EQUINE ENTOZOA. 339 



The males are about one and a half inches long and the 

 females two inches. 



The eggs, which are elliptical and somewhat constricted 

 at the centre, pass from the parent worm and host with the 

 faeces. 



In a few days the rhabditiform larvc^ are hatched, and in 

 three weeks' time change their skin in mud, and at the same 

 time part with their tails. 



They next gain access to the bodies of some intermediary 

 host, where they are still further matured, and from this 

 gain access to the horse. 



From the intestinal canal they get into the small vessels 

 of the intestine, and pass on to the larger arterial trunks, 

 producing aneurism, caused by inflammation and thicken- 

 ing of the intima (endo-arteritis). 



Lastly, these parasites make their way out of the vessels, 

 and from thence endeavour to regain the colon, where they 

 again change their skins, and, adhering to the mucous lining 

 of the bowel by means of their spines, attain sexual matu- 

 rity. During their wanderings they are apt to stray. 



Verminous Aneurism.— Occurs in a large percentage of 

 horses and asses, and is especially found in the aorta'' and 

 anterior mesenteric artery. 



These aneurisms assume various forms, e.g., thumb- 

 shaped, or bottle-shaped, etc. They may be simpl'e or com- 

 pound, and vary in size from a pea to a man's ^head, and 

 occur in animals six months old and upwards. The number 

 of worms in one aneurism varies, and is usually nine to ten, 

 the highest number in one horse being Vll. 



We append a few extracts of Dr. Cobbold's summary of 

 the results of Bollinger's investigations of this worm : 



* The favourite seat of the wonn-aneurism is the trunk of the anterior 

 mesenteric artery, dn^ectly at its origin from the abdominal aorta. ^Ct 

 frequently that part of the arterial trunk is dilated, from ^^■hich the 



00 () 



