Abstract
Optical diffraction studies indicated that the periodic lattice structure in electron micrographs of the capsids of two granulosis and two nuclear polyhedrosis viruses were indistinguishable. The capsid is composed of stacked rings spaced 4.5 nm apart.
Comparison of the intracellular forms of Bombyx mori nuclear polyhedrosis virus with negatively stained virus particles leads us to encourage the more general use of the term capsid instead of intimate membrane and the term virus membrane in place of developmental membrane. These terms are consistent with those currently used for most animal and plant viruses.