Animal Life and Intelligence

CHAPTER IV.. Variation and Natural Selection.

VARIATION AND NATURAL SELECTION.

The law of persistence 61 The occurrence of variations 63 Application of the law of increase 76 Natural selection 77 Elimination and selection 79 Modes of natural elimination illustrated 80 Protective resemblance and mimicry 82 Selection proper illustrated 93 The effects of natural selection 95 Isolation or segregation 99 Its modes, geographical, preferential and physiological 99 Its effects 108 Utility of specific characters 110 Variations in the intensity of the struggle for existence 112 Convergence of characters 117 Modes of adaptation: Progress 119 Evolution and Revolution 120

CHAPTER V.. Heredity and the Origin of Variations.

HEREDITY AND THE ORIGIN OF VARIATIONS.

Heredity in the protozoa 123 Regeneration of lost parts 124 Sexual reproduction and heredity 129 The problem of hen and egg 130 Reproductive continuity 131 Pangenesis 131 Modified pangenesis 134 Continuity of germ-plasm 138 Cellular continuity with differentiation 142 The inheritance or non-inheritance of acquired characters 146 Origin of variations on the latter view 149 Hypothesis of organic combination 150 The extrusion of the second polar cell 153 The protozoan origin of variations 156 How can the body influence the germ? 159 Is there sufficient evidence that it does? 162 Summary and conclusion 175

CHAPTER VI.. Organic Evolution.

ORGANIC EVOLUTION.

The diversity of animal life 177 The evolution theory 181 Natural selection: not to be used as a magic formula 183 Panmixia and disuse 189 Sexual selection or preferential mating 197 Use and disuse 209 The nature of variations 216 The inheritance of variations 223 The origin of variations 231 Summary and conclusion 241

CHAPTER VII.. The Senses of Animals.

THE SENSES OF ANIMALS.

The primary object of sensation 243 Organic sensations and the muscular sense 244 Touch 245 The temperature-sense 249 Taste 250 Smell 257 Hearing 261 Sense of rotation or acceleration 269 Sight 273 Restatement of theory of colour-vision 278 Variation in the limits of colour-vision 281 The four types of "visual" organs 293 Problematical senses 294 Permanent possibilities of sensation 298

CHAPTER VIII.. Mental Processes in Man.

MENTAL PROCESSES IN MAN.

The physiological aspect 302 The psychological aspect 304 Sensations: their localization, etc. 306 Perceptual construction 312 Conceptual analysis 321 Inferences perceptual and conceptual 328 Intelligence and reason 330

CHAPTER IX.. Mental Processes in Animals: Their Powers of Perception

MENTAL PROCESSES IN ANIMALS: THEIR POWERS OF PERCEPTION AND INTELLIGENCE.

The two factors in phenomena 331 The basis in organic evolution 336 Perceptual construction in mammalia 338 Can animals analyze their constructs? 347 The generic difference between the minds of man and brute 350 Perceptual construction in other vertebrates 350 "Understanding" of words 354 Perceptual construction in the invertebrates 356 "The psychic life of micro-organisms" 360 The inferences of animals 361 Intelligent not rational 365 Use of words defined 372 Language and analysis 374

CHAPTER X.. The Feelings of Animals: Their Appetences and Emotions.

THE FEELINGS OF ANIMALS: THEIR APPETENCES AND EMOTIONS.

Pleasure and pain: their organic limits 379 Their directive value 380 An emotion exemplified 382 Sensitiveness and sensibility 385 The expression of the emotions 385 The postponement of action 385 The three orders of emotion 390 The capacities of animals for pleasure and pain 391 Sense-feelings 393 Some emotions of animals 395 The necessity for caution in interpretation 399 The sense of beauty 407 Can animals be moral? 413 Conclusion 414

CHAPTER XI.. Animal Activities: Habit and Instinct.

ANIMAL ACTIVITIES: HABIT AND INSTINCT.

The nature of animal activities 415 The outer and inner aspect 417 The inherited organization 419 Habitual activities 420 Instinctive activities 422 Innate capacity 426 Blind prevision 429 Consciousness and instinct 432 Mr. Romanes's treatment of instinct 434 Lapsed intelligence and modern views on heredity 435 Three factors in the origin of instinctive activities 447 The emotional basis of instinct 449 The influence of intelligence on instinct 452 The characteristics of intelligent activities 456 The place of volition 459 Perceptual and conceptual volition 460 Consciousness and consentience 461 Classification of activities 462

CHAPTER XII.. Mental Evolution.

MENTAL EVOLUTION.

Is mind evolved from matter? 464 Kinesis and metakinesis 467 Monistic assumptions 470 The nature of ejects 476 The universe as eject 478 Metakinetic environment of mind 481 Conceptual ideas not subject to natural selection 483 Elimination through incongruity 486 Interneural evolution 490 Interpretations of nature 492 Can fetishism have had a natural genesis? 493 The origin of interneural variations 496 Are acquired variations inherited? 497 Summary and conclusion 501

LIST OF ILLUSTRATIONS.

FIG. PAGE

Kentish Plover with Eggs and Young: Frontispiece 1. Spiracles and Air-tubes of Cockroach 3 2. Gills of Mussel 4 3. A Cell greatly magnified 11 4. Amba 12 5. Egg-cell and Sperm-cell 13 6. Diagram of Circulation 23 7. Protozoa 38 8. Hydra Virides 43 9. Aurelia: Life-cycle 45 10. Liver-Fluke--Embryonic Stages 47 11. Diagram of Development 51 12. Wing of Bat (Pipistrelle) 64 13. Variations of the Noctule 67 14. Variations of the Long-eared Bat 68 15. Variations of the Pipistrelle 69 16. Variations of the Whiskered Bat 70 17. Variations adjusted to the Standard of the Noctule 73 18. Caterpillar of a Moth on an Oak Spray 85 19. Locust resembling a Leaf 86 20. Mimicry of Bees by Flies 91 21. Egg and Hen 141 22. Stag-Beetles 180 23. Tactile Corpuscules 247 24. Touch-hair of Insect 248 25. Taste-buds of Rabbit 250 26. Antennule of Crayfish 259 27. Diagram of Ear 263 28. Tail of Mysis 266 29. Leg of Grasshopper 266 30. Diagram of Semicircular Canals 270 31. The Human Eye 274 32. Retina of the Eye 274 33. Variation in the Limits of Colour-vision 281 34. Pineal Eye 288 35. Skull of Melanerpeton 288 36. Eyes and Eyelets of Bee 289 37. Eye of Fly 290 38. Diagram of Mosaic Vision 291 39. Direction-retina 295 40. Antennary Structures of Hymenoptera 297

ANIMAL LIFE AND INTELLIGENCE.

CHAPTER I.. The Nature of Animal Life.

THE NATURE OF ANIMAL LIFE.

I once asked a class of school-boys to write down for me in a few words what they considered the chief characteristics of animals. Here are some of the answers--

1. Animals move about, eat, and grow.

2. Animals eat, grow, breathe, feel (at least, most of them do), and sleep.

3. Take a cat, for example. It begins as a kitten; it eats, drinks, plays about, and grows up into a cat, which does much the same, only it is more lazy, and stops growing. At last it grows old and dies. But it may have kittens first.

4. An animal has a head and tail, four legs, and a body. It is a living creature, and not a vegetable.

5. Animals are living creatures, made of flesh and blood.

Combining these statements, we have the following characteristics of animals:--

1. Each has a proper and definite form, at present described as "a head and tail, four legs, and a body."

2. They breathe.

3. They eat and drink.

4. They grow.

5. They also "grow up." The kitten grows up into a cat, which is somewhat different from the kitten.

6. They move about and sleep.

7. They feel--"at least some of them do."

8. They are made of "flesh and blood."

9. They grow old and die.

10. They reproduce their kind. The cat may have kittens.

11. They are living organisms, but "not vegetables."

Now, let us look carefully at these characteristics, all of which were contained in the five answers, and were probably familiar in some such form as this to all the boys, and see if we cannot make them more general and more accurate.

1. An animal has a definite form. My school-boy friend described it as a head and tail, four legs, and a body. But it is clear that this description applies only to a very limited number of animals. It will not apply to the butterfly, with its great wings and six legs; nor to the lobster, with its eight legs and large pincer-claws; to the limbless snake and worm, the finned fish, the thousand-legs, the oyster or the snail, the star-fish or the sea-anemone. The animals to which my young friend's description applies form, indeed, but a numerically insignificant proportion of the multitudes which throng the waters and the air, and not by any means a large proportion of those that walk upon the surface of the earth. The description applies only to the backboned vertebrates, and not to nearly all of them.

It is impossible to summarize in a sentence the form-characteristics of animals. The diversities of form are endless. Perhaps the distinguishing feature is the prevalence of curved and rounded contours, which are in striking contrast to the definite crystalline forms of the inorganic kingdom, characterized as these are by plane surfaces and solid angles. We may say, however, that all but the very lowliest animals have each and all a proper and characteristic form of their own, which they have inherited from their immediate ancestors, and which they hand on to their descendants. But this form does not remain constant throughout life. Sometimes the change is slight; in many cases, however, the form alters very markedly during the successive stages of the life of the individual, as is seen in the frog, which begins life as a tadpole, and perhaps even more conspicuously in the butterfly, which passes through a caterpillar and a chrysalis stage. Still, these changes are always the same for the same kind of animal. So that we may say, each animal has a definite form and shape or series of shapes.

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