384 Veterinary Medicine. 



Strongylus Micrurus : Pointed tailed strongle. This is a 

 delicate white filiform worm having a rounded, wingless head, 

 and terminal, round, nude mouth. The male is i inch and the 

 female 2 to 3 inches long. The caudal membrane of the male is 

 small and supported by five ribs on each side, the posterior trifid, 

 the anterior bifid and the middle simple. The tail of the female 

 is sharply pointed, and the vulva in the posterior sixth of the 

 body. Ovoviviparous. 



Habitat. The bronchia of bovine animals especially calves. 

 It was supposed to infest horses and asses as well, until the 

 strongylus Arnfieldi was demonstrated to be distinct. 



Strongylus Pulmonaris. This is smaller than the Strongylus 

 Micrurus (7 lines to ij^ inch long), and its terminal mouth is 

 surrounded by a row of rounded papillse. In the male the caudal 

 membrane is bell-shaped, with 7 rays. The tail of the female is 

 very attenuated and sharp. Ovoviviparous. 



Habitat. Bronchia of bovine animals, especially calves. 



History of the Disease. The existence of lung worms in 

 calves was noted in 1744 by Ruysch, in 1756 by Nichols, in 1803 

 by Camper, and very frequently since. 



Life History. Development. This has not been fully traced 

 for the lung worms of cattle but it may be assumed that the de- 

 velopment closely resembles that of the strongylus filaria. The 

 eggs and embryos expelled in coughing live for a time in fresh 

 water or moist earth, where there is reason to believe that they 

 moult or undergo other change that fits them to once more take 

 up the life in the bronchia. They do not persist indefinitely, 

 generation after generation in the .same animal's lungs, and hosts, 

 that harbored them when calves, are usually free from them be- 

 fore they reach maturity. 



Conditions that Favor Infesting are essentially the same as 

 for the lung worms of sheep, wet lands, and seasons, inundations, 

 fresh water in puddles, ponds, lakes, swamps, streams and open 

 wells, dry seasons after wet, water-shed, overstocking, low con- 

 dition, ill health, starvation, youth, etc., are prominent accessory 

 factors. I^euckart and Kasparek have separately preserved the 

 ova for 2 to 3j^ years, with the embryos still alive, showing the 

 need of prolonged abandonment of infested grounds, streams, 

 ponds and buildings. 



