Abstract
When particles of tobacco rattle virus (TRV) were progressively degraded by alkali, detergent or urea a number of particles of specific lengths were produced. Some of the breakdown products had lengths similar to those of the naturally occurring short rods characteristic of various isolates of TRV. Loss of infectivity was associated with increasing heterogeneity of sedimentation of the long TRV particles during density gradient centrifugation. Cleavage of different strains of TRV produced relatively few fragments from 1800 to 1900 Å resembling the naturally occurring shorter rods.