THE EFFECT OF WASHING FROZEN MOSAIC LEAVES ON THE LENGTH OF TOBACCO MOSAIC VIRUS PARTICLES

Considerable contradictory evidence has been presented regarding the length of tobacco mosaic virus particles. Stanley and Anderson (1941), Rawlins, Roberts, and Utech (1946), and numerous other workers have shown that the virus obtained from expressed juice is usually composed of at least two distinct groups of particles. Roughly 70 per cent of the particles are in a group composed of particles between 225 and 450 m, long; this group has its mode somewhere around 300 m,&. The different values that have been obtained for this mode apparently depend on the methods that have been used in calibrating the micro-scopes. Most of the remainder of the particles are usually in a group of short particles less than 225 m,u long. In some cases a group of long particles longer than 450 m, & may be present. There is considerable evidence that these long particles result from aggregation of shorter particles. Bawden and Pirie (1945) and Crook and Sheffield (1946) presented evidence indicating that frozen infected tissues washed thoroughly with distilled water to remove salts yielded shorter particles than did unwashed frozen tissues. The