ANIMAL PARASITES. 125 



the nose, and nocturnal grinding of the teeth. How- 

 ever, convulsions, epileptiform attacks, vertigo, and 

 chorea, have also been described. The worms are 

 quickly expelled by santonin (gr. J-i for child, gr. 1-2 

 for adult) given either alone and followed by the same 

 quantity of calomel or a saline purge; or equal quanti- 

 ties of santonin and calomel may be given night and 

 morning until bowels are well moved. 



The parasite is contracted from water or food con- 

 taining the ova, so that a host may not only convey the 

 parasites to others, but may re-infect hin^self. 



Also known as the pin-worm, thread-worm, 

 OxYURis g^j^j seat-worm, has its habitat in the caecum, 



colon and rectum. It is a very common 



LARIS. . ^ 



human parasite the world over. Found 

 particularly in children, there is no period in life when 

 they may not be contracted. 



As its name implies, it is a small thread-like worm 

 from 4 millimeters (male)- 10 millimeters (female) in 

 length, and is readily seen on examination of the 

 stools. The eggs, which are also passed in the stools, 

 are probably taken into the stomach with water or 

 salads, or directly from the contaminated hands of the 

 host. 



The symptoms occasioned by the parasite are irrita- 

 bility, nocturnal restlessness, and itching, particularly 

 about the anus. The worms may leave the rectum at 

 night and deposit eggs on the perineum — or in females 



