Search

The nuclear polyhedral bodies fromMalacosoma neustria are enclosed within a membrane. The diameter of the nuclear polyhedra varies from 0.9 to 2.8 μ with an average of 1.8 μ. In the nuclear polyhedra the rod-like virus particles occur both singly and in bundles. The single virus rods are enclosed within two membranes, namely the intimate membrane and the developmental membrane. The virus rods which occur in bundles have an intimate membrane just like the single virus rods, whereas the developmental membrane encloses the whole bundle. The virus rods are closely packed by the intimate membrane and between the intimate and the developmental membrane is a space. The diameter of the virus rods without membranes, determined from sectioned polyhedra, is about 25 mμ and the length 250 mμ.

The fine structure of haustoria isolated from cucumber leaves infected with powdery mildew (Sphaerotheca fuliginea) was studied. Electron microscopy showed a haustorial body of 5–7 μ which contains many mitochondria and is surrounded by an electron lucent sheath of up to 4 μ in thickness. The sheath is limited by a heavily invaginated membrane of about 0.03 μ. The central body is connected with the sheath membrane by fingerlike convoluting protrusions.