The transmission of plant viruses by aphides

Abstract
1. Experiments are described on the transmission of mottle and vein-distorting viruses by aphides.2. A quantitative analysis is made of Watson's experiments on the aphis transmission of persistent and non-persistent viruses. The principal features of the experimental results can be explained in terms of different rates of inactivation of the virus in the insect.3. It is shown that these considerations explain why non-persistent viruses are more commonly sap-transmissible than persistent viruses.