THE THORN-HEADED WORM. THE LEECHES 307 



the southern portion. The miplantation of the worms upon the in- 

 testinal wall b}' means of their hooked rostrum causes limited infiam- 

 mator}' areas of red or 3'ellowish 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 applies to helminthiasis in general, the 

 disturbances which these worms produce will 

 be in proportion to their number. Pain may 

 be evidenced b}' continual grunting and rest- 

 lessness, and there is the general derangement 

 of digestion and the unthrift usual to hea\y 

 invasion of the intestines by worms. Young 

 pigs suffer most and, in these particularh', 

 there may be nmscular twitchings and epilep- 

 tiform seizures, such s\nuptoms usually l^eing 

 followed by death. 



Treatment. — Due to the 

 firm attachment of the 

 worms, little 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. 



Coelhelminthes (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. Annelida (p. 307). — This order includes the 

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

 is flattened doiso-ventrally and lacks the appendages for locomotion 

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

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

 attachment, the othei- 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 



