3S 



The Form of Insects 



is seen to be made up of four sections {rhabdomeres) 

 arranged lengthwise. These are closely applied 

 together for the greater part of the length of the 

 rod, but at its outer end they are separated from 

 one another, forming a kind of fork within which 



Fig. 29. — A. Single element (rod, cone and corneal acets) of Cockroach's eye 

 (after Grenacher). B. Section through compound eye (after Miall & Denny). 

 C. Organs of smell in Cockchafer (after Kraepelin). D. a. fi. Sensory pits 

 on cercopods of Golden-eye fly ; c. sensory pit on palp of Stone-fly (after 

 Parkard). £. Sensory hair (after Miall & Denny). /^. Ear of long-horned 

 Grasshopper ; a. front shin showing outer opening and air-tube ; d. section 

 (after Graber) (see also fig. 34). G. Ear of Locust from within (after 

 Graber). All highly magnified. From Riley, Insect Life, vol. 7 (U.S. 

 Dept. Agr.). 



the tip of the cone rests (fig. 29 ^). The rod is 

 surrounded by elongate nerve-cells, each cell (n't'miila) 

 corresponding with a rhabdomere. These cells con- 

 tain much dark pigment, and are in connection with 



