PARASITOLOGY. 117 



Haemonchus Contortus (Contortus — twisted). 



U^—^ Synonym. — Strongylus Contortus. 



^ Distribution. — Common in many states, 

 / especially in the South and middle West. 

 Description. — Hair-like in appearance ; 

 Strongylus body white or pinkish white in color ; 

 Contortus the mouth is nude ; two lateral papillae 

 b, Female. ^^^ notcd a short distance from the head ; 

 the cuticular surface has fine transverse 

 striations ; the caudal pouch is bilobate, i. e., the 

 pouch is divided into two parts ; the body of the 

 female terminates in a pointed tail ; the male meas- 

 ures four-fifths of an inch in length, the female about 

 one inch. 



Life Cycle. — The female is oviparous. The ova 

 are passed from the animal in the feces ; the egg 

 thus passed has been found to be undergoing seg- 

 mentation, and has hatched in from two to three 

 days. The embryo is very small and is provided 

 with a fine-pointed tail. In the development from 

 the embryonic to the fully developed larval stage, it 

 moults at least twice ; the em?bryo becomes shriv- 

 eled in the last moult, and remains in the skin, in 

 which state it is usually found upon blades of grass 

 or other objects. In this state it can retain its vital- 

 ity for several weeks, withstanding desiccation and 

 freezing. When taken into the stomach the larva 

 becomes revivified and developes into the adult 

 stage. The worm is a bloodsucker and is often 

 found attached to the mucous membrane, holding on 

 by means of its buccal armature. 



Animals Infested. — The ox, the sheep and the goat. 

 Parts Infested. — Abomasum and intestines- 



