A short history of tissue fractionation.

The period immediately following the end of World War II will be remembered in the history of cell biology as that of the great breakthrough . As with many scientific advances, new tools, not newthoughts, rendered possible the massive invasion of the subcellular world that was launched at that time . The availability of the electron microscope, and the development of procedures allowing the examination of biological samples with this instrument, made the cell accessible to detailed mor- phological exploration . At the same time, the introduction of chromatography, of radioisotopes, and of spectrophotometers and other refined physical instruments, enhanced enormously the power and incisiveness of biochemical analysis. Revolutionary as these developments were, they would, nev- ertheless, not have sufficed in themselves for the construction of a true cell biology. What was needed, in addition, was a bridge between morphology and biochemistry, a junction be- tween the essentially parallel avenues opened by these two disciplines, a hybrid methodology whereby the visible and the measurable could be correlated into a unified picture of the living cell .