42 



The Form of Insects 



tion of insect sight. Some naturalists suppose, from 

 the accuracy and rapidity of an insect's flight, that its 

 sight must be in all respects better than our own. 

 Others, on the ground that there is no provision in 

 the compound eye for the formation and reception of a 

 distinct image, conclude that insects perceive the form 

 of objects very imperfectly, though they are able to 

 realise the smallest motion within their field of view. 

 On the whole, it seems that the structure of the 



Fig. 32. — Section through an insect's simple eye. L. lens; Cr. crystalline cones ; 

 R. nerve-rods;- cA cuticle of head ; hyp. hypodermis cells; N.Op. optic 

 nerve. From Miall & Denny, after Grenacher. 



compound eye marks it as specially adapted for per- 

 ceiving sensations of light and motion rather than of 

 form. The appreciation of motion must be of the 

 first importance in enabling the insect to govern its 

 flight, whether the object of the flight be escape, 

 pursuit, or love ; while imperfection in the perception 

 of form must be largely compensated by the extreme 

 sensibility of insects to scents, their sense of smell 



