June 17. 1918 Effects of Ckemtcals on Virus of Mosaic Disease 627 



between the carbolic-acid solution and the carbolic-acid and salt solutions 

 in their effects upon the infective principle of the virus. 



Phenoco has been shown by Anderson and McClintic ^ to have a phenol 

 coefficient of 15 when tested upon the typhoid bacillus without organic 

 matter, and a coefficient of 9.86 when tested in the presence of organic 

 matter. Although this preparation appears to be a much more power- 

 ful germicide than carbolic acid when tested upon the typhoid bacillus, 

 no especially marked differences are shown when tested upon the infec- 

 tive principle of the mosaic disease of tobacco. 



The virus of the mosaic disease very quickly loses its power to infect 

 healthy plants when preserved in the higher strengths of ethyl alcohol. 

 In the following tests the expressed sap was filtered through filter paper 

 and mixed with different proportions, by volume, of absolute alcohol. 

 In the process of obtaining the different strengths, the virus at most was 

 diluted but a few times. This sHght dilution is without significance 

 since earUer experiments have shown that a dilution of i ,000 times with 

 water does not materially reduce the power to infect. Throughout 

 these tests the plants in each series were kept under observation for a 

 considerable period after the first appearance of symptoms of the disease. 

 There was no noticeable difference, however, in the inoculation period 

 at any time. At present there is no means of knowing whether or not 

 it is possible for the virus of the mosaic disease to retain a certain degree 

 of viabiUty after the power to infect healthy plants has been lost. The 

 results of any germicidal tests are influenced by the concentration of 

 the germicide and the time during which it acts. It is evident that both 

 factors have had more or less influence upon the results obtained for 

 the alcoholic tests presented here. The effect of different concentra- 

 tions of alcohol upon the infectivity of the virus is given in Table II. 



Table II. — Effect of various concentrations of alcohol upon the infectivity of the virus 



of the mosaic disease 



VIRUS A (preserved in 25-80 PER CENT ALCOHOL ON FEBRUARY 27, I914) 



1 Anderson, J. F., and McClintic. T. B. method of standardizing disinfectants with and with- 

 out ORGANIC MATTER. In Pub. Health and Mar. Hosp. Serv. U. S. Hyg. Lab. Bui. 82, p. 1-34. 1912. 



