ENTOZOA IN THE ALIMENTARY CANAL. 61 



Chapter III. 



GENEEAL EEMAEKS CONCEENING THE ENTOZOA 

 WHICH AEEECT THE ALIMENTAET CANAL. 



As might be supposed from the facility of external 

 communication tln-ough the medium of the mouth 

 and oesophagus, and from the fact of the entozoa being 

 carried into the body, in the form of ova, along with 

 various articles used as food, the intestinal canal is 

 more subject to the invasions of these parasites than 

 any other part of the body. 



Generally speaking, only one species of intestinal 

 worm occurs, in one individual, at the same time, but 

 the existence of one species does not necessarily 

 prevent that of another. E-osen reports the case of 

 a child, four years old, who passed at the same time 

 ten ascarides lumbricoides, a large number of 

 oxyurides, and a considerable portion of a taenia. 

 Facts similar to this are very rare ; but cases in 

 which two species of entozoa are present in the 

 intestines are not uncommon. 



Children are comparatively more subject to nema- 

 toid, and adults to cestoid, worms ; and females 

 suffer from intestinal entozoa more frequently than 

 males do. 



As a common rule, persons are only affected by 

 these parasites during a limited period ; although 

 there are some individuals who are never entirely 

 exempt from them. 



The presence of worms in the intestines does not 

 always give rise to marked symptoms, and may even 



