no 



THE PHYSICS OF VIRUSES 



shown in Fig. 4.8. The natviral h)<>arithm of the virus concentra- 

 tion, as determined by counting h)cal lesions on the appropriate 

 plants, is plotted against time, in minutes, for the four viruses 

 tobacco ringspot, tobacco mosaic, tobacco necrosis, and alfalfa 



20 30 40 



Time (Minutes) 



50 



60 



70 



Fig. 4.3. Inactivation of four plant viruses as measured by Price (1940). 

 The logarithm of the concentration is plotted versus time, and first-order 

 kinetics are obeyed. 



mosaic at the temperatures indicated. In the case of tobacco 

 mosaic virus, Thornberry, Valleau, and Johnson (1938) have 

 studied the thermal inactivation in the dried leaf of the host 

 plant, white burley tobacco, over a very wide temperature 

 range. 



The data on the dried virus just mentioned can be analyzed 

 according to the Eyring relation. The resulting values found 



