CHAPTER V 



RETINAL STRUCTURE AND ANIMAL HABITS 



So closely correlated is the mode of life of the animal with 

 the structure of the retina that, from a histological section, 

 one can predict something of the habits of the animal, as 

 well as its visual ability. The majority of vertebrates possess 



Fig. 40 (Left). Photomicrograph showing the essentially cone-bearing retina 

 of the turtle (Chrysemys picta). Note large paraboloids and oil globules. 

 X 850. 



Fig. 41 (Right). Photomicrograph showing pure rod retina of the nocturnal 

 lizard (Gecko). X 850. 



rods and cones and are equipped for both day and night 

 vision. Many animals, however, possess only one type of 

 visual cell and accordingly are spoken of as diurnal (cone 

 bearing) or nocturnal (rod bearing). 



This condition is well illustrated by the reptiles, among 

 which are many forms which have cones only, and are diurnal 

 in their habits. In this group may be placed the diurnal 



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