216 Veterinary Medicine. 



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

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

 may pass out at once with the manure or they 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 

 yl to yi mm. long, thick in front and with a filiform tail. In 

 moist environment but especially in damp manure they grow to 

 i mm. or i . 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 

 caeum and colon they bore their way into the mucosa and encyst 

 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 through the mucosa and reaching the intestine becomes 

 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 

 cysts it does not exceed 3^ lines. Yet Neumann holds that 

 after leaving 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 111 the perforations made by the para- 

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

 at once encysted itself in the mucosa. 



Leuckart imagines that the embryo found in the faeces or in 

 water outside the body of the soliped, should pass 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- 



