A demonstration of the nature of polyhedra using alkaline solutions.

The composition of the polyhedral bodies formed within the tissues of insects infected by certain viruses has been the subject of many studies. Glaser and Chapman (1916) believed that polyhedral bodies were composed of an inner dense substance and a lighter peripheral substance. Dikasova (1942) concluded that the polyhedron was an aggregation of ovoid particles but did not state whether or not she believed these to be the virus particles. She also considered this aggregation of particles to be confined within a "lipoid-protein membrane." Bergold (1947) refers to findings of Brill and Kratky to the effect that 82 per cent of the weight of the polyhedron is noninfectious protein and another 5 per cent is the virus. In a communication to Steinhaus (1949), Bergold has stated that about 95 per cent of the polyhedron consists of a noninfectious nucleoprotein and that the remaining 5 per cent is infectious virus. The virus particles of some of the polyhedral viruses have been shown to be rod-shaped particles that may occur in bundles of several rods per bundle (Bergold, 1947; Steinhaus, 1949). That polyhedra will dissolve in a weak alkali has been well established. Glaser and Chapman noted this characteristic in 1916. Bergold purified the virus of the silkworm and certain other polyhedroses by dissolving the polyhedral bodies in dilute sodium carbonate. Similar methods have been used successfully in the Laboratory of Insect Pathology, University of California, in studying the polyhedroses of the alfalfa caterpillar and other insects.