STRONGYLUS ARMATUS. 389 
eem Bollinger’s summary of the whole subject in relation to 
le hippopathological aspects of parasitism, that I feel it de- 
rable to record his conclusions at full length. No profes- 
onal man having any pretentions to a knowledge of the vet- 
dnary art—or, for that matter, to parasitism in relation to 
initation—should remain uninformed on this subject. Dr. 
-ollinger’s results are thus stated : 
1. The worm aneurism of the visceral arteries of the 
orse, existing in 90 to 94 per cent, of adult horses, has a gen- 
al correspondence with the aneurisma verum mixtum of 
ian. it is, however, distinguishable from the same by its 
?at, cause, character of its walls, contents, and mode of ter- 
ination. The worm aneurism arises from a parasitism of 
ie palisade worm (Strongylus armatus), owing to an inflam- 
atory affection of the arterial walls which it causes, and 
hich one may describe as a recurrent traumatic endo- 
teritis. This holds good for all the visceral arteries, with 
ie exception of the abdominal aorta, in which an aneurism 
ay arise from local increase of pressure. 
2. The formation and further development of the aneurism 
also favored by the narrowing of the arterial calibre, which 
caused by the inflammatory swelling of its walls, and also 
? the contemporaneous formation of a thrombus (clot), this 
tter still further supporting and exciting the inflammation 
the inner coat. 
3. Whilst the causes above mentioned (and of these more 
irticularly the continued presence of the palisade worms 
id the plugging of the smaller arieries by thrombi) favor 
e growth of the worm aneurism, the small size of the same, 
^withstanding the years it has existed, is explained by the 
msiderable hypertrophy of the muscular layer, by the tough 
)rous capsule formed in many cases by the connective tissue 
the mesentery, and by the adhesion of the intestines to the 
irpendicular and free-lying anterior mesenteric artery; in 
trticular this last named circumstance does not allow of any 
;ry considerable shortening of the mesenteric artery, which 
ould necessarily be accompanied by considerable dilation of 
e arterial tube. 
