Round Worms of the Abomasum. 253 



fold over vulva, 3 to 6 lines long, free in stomach or encysted in mucosa ; 

 nodules with orifices. Hosts: Ox, common in Berlin, Texas, etc. Symp- 

 toms : Anaemia, pallor of mucosse, emaciation, dropsies, irritable bowels, 

 mucous stools, ova in fseces. Treatment as for contortus. Prevention : 

 Avoid infested pastures, waters, and animals ; put pastures under rotation 

 of crops. Str. Vicarius : Smaller than Ostertagi ; lacks the membraneous 

 fold over the vulva. Host : Sheep in Southern States. Produces anaemia, 

 emaciation and unthrift. Treatment as for Ostertagi. 



Three species of strongyli have been found in the stomach of 

 ruminants, all of which are seriously pathogenic, so that the 

 lesions caused by them might appropriately be included among 

 pestilential diseases. 



Genus : Strongylus. Among the characters of the genus are 

 long, cylindroid body, generally narrowed toward the head ; 

 head small, nude or with lateral membraneous alae ; mouth small, 

 round or triangular, nude or papillated ; oesophagus elongated. 

 Male with caudal clasping membrane ; one or two spicula. 

 Female with conical, obtuse or pointed tail ; one or two ovaries ; 

 genital orifice behind the middle of the body, sometimes close to 

 the anus. 



Strongylus Contortus. (Twisted). Its body is red or 

 white from ingestion of blood or abstinence, and narrowed toward 

 the extremities. Two papillae, curved backward, are on the sides 

 near the anterior extremity. Male 5 to 8 lines in length, with 

 bilobed caudal membrane. Female 8 to 13 lines ; tail pointed ; 

 vulva toward the posterior fifth of the body, covered by a tongue- 

 like process directed backward. Ova elliptical. Ovoviviparous. 



Biology. This parasite is common in the abomasum of sheep, 

 goat, argali and chamois (less so in cattle) in Europe and Amer- 

 ica. In its adult form it lives by sucking blood and thereby 

 acquires a brown color, modified by the white oviducts which are 

 wound around the alimentary canal, giving its peculiar twisted 

 appearance. 



Leuckart traced the development of the embryos in impure 

 water through .several moultings, after which they were capable 

 of reaching maturity in the stomach of the ruminant. Baillet 

 failed to develop them in pure water. Manifestly they live out 

 of the body in their immature condition in foul, stagnant water 

 and damp soils. 



Lesions. Pathogenesis. In infested districts the strongylosis 



