The sense of hearing-Organs of sound-Mollusca-Crustacea— ing in insects-Sense of hearing in insects The organs of hearing-Structure of the human ear-The organ of Corti-Mode of action of auditory organs-Organs of hearing in the lower animals-Medusa-Auditory hairs- Mollusca-Annelides-Crustacea-Use of grains of sand as otolithes-Ear in tail of Mysis-Mode of hearing-Organs of hearing in insects-Seat of the sense of hearing in insects -Different seats of organs of sense-Ears in legs of crickets -Ear of grasshoppers-Structure of ear-Auditory rods- Ear of locusts-Peculiar structure in leg of ant-Origin of ear-Ear of fly-Peculiar sense-organs--Auditory rods in beetles-Position of auditory rods-Chordotonal organs- The sense of sight-Three possible modes of sight-Different forms of eye-The vertebrate eye-Structure of the eye- The retina-The rods and cones-The blind spot in the eye -Inversion of the rods--The pineal gland--The rudimentary median eye-The median vertebrate eye-The organs of vision in the lower animals-Color-spots-Echinoderms- The organs of vision in Insects and Crustacea-Ocelli-Compound Eu- of Crustacea-Structure of eye-Mysis-Corycæus-Copilia .-On the function of ocelli-Difficulty of subject-Experi- On problematical organs of sense-Muciferous canals of fish- Deep-sea fish-Light-organs-Living lamps-Problematical organs in lower animals-Medusa-Insects-Crustacea- Difficulty of problem-Size of ultimate atoms-The range On bees and colors --Experiments with colored papers-Dr. On the limits of vision of animals-Ants and colors-The ultra-violet rays-The limits of vision in ants-Supposed perception of light by the general surface of the skin- Experiments with hoodwinked ants-Confirmation of my experiments on ants-Experiments with Daphnias-Daph- nias and colors-Preference for yellowish green-Experi- ments-Limits of vision of Daphnias-Perception of ultra-violet rays-Objections of M. Merejkowski—Suggestion On recognition among ants-Experiments with intoxicated ants pupæ and subsequently restored-Experiments with drowned ants-Recognition after a year and nine months-Supposed recognition by scent-Recognition by means of the antennæ 232 On the instincts of solitary wasps and bees-Instinct of render- ing victims insensible-Origin of instincts-Habits not invariable-Change of instincts-Bembex-Odynerus-Am- mophila―Modifiability of instincts-Differences under different circumstances-Origin of the habits of Sphex- Race differences-Limitation of instinct-Toleration of para- sites-Cases of apparent stupidity—M. Fabre's experiments -Limitation of instinct-Instinct and habits-Inflexibility of instinct-Different habits of males and females-Arrange- On the supposed sense of direction-Experiments with bees- Whirling bees-Behaviour of bees if taken from home- Mode of finding their way-Experiments with ants-Mr. On the intelligence of the dog-Education of the deaf and dumb -Laura Bridginan-Application of the method followed with the deaf and dumb to animals-My dog Van and his cards-Use of cards with words on them, "food," "water," "tea," etc.-Recognition of the separate cards-Association of the card with the object-Realization that bringing a card was a request-Attempts to convey ideas-Arithmetical LIST OF ILLUSTRATIONS. FIGURE 1. Diagram to illustrate possible origin of a sense-organ. c, Cuticle; h, cellular or hypodermic layer 2. Diagram to illustrate possible origin of a sense-organ. c, Cuticle; h, cellular or hypodermic layer 3. Diagram to illustrate possible origin of a sense-organ. c, Cuticle; h, hypoderm; n, nerve 4. Diagram of further stage in the origin of a sense-organ 5. Diagram illustrating a second possible origin of a sense-organ 6. Diagram of further stage in the origin of a sense-organ 7. Section through the simple eye of a young Dytiscus larva. h, Hypoderm; 7, lens; o, optic nerve; g, p, modified hypodermic cells; r, retina 8. Auditory vesicle of Ontochis 9. Pacinian corpuscle. a, Neurilemma; b, nerve-fibril; c, capsule; d, peculiar fibres; e, central cylinder 10. Papilla from the surface of the hand, × 350. a, Cone-like body; b, nerve; c, end of nerve 11. Portion of the skin of the back of the hand. The centre figure represents the arrangement of the hairs; CP, the cold-points; 12. Half a cross section through the brain and hinder pair of eyes of PAGE 3 455 6 10 12 12 13 xii LIST OF ILLUSTRATIONS. FIGURE PAGE hy, hypoderm; c, cuticle; b, anterior part of brain; ɑ, eye; 13 16. Diagrammatic section through a papilla of touch of Onchidium. a', a", two layers of the cuticle; a, biconvex thickened portion of the cuticle; b, enlarged epithelial cells; b', ordinary epithelial cells; c, cellular body; d, cells; n, nerve 17. Diagram of the structure of the soft and some of the hard parts in the tegmentum of a shell of a Chiton (Acanthopleura spiniger), as seen in a section vertical to the surface, and with the margin of the shell bordering on the girdle lying in the direction of the left side of the drawing. f, Calcareous cornea; h, iris; g, lens; k, pigmented capsule of eye; n, optic nerve; r, rods of retina; n', branches of the optic nerve, perforating the capsule wall, and terminating in b', b', b', ocular sense-organs; p, p, nerves to sense-organ; m, body of sense-organ cut across; a, p, fusiform body of sense-organ entire; a, obconical termination of sense-organ; e, nerve given off by one sense-organ to another, b" 18. Diagram of forms of hairs in insects. a, Ordinary surface hair; 20. Right half of eighth segment of the body of the larva of a guat (Corethra plumicornis). EG, Ganglion; N, nerve; g, auditory ganglion; gb, auditory ligament; Ch, auditory rods; a, auditory nerve; e, attachment of auditory organ to the skin; b, attachment of auditory ligament; hn, hn', termination of skin-nerve; tb, plumose tactile hair; h, simple hair; ty, ganglion of tactile hair; Im, longitudinal muscle .. 21. Taste-buds of the rabbit, × 450 .. .. 14 15 16 17 18 22. a, Isolated taste-cells from the mouth of a rabbit; b, two covercells and a taste-cell in their natural position, × 600 23. Termination of the nerves of taste in the frog, showing the ramifications of the nerve-fibres and their connections with the cells of taste, × 600 24. Inner layer of skin of the proboscis of Asterope candida, × 400. 20 |