SOLIDUNGULA 367 



The nematodes of solipeds are very numerous, and first in 

 importance must be placed the palisade worm (Strongylus 

 armatus). This worm was known to Euysch (1721). The old 

 naturalists recognised two varieties (major and minor). These 

 we now know to be merely the final stages of growth of one 

 and the same entozoon ; and in both stages the worm inflicts 

 severe injury upon the bearer, chiefly, however, whilst wander- 

 ing through the tissues. The palisade worm has acquired no- 

 toriety principally on account of its causing verminous aneurism, 

 nevertheless, this pathological change is not, in itself, the most 

 disastrous evil produced by the worm. In the adult state the 

 female reaches a length of two inches, whilst the male rarely 

 exceeds an inch and a half. The posterior ray of the caudal 

 membrane or hood of the male is three- cleft. In both sexes 

 the head is armed with numerous, closely- set, upright denticles, 

 presenting the appearance of the teeth of a circular saw or 

 trephine. The eggs are elliptical and somewhat constricted at 

 the centre, their contents forming embryos after expulsion from 

 both parent-worm and host. The larvae are rhabditiform, 

 changing their skin, in moist earth, in about three weeks, at 

 which time they part with their long tails. According to 

 Leuckart, they pass into the body of an intermediate bearer 

 before entering the stomach of the definitive or equine host. 

 From the alimentary canal they pass to the blood-vessels, 

 causing aneurism, and thence they seek to regain the intestinal 

 canal, where they arrive at sexual maturity. It is during 

 their migratory efforts that they give rise to dangerous sym- 

 ptoms in the bearer, not unfrequently causing the death of 

 young animals, especially yearlings. In the adult state the 

 worm is also dangerous to the bearer, as it produces severe 

 wounds by anchoring to the mucous membrane of the gut. 



The proofs we possess as to the frequency of abdominal, espe- 

 cially mesenteric, aneurism from this source are overwhelming. 

 Prof. Bruchmiiller estimated the percentage of aneurismal 

 horses, six years old and upwards, at 91 per cent., and it is a 

 matter of common observation in veterinary dissecting rooms 

 that verminous aneurism is rarely or never absent in the ass. 

 Professors Dick, Simonds, Pritchard, Williams, and many other 

 English and Scotch veterinarians of eminence, have all borne 

 testimony of this kind, and, for myself, I may say that one of 

 the earliest pathological appearances with which I became 

 familiar, some thirty years back, was that presented by mesen- 



