THE ASCARIS 



105 



slightly muscular and is known as the rectum. Correlate the relatively 

 undifferentiated digestive system with the food and habitat of the 

 animal. 



(e) What is called an excretory system consists of a longitudinal 

 excretory tube along each side in the body wall. These tubes are 



/770uth circumpharifngeal 



uterc/5 



o^ar/es ^^ 



pseudocoe/ 



€xcretorc/ phari/nx fe/7/ta/pore /ntesc/r7<s. boat/ rya// 

 pore ^ 



a/7a:> 



ov/afact 



ot^ari/ 



uteri/5 



pseuofocoe/ 



vagrmoc 



J) -^ £ 



cut/c/e 1 /nteeUne, 

 ep/'c^er/Tt/sr ijod^ y/a// 



/7?asc/e ) ^emma/ ves>/cJe 



cut/c/e seta/ 

 /ntest/ne 



rectum 

 CJccretoru cana/ 



pert/ct/ 

 Oi</duct setae' 



te3t/s 



c/uctas c/eferer?B 



sem/na/ ye^/ch 



ejacu/atory o/uct 



pseudocoeJ 



oyan/ 

 ner/e cord 



a/7Ui 



3 



Fig. 51. — Internal structure of A^carx^ lumbricoides. A. dissection of a 



female, from lateral view; diagrammatic. B, cross section of the body in the 



mid-region. C, longitudinal section of the posterior end of the male. D, the 



female reproductive system. E, the male reproductive system. 



(Redrawn, with modifications, from R. Leuckart, "Die menschlichen Parasiten," 1876.) 



closed at their posterior ends and open to the outside through a single 

 ventrally located excretory pore near the anterior end. 



(f) The nervous system consists of a circumpharyngeal nerve ring 

 and dorsal and ventral longitudinal nerve cords with their smaller 

 branches. 



(g) The reproductive system of the male consists of a single coiled 

 tube in which four regions are recognizable. The testis leads into 



