ASCARIS LUMBRICOIDES LINNAEUS 85 



nerves run in the subcuticle. The lateral lines inclose also each 

 a longitudinal lateral nerve which, however, takes its origin from 

 the lateral cephalic ganglion. The longitudinal nerves of each 

 side are connected with the dorsal and ventral nerves by thin 

 commissures which are asymmetric and form right and left 

 semicircles. 



The sense organs are represented only by six oral papilla; 

 situated on the lips and in the case of the male by from seventy 

 to seventy-five anal papilla. Higher sense organs are absent. 



Circulatory and respiratory organs are absent. 



Reproductive system, (a) Female. About one-third from 

 the anterior end of the body is a small transverse slit in the mid- 

 ventral line. This is the genital opening or vulva. It leads into 

 a short vagina which soon splits into two very long, convoluted 

 tubes. Each of these tubes is ten times as long as the entire 

 worm and may contain over ten million eggs. The portion of the 

 tube, which is nearest the vagina has a considerable diameter 

 and represents the uterus. The middle portion is the oviduct 

 and the thin end portion is the ovary. The ovary ends blindly. 

 Inclosed in the ovary is a long central rod or rachis round which 

 the young eggs are arranged at first regularly, then more or 

 less in small clusters. The division line between the ovary and 

 the oviduct is not apparent externally, but the oviduct is lacking 

 the rachis and contains free eggs. The end of the oviduct is 

 somewhat distended and functions as a sperm receptacle. Here 

 the eggs are fertilized. The uterus contains therefore only 

 fertilized eggs and its walls secrete an albuminous substance in 

 which the eggs are inclosed. 



(b) Male. The male reproductive organs are situated in the 

 posterior third of the body. They consist of a single tube 

 which opens into the cloaca or the short portion of the ali- 

 mentary tract between the rectum and the anus. The tube is 

 from seven to eight times as long as the entire worm and is 

 clearly divided into three uneven portions. The longest portion 

 is the testis which has the shape of a thin convoluted tube. 



