METHODS 691 



fatal case is ground up with sand and saline (the brain tissue 

 forming 5 per cent, of the whole). The product is centrifuged, 

 and the supernatant fluid, filtered through paper, is used for the 

 inoculation. Portions of the central nervous system may be 

 placed in glycerin when transmission to a laboratory is necessary. 

 In certain cases information might be obtained by inoculating 

 material from swabs of sterile wool allowed to remain in the 

 nasal passages, in order that the mucus may be absorbed. 

 Portions of tissue removed from the tonsils might also be useful ; 

 in each case the material may again be immersed in small 

 quantities of glycerin, or advantage may be taken of the fact 

 that the virus can survive exposure to 1 per cent, phenol for 

 several days. 



