196 



SJKONGYLUS OVIS-PULMONALIS, Diesing. 



Plate XXXI. 



Left lung diseased by Strongylus ovis-ptlmonalis, tlie hair lung-worm. Nattoral 

 size. Each dot is caused by the irritation set up by a yonug worm, and its size cor- 

 responds to the age of the worm. The larger patches consist at first of separate 

 dots ; as these enlarge they run together and finally become so fused that their 

 identity is lost. The patches show the stage at which the worms become adult and 

 produce their young, which wander into the adjacent air cavities. 



