652 



Journal of Agricultural Research 



Vol. VI, No. 17 



Table III. — Infectivity of mosaic virus after filtering constant quantities of different 

 concentrations through weighed amounts of powdered talc, U. S. P. 



" Paper only. 



b Not timed. 



These results indicate that the infective agents producing" the mosaic 

 disease are readily arrested by means of the talc filter. Likewise, it is 

 shown that filtered solutions giving intense peroxidase reactions are no 

 longer infectious. 



PRECIPITATION OF THE VIRUS WITH ETHYL ALCOHOL 



Experiments have shown that the infective properties of the mosaic 

 disease are quickly destroyed by the higher strengths of ethyl alcohol. 

 Although a strength of 80 per cent appears to destroy the infective prop- 

 erties of the virus in half an hour, the peroxidase continues to give strong 

 reactions with guaiac and hydrogen peroxid. In various experiments 

 the enzyms have been precipitated in solutions of virus of sufficient 

 alcoholic strength to destroy its infective properties. The virus was first 

 passed through filter paper to remove all material in suspension. This 

 gave a clear, dark, wine-colored solution, which was then made up to 

 different alcoholic strengths with absolute alcohol. 



In the first test virus X 16 , giving intense peroxidase and catalase 

 reactions, was used. On November 1, 191 5, 200 c. c. of this virus were 

 made up to a 75 per cent alcoholic strength with absolute alcohol. On 

 November 2 the solution was filtered and the precipitate air dried to 

 remove the alcohol. On November 3 the residue remaining was taken 

 up with 50 c. c. of distilled water. Of the filtrate, 750 c. c. were then evap- 

 orated to dryness at room temperature, from November 2 to November 4. 

 This filtrate contained neither peroxidase nor catalase. After evapora- 

 tion, the amber-colored residue, which is readily soluble, was taken up 

 with distilled water. 



In a second test the highly infectious virus X 20 , giving intense peroxidase 

 reactions but no reaction for catalase, was used, and 400 c. c. of this virus 



