98 



LECTURE VI. 



is less attenuated and straighter, with the anus a little below the apex ; 

 the vulva is situated at a short distance from the anterior extremity. 

 The Strongylus gigas is not confined to the human subject, but 

 more frequently infests the kidney of the dog, wolf, 

 otter, racoon, glutton, horse, and ox. It is generally 

 of a dark blood-colour, which seems to be owing to 

 the nature of its food, which is derived from the 

 vessels of the kidney; as, where suppuration has taken 

 place, the worm has been found of a whitish hue. 



The round-worm {Ascaris lumhricoides Linn.) 

 {Jig. 46.) is perhaps the most anciently known* and 

 common of the human Entozoa, and is that which has 

 been subjected to the most repeated, minute, and 

 successful anatomical examinations. It is found in 

 the intestines of man, the hog, and the ox. In the 

 human subject the round worms are much more 

 common in children than in adults, and are extremely 

 rare in aged persons. They are most obnoxious to 

 individuals of the lymphatic temperament, and such 

 as use gross and indigestible food, or who inhabit low 

 and damp localities. They generally occur in the 

 small intestines. 



The body is round, elastic, with a smooth shining 

 surface, of a whitish or yellowish colour ; attenuated 

 towards both extremities, but chiefly towards the 

 anterior one {fig. 46, a), which commences abruptly 

 by three tubercles, which surround the mouth, and 

 characterise the genus. The posterior extremity {d) 

 terminates in an obtuse end, at the apex of which a 

 small black point may frequently be observed. In 

 the female this extremity is straighter and thicker 

 than in the male, in which it is terminated more 

 acutely and abruptly and is curved towards the ventral 

 side of the body. The anus is situated in both sexes 

 close to the extremity of the tail, in form like a trans- 

 verse fissure. In the female the body generally 

 presents a constriction at the junction of the anterior 

 with the middle third, in which the vulva (e) is 

 situated. 



The body of the Ascaris lumhricoides is trans- 

 versely furrowed with numerous very fine striae, and is marked 



i.j' 



strongylus gigai. 

 Nat. size. 



* It is the (Xfjiivs (TTpoyyvXos of Hippocrates. 



