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Day of the chalone
Most participants in the First International Chalone Conference appear ready to agree that there is such a thing as a chalone.But agreeing on a precise definition is something else again.The chalone, forms of which researchers still are seeking to pinpoint, apparently can inhibit cell division in living things and in the test tube. (One hypothesis is that this is a feedback mechanism of synthesis by mature cells to inhibit reproduction of immature cells at some point.)This seems to be a tissue-specific phenomenon, but apparently is not species-specific. It also appears to be generally agreed that the chalone, once synthesized by the mature cell, circulates in the blood (as well, perhaps, as other places) and does not permanently damage the cells on which it acts. Thus, the action is reversible.But beyond these properties, which have been known for at least four years, there