Book Reviews : Partition of Cell Particles and Macromolecules : distribution and fractionation of cells, viruses, microsomes, proteins, nucleic acids, and antigen-antibody complexes in aqueous polymer two-phase systems, by Per-Ake Albertsson, 231 pp. ALMQVIST & WIKSELL. Stockholm (JOHN WILEY & SONS, New York & London), 1961. £2 16s. 0d. [IQ/71]: