PARASITES FKEE DURING THEIB WHOLE LIFE. 125 



parasites of the mammalia, and three species live at the 

 expense of man : the louse of the head, of which Swam- 

 merdam gave a detailed description 

 in his work entitled "Biblia Naturae"; 

 the body-louse, which lives on the 

 bodies of filthy people, forms a dis- 

 tinct species ; the third species is the 

 louse which occasions the disease 

 called pedicularis, or Phthiriasis. 

 These insects were formerly much 

 more common than they are at the 



J Fig. 17.— Louse of the 



present day. In 1825 Dr. Sichel un- 



published . a monograph concerning them ; and there 

 appeared in the " Gazette Medicale " of 1871, a long 

 article on the history of Phthiriasis, 



It is stated that several great personages have fallen 

 victims to its attack, but these observations date from a 

 period when it was thought that they could be spon- 

 taneously originated. It is in fact difficult to believe, as 

 it has seriously been stated, that lice have been seen to 

 issue from the bodies of men like a spring of water from 

 the earth. A physician of the 16th century, named 

 Amatus Lusitanus, speaks of a great Portuguese noble- 

 man who was so covered with lice that two of his servants 

 were constantly occupied in collecting them and carrying 

 them to the sea. Andrew Murray has published a 

 memoir on the lice of the various races of men. 



The name of helminthiasis has been proposed for 

 worm disease in general, and either taeniaceous or 

 lumbricoidian helminthiasis, according to the species 

 which made its appearance. These parasites were con- 

 sidered to be formed spontaneously, and their presence 



