910 DISEASES CAUSED BY FILTRABLE VIRUS 



pieces of tissue. This increased until the tenth day, when sedimenta- 

 tion began. Microscopical examination by Giemsa's method of stain- 

 ing revealed small globoid bodies measuring from 0.15 to 0.3 micron in 

 diameter, arranged in pairs, short chains, and masses. Similar bodies 

 could later be found in poliomyelitis tissues. Cultures were obtained 

 from glycerinated as well as from fresh virus and from the filtered as 

 well as the unfiltered material. Typical lesions and death have been 

 produced in monkeys with such cultures in a few cases. 



We have few data which throw light upon possible immunity to the 

 disease. Repeated attacks of the disease in the same human being 

 have not been noted; but this, as Flexner and Lewis point out, may 

 be due to the fact that the epidemics are rare, and individuals once 

 afflicted have passed beyond the susceptible age by the time of the sec- 

 ond epidemic. As a matter of fact, however, these workers have not 

 succeeded in reinfecting monkeys that had recovered. 



In chickens a disease has been observed similar in many ways to 

 poliomyelitis, but further study has shown this to be a polyneuritis. 



Of other animals besides monkeys, rabbits only have been success- 

 fully inoculated with this disease. Transmission to these animals was 

 first reported by Kraus and Meinicke 11 and later by Lentz and Hunte- 

 muller. 12 Marks 13 has studied the disease in rabbits thoroughly, and 

 concludes that there is no doubt that the virus can be cultivated 

 through a limited number of generations in rabbits. He was able to 

 transmit to monkeys from rabbit material. The disease, however, does 

 not resemble that of man or monkeys clinically and no definite lesions 

 of the central nervous system are present. The rabbits seem perfectly 

 well for six or seven days, when rapid weakness and death in con- 

 vulsions occur. 



Animals which have been unsuccessfully injected, even with living 

 virus, do not develop immunity. However, animals that have been 

 successfully inoculated and recovered are, like human beings, thereafter 

 immune. Levaditi and Landsteiner, Roemer and Joseph, and Flexner 

 and Lewis have shown that the serum of recovered monkeys will pro- 

 tect normal animals from fatal doses of the virus. That the same pro- 

 tective power for monkeys has been shown in the serum of human 

 recovered cases, is shown by the same authors and by Anderson and 

 Frost and consequently the intraspinous injection of the serum of 



11 Kraus and Meinicke, Deut. med. Woch., xxxv, 1909. 



12 Lentz und Huntemiiller, Zeitschr. f. Hyg., Ixvi, 1910. 

 "Marks, Jour, of Exp. Med., xiv, 1911. 



