MERMITHID.E 4^9 



very improbable that infection takes place directly in the large intestine, 

 as is occasionally stated, because although the harbourers of Oxyuris 

 are frequently liable to auto-infection, this takes place exclusively 

 through the mouth, and is conveyed by the fingers, on which the ova 

 of Oxyuris, and occasionally the female worms, have clung. 



The opportunity for this is afforded every evening, as naturally the troublesome 

 itching caused by the wandering of the worms is met by scratching and rubbing with 

 the ringers. It is therefore possible that the eggs may even thus be introduced into 

 the nose, where the young Oxyuris are perhaps hatched out, if they get high enough 

 up on the moist pituitary mucous membrane. As a matter of fact, the larvae of 

 Oxyuris have been found in the nose. Moreover, one can understand that the eggs 

 of Oxyuris are transferred from person to person by the hand, directly or indirectly. 

 This again explains the wholesale infections which occur in collective dwellings, 

 after a person harbouring Oxyuris has been admitted into boarding-houses, etc. 

 The primary infection may be also caused in other ways by foods, fruits, vegetables 

 and other articles that are eaten raw, and are polluted with the ova. Perhaps also 

 flies or their excrement play a part in the distribution of the parasite, similar to that 

 demonstrated by Grassi as taking place in the spread of the ova of Trichocephalus 

 and Taenia. 



The assumption of a direct development without an intermediary 

 host was first substantiated by Leuckart by experiments on himself 

 and three of his students ; about fourteen days after swallowing the 

 eggs the Oxyuris has attained 6 to 7 mm. in length ; Grassi, and 

 later on Calandruccio, infected themselves by swallowing adult female 

 Oxyuris, with the same results. Heller found worms in the gut 

 (appendix vermiformis) of a male child five weeks old. 



Other species are : O. compar in the cat ; O. curvula and O. mastigodes in horse, 

 ass, mule ; 0. ambigua in the rabbit ; O. poculum in the horse ; O. tenuicauda in the 

 horse. Many species occur in insects, especially in Blattida and Hydrophilida 

 (aquatic beetles). 



Family. Mermithidae. 

 Genus. Mermis, Dujardin, 1845. 

 With characters of the family. 



Mermis hominis oris, Leidy, 1850. 



Fourteen centimetres in length, 0-16 mm. in breadth ; mouth 

 terminal ; posterior extremity obtuse and provided with a recurved 

 hook 50 //, long. 



The parasite was " obtained from the mouth of a child." Stiles considers it to 

 be probably a Mermis, possibly swallowed in an apple. 



