June 17, 1918 Effects of Chemicols on Virus of Mosaic Disease 633 



The virus does not appear to lose instantly its power to produce infection. 

 In a few minutes, however, the virus appears to lose much of its original 

 power to produce infection. 



Heintzel ^ treated fresh, mosaic-diseased leaves with 50 per cent alcohol 

 and used the filtered extract for inoculations. This extract produced the 

 disease in healthy plants. In this test it is evident that the water con- 

 tained in the fresh leaves would reduce the alcohol below the 50 per cent 

 Strength used. It also appears that the extract was used at once for 

 inoculation. It would be expected that these extracts would produce 

 infection, since the writer's experiments indicate that the virus may re- 

 tain its infectivity for a number of days in alcoholic solutions below a 50 

 per cent strength. Heintzel also treated fresh, unfiltered sap with 

 strong alcohol and filtered out and dried the precipitate. This also 

 produced infection in healthy plants. Since no exact data are given as 

 to the time of treatment and the amount of sap and alcohol used, one 

 can not interpret these results without further details of the methods used. 



Koning ^ treated the sap of mosaic-diseased plants with alcohol several 

 times, pouring off the clear, supernatant solution and renewing the 

 alcohol each time. The precipitate which was finally used for inocula- 

 tion had lost its infectious properties, as would be expected from the 

 writer's results with the higher alcoholic concentrations. 



Chloral hydrate in concentrations of i in 10, i in 20, i in 200, i in 500, 

 I in 800, and i in i ,000 parts of virus solution did not appreciably affect 

 the infectivity of the virus after 17 days' treatment. 



Tannic acid in concentrations of i in 20 and i in 50 parts of virus solu- 

 tion killed the infectivity of the virus, as these were no longer infectious 

 after 5 days' treatment. In concentrations of i in 100 and i in 200 

 the virus had almost entirely lost its infective properties in the same 

 period. Lecithin had no appreciable effect upon the infectivity of the 

 virus after 5 days in i, 2, 5, 10, and 20 per cent strengths. 



Benzoate of soda in concentrations of i in 25, i in 50, and i in 500 

 parts of virus solution had apparently not changed the infectivity of the 

 virus after 48 days' treatment. In concentrations of i in 100 and i in 

 200 parts of virus solution the virus had not entirely lost its infectivity 

 after loi days' treatment, although it had been greatly weakened. 



Quinine bisulphate in concentrations of i in 25, i in 500, and i in 1,000 

 parts of virus solution did not noticeably affect the infectivity of the virus 

 after 19 days' treatment. 



Sodium taurocholate in i and 2 per cent strengths did not destroy the 

 infectivity of the virus after 5 days' treatment. In 5 and 10 per cent 

 strengths the virus had completely lost its infectivity in the same period. 



> HemTZEl,, K. G. E. CONTAGIOSB PFLANZEiSrKRANKHBITEN OHNE MICROBEN, UKTER BESONDERER 



BBRi'CKSiCHTiGUNG DER MOSAiKKRANKHEiT DER TABAKSBLATTER. 46 P-, pl- Erlangen, 1900. (Inaugural 

 Dissertation. ) 



2 Koning, C. J. der tabak. studien uber seine kux,tur und biologie. 86 p., 15 fig. Amster- 

 dam, Leipzig, 1900. 



