PLASSOMYXINEAE 109 



diatoms, the Chamberland is of porcelain, and the ' F ' is its 

 ordinary form. The filter must be new and be sterilised 

 before use. Filtration must be done soon after the liquid 

 to be filtered is prepared: Dr. Perkins tells me that with 

 time typhoid bacilli will grow through any filter. As a 

 control the water used for dilution may contain motile 

 bacteria. 



Historical Notes of Virus Filtration. The virus of foot 

 and mouth disease was the first to be filtered by Loeffler 

 and Frosch. Borrel found no cell-inclusions in this disease, 

 but areas of leucocytic invasion between the layers of 

 epidermal cells. 



Pleuropneumonia of cattle was filtered by Nocard and 

 Roux in 1898. This virus in rabbit's serum requires to be 

 diluted with 20 to 30 vols. of water before it can pass into a 

 collodion sac. 



Saponin does not affect bacteria, but it has been found 

 to kill microhenads except those of trachoma and cyano- 

 lophia gallinarum. Saponin is a nitrogen-free gluco- 

 side obtained from the horse-chestnut and many other 

 plants. 



Remlinger, who first showed that rabies virus can be 

 filtered, began his account : " It is classic to say that the 

 virus of rabies is stopped by filters." In the same way we 

 can say that it is " classic " to say that the virus of syphilis 

 is not filtrable. Now, from the presence of large plasson 

 bodies in this disease, I am sure that, if taken at the right 



