Vlll CONTENTS. 



CHAPTER JII. 



THE INFLUENCE OF LIGHT. 



PAGE 



The Difference between Animals and Flams. General Relations 

 between Light and the Vital Activity of Animals ; between 

 Light and Sight. Blind Animals in Caves and at great 

 Depths. Phosphorescence. The Chromatic Function in 

 Fishes. Chromatophores. Pigment and Colour 70 



CHAPTER IV. 



THE INFLUENCE OF TEMPERATURE. 



Acclimatisation. Mean Temperature no Guide to Classification. 

 Em-ytltermal and Stenotliermal. A Falling Temperature. 

 Experiments on Infusoria. Chill- Coma. Hibernation. A 

 Rising Temperature. Its Stimulating Effects. Heat-Coma. 

 Optimum of Temperature. Winter and Summer Generations 

 and Larva-forms. Temperature as affecting the Development 

 of Young Animals. A Constant Temperature. Extreme Cli- 

 mates. Acclimatisation of Parrots. Periodicity. Equable 

 Temperature of the Sea . . . . . . . .101 



CHAPTER V. 



THE INFLUENCE OF STAGNANT WATER. 



Water indispensable to every Form of Existence. Chemical Com- 

 position of Water; Saltness of Inland Seas. Fresh- water 

 Animals that can live in the Sea. Insects. Worms in Urine 

 Springs. Mollusca. Sopyrus. Polyps. Plateau's Experi- 

 ments on Articulata. Beudant's on Mollusca. Transition 

 from Branchipus to Artemia. Influence of Volume. Experi- 

 ments on Lymneea stagnalis. An Unknown Stimulant. In- 

 fluence of Oxygen or Air in the Water. Respiration a 

 Function of Protoplasm. Organs specially adapted for Re- 

 spiration. The Skin ; Gills ; the Intestine ; the Air-bladder. 

 Power of enduring Desiccation. Eggs of Apiis and Cypri-s. 110 



