304 PROCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE. 



As previously stated the presence of the virus in suspensions made from 

 spinal cord and its filterability was first positively demonstrated by Land- 

 steiner and Popper and soon after hy Flexnor and Lewis. The virus passed 

 readily through Pasteur-Chamberland, Berkefeld, and Pukall filters, al- 

 though the virulence is decreased after such treatment, as is noted by a longer 

 incubation period. In this connection it would be interesting to know if 

 the virus could be made to pass through collodium sacs. The rabic virus 

 which resembles the poliomyelitis virus in some respects can be filtered 

 through collodium. 



A temperature of 50° C. to 55° C. for one-half hour will destroy the virus, 

 whereas it will retain its virulence for several days at room temperature, 

 22° C. to 25° C. Freezing does not injure the virus but on the contrary it 

 seems that at a temperature of minus ten or minus fifteen degress Centigrade 

 the virulence is best pi'eserved, as it is retained for months under these 

 conditions. 



The virus of Poliomyelitis i. resistant to glycerin. Therefore, in order 

 to conserve its virulence it is advisa])le to keep it in 33% to 50% glycerin in 

 the ice-bo.x. In this condition it will survive for more than six months. 

 The virulence of the virus remains after drying over caustic sodium or po- 

 tassium for twenty or thirty days. It is destroyed by the ordinary disin- 

 fectants. 



Although Ihc clKiracteristics of the virus of Poliomyelitis were fairly well 

 worked out, they were not free from olijeclion until its presence was demon- 

 strated by microscopic and cultural metliods. Cultivation experiments were 

 undertaken by Flexnor and Lewis, and Levaditi. They noticed that when 

 scrum bouillon was inoculati'd with filtered virus and incubated at 37 ^°C'. for 

 fifteen days that a slight cloiuliness developed andtlu't if a small amount of 

 this cloudy lUiid was transferred to a similar medium cloudiness appeared 

 in these tubes. However, Romer by using the same medium eoidd not dup- 

 licate these results. The latter investigator also obtained negative results 

 by placing collodium sacs containing suspensions of the infecting material 

 in the intraperitoneal cavity of animals. New attempts were pursued by 

 Flexnor and Xoguclii and i)ositive results were obtained in 1913 by using 

 a medium similar to that used by Noguchi in cultivating the spirochaete 

 of syphilis. The medium used consists of ascitic fluid, sterile fresh tissue, 

 usually kidney of a rabbit, although brain tissue may also be used. Oxygen 

 must be excluded and is mechanically accomplished by paraffin oil. The 

 technique employed is as follows; about 15 cc of ascitic fluid and a piece of 

 sterile fresh kidney obtained from a rabbit is placed in a sterile tube. This 

 is inoculated with a i)hysiological salt emulsion of brain. The tubes are 

 incubated at 37° C. and are not disturbed for seven to twelve days. Tubes 

 revealing the presence of growth in a few days are discarded because of con- 

 tamination. A faint opalescence should, however, apj)ear just around the 

 tissue in about five days. Cultures were also obtained using a solid medium 

 which was prepared in a similar manner as abo\e plus 2% agar. The 



