34 THE INSECT WOELD. 



by four fine hairs, fixed to one another, and seated in its interior. 



It is by means of this complicated apparatus that the louse pricks 

 and sucks the skin of the head. The thorax is nearly 

 square, and divided into three parts by deep incisions. 

 The abdomen, strongly lobed at the sides, is composed 

 of eight rings, and is provided with sixteen spiracles. 

 The limbs are in two parts, consisting of a thigh ; and a 

 shank and tarsus in a single joint, and are very thick. 



Fig. is. Louse A strong; nail, which folds back on an indented proiec- 



(Pediculus capi- . . . 



tis) magnified, tion, thus forming a pmcer, terminates the tarsus. It 

 is with this pincer that the louse fastens itself to the hair. 



Lice are oviparous. Their eggs, which remain sticking to the 

 hair, are long and white, and are commonly called " nits." The 

 young are hatched in the course of five or six days; and in 

 eighteen days are able to reproduce their kind. Leuwenhoek 

 calculated that in two months two female lice could produce ten 

 thousand ! Other naturalists have asserted that the second gene- 

 ration of a single individual can amount to two thousand five 

 hundred, and the third, to a hundred and twenty-five thousand ! 

 Happily for the victims of these disgusting parasites, their repro- 

 duction is not generally to this prodigious extent. 



Many means are employed to kill lice. Lotions of the smaller 

 centaury or of stavesacre, and pomatum mixed with mercurial 

 ointment, are very efficacious. Eut the surest and easiest remed}^ 

 is to put plenty of oil on the head. The oil kills the lice by 

 obstructing their tracheae, and thus stopping respiration. 



There are other kinds of lice, but we will only mention 

 the louse which infests beggars and people of unclean habits, 

 Pediculus humanus corporis, producing the complaint called 

 phthiriasis. In the victims of this disease these parasites increase 

 with fearful rapidity. This dreadful disorder is often mentioned 

 by the ancients. King Antiochus, the philosopher Pherecydes of 

 Scyros, the contemporary and friend of Thales, the dictator Sylla, 

 Agrippa, and Valerius Maximus are said to have been attacked 

 by phthiriasis, and even to have died of it. Amatus Lusitanus, a 

 Portuguese doctor of the sixteenth century, relates that lice increased 

 so quickly and to such an extent on a rich nobleman attacked with 

 phthiriasis, that the whole duty of two of his servants consisted 



