf,) the latter of a 
very peculiar kind. Even those fishes which have a more 
regular shape, as the Dipterus, (c,) have not horny scales 
like our common fishes, but are protected by a coat of bony 
plates, covered with enamel, like the gar-pikes of the 
American rivers. Moreover, they all exhibit certain char- 
acteristic features, which are very interesting in a physio- 
logical point of view. They all have a broad head, and a 
tail terminating in two unequal lobes. What is still more 
curious, the best preserved specimens show no indications 



AGES OF NATURE. 227 

of the bodies of vertebrae, but merely of their spinous pro- 
cesses ; from which it must be inferred that the body of the 
vertebra was cartilaginous, as it is in our Sturgeons. 

479. Recurring to what has been stated on that point, in 
Chapter Twelfth, we thence conclude, that these ancient 
fishes were not so fully developed as most of our fishes, 
being, like the Sturgeon, arrested, as it were, in their devel- 
opment ; since we have shown that the Sturgeon, in its or- 
ganization, agrees, in many respects, with the Cod or Salmon 
at an early age. 

480. Finally, there was, during the Paleozoic age, but 
little variety among the animals of the different regions of 
the globe ; and this may be readily explained by the pecu- 
liar configuration of the earth at that epoch. Great moun- 
tains did not then exist ; there were neither lofty elevations 
ner deep depressions. The sea covered the greater part, if 
not the whole, of the surface of the globe ; and the animals 
which then existed, and whose remains have been preserved, 
were all, without exception, aquatic animals, breathing by 
gills. This wide distribution of the waters impressed a very 
uniform character upon the whole Animal Kingdom. Be- 
tween the different zones and continents, no such strange 
contrasts of the different types existed as at the present 
epoch. The same genera, and often the same species, were 
found in the seas of America, Europe, Asia, Africa, and 
New Holland ; from which we must conclude that the 
climate was much more uniform than at the present day. 
Among the aquatic population, no sound was heard. All 
creation was then silent. 

481. THE SECONDARY AGE. Reign of Reptiles. The 
Secondary age displays a greater variety of animals as well 
as plants. The fantastic forms of the Palaeozoic age disap- 
pear, and in their place we see a greater symmetry of shape. 
The advance is particularly marked in the series of verte- 



228 GEOLOGICAL SUCCESSION OF ANIMALS. 

brates. Fishes are no longer the sole representatives of 
that department. Reptiles, Birds, and Mammals successive- 
ly make their appearance, but Reptiles are preponderant, 
particularly in the oolitic formation ; on which account we 
have called this the Reign of Reptiles. 

482. The carboniferous formation is the most ancient of 
the Secondary age. Its fauna bears, in various respects, a 
close analogy to that of the Palaeozoic epoch, especially in 
its Trilobites and Mollusks.* Besides these, we meet here 
with the first air-breathing animals, which are Insects and 
Scorpions. At the same time, land-plants first make their 
appearance, namely, ferns of great size, club-mosses, and 
other fossil plants. This corroborates what has been already 
said concerning the intimate connection that exists, and 
from all times has existed, between animals and the land- 
plants, (399.) The class of Crustaceans has also improved 
during the epoch of the coal. It is no longer composed ex- 
clusively of Trilobites, but the type of horse-shoe crabs also 
appears, with other gigantic forms. Some of the Mollusks 
seem also to approach those of the Oolitic period, particularly 
the Bivalves. 

483. In the Trias period, which immediately succeeds the 
Carboniferous, the fauna of the Secondary age acquires its 
definitive character ; here the Reptiles first appear. They are 
huge Crocodilian animals, belonging to a peculiar order, the 
Rhizodonts, (Protosaurus, Notosaurus, and Labyrinthodon.) 
The well-known discoveries of Professor Hitchcock, in the 
red sandstone of the Connecticut, have made us acquainted 

* This circumstance, in connection with the absence of Reptiles, has 
caused the coal-measures to be generally referred to the Palseozoic epoch. 
But there are other reasons which induce us to unite the carboniferous 
period with the secondary age, especially when considering that here the 
land animals first appear, whereas, in the Palseozoic age, there are only 
marine animals, breathing by gills ; and, also, that a luxuriant terrestrial 
vegetation was developed at that epoch. 



AGES OF NATURE. 



229 



with a great number of birds' tracks (Fig. 158, a, b) belong- 
ing to this epoch, for the most part indicating birds of gigan- 
tic size. These impressions, which he has -designated under 
the name of Ornithichnites, are some of them eighteen inches 






a 





Fig. 158. 

in length, and five feet apart, far exceeding in size the tracks 
of the largest ostrich. Other tracks, of a very peculiar shape, 
have been found in the red sandstone of Germany, and in 
Pennsylvania. They were probably made by Reptiles which 
have been called Cheir other ium, from the resemblance of the 
track to a hand, (c.) The Mollusks, Articulates, and Radiates 
of this period, approach to the fauna of the succeeding period- 
484. The fauna of the Oolitic formation is remarkable for 
the great number of gigantic Reptiles which it contains. In 




a 



Fig. 159. 



this formation we find those enormous Amphibia, known 
under the names Ichthyosaurus, Plesiosaurus, Megalosaurus, 
and Iguanodon. The first, in particular, the Ichthyosaurus, 
(Fig. 159, a,) greatly abounded on the coast of the continents 
of that period, and their skeletons are so well preserved, that 
we are enabled to study even the minutest details of their 
structure, which differs essentially from that of the Reptiles 
of the present day. In some respects they form an inter- 
mediate link between the Fishes and Mammals, and may be 
considered as the prototypes of the Whales, having, like 
20 



230 



GEOLOGICAL SUCCESSION OF ANIMALS. 




then), limbs in the form of oars. The Phsiosaurus (b) 

agrees, in many respects, with 
the Ichthyosaurus, in its struc- 
ture, but is easily distinguished 
by its long neck, which resem- 
bles somewhat the neck of 
some of our birds. A still 
more extraordinary Reptile is 
Fig- 160. the Pterodactylus, (Fig. 160,) 

with its long fingers, like those of a bat, and which is thought 

to have been capable of flying. 

485. It is also in the upper stages of this formation that 
we first meet with Tortoises. Here also we find impressions 
of several families of insects, (Libettulce, Coleoptera, Ichneu- 
mons, fyc.} Finally, in these same stages, the slates of 
Stonesfield, the first traces of Mammals are found, namely, 
the jaws and teeth of animals having some resemblance to 
the Opossum. 

486. The department of Mollusks is largely represented 
in all its classes. The peculiar forms of the primary age 
have almost all disappeared, and are replaced by a much 
greater variety of new forms. Of the Brachiopods only one 

b c d 






Fig. 161. 

type is very abundant, namely, the Terebratula, (Fig. 161, a.) 
Among the other Bivalves there are many peculiar forms, as 
the Goniomya (b) and the Trigonia, (c.) The Gasteropods 
display a great variety of species, and also the Cephalopods, 
among which the Ammonites are the most prominent, (d.) 
There are also found, for the first time, numerous represen- 
tatives of the Cuttle-fishes, under the form of Belemnites, 



AGES OF NATURE. 



231 




Fig. 162, 



(Fig. 162,) an extinct type of animals, protected by a sheath, 
and terminating in a conical body, somewhat similar to the 
bone of the Sepia, which 
commonly is the only 
part preserved, (&.) 

487. The variety is 
not less remarkable 
among the Radiates. 
There are to be found representatives of all the classes ; 
even traces of Jelly-fishes have been made out in the 
slate of Solenhofen, in Bavaria. The Polyps were very 
abundant at that epoch, especially in the upper stages, one 
of which has received the name of Coral-rag. Indeed, 
there are found whole reefs of corals in their natural po- 
sition, similar to those which are seen in the islands of the 




Pacific. Among the most remarkable types of stony Polyps 
may be named the fan-like Lobophyllia, (L. Jldbellum^ a,) 
and various forms of tree-corals, Lithodendron pseudosty- 
lina, &.) But the greatest variety exists among the Echino- 
derms. The Crinoids are not quite so numerous as in 
former ages. Among the most abundant are the Pentacri- 
nus, (c.) There are also Comatula-like animals, that is to 
say, free Crinoids, (Pterocoma pinnata, d.) Many Star- 
fishes are likewise observed in the various stages of this 
formation. Finally, there is an extraordinary variety of 



232 



GEOLOGICAL SUCCESSION OF ANIMALS. 



Echini, among them Ciclaris, (e,) with large spines, and 
several other types not found before, as, for example, the 
Dysaster, (/) and the Nucleolites, (g.) 

488. The fauna of the Cretaceous period bears the 
same general characters as the Oolitic, but with a more 
marked tendency towards existing forms. Thus, the Ich- 
thyosauri and Plcsiosauri, that characterize the preceding 
epoch, are succeeded by gigantic Lizards, more nearly 
approaching the Reptiles of the present day. Among the 
Mollusks, a great number of new forms appear, especial- 
ly among the Cephalopods,* some of which resemble the 



a 



d 



f 





c Fig. 164. e 

Gasteropods in their shape, but are nevertheless cham- 
bered. The Ammonites themselves are quite as numerous 




Fisr. 165 



as in the Oolitic period, and are in general much orna- 
mented, (.) The Acephala furnish us, also, with peculiar 
types, not occurring elsewhere, Magas, (#,) the Inoceramus^ 



* (a) Ammonites; (b) Crioceras ; (c) Scaphites ; (d) Ancyloceras; 
(e) Hamites ; (f) Baculites ; (g} Turrilites. 



AGES OF NATURE. 



233 



the Hippurites, (c,) and peculiar Spondyli, with long 
spines, (d.) There is also a great variety of Gastero- 
pods, among which are some peculiar forms of Pleu- 



a 






Fig. 166. 

rotomaria, (e.) The Radiates are not inferior to the others 
in variety.* 



489. TERTIARY AGE. Reign of Mammals. The most 
significant characteristic of the Tertiary faunas is their 
great resemblance to those of the present epoch. The ani- 
mals belong in general to the same families, and mostly 
to the same genera, differing only as to the species. And 
the specific differences are sometimes so slightly marked, 
that a considerable familiarity with the subject is required, 
in order readily to detect them. Many of the most abundant 
types of former epochs have now disappeared. The changes 
are especially striking among the Mollusks, the two great 
families of Ammonites and Belemnites, which present such 
an astonishing variety in the Oolitic and Cretaceous epochs, 
being now completely wanting. Changes of no less impor- 
tance take place among the Fishes, which are for the most 
part covered with horny scales, like those of the present 
epoch, while in earlier ages they were generally covered 
with enamel. Among the Radiata, we see the family of 
Crinoids reduced to a very few species, while, on the other 
hand, a great number of new Star-fishes and Sea-urchins 
make their appearance. There are, besides, innumerable 

* (a) Diplocteniuni cordatum ; (b) Marsitpites ; (c) Salenia ; (d) Ga 
krites ; (e) Micraster cor-anguinum. 

20* 



234 



GEOLOGICAL SUCCESSION OF ANIMALS. 




Fig. 167. 



remains of a very peculiar type of animals, almost 
unknown to the former ages, as well as to 
the present period. They are little cham- 
bered shells, known to geologists under the 
name of Nummulites, from their coin-like ap- 
pearance, and form very extensive layers of 
rocks, (Fig. 167.) 

490. But what is more important in a philosophical point 
of view is, that aquatic animals are no longer predominant 
in Creation. The great marine or amphibian reptiles give 
place to numerous mammals of great size ; for which rea- 
son, we have called this age the Reign of Mammals. Here 
are also found the first distinct remains of fresh-water 
animals. 

491. The lower stage of this formation is particularly 
characterized by great Pachyderms, among which we may 
mention the Paleotlierium and Anoplotherium, which have 
acquired such celebrity from the researches of Cuvier. 
These animals, among others, abound in the Tertiary forma- 
tions of the neighborhood of Paris. The Paleotheriums, of 




Fig. 168. Fig. 169. 

which several species are known, are the most common ; 
they resemble, (Fig. 168,) in some respects, the Tapirs, 
while the Anoplotheriums are more slender animals, (Fig. 
169.) On this continent are found the remains of a most 
extraordinary animal of gigantic size, the Basilosanrus, a 
true cetacean. Finally, in these stages, the earliest remains 
of Monkeys have been detected. 



AGES OF NATURE. 235 

492. The fauna of the upper stage of the Tertiary forma- 
tion approaches yet more nearly to that of the present epoch. 
Besides the Pachyderms, that were also predominant in the 
lower stage, we find numbers of carnivorous animals, some 
of them much surpassing in size the lions and tigers of our 
day. We meet also gigantic Edentata, and Rodents of great 
size. 

493. The distribution of the Tertiary fossils also reveals 
to us the important fact, that, in this epoch, animals of the 
same Species were circumscribed in much narrower limits 
than before. The earth's surface, highly diversified by 
mountains and valleys, was divided into numerous basins, 
which, like the Gulf of Mexico, or the Mediterranean of this 
day, contained species not found elsewhere. Such was the 
basin of Paris, that of London, and, on this continent, that of 
South Carolina. 

494. In this limitation of certain types within certain 
bounds, we distinctly observe another approach to the present 
condition of things, in the fact that groups of animals which 
occur only in particular regions are found to have already 
existed in the same regions during the Tertiary epoch. Thus 
the Edentata are the predominant animals in the fossil fauna 
of Brazil as well as in its present fauna ; and Marsupials were 
formerly as numerous in New Holland as they now are, 
though in general of much larger size. 

495. THE MODERN EPOCH. Reign of Man. The Present 
epoch succeeds to, but is not a continuation of, the Tertiary 
age. These two epochs are separated by a great geological 
event, traces of which we see every where around us. The 
climate of the northern hemisphere, which had been, during 
the Tertiary epoch, considerably warmer than now, so as to 
allow of the growth of palm-trees in the temperate zone of 
our time, became much colder at the end of this period, 
causing the polar glaciers to advance south, much beyond 



236 GEOLOGICAL SUCCESSION OF ANIMALS. 

their previous limits. It was this ice, either floating like ice- 
bergs, or, as there is still more reason to believe, moving 
along the ground, like the glaciers of the present day, that, in 
its movement towards the South, rounded and polished the 
hardest rocks, and deposited the numerous detached frag- 
ments brought from distant localities, which we find every 
where scattered about upon the soil, and which are known 
under the name of erratics, boulders, or graylieads. This 
phase of the earth's history 'has been called, by geologists, 
the Glacial or Drift period. 

496. After the ice that carried the erratics had melted 
away, the surface of North America and the North of Europe 
was covered by the sea, in consequence of the general sub- 
sidence of the continents. It is not until this period that 
we find, in the deposits known as the diluvial or pleistocene 
formation, incontestable traces of the species of animals now 
living. 

497. It seems, from the latest researches of Geologists, 
that the animals belonging to this period are exclusively 
marine ; for, as the northern part of both continents was 
covered to a great depth with water, and only the summits 
of the mountains were elevated above it, as islands, there 
was no place in our latitudes where land or fresh-water 
animals could exist. They appeared therefore at a later 
period, after the water had again retreated ; and as, from 
the nature of their organization, it is impossible that they 
should have migrated from other countries, we must conclude 
that they were created at a more recent period than our 
marine animals. 

498. Among these land animals which then made their 
appearance, there were representatives of all the genera 
and species now living around us, and besides these, many 
types now extinct, some of them of a gigantic size, such as 
the Mastodon, the remains of which are found in the upper- 



CONCLUSIONS. 



237 



most strata of the earth's surface, and probably the very 
last large animal which became extinct before the creation 
of man.* 




Fig. 170. 

499. It is necessary, therefore, to distinguish two periods 
in the history of the animals now living ; one in which the 
marine animals were created, and a second, during which 
the land and fresh- water animals made their appearance, and 
at their head MAN.! 



CONCLUSIONS. 

500. From the above sketch it is evident that there is a 
manifest progress in the succession of beings on the surface 

* The above diagram is a likeness of the splendid specimen disinterred 
at Newburg, N. Y., now in the possession of Dr. J. C. Warren, in Boston ; 
the most complete skeleton which has ever been discovered. It stands 
nearly twelve feet in height, the tusks are fourteen feet in length, and 
nearly every bone is present, in a state of preservation truly wonderful. 

f The former of these phases is indicated in the frontispiece, by a nar- 
row circle, inserted between the upper stage of the Tertiary formation 
and the Reign of Man properly so called. 



238 GEOLOGICAL SUCCESSION OF ANIMALS. 

of the earth. This progress consists in an increasing simi- 
larity to the living fauna, and among the Vertebrates, espe- 
cially, in their increasing resemblance to Man. 

501. But this connection is not the consequence of a 
direct lineage between the faunas of different ages. There 
is nothing like parental descent connecting them. The 
Fishes of the Palaeozoic age are in no respect the ancestors 
of the Reptiles of the Secondary age, nor does Man descend 
from the Mammals which preceded him in the Tertiary 
age. The link by which they are connected is of a higher 
and immaterial nature ; and their connection is to be sought 
in the view of the Creator himself, whose aim, in forming 
the earth, in allowing it to undergo the successive changes 
which Geology has pointed out, and in creating successively 
all the different types of animals which have passed away, 
was to introduce Man upon the surface of our globe. 
Man is the end towards which all the animal creation 
has tended, from the first appearance of the first Palaeozoic 
Fishes. 

502. In the beginning His plan was formed, and from it 
He has never swerved in any particular. The same Being 
who, in view of man's moral wants, provided and declared, 
thousands of years in advance, that " the seed of the woman 
shall bruise the serpent's head," laid up also for him in the 
bowels of the earth those vast stores of granite, marble, coal, 
salt, and the various metals, the products of its several revo- 
lutions ; and thus was an inexhaustible provision made for 
his necessities, and for the development of his genius, ages 
in anticipation of his appearance. 

503. To study, in this view, the succession of animals in 
time, and their distribution in space, is, therefore, to become 
acquainted with the ideas of God himself. Now, if the suc- 
cession of created beings on the surface of the globe is the 
realization of an infinitely wise plan, it follows that there 



CONCLUSIONS. 239 

must be a necessary relation between the races of ani- 
mals and the epoch at which they appear. It is necessary, 
therefore, in order to comprehend Creation, that we com- 
bine the study of extinct species with that of those now 
living, since one is the natural complement of the other. A 
system of Zoology will consequently be true, in proportion 
as it corresponds with the order of succession among ani- 
mals. 



INDEX AND GLOSSARY. 



Abd6men, the lower cavity of the 
body, 41. 

Abranchiates, without gills, 21. 

Acalepha, a class of Radiates, many 
species of which produce tingling 
of the skin when handled, 23. 

Acephala, rnollusks having no dis- 
tinct head, like clams, 22. 

Acoustic, pertaining to the sense of 
hearing, 56. 

Actinia, digestive apparatus of, 97- 

Actinoids, 23. 

Affinity, relationship, 30, 87. 

Ages of Nature, 221. 

Albumen, the white of egg, 42, 111, 
138. 

Alimentary canal, 97. 

Alimentation, the process of nutri- 
tion, 42. 

Allantois, Allantoidian, 149. 

Alligator, teeth of, 105. 

Alternate reproduction, 159 ; con- 
sequences of, 167 ; difference be- 
tween, and metamorphosis, 167. 

Ambling, 91. 

Amblyopsis spelseus, 55. 

Ammonites, 22, 230, 232, 233. 

Amnios, 150. 

Amphibia, 95. 

Amphipods, a family of crusta- 
ceans. 

Amphioxus, its place, 181. 

Amphiuma, 209. 

Analogy, 30. 

Anatifa, metamorphoses of, 177. 

Ancyloceras, 232. 

Animalcule, a minute animal, 24. 

Animal heat, 122. 

Animal life, 44 ; organs of, 44. 

Animals, number of, 27 ; distribu- 
tion in space, 186 ; in time, 214. 
21 



Animals and plants, differences be- 
tween, 41. 

Animate, possessed of animal life, 
43. 

Anoplotherium, 234. 

Antenna, the jointed feelers of lob- 
sters, insects, &c., 77- 

Aorta, the great bloodvessel arising 
from the heart, 116. 

Aphides, reproduction of, 162, 163. 

Apophysis, a projection from the 
body of a bone, 181. 

Apparatus of motion, 73. 

Aptera, wingless insects, 21. 

Aquatic, living in water. 

Aqueous, like water. 

Aqueous humor, 50. 

Arctic fauna, 197. 

Areolar tissue, 38. 

Arges, 225. 

Aristotle's lantern, 102. 

Arm, 82 ; different forms of, 83. 

Artery, 113. 

Articulates, composed of joints, like 
the lobster or caterpillar, 21 ; 
number of, 27. 

Ascidia, bottle-shaped mollusks 
without a shell. 

Assimilation, the change of blood 
into bone, muscle, &c., 122. 

Astacus pellucidus, 55. 

Asteridse, the family of star-fishes, 
23. 

Auditory, pertaining to the sense 
of hearing, 56. 

Auricle, a cavity of the heart, like 
a little ear, 115. 

Avicula decussata, 224. 

Axolotl, 209. 

Baculites, 232. 



242 



INDEX AND GLOSSARY. 



Balanus, the barnacle, 176. 
Basilosaurus, 234. 
Batrachians, the frog tribe, 20. 
Beak, 104. 

Belemnites, 230, 233. 
Bird-tracks, in red sandstone, 229. 
Birds, number of, 27. 
Bivalve, having two shells, like the 

clam, 27- 
Blastoderm, the embryonic germ, 

141. 

Blind-fishes, 55. 
Blood, 111, 121. 
Boulders, 236. 
Brachionus, jaws of, 103. 
Brachiopods, a class of mollusks, 

22. 

Brain, 45. 

Branchiae, gills, 120. 
Branchifers, univalve mollusks 

breathing by gills, 22. 
Bronchi, tubes branching from the 

windpipe in the lungs, 119. 
Brontes, 225. 
Bryozoa, 23, 225. 
Bucania expansa, 224. 

Calcareous, composed of lime, 75, 

134. 
Campanularia, reproduction of, 165, 

170. 

Canine teeth, 106. 
Caninia flexuosa, 224. 
Canker-worm, metamorphoses of, 

176. 

Cannon-bone, 86. 
Canter, 91. 

Capillary vessels, 113. 
Carapace, the upper covering of the 

crab or tortoise, 75. 
Carbon, the basis of charcoal and 

most combustibles, 41. 
Carboniferous rocks, 218, 228. 
Cariocrinus ornatus, 224. 
Carnivora, animals feeding on flesh, 

20 ; teeth of, 107. 
Carpus, the wrist, 83. 
Cartilage, gristle, 39. 
Cartilaginous tissue, 38. 
Cell, 37 ; nucleated, 38. 
Cellule, a little cell, 37. 
Cephalopods, mollusks with arms 

surrounding the head, like the 

cuttle-fish, 22. 

Cercaria, reproduction of, 160, 171. 
Cerebral, pertaining to the brain, 45. 
Cestracion Philippi, 204. 



Cetaceans, marine animals which 
nurse their young, like the whale, 
porpoise, &c., 20. 

Chsetetes lycoperdon, 224. 

Chalaza, the albuminous thread by 
which the yolk of the egg is sus- 
pended, 138. 

Chalk formation, 218. 

Chambers of the eye, 50. 

Chamois, 192. 

Cheirotherium, 229. 

Chelonians, reptiles of the tortoise 
tribe, 20. 

Chorion, 151. 

Choroid, coat of the eye, 49. 

Chrysalis, the insect in its passage 
fr-om the worm to the fly state, 
174. 

Chyle, 100, 112. 

Chyme, 100, 112. 

Cicatricula, 141. 

Cilia, microscoj 
lashes, 81, 11 



ic hairs, like 
, 116, 120. 



eye- 



Circulation, 97; great, 111; pulmo- 
nary or lesser, 116 ; complete, 
116 ; incomplete, 116. 

Cirrhipedes, Crustacea having curled 
feelers, like the barnacles, 27. 

Class, 18. 

Clavicle, the collar-bone, 83. 

Climate, influence on a fauna, 188. 

Climbing, 92. 

Cocc6steus, 226. 

Cochlea, 58. 

Cold-blooded animals, 122. 

Coleopterous, insects with hard 
wing cases, like the dor-bug, 27. 

Collar-bone, 83. 

Columnaria alveolata, 224. 

Comatula, metamorphosis of, 179, 
180. 

Condor, 191. 

Constancy of species, 67. 

Coral-rag, 231. 

Cornea, the transparent portion of 
the eyef 49. 

Corpuscles, minute bodies, 39. 

Cossus ligniperda, muscles of, 77- 

Cretaceous, or chalk formation, 218. 

Cricoid, ring-like, 65. 

Crinoid, lily-like star-fishes, 23. 

Crioceras, 232. 

Crustacea, articulated animals hav- 
ing a crust-like covering, like the 
crab and horse-shoe, 27 ; heart 
of, 117. 

Crystalline lens, 49. 



INDEX AND GLOSSARY. 



243 



Ctenoids, fishes which have the 

edge of the scales toothed, 20. 
Ctenophori, soft, radiated animals, 

moving by cilia, 23. 
Cutis, 128. 
Cuttle-fish, jaws of, 102; heart of, 

117; metamorphosis of, 180; 

mode of swimming, 95. 
Cyathocrinus ornatissimus, 224. 
Cyathophyllum quadrigeminum, 

224. 
Cycloids, fishes with smooth scales, 

21. 

Deciduous, not permanent during a 

lifetime, 199. 
Deglutition, the act of swallowing, 

108. 
Dentition, form and arrangement 

of the teeth. 
Department, a primary division of 

the animal kingdom, 18. 
Development of the white-fish, 

145. 

Devonian rocks, 218. 
Diaphragm, the partition between 

the chest and abdomen, 74, 119. 
Diastole, the dilatation of the heart, 

115. 

Digestion, 97. 

Diploctenium cordatum, 233. 
Dipterus, 226. 
Discophori, disk-shaped animals, 

like the jelly-fish. 23. 
Disk, a more or less circular, flat- 
tened body, 14. 
Distoma, reproduction of, 161 ; in 

the eye of the perch, 171. 
Distribution of animals, laws of, 

186 ; in space, 186 ; in time, 214. 
Dodo, its disappearance, 210. 
Dorsal cord, 143. 
Dorsal vessel, 114. 
Dorsibranchiates, mollusks having 

gills upon the back, 21. 
Drift, 219, 236. 
Drinking, 109. 

Duck-barnacle. See Anatifa. 
Dysaster, 232. 

Ear, 55. 

Echinoderms, radiate animals arm- 
ed with spines externally, like 
the sea-urchin, 23. 

Echinus, the sea-urchin, 23; jaws 
of, 102 ; heart of, 117 ; mode of 
progression, 81. 



Echinus sanguinolentus, metamor- 
phosis of, 178. 

Egg, 131 ; form of, 133 ; formation 
of, 133 ; ovarian, 133 ; laying of, 
135 ; composition of, 137 ; devel- 
opment of, 139 ; of Infusoria, 172. 

Elementary structure of organized 
bodies, 36. 

Embryo, the young animal before 
birth, 33, 132; development of, 
139. 

Embryology, 131, 139; importance 
of, 153. 

Endosmose, 127. See Exosmose. 

Engeena, a large orang, 206. 

Entomostraca, 21. 

Eocene formation, 218. 

Ephyra, 164, 169. 

Epidermis, the scarf-skin, 129. 

Epithelium-cells, 126. 

Equivocal reproduction, 158. 

Erratics, rolling stones, 236. 

Euomphalus hemisphericus, 224. 

Eurypterus remipes, 225. 

Eustachian tube, 57- 

Excretions, 127. 

Exhalation, 128. 

Exosmose and Endosmose, the pro- 
cess by which two fluids pass 
each way through a membrane 
which separates them, so as to 
become mingled, 127. 

Eye, 48 ; simple, 51 ; aggregate, 
53 ; compound, 54 ; destitution 
of, 55 ; compared to a camera 
obscura, 51. 

Fa9ette, a very small surface, 54. 

Family, a group including several 
genera, 18. 

Fauna, 186 ; distribution of, 194. 

Femur, the thigh bone, 87. 

Fibula, the smallest of the two 
bones of the leg, 87. 

Fins, 93. 

Fishes, number of, 27; heart of, 
116 ; reign of, 222, 223. 

Fissiparous reproduction, propaga- 
tion by fissure or division, 156. 

Flight, 92. 

Flora, influence on a fauna, 187. 

Fluviatile, pertaining to rivers, 27. 

Foraminifera, 22. 

Formation, geological, 217. 

Fossil, dug from the earth, applied 
to the remains of animals and 
plants. 



244 



INDEX AND GLOSSARY. 



Function, the office which an organ 
is designed to perform, 29. 

Galeopithecus, its facilities for 
leaping, 93, 207. 

GalerHes, 233. 

Gallinaceous, birds allied to the do- 
mestic fowl, 190. 

Gallop, 91. 

Ganglions, scattered nervous mass- 
es, from which nervous threads 
arise, 46. 

Ganoids, fishes having large, bony, 
enamelled scales, mostly fossil, 20. 

Gar-pike, 192. 

Gasteropods, mollusks which crawl 
by a flattened disk, or foot, on 
the under part of the body, like 
the snail, 22. 

Gastric juice, 99. 

Gavial, a crocodile, with a long, 
slender head. 

Gemmiparous reproduction, propa- 
gation by budding, 156. 

General properties of organized 
bodies, 35. 

Genus, 17- 

Geographical distribution of ani- 
mals, 186 ; conclusions, 207. 

Geological succession of animals, 
214. 

Germ, the earliest manifestation of 
the embryo, 42, 141. 

Germinative disk, 133, 137, 141 ; 
vesicle, 133, 137, 138; dot,137,138. 

Gestation, the carrying of the young 
before birth, 135. 

Gills, 31, 120, 124. 

Gizzard, 99. 

Glacial period, 236. 

Glands, 127 ; salivary, 127. 

Globules of chyle, 100. 

Glottis, 65. 

Goniomya, 230. 

Grallatores, birds with long legs for 
wading, 20. 

Grand-nurses of Cercaria, 162. 

Granivorous, birds feeding on grain. 

Grit, coarse sandstone, 216. 

Gullet, 99. 

Karaites, 232. 

Hand, 83. 

Harmony of organs, 106. 

Harpes, 225. 

Hearing, 55. 

Heart, 114. 



Herbivora, animals feeding on grass 
and leaves, 20. 

Hibernation, torpid state of ani- 
mals during winter, 123. 

Hippurltes, 233. 

Holothurians, soft sea-slugs, biche- 
le-mar, 23. 

Homogeneous, uniform inkind,126. 

Homology, 30. 

Humerus, the shoulder-bone, 81. 

Hyaline matter, pure, like glass, 39. 

Hydra, egg of, 133 ; propagation of, 
156, 158. 

Hydrogen, a gas which is the prin- 
cipal constituent of water, 41. 

Hydroids, a family of polyps, 23. 

Ichthyosaurus, 229, 232. 

Icterus Baltimore, nest of, 70. 

Igneous, that have been acted upon 
bv fire, 215. 

Iguanodon, 229. 

Imbibition, 127. 

Inanimate, destitute of life, 43. 

Incisor teeth, 106. 

Incubation, hatching of eggs by the 
mother, 136. 

Infusoria, microscopic animals in- 
habiting water, not yet fully ar- 
ranged in their proper classes, 24, 
32 ; motions of, 40 ; generation of, 
172. 

Inoceramus, 232. 

Inorganic, not made up of tissues,35. 

Insaiivation, 108. 

Insects, number of, 27- 

Insessores, perching birds, like 
birds of prey, 20. 

Instinct, 67, 69. 

Intelligence, 67, 68. 

Intercellular passages, 37. 

Invertebrates, animals destitute of 
a back-bone. 

Iris, the colored part of the eye, 40. 

Isotelus, 225. 

Jelly-fish. See Medusa. 
Judgment, 68. 

Kidneys, 130. 

Labyrinthodon, 228. 

Lacertans, animals of the lizard 

tribe, 20. 
Lacteals, vessels which take up the 

nutriment, 100. 
Lamellibranchiates, mollusks hav- 



INDEX AND GLOSSARY. 



245 



ing gills arranged in sheets, like 

the clam and oyster, 22. 
Larva, the caterpillar or worm state 

of an insect. 
Larynx, 65. 
Lasso-cells, 110. 
Layers of the embryo, 142. 
Leaping, 91. 
Lemming, 190, 197. 
Leptccna alternata, 224. 
Lestris, 72. 
Life, 35, 44. 
Limbs, 54. 

Limnca, parasites of, 160, 162. 
Lingula prima, 224. 
Lithodendron pseudostylina, 231. 
Liver, 129. 

Lobophyllia flabellum, 231. 
Lobsters, mode of swimming, 94 ; 

nervous system, 46. 
Locomotion, 79 ; organs of, 82 ; 

modes of, 88. 
Loligo, arms of, 180. 
Lungs, 118. 
Lymphatic vessels, 100. 

Magas, 232. 

Malacostraca, 21. 

Mammals, animals which nurse 
their young, 19 ; number of, 27 ; 
reign of, 222, 233. 

Man, reign of, 222, 234 ; races of, 
212 ; his twofold nature, 25. 

Manatee, 206. 

Manducata, insects furnished with 
jaws, 21. 

Marchantia polymorpha, reproduc- 
tion of, 166. 

Marl, earth principally composed 
of decayed shells and corals, 216. 

Marsupials, animals with a pouch 
for carrying their young, as the 
opossum ; gestation of, 183. 

MarsupUes, 233. 

Mastication, 101. 

Mastodon, 236. 

Matrix, the organ in which the em- 
bryo is developed, 152. 

Medulla oblongata, continuation of 
the brain into the back-bone. 

Medusa, jelly-like animals living in 
the sea, 23 ; development of, 163 ; 
digestive organs, 98 ; motion 80. 

Megalobatrachus, 209. 

Megalosaurus, 229. 

Melocrinus amphora, 224. 

Memory, 68. 

21* 



Menobranchus, 202, 209. 

Menopoma, 202, 209. 

Merganser, an aquatic bird allied to 
the goose, 66, 193. 

Metacarpus, the wrist, 83. 

Metatarsus, 87. 

Metamorphic rocks, 216. 174. 

Metamorphosis, 149, 167; of the 
silk-worm, 175 ; canker-worm, 
176: duck-barnacle, 177; star-fish, 
178 ; comatula, 179. 

Micraster cor-anguinum, 232. 

Miocene formation, 219. 

Modern age, 222, 235. 

Molar teeth, 106. 

Molecules, very minute particles, 35. 

Mollusks, soft animals of the snail 
and oyster kind; heart of, 117; 
liver of, 129 ; number of, 27 ; meta- 
morphosis of, 179. 

Monkey, teeth of, 107, 20-5. 

Monoculus, mode of carrying eggs, 
135 ; motion, 73 : apparatus of, 73. 

Moulting, the shedding of feathers, 
hair, &c., 128. 

Muscles, 73; disposition of, in in- 
sects, 77 ; in fishes, 78 ; in birds, 
79. 

Muscular tissue, 39. 

Myxine glutinosa, its eye, 55. 

Natatores, birds with webbed feet 
for swimming, 20. 

Natica, tongue of, 102 ; heart of, 117. 

Nautili, 22. 

Neptunian rocks, 215. 

Nereis, jaws of, 102; gills of, 81 ; 
eye, 53. 

Nervous system, 44 ; in mammals, 
45 ; in articulates, 46 ; in crusta- 
ceans, 46 ; in radiates, 47. 

Nervous tissue, 39. 

Nest of Baltimore oriole, 70 ; of tai- 
lor bird, 70 ; of Ploceus, 71. 

Nomenclature, the naming of ob- 
jects and their classes, family, &c. 

Nostrils, 60. 

Notosaurus, 228. 

Nucleolites, 232. 

Nucleolus, a little nucleus, 38. 

Nucleus, a kernel, or condensed 
central portion, 38. 

Nudibranchiates, mollusks having 
the gills floating externally, fig. 91. 

Nummulites, 234. 

Nurses, of Cercaria, 162; of ants 
and bees, 163. 



246 



INDEX AND GLOSSARY. 



Nutrition, 96. 

Ocelli, minute eyes, 52. 

Octopus, arms of, 180. 

Odors, 61. 

(Esophagus, the gullet, 46, 99. 

Olfactory, pertaining to the sense 

of smell, 45, 60. 
Omnivora, feeding upon all kinds 

of food, 107. 
Oolitic formation, 218. 
Operculum, a cover for the aperture 

of a shell. 
Ophidians, animals of the serpent 

kind, 20. 
Optic nerves, 48. 
Orbits, 48. 
Orders, 18. 
Organism, 37. 
Organized bodies, general properties 

of, 35 ; elementary structure, 36, 

37. 

Ornithichnites, 229. 
Orthoceras fusiforme, 225. 
Osseous tissue, 39. 
Otolites, little bones in the ears of 

mollusks and Crustacea, 59. 
Ovary, the organ in which eggs 

originate, 133. . 
Oviduct, the passage through which 

the egg is excluded, 134. 
Oviparous, producing eggs, 131. 
Ovis montana, 192. 
Ovo-viviparous, animals which 

hatch their eggs within their 

body, 135. 
Ovulation, the production of eggs, 

134. 

Oxygen, its consumption in respira- 
tion, 41, 113, 121. 

Pachydermata, thick-skinned ani- 
mals, like the elephant, hog, &c., 
107, 234. 

Pacing, 91. 

Paleont61ogy, 215. 

Palaeozoic age, 222, 223. 

Paleotherium, 234. 

Palpation, the exercise of the touch, 
64. 

Palpi, jointed organs for touch, 
about the mo\ith of insects, 64. 

Papilla, a little pimple, 62. 

Paramecia, reproduction of, 157. 

Parasitic, living on other objects. 

Passerine, birds of the sparrow kind, 
201. 



Peduncle or Pedicle, a slender stem. 

Pelvis, the cavity formed by the 
hip bones, 87. 

Pentacrinus, 231 ; metamorphosis 
of, 180. 

Perception, 67. 

Perchers, a class of birds, 20. 

Peripherie, exterior surface, 152. 

Peristaltic motion, 100. 

Petrifactions, 215. 

Phalanges, 83. 

Pigment, a coloring substance, 40. 

Pituitary membrane, 61. 

Placenta, the organ by which the 
embryo of mammals is attached 
to the mother, 152. 

Placoids, fishes with a rough skin, 
like the shark or skate, 20. 

Planaria, its digestive apparatus, 
98 ; an eye of, 53. 

Plant-lice. See Aphides. 

Plants compared with animals, 41. 

Platynotus, 225. 

Pleiocene formation, 219. 

Plesiosaurus, 229, 232. 

Pleurotomaria, 233. 

Ploceus Philippinus, nest of, 70. 

Plutonic rocks, 215. 

Podurella, mode of leaping, 92 ; em- 
bryo of, 144 ; egg of, 133. 

Polyps, a small animal fixed at one 
end, with numerous flexible feel- 
ers at the other, 27, 53; repro- 
duction of, 158. 

Prehension, act of grasping, 109. 

Primary age, 222. 

Primitive stripe, 143. 

Progression, 88, 90. 

Proligerous, the part of the egg 
bearing the embryo, 141. 

Proteus, 209. 

Protosaurus, 228. 

Protractile, capable of being ex- 
tended. 

Pterichthys, 226. 

Pter6coma pinnata, 231. 

Pterodactylus, 230. 

Pteropods, mollusks with wing-like 
expansions for swimming, 22. 

Pulmonary, relating to the lungs, 
116. 

Pulmonates, mollusks which 
respire air, 22. 

Pupil ; 40. 

Pyrula. egg-cases of. 135. 

Quadrumanous, four-handed, 201 



INDEX AND GLOSSARY. 



247 



Quadruped; animals with four legs, 
40. 

Radiata, animals whose organs ra- 
diate from a centre, 23, 27. 

Radius, one of the bones of the 
arm, 83. 

Reign of fishes ; of man, 235 ; of 
mammals, 233; of reptiles, 238. 

Relation, functions of, 44. 

Reproduction, 131 ; peculiar modes, 
156. 

Reptiles, number of, 27; reign of, 
222, 227. 

Respiration, 9", 118. 

Rete mucosum, 129 ; retina, 49. 

Retractile, that may be drawn 
back, 84. 

Rhizodonts, 20 ; of the trias, 228. 

Rhizopods, 22. 

Rocks, classification of, 215 ; defi- 
nition of, 215. 

Rodents, quadrupeds with teeth for 
gnawing, 107. 

Rotifers, jaws of, 103 ; eggs of, 172. 

Ruminants, quadrupeds which chew 
the cud. 107. 

Running, 91. 

Rytlna Stelleri, 210. 

Salenia, 233. 

Saliferous formation, 218. 

Saliva, 108. 

Salivary glands, 127. 

Salpa, reproduction of, 159 ; motion 
of, 80. 

Scansores, birds adapted for climb- 
ing, 20. 

Scaphites, 232. 

Scapula, 82. 

Sclerotic, the principal coat of the 
eye, 49. 

Scutella, jaws of. 101. 

Sea-anemone. See Actinia. 

Sea-urchin, eye of, 53; digestive 
organs, 98 ; heart, 117. 

Secondary age, 222, 227. 

Secretions, 97, 126. 

Sedimentary rocks, 215. 

Segment, portion of a circle or 
sphere. 

Sensation, general, 43, 47. 

Senses, special. 48. 

Sepia, 231. 

Serous, watery, 142. 

Shark, egg of, 133. 

Shoulder-blade, 82. 



Sight, 48. 

Silex, flinty rock. 

Siliceous, made of flint. 

Silk-worm, metamorphosis of, 175. 

Silurian rocks, lower, 217 ; upper, 
218. 

Sinuous, bending in and out, 22. 

Siphonophori, 23. 

Siren, 209. 

Skeleton, 74, 77. 

Skin, structure of, 128. 

Smell, 60. 

Species, constancy of, 67 ; definition 
of, 17, 159. 

Spinal marrow, 45. 

Spondyli, 233. 

Sponges not animal, 41. 

Spontaneous generation, 171. 

Spores, the germs of sea-weeds, 
ferns, &c., 170. 

Standing, 88. 

Stapes, 57- 

Star-fish, metamorphoses of, 178 ; 
eye of, 53 ; mode of progression, 
81 ; reproduction of parts, 126. 

Stigmata, openings in insects for 
the admission of air, 118. 

Stomach, 97. 

Stratified rocks, 215. 

Stratum, a layer. 

Strobila, 164, 169. 

Structure of the earth's crust, 214. 

Sturgeon, compared with white- 
fish, 180. 

Suctoria, insects taking their food 
by suction, 21. 

Swimming, 93. 

Sylvia sutoria, nest of, 70. 

Systole, the contraction of the heart 
to force out the blood, 115. 

Tape-worm, reproduction of, 140. 

Tapir, 204, 234. 

Tarsus, the ancle, 87- 

Taste, 62, 

Teeth, 104. 

Temperate faunas, 198. 

Temporal, relating to the temples, 
104. 

Tentacle, the horn-like organs on 
the head of mollusks, usually 
bearing the eyes, 52. 

Terebratula, 230. 

Tertiary age, 222, 233. 

Tertiary formation, lower, 218 ; up- 
per, 219. 



248 



INDEX AND GLOSSARY. 



Test, the bristle crust covering the 
crustaceans, &c., !). 

Teuthideans, the iamily of cuttle- 
fishes, 22. 

Tibia, one of the bones of the leg, 87. 

Tissues, 37 ; areolar, 38 ; cartilagi- 
nous, 38 ; muscular, 39 ; osseous, 
39 ; nervous, 39. 

Tongue, 62. 

Touch, 63. 

Trachea, the windpipe, 119. 

Tracheae, the air-tubes of insects, 
118, 123. 

Transudation, 127- 

Trias formation, 218, 228. 

Trigonia, 230. 

Trilobites, 21, 32. 

Trocholites ammonius, 225. 

Trophi, organs for feeding, of in- 
sects, crabs, &c. 

Tropical faunas, 204. 

Trot, 91. 

Tubulibranchiates, 21. 

Tunicata, mollusks with a leathery 
covering, 159. 

Turrilites, 232. 

Tympanum, a drum ; the membrane 
separating the internal and exter- 
nal ear, 57. 

Type, an ideal image, 18. 

Ulna, one of the bones of the arm, 

83. 

Ultimate, final. 
Univalve, having a single shell, like 

the snail, 27- 

Vascular, composed of vessels, 129. 
Vegetative life, 44, 96 ; layer, 142. 
Veins, 113. 



Ventricle, a cavity of the heart, 115. 

Vermicular, 100. 

Vertebra, a joint of the back-bone, 

46, 77. 
Vertebrate, having a back-bone, 19, 

27. 

Vertical, in a perpendicular direc- 
tion, 48. 
Vesicle, a small membranous bag, 

37. 
Vestibule, a porch ; the entrance to 

one of the cavities of the ear, 58. 
Vibratile, moving to and fro, 112. 
Viscera, 159. 

Vitelline membrane, 138. 
Vitellus, 137. 
Vitreous humor, 50. 
Viviparous, producing living young, 

131. 

Vocal cords, 65. 
Voice, 64. 
Voluntary, under control of the will, 

43. 
Vorticella, reproduction of, 157, 158. 

Walking, 90. 

Wapiti, 211. 

Warm-blooded animals, 122. 

Water-tubes of aquatic animals, 123. 

Whale, fans of, 104. 

Whales, mode of swimming, 94. 

White-fish, development of, 145. 

Windpipe, 119. 

Worms, 21 ; eye of, 53. 

Zoology, its sphere, 25. 
Zoophytes, animals of a very low 

type, mostly fixed to the ground. 

of a plant-like form. 



249 



LIST OF THE MOST IMPORTANT AUTHORS 

WHO MAY BE CONSULTED IN REFERENCE TO THE 
SUBJECTS TREATED IN THIS WORK. 



GENERAL ZOOLOGY. 

Aristotle's Zoology; Linnaeus, System of Nature; Cuvier's Animal 
Kingdom ; Oken's Zoology ; Humboldt's Cosmos, and Views of Nature ; 
Spix, History of Zoological Systems ; Cuvier's History of the Natural 
Sciences. 



ANATOMY AND PHYSIOLOGY. 

Henle's General Anatomy ; and most of the larger works on Compara- 
tive Anatomy, Physiology, and Botany, such as those of Hunter, Cuvier, 
Meckel, Mailer, Todd and Bowman, Grant, Owen, Carpenter, Rymer 
Jones, Hassall, Quain and Sharpey, Bourgery and Jacob, Wagner, 
Siebold, Milne Edwards, Carus, Schleiden, Burmeister, Lindley, Robert 
Brown. Dutrochet, Decandolle, A. Gray. 



SPECIAL SUBJECTS OF ANATOMY AND PHYSIOLOGY MAY BE 

CONSULTED 

Schwann, on the Conformity in the Structure and Growth of Animals 
and Plants. 

Dumas and Boussingault, on Respiration in Animals and Plants. 

Valentin, on Tissues ; and Microscopic Anatomy of the Senses. 

Soemmering, Figures of the Eye and Ear. 

Kolliker, Theory of the Animal Cell. 

Breschet, on the Structure of the Skin. 

Locomotion ; Weber, and Duges. 

Teeth; Fred. Cuvier, Geoff. St. Hilaire, Owen, Nasmyth, Retzius. 

Blood ; Dollinger, Barry. 

Digestion; Spallanzani, Valentin and Brunner, Dumas and Boussin- 
gault, Liebig, Matteucci, Beaumont. 



INSTINCT AND INTELLIGENCE. 

Kirby, Blumenbach, Spurzheirn, Combe. 



250 



EMBRYOLOGY. 

D' Alton, Von Baer, Purkinje, Wagner, Wolfe, Rathke, Bischoff, 
Velpeau, Flourens, Barry, Leidy. 



PECULIAR MODES OF REPRODUCTION. 

Ehrenberg, Trembly, Rosel, Sars, Loven, Steenstrup, Van Beneden. 

METAMORPHOSIS. 

St. Merian, Rosel, De Geer, Harris, Kirby and Spence, Burmeister, 
Reaumur. 

GEOGRAPHICAL DISTRIBUTION. 

Zimmerman, Milne Edwards, Swainson, A. Wagner, Forbes, Pennant, 
Richardson, Ritter, Guyot. 

GEOLOGY. 

The Works of Murchison, Phillips, Lyell, Mantell, Hugh Miller, 
Agassiz, D'Archiac, De Beaumont, D'Orbigny, De Verneuil, Cuvier, 
Brongniart, Deshayes, Morton, Hall, Conrad, Hitchcock, Troost, and the 
Reports on the various local Geological Surveys. 

Very many of the papers of the authors above referred to are not pub- 
lished in separate volumes, but are scattered through the volumes of 
Scientific Periodicals ; such as the 

Transactions of the Royal Society of London. 

Annals and Magazine of Natural History. 

Annales, and Archives, du Museum d' Hist. Naturelle. 

Annales des Sciences Naturelles. 

Wiegmann's Archiv ftlr Naturgeschichte, 

Mailer's Archiv. 

Oken's Isis. 

Berlin Transactions. 

Transactions of the American Philosophical Society 

Memoirs of the American Academy. 

Journal of the Academy of Nat. Sciences, Philadelphia. 

Silliman's Journal. 

Journal of Boston Society of Natural History. 

END OF PART I. 



VALUABLE SCIENTIFIC WORKS, 

PUBLISHED BY GOULD AND LINCOLN. 



LAKE SUPERIOR, 



ITS PHYSICAL CHARACTER, VEGETATION, AND ANIMALS, COMPARED 
WITH OTHER AND SIMILAR REGIONS ; 

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FOOT-PRINTS OF THE CREATOR; 

OR 

THE ASTEROLEPIS OF STROMNESS. 

BY HUGH MILLEK. 

WITH MANY ILLUSTRATIONS. 
IROM THE THIUD LONDON E D I T I O >*. WI T II A MEMOIR OF THE AUTHOB 

BY LOUIS AGASSIZ. 

In its purely geological character, the 'Foot-prints' is not surpassed by any modern 
of the same Glass. In this volume, Mr. Miller discuses 'lie development hypothesis, 
or the hvpotbe.sH ot' natural law, as maintained by Lamarck, and by the author of the 
'Vestiges of Creation,' and has subjected it, in its geological aspect, to the mo-a vigorous 
examination. llv.- ha-; stripped even of its semblance of truth, and restored to the Creator, 
as govemor cf the universe, that power and those functions which lie was supposed to hava 
resigned at its birth. * * * The earth has still to surrender mighty secrets, and great rev- 
elations are yet to bsue from sepulchres of stone. It is from the vault.? to which ancient 
life has been consigned that the history of the dawn of life -is to be composed." ^VoriA 
Britisli Review. 

" Scientific knowledge equally remarkable for comprehensiveness and accuracy ; a style 
at all times singularly clear, vivid, and powerful, ranging at will, and without effort, from 
the most natural and gTaceful simplicity, through the playful, the graphic, and the vigor- 
ous, to the impressive eloquence of great thoughts greatly expressed; rca-onmg at once 
comprehensive in scope, strong in grasp, and pointedly direct in application, these qual- 
ities combine to render the. 'Foot-prints ' one of the most perfect refutations of error, and 
defences of truth, that ever exact science has produced." Free Church Magazine. 

DK. BUCKLAND, at a meeting of the ; British Association, said he had never been so much 
astonished in his life, by the powers of any man. as he had been by the geological descriptions 
of Mr. Miller. That wonderful man der.c'ribed these objects with a facility which made him 
ashamed of the comparative meagreness and poverty of his own descriptions in the ' Bridge- 
water Treatise," which had cost him hoars and days of labor. He would_ give his left hand 
to possess such powers of description as (Ms ma/t ; and if it pleased Providence to spare his 
useful life, he, if any one, would certainly render science attractive and popular, and do 
equal service to theology and geology. 

" The style of this work is most singularly clear and vivid, rising at times to eloquence, 
and always impressing the reader with the idea that he is brought in contact with great 
thoughts. Where, it is necessary, there are engravings to illustrate the geological remains. 
The whole work forms one of the best defences of Truth that science can produce." Albany 
State Register. 

"The ' Foot-Prints of the Creator 1 is not onlv a good but a great book. All who have 
read the ' Vestiges of Creation ' should study the ' Foot-Prints of the Creator.' This vol- 
ume is especially worthy the attention of those who are so fearful of the skeptical tenden- 
cies of natural science. We expect this volume will meet with a very extensive sale. It 
should be placed in every Sabbath School Library , and at every Christian fireside. ".Boston 
Traveller. 

"Mr. Miller's style is remarkably pleasing; his mode of popularising geological knowl- 
edge unsurpassed, perhaps unequalled; and the deep vein of reverence for Divine llevela- 
tion pervading all, adds interest and value to the volume." New York Com. Advertiser. 

"The publishers have again covered themselves with honor, by giving to the American 
public, with the Author's permission, an elegant reprint of a foreign work of science. 
We earnestly bespeak for this work a wide and free circulation, among all who love science 
much and religion more." Puritan Recorder. 

" The book indicates a mind of rare gifts and attainments, and exhibits the workings of 
poetic genius in admirable harmony with the generalizations of philosophv. It is, withal 
pervaded by a spirit of devout reverence and child-like humilitv, such as all men delight to 
behold in the interpreter of nature. We are persuaded that no intelligent reader will go 
through the chapters of the author without being instructed and delighted with the views 
they contain," Providence Journal. 

" Hugh Miller is a Scotch geologist, who, within a few years, has not onlv added largely 
to the facts of science, but has stepped at once among the leading scientific writers of the 

age, by his wonderfully clear, accurate, and elegant geological works. Mr. Miller, taking 
*i ,!,*=, _, _,L___>I_ s _ .... a. 




ness, ease, and elegance that are both astonishing and delightful. Throughout, the. entire 
geologic portion, thereasoningismarkeii.lv close, shrewd, 'and intelligible the facts art, 
evidently at the finger's end of the author and the most unwilling, I'autimis. and antago- 
nistic reader is compelled to yield his thorough assent to the argument." Boston Post. " 

GOFLD ASP LTNCOI,X ; PUBIJSHKBS, BOSTON. 



FOOT-PRINTS OF THE CREATOR. 



NOTICES OF THE PEESS. 

l * This is a very rich and valuable book. It is rich in the treasures of scientific knowledge, 
which are interwoven in an argument, remarkably clear, in a style graceful, vigorous, 
graphic, and of great power rendering it a most perfect refutation of the atheistical error 
propagated in the work entitled, the ' Vestiges of Creation.' "Philad. Christian Observer. 

'Around the name of Hugh Miller already gathers the halo of a most pure and grateful 
famo. Receiving hi- geological education among the rocks of the quarry, where he labored 
for fifteen .tears; writing in a style of peculiar simplicity and elegance, and devoting the 
exact knowledge derived from walking in the Creator's*' foot-prints ' to the, cause of true 

in doing him honor, have 
o mnlgation." Springfield 



reliu. m, the proudest devotees of science have taken pleasure in 
delighted to listen to his teachings, and rejoiced to aid in their pro 
lit i itohcan, 

" This is one of the most remarkable and deeply profound works of the present ago. 
author's name will not be soon forgotten, in the scientific world, and his productio 
not tail to bo read and admired, wherever true science is promulgated. 
aMv clear, concise, and powerful, in his arguments; profound in his rese 
sive in his reasoning." JVe fork Farmer and Mechanic. 



The 

oductions will 
He is most remark- 
researches, and conclu- 



"There is poetry and philosophy combined in this work. The author had a mind which 
revelled, so to speak, in the beauties and wonders of science. From a child, almost, he 
delighted in the works of nature. . . . He has gone from one step to another, till now he is 
justly esteemed as among the great Geologists of the world. It is a book in which the mau 
of science will delight, but it is also one which the general reader will peruse with instruct- 
ion and satisfaction." Baltimore Patriot. 

"The publishers are entitled to the thanks, not only of scientific men but of Christians, in 
this country, for presenting this work to the American public. 1 ' Christian Secretary. 

"A remarkable work by a remarkable man. Mr. Miller is self-made, and has elevated 
himself, by the force of his genius, from the position of an ordinary laborer in a stone 
quarry, to that of one of the first Geologists of the age. For careful investigation, accuracy, 
fullness, and beauty of description, combined with "a proper estimate of the true claims of 
science, and a high reverence for sacred things, he is not surpassed by anv writer on natural 
science at the present day. All who have taken any interest in the discussion of geological 
topics, and particularly their connection with the Sacred Writings, will read this volume 
with admiration and advantage. Its subject, spirit, style, and manner of publication, all 
commend it ; and it is destined to an extensive circulation. It is one of the noblest and 
most admirable contributions lately made to Science and Christianity." Christian Herald. 

"Within a few days, this enterprising house, has republished one of the most charming 

scientific works of "modern times a work which, from the simple love of truth which per- 

vades it, its clearness, authenticity, and wonderful revelations, may be called a work of 

genius, as appropriately as a fine poem. It is entitled ' Foot-Prints of the Creator.' 

Willis' Ilome Journal. 

"A work so beautifully written, filled with such curious, new, and interesting facts, and 
breathing in every page the purest philosophy and Christianity, could scarcely meet with 
adequate praise, in a limited space. It should be added to the library of every one." 
Washington Union. 

" We have never read a work of the kind with so much interest. Its statements of fact 
and its descriptions are remarkably clear. From minute particulars it leads us on to broad 
views of the creation ; and the earth becomes the witness of a succession of miracles, as 
wonderful as any recorded in the Scriptures." Christian Register. 

" This splendid work should be read by every man in our land. We recommend the study 
of this science to our young men; let' them approach it with open, and not unfaithful 
breasts, for amid our mountains, grand and tall, our boundless plains, and flowing rivers, 
vast and virgin fields for exploration yet present themselves." Scientific American. 

"This is one of the most able and learned works which has ever been issued from the 
American press. The North British Review says 'That in its geological character it is not 
surpassed by anymodem work of the same class.' The style of the'work is clear, rich, and 
strong; its statements of truth are plain and accurate, and its arguments are, presented 
with mastcrlv force. Its author, Hugh Miller, is a man of very superior talents and attain- 
ments." New York Christian Messenger. 

" The author resembles Burns, in the freshness, and vigor, and enthusiasm of genius; and 
had he ventured into the realm of poetry, the greatest of Scottish bards might have wel- 
comed his company. We hope the volume, mav be widelv circulated, especially among 
intelligent Christians. . . . This work is written in a bold and eloquent style, and though 
penetrating to the inner shrine of the Geological temple, and necessarily dealing w.Hh hard 
words and harder tilings, it will secure many readers." Christian Chronicle. 

GOULD AND LINCOLN, PUBLISHERS, BOSTON. 



THE OLD 11KD SANDSTONE; 



OK 



NEW WALKS IN AN OLD FIELD. 

BY HUGH MILLEK, 

PROM THE FOURTH LONDON EDITION ILLTJSTKAT O 



A writer, in noticing Mr. Miller's "First Impressions of England and the People," in 
the New En glan der, of May, 1850, commences by saying, "We presume it is not necos- 
sar.r formally to introduce Hugh Miller to our readers; the author of 'The Old Eed Sand- 
stone ' placed himself, by that production, which was first, among the most successful 
geologists, and the best writers of the age. "We well remember with what mingled emotion 
and delight AVC first read that work. Rarely has a more remarkable book come from the 
press. . . . For, besides the important contributions which it makes to the science of Geol- 
ogy, it is written in a style which places the author at once among the most accomplished 
waiters of the age. . . . He proves himself to be in prose what Burns has been in poetry. 
"We are not extravagant in saying that there is no geologist living who, in the descriptions 
of the phenomena of the science, has united such accuracy of statement with so much 
poetic beauty of expression. What Dr. Buckland said was not a mere compliment, that 
'he had never been so much astonished in his life, by the powers of any man, as he had 
been by the geological descriptions of Mr. Miller. That wonderful man described these 
objects with a felicity which made him ashamed of the comparative meagreness and pov- 
erty of his own descriptions, in the Briclgewatcr Treatise, which had cost him hours and 
days of labor. 1 For our own part we do not hesitate to place Mr. Milicr in the front rai.k 
of English prose writers. Without mannerism, without those extravagances which give a 
factitious reputation to so many writers of the day, Li; c ;tyle has a classic purity and ele- 
gance, which remind one of Goldsmith and Irving, while there is an ease and a naturalness 
in the illustrations of the imagination, which belong only to men of true genius." 

"The excellent and lively work of our meritorious, self-taught count) pman, Mr. Miller, 
is as admirable for the clearness of its descriptions, and the sweetness of its composition, 
as for the purity and gracefulness Wnich pervade it." Edinburgh Review. 

"A geological work, small in size, unpretending in spirit and manner; itj contents, the 
conscientious narration of fact; its style, the beautiful simplicity of truth; and altogether 
possessing, for a rational reader, an interest superior to that of a novel." Dr. J. Pye Smith. 

"This admirable work evinces talent of the highest order, a deep and healthful mora. 
feeling, a perfect command of the finest language, and a beautiful union of philosophy and 
poetry. Xo geologist can peruse this volume without instruction and delight. "Silli- 
man's American Journal of Science. 

"Mr. Miller's exceedingly interesting book on this formation is just the sort of work to 
render any subject popular. It is written in a remarkably pleasing style, and contains n 
wonderful amount of information." Westminster Review. 

" In Mr. Miller's charming little work will be found a very graphic description of the Old 
Kedfishes. I know not of a more fascinating volume on any branch of British geology." 
MantelVs Medals of Creation. 

SIR RODERICK MrRCHisoN, giving an account of the investigations of Mr. Miller, spoke 
in the highest terms of his perseverance and ingenuity as a geologist. With no other advan 
tages than a common education, by a careful use of his means, he had been able to give 
himself an excellent education, and to elevate himself to a position which any man, in any 
sphere of life, might well envy. He had seen some of his papers on geology, written in a 
style so beautiful and poetical as to throw plain geologists, like himself, in the shade. 

GOULD AND LINCOLN, PUBLISHERS, BOSTOX. 



THE POETRY OF SCIENCE; 

OB, STUDIES OF THE PHYSICAL PHENOMENA OF NATURE 

BY ROBERT HUNT, 

AUTHOR OF "PANTHEA," " RESEARCHES ON LIGHT," ETC. 



NOTICES OF THE PRESS. 

" We know of no work upon science which is so well calculated to lift the mind from the 
admiration of the wondrous works of creation to the belief in, and worship of, a First Great 
(/ause, One of the most readable epitomes of the present state and progress of 

science we have perused." Mornin a Herald, London. 

"The design of Mr. Hunt's volume is striking and good. The subject is very well dealt 
with, and the object very well attained; it displays a fund of knowledge, and is the work 
of an eloquent and earnest man." The Examiner, London. 




, _ the 

orbit of a star, or in the color of a flower the more awakened will be his wonder and his 
veneration, and the more call will there be upon his highest powers of the intellect and the 
imagination." Boston Post. 

" It was once supposed that poetry and science were natural antipodes ; and lo ! they now 
are united in loving bonds. Mr. lUint has certainly demonstrated that the divinest poetry 
lies hidden in the depths of science, and needs but a master spirit to evoke it in shapes of 
beauty. ' ' Christian Chronicle. 

" It may be read with interest, by the lovers of nature and of science." N. T. Tribune. 
"Itis written in a style not unworthy of the grandeur of the subject." N. Y. Eve. Post. 

" The author, while adhering to true science, has set forth its truths in an exceedingly 
captivating style." Neic York Commercial Advertiser. 

ork re-nublished in America. It is a book 



" We arc hoar til v glad to see this interesting w 
that is a book." Scientific American. 



" From the arcana of science especially, has the author gleaned what may be properly 
termed her pnotn-. which will make the book one of the most interesting character to the 
intelligent reader." Christian Herald. 

" It is re all v a scientific treatise, fitted to instruct and enlarge the mind of the reader, but 
at the same time it invests the subjects it describes with the radiance of the imagination, 
and with the channinu association of poetry. The book well deserves the title it bears, and 
i<? a beautiful illustration of the'poetic interest that belongs to many of the discussions of 
the science." PnrciJ.'; ce Journal. 

" It is one of the mot readable, interesting, and instructive works of the kind, that we 
have ever seen/' Phiha'. Ij hia Christian Observer. 

" In this admirably production, Mr. ITur.t o(Ters a beautiful epitome of the physical phe- 
nomena of Nature, in v.-hi--h. fro>i! their ultimate facts, he leads his reader by inductive 
processes, to the contemplation of vast eternal truths. Though full of information, the 
facts cited in hi- pa.es are not collected solelv because they are such, but with true philo- 
sophical acumen, t<> build ur> the edifice : and if curious or rare, they are selected merely to 
strengthen the position in which they are placed." Wasldngion Union. 

" We anticipate a wide circulation for it in this country." Albany State Register. 

" The scientific com;>ass of the volume is large, and its execution is exceedingly fine and 
Interesting." Zion's Herald. 

" We noticed this eloquent work, while, it wa in the course of publication. It is now out 
in beautiful stvle, and makes with the notes, which are full and as valuable as the text, a 
volume of nearly four hundred r>a< v cs. The publishers could not have done the poets of the 
land a better service, than by thus siinplvinar them with exhaustless materials, collected 
from all branches of science, and admirably arranged for their more substantial structure." 
Watchman and Reflector. 

"Here we have an illustration of the true and beautiful, and how that they are always 
one. The mysterious laws of nature, and the phenomena by which they are manifested, 
are brought before the reader in a way that enchants and improves. There is poetry in 
science, as no one may deny, after he reads this book." Baltimore Patriot. 

GOULD AND LINCOLN, PUBLISHERS, BOSTON. 



THE EARTH AND MAN: 

Lectures on Comparative Physical Oeography, in its Relation to tlw History of MankinA 

BY ARNOLD GUVOT, Prof, Phys. Geo. & Hist., Ncucluilel. 
Translated from the French, by PROF. C. C. FELTON. With niuttrations. 

12mo. PRICE $1.25. 



" Those \vbo have been accustomed to regard Geography as a merely cJescriptua 
branch of learning, drier than the remainder biscuit after a voyage, will be delighted 
to find this hitherto unattractive pursuit converted into a science, the principles cf 
which are definite and the results conclusive ; a science that embraces the investiga- 
tion of natural laws and interprets their mode of operation ; which piofesses to dis- 
cover in the rudest forms and apparently confused arrangement of the materials com- 
posing the planets' crust, n. new manifestation of the wisdom which has filled the 
earth with its riches. * * * To the reader we shall owe no apology, if we have 
said enough to excite his curiosity and to persuade him to look to the book itself for 
further instruction." North American Review. 

" The grand idea of the work is happily expressed by the author, where he caliy H 
the geographical march of history. * * * The man of science will hail it as a beauti- 
ful generalization from the facts of observation. The Christian, who trusts in a nier 
ciful Providence, will draw coinage from it, and hope yet more earnestly for the 
redemption of the most degraded portions of mankind. Faith, science, learning, 
poetry, ta.*te, in a word, genius, have liberally contributed to the production of the 
wo.rk under review. Sometimes we feel as if we were studying a treatise on the 
exact sciences ; at others, it strikes the ear like an epic poem. Now it reads like 
history, and now it sounds like prophecy. It will find readers in whatever language 
it may be puMisIu'd ; and in the elegant English dress which it lias roicived from the 
accomplished pen of the translator, it will not fail to interest, instruct ;md inspire. 

YVY; congratulate tho lovers of history and of physical geography, a? WP!! a^ rvii 
those who are interested in the growth and expansion of our common education, that 
Prof. Guyot contemplates the publication of a series of elementary works on 5'hysical 
Geography, in which these two great branches of study which God has so closely 
joined together, will not, we trust, be put asunder." Christian Examiner. 

" A copy of this volume reached us at too late an hour for an extended iv-tice. Tha 
woik is on.-; of higii merit, exhibiting a wide range of knowledge, groat research, and 
a philosophical spirit of investigation. Ita perusal will well repay the most learned 
in ucli subjects, and give new views to uil, of man's relation to the globe !KJ inhabits." 
Silliman's Journal, July, 1849. 

"These lectures form one of the most valuable contributions to gsogrnphical science 
that has ever been pnMislicu in this country. They invest the study of gooirraphv 
with an interest which will, we sioubt not, surprise and delight many. They will 
open an entire new world to r:u t readers, a;i;l will be found an invaluable aid to the 
teacher and student if geography." Evc.ninrr Traveller. 

" We venture to pronounce this one of the most interesting and instructive books 
which have c^ me from the American pre^s for many a nicvith. The science of wbicli 
it treats is comparatively of recent origin, but it is of grf;it import -m-i.-, not only on 
account of its connection wish other branches of knowled/o, out for its IK-RIMI;! up;jn 
many of the interests of society, fn ihe.se lectures ii is ioii;;vf(! nf s;>,iU:ic:rl details, 
and presented only in its ^rande^t features. It thus- not. only places iieiiire us most 
instructive f.'.cts relating to the condition of the eiith, but al=o awakens within us n 
stronger sympathy with the beings that inbuilt it, und a pioibuniii-i revcr-nce for the 
beneficent Creator who formed it, and of whose character it is a manli'i 'station and 
expression. They abound with tho richest intr-rost and instruction to every intclli- 
ge.r.-. jecder, and especially fitted to awaken enthusiasm iuui *l.\ ; j!a in all who :.co 
devoted .^ the study either of natural *ei; are, or the history of mankind." Providence 
Journal. 

:c Geography is here presented under a now a:id attractive pr.^so ; it is no !o;;':er e 
dry description of the. features of the earth's surface. The influence of soil scenery 
and climate upini character, has not yet received ths consideration duo to it fio:n I;is- 
tor'mns and philosophers. In the volume before us tho profound invcsligations of Ilurn- 
bolilt, tlittur and others, in Physical Geography, are presented in a popular form, a::d 
with the clearness and vivacity so characteristic of Frcn-jli tieati.-":-" on sfience. Tha 
work should be introduced into our higher schools." Ths Independent, _\Vzr Yuri:. 



" Geography is hero m^fle to assume a dignity, not heretofore attached to it. Tha 
knowledge communicated in these Lectures is curious, unexpected, aborhiii-r." 
Christian Mirror, Portland, 



CONTRIBUTIONS TO THEOLOGICAL SCIENCE. 

BY JOHN HARRIS, D. D. 



I. THE PRE-ADAMITE EARTH. 

NOTICES OF THE PRESS. 

:< As we have examined every page of this work, and put forth, our best efforts to un- 
derstand the full import of its varied and rich details, the resistless impression has come 
over our spirits, that the respected author has been assisted from on high in his labo- 
rious, but successful undertaking. May it please God yet to aid and uphold him, to 
complete his whole design ; for we can now see, if we mistake not, that there is great 
unity as well as originality and beauty in the object which he is aiming to accomplish. 
If we do not greatly mistake, this long looked for volume, will create and sustain a 
deep impression in the more intellectual circles of the religious world." London Evan- 
gelical Magazine. 

'* The man who finds his element among great thoughts, and is not afraid to push 
into the remoter regions of abstract truth, be he philosopher or theologian, or both, 
will read it over and over, and will find his intellect quickened, as if from being in con- 
tact with a new and glorious creation." Albany Argus. 

"Dr. Harris states in a lucid, succinct, and often highly eloquent manner, all the 
leading facts of geology, and their beautiful harmony with the teachings of Scrip- 
ture. As a work of paleontology in its relation to Scripture, it will be one of the mosfc 
complete and popular extant. It evinces great research, clear and rigid reasoning, and 
a style more condensed and beautiful than is usually found in a work so profound. 
It will be an invaluable contribution to Biblical Science." New York Evangelist. 

" He is a sound logician and lucid reasoner, getting nearer to the groundwork of a 
subject generally supposed to have very uncertain data, than any other writer within 
our knowledge." New York Com. Advertiser. 

" The elements of things, the laws of organic nature, and those especially that lie afc 
the foundation of the divine relations to man, are here dwelt upon in a masterly man- 
ner." Christian Reflector, Boston. 

II. MAN PRIMEVAL; 

OR THE CONSTITUTION AND PRIMITIVE CONDITION OF THE HUMAN BEING. 

WITH A FINE POETRAIT OF THE AUTHOR. 
NOTICES OF THE PRESS. 

"It surpasses in interest its predecessor. It is an able attempt to carry out the 
author's grand conception. His purpose Ls to unfold, as far as possible, the successive 
steps by which God is accomplishing his purpose to manifest His All-sufficiency. * * * 
The reader is led along- a pathway, abounding with rich and valuable thought, going 
on from the author's opening propositions to their complete demonstration. To stu- 
dents of mental and moral science, it will be a valuable contribution, and will assuredly 
secure their attention." Christian Chronide, Philadelphia. 

" It is eminently philosophical, and at the same time glowing and eloquent. It can- 
not fail to have a wide circle of readers, or to repay richly the hours which are given 
to its pages." New York Recorder. 

'" The reputation of the author of this volume is co-extensive with the English lan- 
guage. Tiie work before us manifests much learning and metaphysical acumen. Its 
great recommendation is, its power to cause the reader to think and reflect." Boston 
Recorder. 

"Reverently recognizing the Bible as the fountain and exponent of truth, he is as in- 
dependent and fearless as he is original and forcible ; and he adds to these qualities 
consummate skill in argument and elegance of dinion." X. Y. Com. Advertiser. 

"' His copious and beautiful illustrations of the successive laws of the Divine Mani- 
festation, have yielded us inexpressible delight." London Eclectic Revieiv. 

"The distribution and arrangement of thought in this volume, are such as to afford 
ample scope for the author's remarkable powers of analysis and illustration. In look- 
ing with a keen and searching eye at the principles which regulate the condxict of God 
towards man, as the intelligent inhabitant of this lower world, Dr. Karris has laid down 
for himself three distinct, but connected views of the Divine procedure : First, The End 
aimed at \)j God ; Second, the Reasons for the employment of it. In a very masterly 
way does our author grapple with almost every difficulty, and perplexing subject which 
comes within the range of his proposed inquiry into the constitution and condition 
>f Man Primeval." London Evangelical History. 

III. THE FAMILY; 

ITS CONSTITUTION, PROBATION AND HISTORY. 

- - -. - 



CLASSICAL STUDIES. 

ESSAYS ON 

ANCIENT LITERATURE AND ART. 

With the Biography and Correspondence of Eminent Philologists. 

By BARNAS SEARS, President of Newton Theol. Institution, B. B. 

EDWARDS, Prof. Anclover Theol. Seminary, and C. C. FELTON, 

Prof. Harvard University. 12mo. Price $1.25. 

SECOND THOUSAND. 

" The collection is a most, attractive one, and would be acceptable in any circum- 
tances. The discourses, particularly those of Jacobs, are written in words that burn. 
A general could not exhort his troops with more energy and spirit, than are used 
by the German Professor in stimulating the youth before him to labor in the acqui- 
sition of classical learning. The biographical portions of the book, naturally lesi 
exciting, no less tend to the same end." London Lit. Examiner, by John Forster, Esq. 

" This elegant book is worthy of a more extended notice than our limits at present 
will permit us to give it. Groat labor and care have been bestowed upon its typo- 
graphical execution, which does honor to the American press. It is one of the rare 
beauties of the page, that not a woid is divided at the end of a line. The mechanical 
part of the work, however, i.s its least praise. It is unique in its character standing 
alone among the innumerable books of this book-making age. The authors well 
deserve the thanks of the cultivated and disciplined portion of the community, for the 
service which, by this publication, they have done to the cause of letters. The book 
is of a high order, and worthy of the attentive perusal of every scholar. It is a noblo 
monument to the taste, and judgment, and sound learning of the projectors, and will 
yield, we doubt not, a rich harvest of fame to themselves, and of benefit to our 
literature.'' Christian Review. 

" It is refreshing, truly, to sit down with such a book as this. When the press is 
teeming with the hasty works of authors and publishers, it is a treat to take up a book 
that is an honor, at once, to the arts and the literature of our country." New York 
Observer. 

" This is truly an elegant volume, both in respect to its literary and its mechanical 
execution. Its typographical appearance is an honor to the American press ; and with 
equal truth it may be said, that the intrinsic character of the work is highly credit- 
able to the age. It is a novel work, and may be called a plea for classical learning. 
To scholars it must be a treat 5 and to students we heartily commend it." Boston 
Recorder. 

" This volume is no common-place production. It is truly refreshing, wnen we are 
obliged, from week to week, to look through the mass of bonks which increases upon 
our table, many of which are extremely attenuated in thought and jejune in style, to 
find something which carries us back to the pure and invigorating influence of the 
master minds of antiquity. The gentlemen who have produced this volume deserve 
the cordial thanks of the literary world." New England Puritan. 

" We heartily welcome this book as admirably adapted to effect a most noble and 
much desired result. We commend the work to general attention, for we feel sure it 
must do much to awaken a zeal for classical studies, as the surest means of attaining 
the refinement and graceful dignity which should mark the strength of every nation." 
Ncto York Tribinie. 

"We make no classical pretensions, or we might say more about the principal 
articles in this volume ; but it needs no such pretensions to commend, as we heartily 
do, a book so full of interest and instruction as the present, for every reader who is ut 
all imbued with a love of literature." Salem Gazette. 

"This book will do good in our colleges. Every student will want a copy, anj 
many will be stimulated by its perusal to a more vigorous and enthusiastic pursuit of 
that higher and more solid learning which alone deserves to be called 'classical.' 
The recent tendencies have been to the neglect of this, and we rejoice in this timely 
effort of minds so well qualified for such a work." Christian Reflector. 

" The volume is, in every way, a beautiful affair of its kind, and we hazard nothing 
in recommending it to the literary world.' Christian Secretary, Hartford. 

" The design is a noble and generous one, and has been executed with a taste and 
good sense, that do honor both to the writers and the publishers." Prov. Journal- 



C H A M B E B. S ' rf . 

CYCLOPEDIA OF ENGLISH LITERATURE. 

A. SELECTION 1 OF THE CHOICEST PRODUCTIONS OF ENGLISH AUTHORS, FROM THH 

EARLIEST TO THE PRESENT TIME: CONNECTED BV A CRITICAL 

AND BIOGRAPHICAL HISTORY. 

EDITED BY ROBERT CHAMBERS. 

ASSISTED BV ROBERT C ARKUTHER3 A \ J uTH.'R E.'.j'lN/lNT C " .NTLEMEX . 

Complete in two imperial octavo volu/ncs, of r. .">//; than fourteen 

hundred pages of double column Ictta'prc^x, and ^(c.u'ds of 

three hundred elegant illustrations. 



This valuable work has now become so general! ;t !;noa:i ami appreciated, that there nt-id 
scarcely be any thing said in commendation, except to those who have iu-i yet seen it. 

The icork embraces about One Thousand Jiuih,irs, dtrtmotogicaily arranged and classed 
<a Poets, Historians, Dramatists, Philosophfrs, J>Ie(e/'i!i.--ici::t:s, Dinnes, etc., with choice 
selectionsfrom their writings, coiincfLcd b>_: a Biugrayhital, lii.^toric-il, ,i;i.l Critical JVarra- 
live ; thus presenting a complete vie,- of English Literature, fn-m Hie iarlie.--t.to the present 
time. Let the reader open where he will, he cunn.ittf.til infant muli.cr fur projit and delight, 
which, for the most part, too, repeated perusals will only .--errs t,i nwlie. hi, a enjoy the more. 
We have indeed infinite riches in a little room. .Yj an-, who u t.a.--!c far literature, 

should allow himself, for a trifling consideration, to be without a work which throws so 
much light upon the progress of the English lanjtif;?e. The select i./ns arc ^c ;;?.} a mass 
of valuable information in a condensed and elegant f 

EXTRACTS FROM COMMENDATORY NOTICES. 

From W. II. Prescott, Jln'Jwr of"Fc,- : i::-nnl .;./ A ;r,^ '-/;." u The p]:-.u of the \vcrk 
is" very judicious. * * It will put the reader in the proper point of view, for survey- 
ing tlu- whole ground over which h.- i; tivivi.'iiiiig. s ~ :r'uc.h readers c".;:not tail to 
profit largely by the labors of the critic; who h is tl\e i .\\s\\\ ::irl ta<t,-- to separate what 
is really be.iutiful and worthy of their study from '.vliar is su itis.' J 

"I concur in the foregoing opinion of Mr. Prescott." l.dicard J^rereff. 

" It will be a useful and popular work, indispensable to the library oi" a student ol 
English literature." Francis Wayland. 

'We hail with peculiar pleasure the appearance of this work, and more especially 
its republication in this country at a price which places it within the reach of a great 
number of readers." North American Recieio. 

"This is the most valuable and magnificent contribution to a sound popular litera- 
ture that this century has brought forth. It fills a place which was beibie a blank. 
Without it, English literature, to almost all of our conn'ryn^n, (.-ducat ?d or unedu- 
cated, is an imperfect, broken, disjointed mass. Much tlu.t is beautiful the moat 
perfect and graceful portions, undoubtedly was already possessed ; but it wns not 
a whole. Evei'y intelligent man, every inquiring mind, every scholar, iblt that the 
foundation was missing. Chambers's Cyclcps;'i:i supplies this radical defect. It he- 
gins with the beginning ; and, step by step, gives to every one who has the intellect or 
taste to enjoy it a view of English literature in all its complete, beautiful, and perfect 
proportions." Onondaya Democrat, JV. Y. 

" We hope that teachers will avail themselves of an early opportunity to obtain a 
work so well calculated to impart useful knowledge, with the pleasures and ornaments 
of the English classics. The work will undoubtedly find 'a place in our district and 
other public libraries ; yet it should be the ' vade mecuin ' of every scholar." 
Teachers' Jldi-ocatr, Syracuse, JV*. 1*. 

" The work is finely conceived to meet a popular want, is fuil of literary instruction, 
and is variously embellished with engravings illustrative of English n::tifjuilics, his- 
tory, and biography. Tte typography throughout is beautiful." Christian Reflector, 
Boston. 

" The design has been well executed by the selection and concentration of some of 
the best productions of English intellect, from the earliest Anglo-Saxon writers down 
to those of the present day. No one can give a glance at the work without being 
struck with its beauty and cheapness." Soston Courier. 

" We should be glad if any thing we can say would favor this design. The elegance 
of the execution feasts the eye with beauty, and ihe whole is suited to rcii.ie and ele- 
vate the taste. And we might ask, who can fail to go back to its l>"<:in:iinu, and trace 
his mother-tongue from its rude infancy to its present maturity, i. -1: ^a;ice, and richness .' " 
Christian Mirror, Portland. 

.* Ths Publishers of the AMERICAN Edition of this valuable v.-urk desire to st.ite t'nr t, ^-ii.lt s the 
numerous pictorial illustrations in the English Edition, tliey have greatly enriched the work Ly the addition 
of fine steel and mezzotint engravings of the heads of Shakspeare, AddUon, Byron ; a full length portrait 
of Dr. Johnson, and a beautiful scenic representation of Oliver Goldsmiih and Dr. Johnson. These impor- 
tant and elegant additions, together with superior pap^r and bin/iing, must eive this a decided preference 
all oilier editions. 



FOR SCHOOL AND FAMILY LIBRARIES, 



CHAMBER'S MISCELLANY 

OF USEFUL AND ENTERTAINING KNOWLEDGE, 

TEN VOLUMES, ELEGANTLY ILLUSTRATED. 



The design of the MISCELLANY is to supply the increasing demand for useful, 
instructive, and entertaining reading, and to bring all the aids of literature to bear 
on the cultivation of the feeling's and understanding' of the people to impress correct 
views on important moral and social questions to furnish an unobtrusive friend 
and guide, a lively fireside companion, as far as that object can be attained through 
the instrumentality of books. 

This work is confidently commended to Teachers, School Committees, and 
all others interested in the formation of "School Libraries," as the very best work 
for this purpose. Its wide range of subjects, presented in the most popular style, 
makes it exceedingly interesting and instructive to all classes. The most flat- 
tering testimonials from distinguished school teachers and others, expressing an 
earnest desire to have it introduced into all school libraries, have been received by 
the publishers. 

From George 8. Emerson, Esq., Chairman of the Book Committee of the Boston Schools. 
"I have examined with a good deal of care ' Chambers's Miscellany of Useful 
and Entertaining Knowledge,' particularly with reference to its suitableness to 
form parts of a library for young persons. It is, indeed, a library in itself, and one 
of great value, containing very choice selections in history, biography, natural 
history, poetry, art, physiology, elegant fiction, and various departments of science, 
made with great taste and judgment, and with the highest moral and philanthropic 
purpose. It would be difficult to find any miscellany superior or even equal to it ; 
it richly deserves the epithets ' useful and entertaining,' and I would recommend 
it very strongly, as extremely well adapted to form parts of a library for the young, 
or of a social or circulaiing library, in town or country." 

From the Rev. John 0. Choulcs, D. D. "I cannot resist the desire which I feel 
to thank you for the valuable service which you have rendered to the public by 
placing this admirable work within the reach of all who have a desire to obtain 
knowledge. I arn not acquainted with any similar collection in the English lan- 
guage that can compare with it for purposes of instruction or amusement. I should 
rejoice to see that set of books in every house in our country. I cannot think of 
any method by which a father can more materially benefit his children than by 
surrounding them with good books ; and if these charming and attractive volumes 
can be placed in the hands of the young, they will have their tastes formed for good 
reading. I shall labor to see the Miscellany circulated among my friends, and shall 
lose no opportunity to commend it every where." 

" They contain an excellent selection of historical, scientific, and miscellaneous 
articles in popular style, from the best writers of the language. The work is ele- 
gantly printed and neatly illustrated, and is sold very cheap." Independent Dem- 
ocrat, Concord, N. H. 

" It is just the book to take up at the close of a busy day ; and especially will it 
ehed a new charm over autumn and winter in-door scenes." Christ. World, Boston. 

"The information contained in this work is surprisingly great; and for the fire- 
side, and the young particularly, it cannot fail to prove a most valuable and enter- 
taining companion." New York Evangelist. 

1 We are glad to see an American issue of this publication, and especially in so 
neat and convenient a form. It is an admirable compilation, distinguished by the 
good taste which has been shown in all the publications of the Messrs. Chambers. 
It unites the useful and the entertaining." New York Commercial Advertiser. 

"It is an admirable compilation, containing interesting memoirs and historical 
sketches, which are useful, instructive, and entertaining. Every head of a family 
should supply himself with a copy for the benefit of his children." Corning Journal. 

"The enterprising publishers deserve the thanks of every lover of the beautiful 
and true, for the cheap and tasteful style in which they have spread this truly val- 
uable work before the American people." People's Advocate, Pa. 

" It is filled with subjects of interest, intended for the instruction of the youthful 
mind, such as biography, history, anecdotes, natural philosophy, &c." New 
Orleans Bee. 



Iklucxbk Sdjool JBooks. 



THE ELEMENTS OF MORAL SCIENCE. By FUASCIS 
WATLAND, D.D. President of Brown University, and Professor of 
Moral Philosophy. Fortieth Thousand. 12mo. cloth. Price $1.25 

*** This work has been extensively and favorably reviewed and adopted as a class-book 
In most of the collegiate, theological, and academical institutions of the country. 

From Rev. Wilbur Fisk, Presi lent q ' t!'t W.s1<:ian Unh-e-\-ity. 

"I have examined it with great satisfaction and interest. The work was greatly needed, 
and is well executed. Dr. Waylaiid deserves the trrateful acknowledgments :uid liberal 
patronage of the public. I need say nothing farther to express my high estimate of tha 
work, than that we shall immediately adopt it as a text-book in our university." 



From lion. James Kent, hito Chancellor of Xew York. 

" The work has been read by me attentively and thoroughly, and I think very highly tf 
It The author himself is one of the most estimable of men, and I do not kno-.v :f IEY 
ethical treatise, in which our duties to God and to our fellow-men ore laid down with rr>*'e 
precision, simplicity, clearness, energy, and truth." 

" The work of Dr. Wayland has arisen gradually from the necessity of correcting the 
false principles and fallacious reasonings of Puley. It is a radical inj.-take, in the ed'.'/ 1 ?- 
tion of youth, to permit any bonk to be used by students as a text-book, which contains 
erroneous doctrines, especially when these are fundamental, and tend to vitiate the whole 
system of morals. We have been greatly pleased with tiie method which President Way- 
land has adopted ; he goes back to the simplest and most fundamental principles ; and, in 
the statement of his views, he unites perspicuity with conciseness and precision. In 011 
the author's leading fundamental principles we entirely concur." Biblical Repository. 

" This is a new work on morals, for academic use, and we welcome it with much satis- 
faction. It is the result of several years' reflection and experience in teaching, on the part 
of its justly distinguished author ; and if it is not perfectly what we could wish, yet, in the 
most important respects, it supplies a want which has been extensively felt. It is, we 
think, substantially sound in its fundamental principles ; and being comprehensive and 
elementary in its plan, and adapted to the purposes of instruction, it will be gladly adopted 
by those who have for a long time been dissatisfied with the existing works of Paley." 

The Literary and Theological Review. 

MORAL SCIENCE, ABRIDGED, by the Author, and adapted 
to the use of Schools and Academies. Twenty-fifth Thousand. ISmo. 
half cloth. Price 25 cents. 

The more effectually to meet the desire expressed for a cheap edition, the present edition is issued 
at the reduced price of 25 cents per copy, and it is honed thereby to extend the benefit of moral in- 
struction to all the youth of our lan.l. Teachers and all others engaged in the training of youth, are 
invited to examine this work. 

" Dr. Wayland has published an abridgment of his work, for the use of schools. Of 
this step we can hardly speak too highly. It is more than time that the study of moral 
philosophy should be introduced into all our institutions of education. We are happy to 
see the way so auspiciously opened for such an introduction. It has been not merely- 
abridged, but also re-wriiten. We cannot but regard the labor as well bestowed." 2?orth 
American Review. 

"We speak that we do know, when we express our high estimate of Dr. Wayland's 
ibility in teaching Moral Philosophy, whether orally or by the book. Having listened to 
his instructions, in this interesting department, we can attest how lofty are the principles, 
how exact and severe the argumentation, how appropriate and strong the illustrations 
which characterize his system and enforce it ou the mind." The Christian Witness. 

"The work of which this volume is an abridgment, is well known as one of the best and 
most complete works on Moral Philosophy extant. The author is well known as one of 
the most profound scholars of the age. That the study of Moral Science, a science which 
teaches goodness, should be a branch of education, not onlv iu our colleges, but in iv.,r 
schools and academies, we believe will not be denied. The abridgment of this work 
seems to us admirably calculated for the purpose, and we hope it will be extensively 
applied to the purposes for which it is intended." The Mercantile Journal. 

"We hail the abridgment as admirably adapted to supply the deficiency which has lonjs, 
been felt in common school education, the study of moral obligation. Let the child 
^p.-7 be taught the relations it sustains to man and' to its Maker, the first acciuuinting it 
"TV the duties owed to society, the second with the duties owed to God. and wbo can 
toreteil how many a sad and disastrous overthrow of character will be prevented, and ho 
elevated and pure will be the sense of integrity and virtue?" Evening Gazette. 



Daluabie Scijool 



CLEMENTS OF POLITICAL SCONOSIY. By F 

\V.\YLANO, D.D., Preiii<-::t of Brown TJniver.sit v. Fifteenth Thousand. 
12mo. cloth. Price $1.25 

" His object has been to write a bock, which any one who chooses mr.y understand. Ha 
has, therefore, labored to express the general principles ic the plainest manner possible, 
ind to illustrate tb.em by ca^cs wiili which every j.'tTsoii is familiar. It has been to th* 
author a source of regret, that the rour-e of discussion in t'ne fol lowing pages, has, uno 
vouk'.bly, led him over ground which has frequently been the arena of poli'.ieui coiilr 1 ). 
ver:-y. In all such cases, he has endeavored to state what seemed to liirn to be truth, 
without fear, favor, or idiection. lie is conscious to himself of 1:0 bias tow;a:l.= nnv party 
whatever, and he thinks that lie who will read the whole work, will be convinced that ho 
h;w been inlluenced by none." Extrwt from the Preface. 

POLITICAL ECONOMY, ABSIDGED, by the Author, an. 
adapted to the use of Schools and Academies. Seventh Thousand. 
18rno. half morocco. Price 50 cents. 

%* The success which has attended the abridgment of " The Elements of Moral 
S-'ience"has induced the author to prepare an abridgment of this work. In this case, 
as in the other, the work has been wholly re-writto'j, and an attempt has been made to 
adapt it to the attainments of youth. 

'' The original work of the author, on Political Economy, has already been noticed on 
our pages ; and the present abridgment stands in no need of a recommendation from us. 
We may be permitted, however, to say, that both the rising and risen generations are 
deeply indebted to Dr. "Wa}-!'nvJ, for the skill and power lie has nut forth to bring a highly 
important subject distinctly before them, within such narrow limits. Though ' abridged 
for the use of academies,' it deserves to be introduced into every private family, and to be 
studied by every man who has an interest in the wealth and prosperity of his country. It 
is a subject little understood, even practically, by thousands, and still less understood 
theoretically. It is to be hoped, this will form a class-book, and be faithfully studied in 
our academies ; and that it will find its way into every family library ; not there to be 
shut up unread, but to afibrd rich material for thought and discussion in the family 
circle. It is fitted to enlarge the mind, to purify the judgment, to correct erroneous 
popular impressions, and assist every man in forming o inking cf public measures, 
which will abide the test of time and experience." Boston Jtucordi ,'. 

" An abridgment of this clear, common sense work, desip-.ed for the us>e of academies 
is just published. We rejoice to see such treatises spreading amoTig the people; and we 
urge all who would be intelligent free men, to read iheiri." ^~<:iv York I'ruiirrript. 

" \Ve can say, with safety, that the topics are well selected and arranged ; that the 
author's name 'is a guarantee' for more than usual excellence. "\Vewishitanextensive 
circulation." ^eio York Wjscrver. 



" It is well adapted fo hi v\ schools, and embraces the soundest system of republican 
polities! economy cf any treatise extant." Daily Advocate. 

I HO TIGHT Sou the present Collegiate System in the United States. 
By FEAXCIS WAYT,AXD, D.D. Price 50 cents. 

" These Thoughts come from a source entitled to a very respectful a'ti-ntion : and as the 
author goes over the whole ground of collegiate education, criticising freely all the arrange- 
ments in every department and in all their bearings, the bock is very full of matter, we 
hope it will prove the beginning of a thorough discussion." 

P A L E Y ' S 5T A T U B A L THEOLOGY. Illustrated by forty plates, 
and Selections from the notes of Dr. I'axton, with additional Notes, 
original and selected, for this edition ; with a vocabulary of Scientific 
Terms. Edited by JOHN WAKE, M.D. 12mo. sheep. Price $1.25. 

" The work before us is one which deserves rather to be studied than merely read. 
Indeed, without diligent attention and study, neither the excellence*; r.f it can be fully dis- 
covered, nor its advantages realized. It is, therefore, gratifying. to find it introduced, as a 
text-book, into the colleges .and literary int-tKutioiis of our country. The edition before us 
is superior to uuv we have seen, and, we believe, superior to any that has yet been pub- 
lished." Spirit of the I'UfrriwK. 

"Perhaps no one of our author's works gives greater satisfaction to all classes of readers, 
the young and the old, the ignorant and the enlightened. Indeed, we recollect no book in 
which the arguments for the existence and attributes of the Supreme Being, to be drnwq 
from Ms works are exhibited in a manner more attractive and more convincing. " 

Christian Examiner,