Too late for the midwife toad - stress, variability and Hsp90

In the 1940s and 1950s, Waddington put forward his theories of canalization and genetic assimilation. These provided a genetic basis to account for th e inheritance of some apparently 'acquired' characters. Rutherford and Lind quist have now provided a molecular framework for these theories. Their res ults are also relevant to observations from the 1950s concerning homozygosi ty and variability, with a bearing on current views concerning the use of i nbred strains.