ARTIFROPODA. 



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271. Reproduction. In addition to the common method 

 of sexual reproduction, many types of insects have the 

 power to lay eggs, which will develop without being 

 fertilized. This is known as parthenogenesis. It is found 

 in the plant-lice, in the scale insects, among some Diptera 



FIG. 105. Diagram illustrating the compound eye in arthropods. A, whole eye 

 shown in section; B, one of the eye elements more highly magnified, c, cuticular 

 facets on outside; ep, epidermis; /, group of cells forming a lens-like body; n, optic 

 nerve fibres; o, optic ganglia; p, pigment cells. 



Questions on the Figure. In what way is each ommatidium (eye 

 element) made independent of the others ? In other words, what is 

 to prevent light from passing obliquely from one to another? In 

 what way is a general image probably formed by means of these 

 numerous eyes? Do all the arthropods have these compound eyes? 

 How do the ocelli (simple eyes) compare with these ? Find figures. 



and Lepidoptera, in many of the social insects, as wasps 

 and bees, and in some of the lower Crustacea. It is often 

 true that the individuals resulting from unfertilized eggs 

 are different from those coming from the fertilized. 



The males and females usually differ considerably in 

 color and size. The females are usually the larger and 

 the males more highly colored. 



