124 INFECTIOUS AND PARASITIC DISEASES. 



ASCARIS 

 LUMBRI- 

 COIDES. 



This, the common round worm of children, 



makes its home in the 



small intestines of man. 

 It is the commonest 

 human parasite, being universally dis- 

 tributed. 



The worm, which is from 4-8 inches 

 (male) to 7-12 inches (female) in 

 length and pointed at both ends, is 

 transversely striated and exhibits four 

 longitudinal bands. It has a yellow- 

 ish-brown or reddish color. Usually 

 the host harbors only a few adults — 

 but there may be many. The eggs of 

 the worm, and occasionally an adult 

 parasite, are passed in the stools. 



The migrations of these worms are 

 remarkable, as they may crawl into 

 the stomach and be vomited, or pass 

 the whole length of the oesophagus 

 into the nose, the middle ear, or the 

 mouth. They have frequently been 

 discovered in the gall-bladder, and 

 have also been known to cause intes- 

 tinal obstruction. Ordinarily symp- 

 toms of their presence are absent, or 

 are limited to minor nervous disturb- 

 ances, such as irritability, picking at 



Fig. 10. — Ascaris 

 lumhricoides: to left, 

 male in lateral aspect; 

 to right, female, ven- 

 tral aspect, natural 

 size. (Tyson after 

 Railliet.) 



