THE PIN WORM 331 



cloaca. The posterior extremity of the male is curved ventrally and has seven 

 pairs of postanal papillae. 



The body of the worm is transversely striated and resembles the ordinary earth- 

 worm, but is more grayish than red. The ova are very characteristic with a rough 

 mammillated exterior. This at times is shelled off and we have a smooth egg which 

 may be mistaken for eggs of other parasites. The eggs leave the body in the fseces 

 and after a long time a few weeks to several months, according to temperature 

 develop an embryo which remains in the shell until swallowed by man. It is stated 

 that they will remain alive for years. On being swallowed, the embryo leaves the 

 egg and we have males and females developing in the small intestine. In countries 

 where such parasites abound, as in Guam and the Philippines, the possibility of their 

 getting into the peritoneal cavity through operative measures on the intestine must 

 always be thought of. 



Guiart considers it probable that Ascaris may suck blood, produce intestinal 

 ulcerations and bacterial infections, and perforate intestine. Their entrance into 

 bile ducts or into larynx (vomited) must be considered. 



At autopsy they may be found perforating the appendix or even filling up the 

 pancreatic duct. 



Some think that the symptoms of itching of nose and anus, vertigo, or convulsions 

 and anasrhia may be due to a toxin secreted by the worm. 



Belascaris mystax. This is a very common parasite of the dog and 

 cat, but is occasionally found in children. It is much smaller than the 

 A. lumbricoides male is 2 to 3 inches (5 cm.) long, female 4 to 5 inches 

 do cm.) in length. The parasites are characterized by the presence 

 of wing-like projections from the anterior end farrow-like head). The 

 egg shells are quite thin. 



Leiper has reported an infection with Toxascaris limbata in an 

 Egyptian. This is the smaller Ascaris of the dog. 



Other Ascaridae reported from man are A. texana and A. maritime, 

 only one case each. 



Oxyuris vermicularis. The parasite is also known as the pin-worm 

 or seat-worm and is more frequent in children than in adults. 



The male is about He inch (4 mm.) long and the female a little less than ^ 

 inch (12 mm.) in length. The male has an incurved tail with a single spicule and the 

 female a long tapering tail. The vulva is in the upper third. 



These worms have a clear slightly bulbous Turkish pipe mouth-piece-like projec- 

 tion surrounding the three-lipped anterior extremity. There is a well-marked bulb 

 oesophagus. 



The eggs are thin-shelled plano-convex, and show a coiled-up embryo. After 

 ingestion of eggs, the adults develop in the small intestine where copulation takes 

 place; the males then die. The fertilized females go to the caecum and colon where 

 they remain until they reach maturity. At this time the females wander to the rec- 

 tum where they either expel their ova or themselves work their way out of the anus. 

 This usually occurs at night, and the scratching induced by the itching causes the 



