Erratum
In the article "Australia antigen and the biology of hepatitis B" by B. S. Blumberg (1 July, p. 17) there are two errors which should be corrected. On page 20, in the section "Virology," paragraph 2, line 5, "millimeters" should be "nanometers" and later in the same paragraph "mm" should be "nm" (lines 11, 13, and 15). On page 23 in the section "Transmission by insects," paragraph 1, line 20, "Amex lectulorius" should read "Cimex lectularius."