Nuclear incorporation of P32 as demonstrated by autoradiographs

Roots of Vicia faba seedlings were grown for periods of 2 to 48 hours in solutions of P³² in the form of NaH₂PO₄. Stripping-film autoradiographs were made of squashes and sectioned material from the meristem and from proximal segments where cell divison is rare. It is concluded (a) that P³² enters into organically bound form (probably desoxyribonucleic acid) in the nucleus during the resting stage, but not during the actual division of the cell; (b) that P³² is incorporated in this form only in nuclei which are preparing for division; (c) that P³² in this form is inherited by the daughter cells.