Continuous observations of cleavage amitosis in dedifferentiating living cells of carrot were made in vitro. The cells observed were taken from root callus. They were first cultured to survive and then began to divide continuously, so that the whole process of cell division in the living body could be observed under phase contrast microscope. According to the cytological characteristics, the whole division process could be divided into four phases—prophase, metaphase, anaphase and telophase. Statistics of time necessary for each phase was made. In the present paper, the cytological characteristics of such amitosis as well as the significance of such amitosis in accelerating the course of division are discussed. Continuous observations of cleavage amitosis in dedifferentiating living cells of carrot were made in vitro. The cells observed were taken from root callus. They were first cultured to survive and then began to divide continuously, so that the whole process of cell division in the living body According to the cytological characteristics, the whole division process could be divided into four phases-prophase, metaphase, anaphase and telophase. Statistics of time necessary for each phase was made. In the present paper, the cytological characteristics of such amitosis as well as the significance of such amitosis in accelerating the course of division are discussed.