In vitro cell transformation of human embryo cells could be induced by the DNA purified from SV 40. The result shows clearly that cell transforms a part of viral DNA into the genome. In addition, for the purpose of clarifying th~ biological differences between the normal and transformants the alteration of cell membraneous structures of transformants (hamster and mouse fibroblasts) were observed from mechanism
of phagocytosis. The iron colloid particles are taken up by normal diploid fibroblasts but not by the human and hamster transformants. This fact suggests a differ~nce in the molecular arrangement of the cell membranes
between the normal and transformants. In the presence of histones, however, the transformants phagocytize the colloid particles very actively. The results show that cell membranes of transformants are altered in the
molecular structure r~sponsible for the surface charge. In addition, there is no remarkable quantative differences of sialic acids on the cell surfaces
of non-malignant and malignant transformants so that phagocytic activity might be correlated to the alteration of molecular composition of cell membrane itself rather than of cell surfaces, i. e, sialic acids.</p
