PH YL UM NEMA THELMINTHES 



129 



epithelio-muscular cells has only a small portion of its bulk differ- 

 entiated into contractile substance lying next to the subcuticula, 

 while the remainder of the cytoplasm, containing the nucleus, 

 protrudes as a rounded mass 

 into the body cavity. 



This muscular layer is not a 

 continuous lining of the body 

 cavity, for it is interrupted by 

 slight breaks in four regions 

 which are designated as the 

 dorsal, ventral, and lateral lines. 

 The fairly conspicuous thicken- 

 ing of the subcuticula which 

 stands in the middle of each 

 lateral surface is known as a 

 lateral line. Less pronounced 

 intrusions of the subcuticula 



'Nerve nnj 



■ExcreforLj pore 



Intestine 



- Ovary 



Vulva 



n 



Anus 



Fig. 70 A. — The nervous system of a 

 nematode. {After Brandes)-. 



Fig. 70 B. — Semidiagrammatic 

 drawing of a female free-living 

 nematode. {After J agerskiold) . 



occur also in the middorsal and midventral lines. In the lateral 

 hues are borne the ducts of the excretory system. Near the 

 anterior extremity of the body, these are united and communi- 



