An envelope addressed to Crick at the Cavendish Laboratory (post-marked 18 December, 1954) containing many small 'squares' of paper with the abbreviated name of an amino acid written on each.
The envelope has written on it in pencil:
"40A
46 subunits
14 ext RNA chain"
The amino acid abbreviations (some unconventional) written on the 'squares' are as follows (full name of the amino acid and the number of 'squares' present given in brackets) :
Ala (Alanine - 6 squares)
Arg (Arginine - 4 squares)
Asp (Aspartic acid - 1 square)
Asp N (Asparagine - 3 squares)
Cys (Cysteine - 6 squares)
Glu (Glutamic acid - 7 squares)
Glu N (Glutamine - 4 squares)
Gly (Glycine - 6 squares)
His (Histidine - 3 squares)
Pro (Proline - 5 squares)
Isol (Isoleucine - 1 square)
Leu (Leucine - 8 squares)
Lys (Lysine - 5 squares)
Met (Methionine - 1 square)
Phe (Phenylalanine - 6 squares)
Ser (Serine - 5 squares)
Thr (Threonine - 1 square)
TRY (Tryptophan - 1 square)
Tyr (Tyrosine - 6 squares)
Val (Valine - 8 squares)
For a comparison between "Gamow's most abundant twenty" amino acids and "Crick and Watson's 'magic twenty'" (with which the above list concurs), see the table in Judson, Eighth Day of Creation (1996), p. 259.