PLANT VIRUS ASSAY 



23 



2 I 



Log. Concentration gms. per liter 



Fig. 1. Data from 4 experiments by Kleczkowski on relationship between 

 virus concentration in inoculum and numbers of local lesions produced on 

 inoculated test plants. Plotted as log numbers of lesions (y) over estimated 

 maximum number of lesions (A^) produced by inocula assimied to have con- 

 stant physical characteristics. Points above the value log y/N=0 are inter- 

 preted to indicate a uniform proportional increase of lesions in all 4 experi- 

 ments. This is due to alteration in the physical properties of the inocula 

 produced by increasing quantities of virus over 0.1 gm. per litre. Curves 

 below the value y/N=0 for experiments 10, 13, and 14 were fitted accord- 

 ing to equations given in the text; the curve for experiment ig was not fitted 

 because of the variability of the data, but was given approximately the form 

 produced by a lesser degree of aggregation than 14. 



