The Structure of Coliphages

Abstract

The detailed morphology of several new coliphages is compared with that of the more familiar types; the resulting information is considered for its taxonomic value. Some were examined at molecular level and new information on the tail structure of the "T even" phages is described. It is shown that the so-called tail fibres are, in fact, the remains of a network which surrounds the extended sheath. From this information it is possible to propose the changes in molecular packing accompanying sheath contraction. A new phage with an octahedral head and contractile tail is described. It is also shown that phage T3 almost certainly has an octahedral head. Electron micrographs of oR (aoX 174 type phage) show that it consists of two parts: an icosahedral protein shell, and morphological subunits attached to each apex.