Contents^ ix 



PAGE 



instinctive powers.— Hibernation.— DiflBculties of the natural selection 

 theory.— Special structures.— The rattlesnake, bee, wasp, and hornet. 

 —Relation of instinct to color and form.— Cases cited from Wallace- 

 Relation of instinct to experience.— Seventeen-year locusts m 



LECTURE VI. 



INSTINCT FOR COMMUNITIES OF ANIMALS. — ITS RELATION TO 

 THE DOCTRINE OF NATURAL SELECTION. 



Illustrations of the community system.— The cow-bird.— Three kinds 

 belonging to the same species. — Necessity for slaves among ants. — 

 The brood or annual flock. — Permanent organization. — Leaders. — Sen- 

 tinels.— Pelicans of Utah Lake.— The beaver.— Morgan's work.— The 

 rank of the beaver. — The muskrat. — Variation of instinct necessary. — 

 Complexity of work no proof of intelligence.— Consideration of theo- 

 ries.— Accumulated work of intelligence.— Instinct like it, in effect.— 

 The honey-bee. — Bumble-bees and wasps. — Slave-ants.— Darwin's 

 explanation.— Difficulties.— Natural selection and variation not suffi- 

 cient— Wallace on natural selection applied to man 137 



LECTURE VIL 



INSTINCT CONNECTED WITH THE PARENTAL RELATION. — AS DE- 

 MANDING CERTAIN CHANGES IN OTHER ANIMALS AND PLANTS. 

 — AS A LAW FOR THE ANIMAL. — AS SUBJECT TO VARIATION. 



Effect of parental instinct.— Completes its course.— Disturbed by domes- 

 tication.— Answering instinct of the young.— Correlation of the three 

 kingdomsofnature.— Hibernation.— Gall-flies. — Ichneumon-flies.~Bot- 

 fly.— Tent-moth.— Oak-pruners.— Borer.— Preservation of the fittest. — 

 Instinct as a law.— Uniformity among animals.— Periodicity and self- 

 regulating power of the appetites. — Instinct can be deceived.— Follows 

 the impression of the senses.— Variation of instinct.— Production of 

 varieties.— Definition of an instinct, and of instinct as a general term, . . 157 



LECTURE VIIL 



HIGHER CHARACTER OF ANIMALS. — ANIMALS COMPARED 

 WITH MAN. 



Knowledge from experience. — Do animals think ? — Definition of thinking. 

 —Conditions of the act to be studied.— Difficulty of the work.— Con- 

 dition of the animal. — Physical structure and growth in men and ani- 

 mals.— The senses in both.— Physiological likeness.— Capacity of 



