SOME HUMAN PARASITES 311 



never occur; probably the young lice do not ordinarily 

 come to maturity in so short a period of time. 



The eggs or " nits " are pear-shaped, whitish, and fastened 

 by their smaller ends to the hairs, especially to those 

 back of the ears, usually near the bases of the hairs. 

 The eggs are glued to the hairs by a gelatinous sub- 

 stance that is secreted by the female louse when they 

 are deposited. 



The usual color of the head louse is light gray, but it 

 varies according to the color of its host. For instance, 

 according to Murray, it is nearly black on the West 

 Africans, dark and smoky on the Hindoos, yellowish on the 

 Chinese and Japanese, orange on the Hottentots, and 

 dark brown on the South American Indians. 



THE BODY LOUSE 



Pediculus corporis (vestimenti) 



This louse (Fig. 107) has been confused with the head 

 louse, older authorities believing them to be the same 

 species. More recent writers generally hold that they are 

 distinct. The body louse is considerably larger than the 

 head louse, with longer antennae, and is of a dirty white 

 color. As the common name indicates, this species fre- 

 quents the body of man. They conceal themselves in the 

 folds of the clothing where it is difficult to find them. 

 Moreover, they lay their eggs along seams and wrinkles of 

 the clothing and do not pass to the skin except to suck 

 blood. Their existence and multiplication depend, there- 

 fore, upon the length of time their host retains the cloth- 

 ing without a change. In the case of soldiers on a long 



