SONIC AND OSMOTIC EFFECTS ON VIRUSES 



175 



Infectivity was treated on bean i)lants at the two-leaf stage, and 

 10 repeats were taken for each determination. As in Oster's work, 

 the nature of the virus was subsequently studied in the electron 

 microscope. 



It was found that after '-200 sec exposure, the lesion counts were 

 down to 5% of the original. Newton concludes that the ultra- 

 sonic irradiation of aged (and hence aggregated) virus suspen- 



2000 4000 6000 



2000 4000 6000 



2000 4000 6000 



2000 4000 6000 



LENGTH IN A 



Fig. 7.2. Histograms of particle lengths of sonically treated TMV prepara- 

 tions, as measured by Oster. The appropriate infectivity is indicated and offers 

 strong presumption that the particle length of 2,800 A is the minimum effective, 



sions produced more infectivity, due to disi)ersion of aggrega- 

 tion. This is an initial effect at relatively low power levels. The 

 end-to-end aggregations become disaggregated into basic units 

 2,800 A long with an increase in infectivity. At high energy levels, 

 the 2, 800- A unit begins to fracture. First it goes at a constant 

 distance from the end of the rod. The fragmentation becomes 

 more and more random as the power increases, but it points to a 

 weakness in structure at one definite ])oint in the rod. This last 

 is not quite what Oster found. The two frequencies of sonic ac- 



