344 MEASLES IN THE PIG. 



in pigs, which, on reaching the human intestine, develope into 

 taenise. 



The very inappropriate term " measles " is applied to that 

 morbid state induced by the presence of cysticercus cellulose 

 in the muscular structures of swine. It is a purely parasitic 

 disease, and depends for its origin on the introduction into 

 the system of the pig of the mature and fecundated ova of 

 tsenia soliuin. 



The process of development has been carefully watched by 

 many observers. The embryos of the tapeworm are globular 

 and armed with spines, which pierce, by working in a hori- 

 zontal plane from within outwards, the mucous membrane 

 of the alimentary canal of the pig. They penetrate the 

 tissues, and are washed through the larger vessels by the 

 blood current until they reach their destination in the mus- 

 cular structures. A very large number of the embryos are 

 thus dispersed, but only in young animals. They cannot 

 find their way through the tissues of adult pigs, and any 

 experiments performed with animals above a year old fail as 

 a rule. This, as we shall afterwards see, is the same with 

 other parasitic diseases. 



Pigs are said to be born measly, and one of the most con- 

 stant means whereby the disease is propagated is by breed- 

 ing from measly sows. French veterinarians long since 

 noticed that if a measly sow was bred from, all her produce 

 was measly, and similar observations have been made in this 

 country by the bacon factors. 



If pigs are born healthy they cannot have fully developed 

 cysticerci in their flesh under two months and a half. Prom 

 30 to 40 days after the introduction of the germs into the 

 body of the pig the parasites vary in size from one to four 

 millimetres. They consist in small cysts, or bladders, con- 

 taining a clear fluid, and in the wall of the cyst there are 



