212 Veterinary Medicine. 



hatching may be effected in the intestine or in manure or water 

 external to the body. When hatched otit in the intestine they 

 ma}' pass out at once with the manure or the}' may envelop 

 themselves in pellets of the finer ingesta and remain for a time 

 in the bowel and finally pass out in this condition. Baillet has 

 traced their development out of the body. In a watery or damp 

 medium they are hatched out in a few days as a cylindroid worm 

 % to y'l mm. long, thick in front and with a filiform tail. In 

 moist environment but especially in damp manure they grow to 

 I mm. or 1.5 mm. and continue for months in this condition, but 

 remain small and asexual, until taken in, in the drink or green 

 food of the soliped. Reaching the intestine and especially the 

 caecum and colon they bore their way into the mucosa and en- 

 cyst themselves, or if they happen to perforate a blood-vessel 

 they make a habitat of that. In the cyst, development proceeds 

 and when it has reached a certain stage the worm once more 

 bores its way tlirough the mucosa and reaching the intestine be- 

 comes sexually mature. 



In this last migration the young worm is liable to perforate a 

 blood-vessel in which case it is destined to a period of existence in 

 the blood. It may, however, have blundered upon a blood-vessel 

 at an earlier stage when seeking a temporary home in the mucous 

 membrane, so that the sclerostomata of aneurisms may be derived 

 from two separate sources. In the blood-vessels the parasite 

 attains a length of i to 8 lines, whereas in the mucous cy.sts it 

 does not exceed 3^ lines. Yet Neumann holds that after leav- 

 ing the blood-vessels they may again encyst themselves in the 

 mucosa before escaping into the intestine. 



Several moultings take place in the asexual condition. 



Other views have been advanced as to the development of the 

 sclerostomata. Colin believed that the ova deposited in the ducts 

 of the mucous glands and in the perforations made by the para- 

 site in blood-sucking, hatched in this situation and the embryo 

 at once encysted itself in the mucosa. 



lycuckart imagines that the embryo found in the faeces or in 

 water outside the body of the soliped, should pa.ss through an 

 intermediate host before it can return to gain sexual maturity in 

 the horse. But no evidence of the existence of such intermediate 

 host is furnished, and the encysted intestinal worms show no in- 



