June 17, 1918 Effects of Chemicals on Virus of Mosaic Disease 635 



instances. Solutions prepared and used for inoculation seven days later 

 gave the following results, 10 Connecticut Broadleaf plants being used 

 in each test: 



Virus in 20 per cent glycerin strength 7 plants mosaic. 



Virus in 50 per cent glycerin strength 5 plants mosaic. 



Virus in 72 per cent glycerin strength 4 plants mosaic. 



Virus in 80 per cent glycerin strength 7 plants mosaic. 



Virus in 90 per cent glycerin strength 2 plants mosaic. 



Virus untreated 9 plants mosaic. 



Tap water only (control) All healthy. 



In another test solutions used nine days later gave the following results : 



Virus in 10 per cent glycerin strength 5 plants mosaic. 



Virus in 25 per cent glycerin strength 2 plants mosaic. 



Virus in 50 per cent glycerin strength 4 plants mosaic. 



Virus in 75 per cent glycerin strength All healthy. 



Virus in 90 per cent glycerin strength i plant mosaic. 



Virus untreated 8 plants mosaic. 



Tap water only (control) All healthy. 



In the higher concentrations of glycerin — that is, 50, 70, 80, and 90 

 per cent — the virus may show very weak infectious properties for a long 

 time. In some tests the virus showed very weak infectious properties 

 in 80 and 90 per cent strength glycerin after 35 days' treatment. In 

 other tests, made with different lots of virus, these strengths appeared to 

 kill the infective principle of the virus in much shorter periods. 



Koning's ^ experiments indicate that, after long periods of treatment, 

 glycerin destroyed the virus. In one experiment fresh, finely cut portions 

 of mosaic-diseased leaves, which were allowed to stand in glycerin all 

 winter, lost their infectivity. 



Heintzel ^ states that glycerin did not aflfect the infectivity of the 

 virus. His experiments, however, can not be considered final, as he 

 added only a few drops of glycerin to the fresh sap. This author does not 

 state how much sap was used, nor give the time of the treatment. His 

 glycerin solutions appeared to be very dilute, and it would appear that 

 they were used for inoculation at once. As a result, glycerin in his tests 

 did not noticeably affect the infectivity of the virus. 



The virus of the mosaic disease of tobacco when mixed v/ith talc, 

 kaolin, or soil frequently loses its infectious properties more quickly 

 than when the virus is merely bottled without the addition of any preserv- 

 ative. In one experiment 25 c. c. of virus were added to about equal 

 volumes of soil, of talc, and of kaolin. After the virus had been added 

 and mixed thoroughly, each lot of material was in the condition of a 

 stifif paste. Forty-three days later each lot of material was thoroughly 

 extracted with 70 c. c. of distilled water, and the solutions were inocu- 

 lated into lots of 10 plants each. The kaohn and the talc preparations 



» KoNiNG, C. J. OP. at. 2 Hbintzei,, G. E. op. ai. 



