Response to light-shade difference in anucleate and polynucleate specimens of Amoeba proteus.

The enucleated specimens of Amoeba proteus, the anucleate fragments, and the polynucleate individuals which all are capable of cortical contraction but not of locomotion, may be reactivated by the light-shade difference established across their body. Individual cells or fragments migrate toward the shade. The motory polarity and coordinated movement disappear immediately after cessation of the stimulus. The results are interpreted according to the earlier hypothesis that the necessary to maintain the motory polarity of amoebae. It is suggested that the anucleate and polynucleate specimens are incapable of coordinated movements when non-stimulated, because of a deficiency or an excess, respectively, of the regulatory relaxing factor secreted by the nucleus of Amoeba proteus.