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dae is more likely to be connected with the rapacious mode- 

 of life. Whereas the supposition that these eyes may be 

 important in their sexual life can hardly be justified, as in 

 this case they are not a male secondary sexual character 

 which serves for finding the female. 



As was described above, the facetted eye of Diopsidae 

 is not uniformly constructed its anterior part possessing a 

 special structure. According to the theories of mosaic vision, 

 as they were expounded by Exner, such an eye cannot pos- 

 sess an acute sense of sight. The convex surface of the ante- 

 rior part of the eye affords a wide field of view, but the 

 small number of facets is insufficient to compose a detailed 

 general picture from the separate pictures. The convexity of 

 the anterior part of the eye is, at least in part, evoked by 

 the elongation of its ommatidia to the exterior. But the fact 

 that the basilar membrane in this portion is not convex, but 

 plane, points to the elongation of the ommatidia in the ante- 

 rior part of the eye to the interior as well. In this process 

 the optic ganglia necessarily afforded a resistance, which 

 was, however, overcome. 



The distinguishment of the moving prey, or female plays 

 a greater role in the life of insects then the distinguishment 

 of immobile objects. And if usually the most highly differen- 

 tiated part of the eye in insects, adapted to that form of 

 vision, lies dorsally, or anteriorly, as in Diopsidae, — this is 

 ({uite understandable, as in this case the eye is adapted to 

 those directions which are most important in quickly attra- 

 cting the activity of the insect in order to catch its prey. 

 When the insect begins to walk or fly it nearly always moves 

 either forward, or upward, and it is just in these directions 

 that the insect can attack its prey more speedily. In the case 

 of Diopsidae it must be concluded that the insect shows the 

 greatest activity in the forward direction, as in this direction 

 the facetted eyes are most strongly developed. 



How far does the development of the eye - stalk agree 

 with these conclusions? As was mentioned above, these stalks 

 are directed to the sides and somewhat dorsally, as well as 

 a little anteriorly. If the stalks were strongly directed forwards, 

 it might be supposed that this is essentila in order to move 

 the eye as near as possible to the object of its vision. .But 

 in the direction in which the eyes are actually develope(J 



