Shape of Tobacco Mosaic Virus Particles in Solution

Abstract

THE ease with which solutions of the tobacco mosaic virus protein show a strong double refraction of flow suggests that the particles present are extremely elongated. It was reported by Bawden and Pirie1, who described the general properties of the virus. Bernal and Fankuchen2 studied the virus by means of X-rays, and pointed out that the long tapering structures which have been called crystals are more strictly paracrystals. There is regularity of arrangement in the cross-section, but not in the direction of the long axis. The paracrystals are believed to consist of long, rigid rods, packed closely side by side, but without order, in the direction of their length. These rods are supposed to exist free in solutions of the virus. By their orientation they give rise to the double refraction of flow.