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 the inheritance of some apparently 'acquired' characters. Rutherford and Lindquist have now provided a molecular framework for these theories. Their results are also relevant to observations from the 1950s concerning homozygosity and variability, with a bearing on current views concerning the use of inbred strains.