||P.547 8th paragraph: "Composition of microbial cells. The analysis of the composition of microbial cells by Morowitz (1968, primary source) is given in Table I. The content of the various classes of macromolecules calculated from these data is given in Table 2." P.548 top paragraph: "The sum of the various macromolecules yields 97.3% (Table 2). It is known that the cells contain in addition about 1.5% of potassium and 0.2% of magnesium (Tempest, Dicks and Hunter, 1966). The phosphorus content of the cells (about 2.4%) exceeds that in phospholipid, RNA and DNA. Consequently [investigators] may conclude that the result of Table 2 which indicates that various macromolecules make up 97.3% of the total dry weight, is very satisfactory." This is good indication for percent of bacterial cell mass that is protein. However, the primary source is a book which does not list primary reference for the number. A better reference is needed.