132 MORE MINOR HORRORS 



ficial vessels of the cattle swarm with the 

 larvae of these thread-worms, which readily 

 pass through the proboscis of the insect into 

 its stomach. They then wriggle through the 

 walls of the stomach and make their way 

 into the thoracic muscles ; here they undergo 

 a ' rest-cure,' and after a time they are readily 

 transferred to a new and possibly uninfected 

 host. 



But by far the worst infection which 

 is attributed to this fly is acute epidemic 

 poliomyelitis, or infantile paralysis. That this 

 disease occurs in epidemics has been known — 

 especially in Scandinavia — for some time ; and 

 eight years ago it attracted serious attention 

 in North America and in our country. In 

 1907 there were many local outbreaks in 

 the United States and Canada, and it is 

 thought that the infection was first intro- 

 duced from Scandinavia along the Atlantic 

 coast, and later, inland, as far as the State 

 of Minnesota, by the numerous Scandinavian 

 immigrants that settle there. 



The disease is one of those which are 

 apparently due to a protozoon too small 

 to be visible under the highest power of the 

 microscope, and so small as to be able to 

 pass through a Berkefeld filter. It can readily 

 be artificially transmitted to monkeys. It 

 is thought that the disease is by no means 



