HUMAN PEDICULI 339 



as well as rubbing snuff into the roots of the hair ; but 

 for such purposes nothing better can be used than very 

 weak solutions of petroleum or carbolic acid. Frequent 

 washing with carbolic soap is also a good thing in this, 

 as in other afflictions connected with the skin. By those 

 who do not object to the use of mercury compounds, an 

 ointment made of " white precipitate " mixed with lard 

 has been found efficacious. 



Whilst P. capitis is usually confined to the head, 

 P. vestimenti, the body louse, is found on the body at 

 large, and, as its scientific name imports, is closely con- 

 nected with clothing. It is rather larger than P. capitis, 

 and as it is found on those parts of the body that are 

 comparatively devoid of hair, it takes advantage of the 

 seams and folds of the inner garments to deposit its eggs 

 upon. Its chances of flourishing, therefore, depend 

 mainly upon the clothing remaining unchanged for a 

 long time ; hence, in long marches, or on other occasions 

 when few opportunities can be obtained for washing or 

 changing clothes, it may become troublesome. It has 

 often been an army pest during long campaigns. When 

 Leeuwenhoek showed some of his specimens to " a certain 

 great personage," the latter exclaimed that they were 

 just like those with which his soldiers were infested, 

 and stated that the men found them much more trouble- 

 some in wet weather than in dry. In the Crimean war, 

 it is said that the soldiers were much annoyed by these 

 horrible creatures, finding them far more of a nuisance 

 than P. capitis. Their attacks produce an intolerable 

 itching of the skin, often accompanied with inflamma- 

 tion. Of course warm baths and a thorough cleansing 

 of the clothing are the chief remedies. 



The crab louse (Fig. 113) is a very different creature 

 from either of those we have been considering, and is 



