Article révisé par les pairs
Résumé : The existence of labile bonds participating in the macromolecular structure and the biological activity of nucleic acids is suggested. Mild conditions (pH 3·2 or heating to 38°C) induce an increase in molecular extinction which might be due to the destruction of such bonds. The critical temperatures are of the same order as those inducing thermal shock responsible for inhibition of embryonic morphogenesis. © 1951 Birkhäuser Verlag.