THE COMMON COCKROACH 127 



time, hence sixteen are passed into the capsule, one from 

 each ovarian tube alternately from the two sides. They 

 are regularly placed, like rows of soldiers, eight on each 

 side, with that aspect turned innermost which will 

 ultimately become the under surface of the insect ; hence 

 the embryos all face inwards towards the central plane, 

 with their heads towards the serrated edge, while they 

 are arranged, not exactly opposite one another, but 

 alternately, to admit of close packing. When full, the 

 case protrudes from the end of the abdomen of the 

 female, and is carried about by her in this position for 

 about a week, after which it is dropped into a suitable 

 crevice in a warm situation. These dark-brown oblong 

 cases, nearly half-an-inch long, may frequently be found 

 during the summer in kitchen cupboards, &c. The 

 eggs, each of which has a thin but tough and prettily 

 ornamented shell or skin of its own, develop in the 

 cases, and the young, when hatched, issue from the 

 slit at the toothed edge above referred to, having pre- 

 viously, according to some observers, softened the cement 

 with which the opening is closed, by means of a fluid 

 secreted by them perhaps their saliva. After their 

 exit, the case closes up and looks much as it did before. 

 On hatching, the larvae are almost colourless, except for 

 their conspicuous black eyes. The female takes no 

 interest in her progeny when once the egg-case is 

 deposited, and the young, when hatched, are left to 

 look after themselves, a business which they perform 

 with entire success. 



Periplaneta orientalis is an insect of a comparatively 

 low type of organisation. One evidence of this is seen 

 in its incomplete metamorphosis, and another in the 

 generalised character of the neuration of its wings; a 

 third may be found in the distinct separation and 



