XIV 



CONTENTS 



2. The Vision of Worms .... 



(a) Unsegmented Worms 

 (6) Segmented Worms 



3. The Vision of Molluscs .... 



(a) Gastropods and Lamellibranchs 

 (6) Cephalopods 



4. The Vision of Arthropods 



(a) Onychophora 

 (6) Myriapods 



(c) Crustaceans 



(d) Arachnids 



5. The Vision of Insects 



(a) The Larvse of Insects .... 



(b) The Dorsal Ocelli of Adults . 



(c) The Compound Eyes of Insects 



(i) Behavioural Experiments 

 (ii) Electro-physiological Characteristics 

 (iii) Spectral Sensitivity 

 (iv) Discrimination of Luminosity-differences 

 (v) Perception of Colour . 

 (vi) Perception of Form . 

 (vii) Perception of Distance 

 (viii) Spatial Appreciation and Localization 

 Accommodation in Invertebrates 



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Chapter XVIII 



The Vision of Vertebrates 



The Role of Vision in Vertebrate Life 



(a) Cyclostomes 



(b) Fishes 



(c) Amphibians 

 {d) Reptiles 

 (e) Birds 

 (/) Mammals 



I. The Perception of Light 



1. The Nocturnal Eye 



(a) The Optical System 



The Tapetum Lucidum 



(b) The Organization of the Retina 



2. The Diurnal Eye .... 



3. The Arhythmic Eye 



(a) Contractile Pupils 

 (6) Occlusible Tapeta . 



(c) Photo -mechanical Changes in the Retina 

 (rf) The Static Organization of the Retina 



4. Absolute Sensitivity to Light . 



6. Discriminati of Variations in Intensity . 



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