CONTENTS 



CHAPTER I. 



PAGE 



latroductory remarks — Difficulty of the subject — The life of a 

 cell — Possible modes of origin of sense-organs — Origin of 

 eye and ear — The sense of touch — The organs of touch — 

 Nerves of touch — Sense of temperature — Cold points — Heat 

 points — Pressure-points— Organs of touch among lower 

 animals — Medusse — Annelides—Mollusca— Crustacea — In- 

 sects— Sense-hairs — Tactile hairs ... ... ... 1 



CHAPTER n. 



The sense of taste — Taste-organs of man — Mammalia — Birds — 

 Reptiles — Taste-organs of the lower animals — Crustacea — 

 Insects — Sense of taste in insects— Organs of taste in 

 insects— The bee— Humble bee— Wasp— Fly— Individual 

 differences ... ... ... ... ... ... 19 



CHAPTER III. 



The sense of smell — Protozoa andCoelenterata — Worms — Mollusca 

 —Insects— Seat of the sense of smell— Different theories as 

 to the seat of the sense of smell in Insects — Experiments 

 with Dinetus — Hydaticus — Silpha — Stag-beetle — Ants — 

 Seat of the sense of smell partly in the palpi, partly in 

 antennae — Organs of smell — Leydig's olfactory cones — 

 Organs of smell in Crustacea — Centipedes — Olfactory 

 cones in insects — Olfactory hairs — Olfactory pits — Ol- 

 factory organs of fly — Antenna of Iclmeumon — Olfactory 

 organs of wasp — Antennal organs of insects — Complex 

 struct ui'e of the antennse — Various uses of antennsB ... 32 



