Renewing their collaboration during Watson's return to the Cavendish laboratory in the fall of 1955, Watson and Crick
in this article laid out a theory for explaining why all plant viruses whose structure had been studied up to that time were
very similar in shape, either rod-shaped (cylindrical) or spherical. In developing their theory they once again benefited
from their complementary expertise, namely Crick's extensive knowledge of X-ray crystallography and Watson's previous
studies with tobacco mosaic virus and ribonucleic acid. They proposed that plant viruses consistently took one of two shapes
because the two chemical components of which they were made up, ribonucleic acid surrounded by a large number of identical
protein subunits, were assembled according to a general plan that was determined by "symmetry elements," structural
requirements imposed by the shape of each protein subunit and by the angles of the bonds they formed with the ribonucleic
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1956-03-10 (March 10, 1956)
Watson, James D.
Periodical: Crick, Francis, and James D. Watson. "Structure of Small Viruses." Nature 177, 4506 (10 March 1956): 473-475. Article.
Nature Publishing Group
Reproduced with permission of the Nature Publishing Group.