THE THREAD LUNG-WORM-VERMINOUS BRONCHITIS- 

 HUSK OR HOOSE-PAPER SKIN. 



Strongylus pilaria, End. 



Plates XXXIV, XXXV, XXXVI. 



The thread Inng worm, or Strongylus filaria, is the best known of the 

 sheep lang worms, for the reason that at times it causes extensive epi- 

 zootics io the floclfs, and that the worm is large enough to see when tiie 

 bronchial tubes are slit and spread open. From personal observation 

 it appears to be much rarer than Strongylus ovis-pulmonalis, and the 

 disease it causes much less extensively distributed as to number of 

 animals iufected than that produced by the latter. In most of the 

 American literature on this subject the disease caused by the hair lung- 

 worm seems to be ascribed to the thread lung worm, and no mention is 

 made of the former. 



Description.— Ma,]6, 33 to 54""° ; female, 55 to 80""". Worm filiform, white, with 

 a dark hair line showing throaghoiit its length ; head obtuse, without notice- 

 able papillae or wings; mouth circular, naked; unicellular neck glands qnite large; 

 cuticle longitudinally striate. Male : Bursa shallow, campanulate, opening later- 

 ally ; five sets of costsB ; the dorsal are trifid, the lateral bifid, and the ventral sepa- 

 rated. Spicula arcuate cylindrical ; 3.35""™ long by 0.075'"'" wide ; short, very 

 thick, dark brown; chitinous portion a curved fenestrated conical tube; fleshy por- 

 tion a membrane, which formsa bulb-like expansion toward their free end. Female : 

 Vulva three-sevenths of her length from the head; uteri symmetrically directed 

 anteriorly and posteriorly ; posterior oviduct becoming continuous with the uterus 

 near its flexure at the tail; ovo viviparous; eggs ellipsoid, 0.075 to 0.120""° long; 

 0.045 to 0.082""" wide. Embryo 0.25 to S"!™. 



The life history of Strongylus filaria is in general that of other para- 

 sites. In some way the young worms arrive in the bronchi, grow, de- 

 velop, become adult, mate, and lay their eggs in the surrounding mucus. 

 The eggs laid are not true eggs, for each eggshell contains a young 

 worm within, a feature which is described by calling the female ovo- 

 viviparous. The inclosed young escape from the shell, and many of 

 them are expelled from the lungs in the coughing fits along with other 

 discharges. These young, which are scattered about watering-places, 

 pastures, sheep-yards, or corrals serve as infecting and reinfecting ma- 

 terial for a considerable length of time. Professor Leuckart [Entwickel 

 ung d. Nematoden, Arch. d. w. Meilkunde, 1865, p. 299), kept the young 

 of this species alive for several weeks on damp earth, and observed them 

 pass through a stage in which they molted or threw off their skins, 



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