Electron Microscopic Counting of Elementary Bodies of the Virus of Meningo-Pneumonitis

Abstract

The counting method of Backus and Williams is described as applied to enumeration of the elementary bodies of the agent of meningo-pneumonitis. The necessity of counting particles of biologic origin but of “indeterminate” nature, present in elementary body suspensions, is described. Homogeneity of the distribution of latex spheres, elementary bodies and other particles of biologic origin appears to be present in the results of this counting technic, at several concentrations of the elementary body suspensions. The estimates of concentration of biologic particles generally, or of elementary bodies alone, have a minimum standard deviation of about 3% resulting from instrumental limitations in determining diameter of latex spheres. Values for concentrations of elementary bodies, and of biologic particles generally, are reported, in which one standard deviation represents approximately 5% of the figure for concentration.