Gödel, Escher, Bach An Eternal Golden Braid by Douglas R. Hofstadter

Tail

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FIGURE 103. The morphogenetic path-
way of the T4 virus has three principal
branches leading independently to the for-
mation of heads, tails, and tailjibers, which
then combine to form complete virus parti-
cles. [From Hanawalt and Haynes, The
Chemical Basis of Life, p. 237.]

Head

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Tail fiber

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