rOLIOMYELlTlti. 757 



The disease has been known for over half a cen- 

 tury, but it has been recognized as an infectious 

 disease for only a few years. 



Although various bacteria have been described 

 in connection with the disease, there has been little 

 reason for considering them other than mixed in- 

 fections or contaminations. 



Flexner and Lewis found that the virus of 

 poliomyelitis is filterable and describe very minute 

 bodies occurring in the infectious filtrate. The 

 bodies can be stained with Loeffler's flagella stain 

 and cause a cloudiness in culture media after suit- 

 able incubation. The transfer of a small amount 

 of such cloudy media to a second clear media re- 

 sults again in cloudiness after incubation. The 

 virus loses its virulence when heated to from 45 

 to 50 C. for half an hour, but resists freezing. 



Landsteiner and Popper, in 1909, and Knopfel- Experimental 



,.,,!,, n n -, ,. Poliomyelitis. 



macner a little iater, succeeded in producing polio- 

 myelitis in monkeys by injection of emulsified 

 cords of children dying of the disease. They were 

 unable to infect second animals with material 

 from the first. Later, in 1909, Flexner and Lewis 

 were able to produce poliomyelitis in monkeys in 

 a way similar to that described by Landsteiner 

 and Popper, and succeeded in transmitting the 

 disease from one monkey to another. 



Infection may be produced in monkeys by in- 

 jecting the virus into the brain, spinal canal sub- 

 cutaneous tissue, peritoneal cavity or into the large 

 nerves. 



Experimental poliomyelitis can be produced bv Distribution 



AT. ..... . T - , of the Virns. 



the injection 01 material irom the blood at the 

 beginning of the infection and by injection of 



