THE THOKN-HEADED WORM. THE LEECHES 307 



the southern portion. The implantation of the worms upon the in 



testinal wall by means of their hooked rostrum causes limited inflam^ 



matory areas of red or yellowish color. The 



tumifaction of the wall causes the serosa to 



be pushed out in the form of nodules which 



may be of yellowish color and somewhat 



tubercular in appearance. Exceptionally it 



has been observed that the parasite has bored 



through the walls of the intestine and given 



rise to a purulent peritonitis. 



As apphes to helminthiasis in general, the 



disturbances which these worms produce will 



be in proportion to their mmiber. Pain may 



be evidenced by continual gruntiag and rest- 

 lessness, and there is the general derangement 



of digestion and the unthrift usual to heavy 



invasion of the intestines by worms. Young 



pigs suffer most and, in these particularly, 



there may be muscular twitchings and epilep- 

 tiform seizures, such symptoms usually being 



followed by death. 



Treatment. — Due to the 

 firm attachment of the 

 worms, nttle or nothing can 

 be accomplished by treat- 

 ment. If this is attempted, 



the same remedies may be used as recommended for the 

 ascarids (p. 241). 



Fig. 165. — Gigantorhynchus 

 hirudinaceus, — natural size 

 (drawn from specimen). 



Class II. Annelida 



Fig. 166. — 

 Armed cephalic 

 extremity of Gi- 

 gantorhynchus hi- 

 rudinaceus, — en- 

 larged. 



Ccelhelminthes (p. 216). — ^The annulated worms differ 

 from those of the class Nemathelminthes in having a 

 segmented body cavity with corresponding ringing or 

 annulation of the body wall. The earthworm is usually 

 taken for type study of the group. 

 Order Hirudinea. AnneHda (p. 307). — This order includes the 

 leeches which differ in many respects from typical annelids. The body 

 is flattened dorso-ventrally and lacks the appendages for locomotion 

 (setse) characteristic of other forms. Locomotion is accomplished by 

 two suckers, one at the posterior end, used only for locomotion and 

 attachment, the other surrounding the mouth, used for locomotion 

 and attachment and also for sucking the food. In moving from place 

 to place the head end is thrust forward and attached by the sucker. 

 The hind sucker is then released and brought close to the anterior sucker 



