SOME HUMAN PARASITES 313 



the two lice to live for six days and obtain their sustenance 

 from his leg. At the end of this period he removed the 

 stocking and found fifty eggs around one of the females and 

 forty eggs in another part of the stocking, evidently laid 

 by the second female which, however, had escaped. He 

 wore the stocking for yet ten days, when on examination 

 he found twenty-five young lice which so disgusted him 

 and dampened his enthusiasm that he threw the whole 

 thing into the street. Since Leeuwenhoek's time the 

 author is not aware that any scientist has ever tried 

 in the same way to study the life history of these 

 lice. 



Recently the body louse has come under suspicion as a 

 carrier of typhus fever from one person to another. Ty- 

 phus fever should not be confused with typhoid fever, for 

 one is quite distinct from the other. Typhus is essentially 

 a disease of temperate and cold climates and is therefore 

 common in Europe and in some parts of America. It also 

 occurs in the tropics but usually only at high altitudes and 

 ceases at the advent of hot weather. It is usually asso- 

 ciated with dirty and unsanitary surroundings and is 

 especially prevalent among the inmates of prisons. It has 

 been called a contagious disease but is now thought to be 

 conveyed from one individual to another probably through 

 the agency of insects. 



Ricketts and Wilder have succeeded in transmitting 

 the typhus fever of Mexico (tabardillo) to the monkey by 

 the bite of the body louse in two experiments. The lice 

 in one instance derived their infection from man and in 

 another from monkey. We are not aware that the fever 

 has been experimentally carried from man to man by the 

 louse, or that it has been conclusively shown that such 



