334 OUR HOUSEHOLD INSECTS 



formerly believed to be the case, spontaneously generated 

 from "dirt, sweat, or excrements," but must have an 

 origin similar to that of more highly organised animals. 

 The sexes of Pediculus capitis differ considerably in 

 size ; the female is about one-eighth of an inch long, but 

 her partner is sometimes not more than half that length, 

 and is proportionately much narrower. They may be dis- 

 tinguished also by the shape of the terminal segment 

 of the body, which in the female, as shown in Fig. no, 

 is notched, but in the male is evenly rounded. A large 

 sharp-pointed organ, which may often be seen protruding 

 from the end of the male's body, was formerly taken for 

 a sting, and was supposed to be one of the causes of the 

 itching produced by the insect. This, however, was a 

 mistake, no such organ as a sting being possessed by 

 these creatures : the instrument in ques- 

 tion is part of the reproductive apparatus. 

 The eggs, generally called "nits," are 

 conical, or rather pear-shaped bodies, 

 which are attached to the hairs of the 

 host, especially near their roots. The 

 secretion with which they are moistened 

 when laid is formed into a sort of long 

 cylindrical collar, which clasps the hair 

 towards the lower and smaller end of the 

 egg, holding it up like a bracket (Fig. 

 112). The eggs hatch after a little more 

 than a week, the young making their exit 

 from the broader end. The young are 

 quite similar in form to the adult, for 

 tne insec t passes through no metamor- 

 phosis whatever, being thus in a more 

 generalised condition than any other we have described, 

 except the "sugar-fish." Like other insects, they 



