OXYUEIS VERMICULABIS. 363 



minating in a three-pointed end, wticli is said to act as a kind of holdfast ; the candal 

 extremity of the male being obtusely pointed ; both sexes present a more or less fasiform 

 body, the anterior end being narrowed to form a somewhat abruptly-truncated head, 

 which is often rendered very conspicuous by a uniform transparent bulging of the in- 

 tegument surrounding the mouth, and presenting in profile the aspect of winged appen- 

 dages ; oral opening tripapUlated, leading into a triangular oesophagus ; integument 

 transversely striated, and of a sUvery- white appearance ; penis simple, single, and very 

 manute ; mode of reproduction oviparous ; eggs oblong, unsymmetrical, measuring about 

 Tios" from pole to pole, and ^" in their greatest transverse diameter. 



Of all the parasites infesting the human body, this is the one 

 concerning which the medical practitioner is most frequently con- 

 sulted, partly on account of its remarkable frequency in children, 

 and more particularly on account of the extreme difficulty expe- 

 rienced in getting permanently rid of it. The Oxyuris vermicularis 

 is, however, by no means confined to young persons, seeing that 

 some adults are troubled with it even to old age. Speaking, more 

 precisely, as to their habitat, these worms commonly infest the ter- 

 minal portion of the intestinal tube, being especially abundant in 

 the sigmoid flexure of the colon. 



Anatomical Peculiarities. — In the main, it may be said that the 

 structure of Oxyuris conforms with that of Ascaris, but there are a 

 few well-marked differences ; and when we come to enter minutely 

 into the subject, which here, indeed, we do not propose to do, it is 

 lamentable to find the discrepancies which exist amongst our lead- 

 ing hehninthologists. At one time, we are called upon to express 

 our admiration of Walter's great discoveries respecting the nervous 

 system of Oxywris ornata, and, shortly afterwards, we are equally 

 compelled to admire the coolness with which he stands prepared to 

 admit that his wonderful display of nerve-cords, filaments, unipolar, 

 bipolar, and multipolar gangHon cells is altogether a mistake. In 

 like manner. Otto, Meissner, and Wedl, made several so-called 

 nerve-discoveries in other nematoda, but these supposed nerves, 

 according to the observations of Schneider and Leydig were only 

 parts of the muscular system, or, in one case, of the oesophagus ! 

 All this is highly unsatisfactory, and tends to throw doubt upon the 

 general value of histological observations among the helminths. 



