308 PHYSIOLOGY". 



woman who frequently suffered from the menstrual flux, in whom the 

 lice appeared in multitudes upon the skin, and indeed came out at her 

 ears and anus, after she had combed herself, as she said, with a, pro- 

 bably, dirty comb ; they were evacuated at the anus chiefly after 

 clysters, which were applied in consequence of anxiety, pain, and colic. 

 As in all these cases a decided transfer of lice probably did not take 

 place, although in the last the patient herself surmised it, we may 

 equally doubt it in children, the majority of whom, at a particular 

 period of their lives, are furnished with them. We know many 

 instances in which head lice are found in the cleanly children of 

 opulent parents who associated merely with their equals, who were 

 likewise kept very clean ; and it appears that, as in childhood, the 

 general constitution of the body favours the origin of lice, the same 

 effect is produced in adults by uncleanliness. In Poland and Russia 

 the body louse (Pediculus vestimenti, Fab.) is so common that the lower 

 classes are seldom found there without them ; to which we may add, 

 the general distribution of lice among warm-blooded animals, almost 

 each of which has its peculiar louse, indeed many harbour several 

 species of parasites, which approach very closely to the true lice. But 

 that these latter may be with facility conveyed from one individual to 

 another is likewise certain, and it is thus that the distribution of lice 

 takes place in many young animals and children; and in these they 

 increase the more rapidly, from the predisposition already existing in 

 young and juicy bodies. Whereas the true Phthiridsis, which presumes a 

 very morbid state of the juices, is not contagious, as was proved by the 

 case at Bonn, for the woman had, for a fortnight previously, slept in 

 the same bed with her husband, who remained perfectly free from the 

 lice. But the body louse, which is rather the parasite of healthy but 

 dirty people, may be conveyed from one individual to another, yet with 

 a little precaution it is easily removed. This, however, is not the case 

 in the louse of the P/tthiriasis, for in some of the preceding cases the 

 greatest cleanliness effected nothing, new lice were produced, and their 

 propagation did not cease until the sufferer dwindled to death. 



Whether all the preceding cases were absolutely Phthiriasis remains 

 uncertain, for in some indeed we are sure that it was not lice, but Acari, 

 which were the destructive creatures. Thus Aristotle* relates of 

 Alcmanus and Pherecydes, that the lice were formed in pustulous swell- 



* Hist. Aiiim , Lib. v. cap. 31. 



