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THE PHYSIOLOGY OF INSECT SENSES 



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Fig. 99. A. Camera lucida drawing of an ocellus of the caterpillar of 

 Isia Isabella to illustrate the congruity of image space and retinal space 

 and the kind of accommodation offered by a vertical rhabdom. 

 Oi, O2, O3, representative objects; Ii, Ig, I3, positions of resultant 

 images; F, focal point; CO, cornea; CR, crystalline lens; DR, distal 

 retinula; PR, proximal retinula. The broken line in the cornea repre- 

 sents the ideal lens curvature. B. Graphic construction of images 

 formed. O, object; Iv, virtual image; Ir, real image; Fi, focal point of 

 corneal lens; Fg, focal point of crystalline lens; F, focal point of entire 

 lens system. (From Dethier, 1943.) 



