OCTOBEE 10, 1913] 



SCIENCE 



505 



bodies belong. It is obvious tbat tbe cultural 

 conditions are those that apply more particu- 

 larly to the bacteria. 



On the other hand, the microorganism is 

 associated with the production of an acute 

 disease in which suppuration does not form 

 a prominent part. No special attention at the 

 present time has been given to the solution 

 of the question as to whether the microorgan- 

 ism actually belongs to the bacteria or to the 

 protozoa. In the manner of evolution of the 

 symptoms, and in the appearance of the le- 

 sions, the experimental disease caused by the 

 inoculation of the cultures resembles that 

 produced by the virus of poliomyelitis as 

 ordinarily employed. The central nervous 

 organs of monkeys infected with the cultures 

 bear preservation and glycerinization as do 

 the infected human tissues, or the monkey 

 tissues infected directly from human tissues. 

 Cultures to which glycerin is directly added 

 survive in the refrigerator at least eight days. 



The microorganism passes through Berke- 

 feld filters and the filtrates yield upon reculti- 

 vation the particular microorganism con- 

 tained within the filtered culture. Moreover, 

 Berkefeld filtrates prepared from the nervous 

 tissues of infected human beings and mon- 

 keys yield also in culture the identical micro- 

 organism. 



By employing a suitable staining method 

 the microorganism has been detected in film 

 preparations and sections prepared from hu- 

 man nervous tissues, and from the corre- 

 sponding tissues of monkeys inoculated with 

 the usual virus or with cultures or filtrates 

 prepared from monkeys previously injected 

 with cultures. From all the infected mater- 

 ials mentioned, irrespective of the manner of 

 their origin, the microorganism has been re- 

 covered in cultures. As would be expected it 

 is more uniformly recoverable from the orig- 

 inal nervous tissues than from filtrates, and 

 doubtless for the reason that in the former 

 it exists in greater abundance. 



To obtain the initial culture is difficult, 

 and this irrespective of whether the tissues 

 submitted to cultivation have come immedi- 

 ately from man or from monkeys previously 



inoculated with the ordinary virus or even 

 with the cultures. Once the microorganism 

 adapts itself to a parasitic state it is de- 

 veloped with greater difficulty under sapro- 

 phytic conditions. Whenever the nervous 

 tissues have been shown to be infectious, the 

 microorganism has been recoverable, not- 

 withstanding long preservation and glycerina- 

 tion. In other words, infectivity of the ner- 

 vous organs and the presence of the micro- 

 organism exist together. It has indeed hap- 

 pened that a specimen of infected nervous 

 tissue has at the first attempt not yielded the 

 initial growth, although it has yielded it 

 upon the second attempt. Persistence will 

 usually lead to a successful cultivation, pro- 

 vided no technical fault is committed. An 

 important factor in the technique of cultiva- 

 tion is the sample of ascitic fluid. Not all 

 samples are suitable, and a preliminary test 

 is necessary, using for the purpose a growing 

 culture, in selecting samples for culture pur- 

 poses. Once a suitable ascitic fluid is ob- 

 tained it should be carefully husbanded in 

 the refrigerator. Even with this precaution 

 failure may still occur. In such an instance 

 repetition, using the same materials but in 

 two series, one of which is prepared for en- 

 closure in the anaerobic jar, while the other 

 is allowed to remain outside, may yield the 

 desired result; or the result may come on a 

 second trial that appears to be an exact repe- 

 tition of the first. 



Only the exceptional cultures possess the 

 degree of pathogenicity sufficient to cause 

 specific infection, and the production of ex- 

 perimental poliomyelitis. A pathogenic 

 strain may be eilective at different and even 

 remote generations, and a non-pathogenic 

 strain may lack pathogenicity even in the 

 second generation. This important fact indi- 

 cates strongly that the pathogenic effect is 

 not due to mere mechanical carrying over into 

 the cultures of an invisible parasite or virus 

 with which the cultivated microorganism is 

 accidentally associated. If such accidental 

 association were the cause of the experi- 

 mental disease produced by the cultures in 

 monkeys, it would display itself preferably in 



