Abstract: Immediately after its fertilization the ovum of tortoise underwent stages of both segmentation and blastula in the uterine tube of the female.Following the phases of its greatest conspicuousness in young embryos the mesoblastic sac rapidly becomes both relatively and actually smaller.The extraembryonic membranes of the tortoise are four in number,the yolk-sac,the amnion,the serosa,and the allantois.The yolk-sac is the first of these to make its appearance.During the later stage of development,the allantois pushes out of the body of the embryo into the extra embryonic coelem and extends into the sero-amniotic cavity and finally encompasses the embryo and the yolk-sac.When an egg has been laid,development ceases unless the temperature of the egg is kept nearly up to the normal incubative temperature.Moderate cooling of the egg does not,however,result in the death of the embryo.In incubating eggs artificially,the incubators or artificial hotbed are usually regulated for a heat of 33±1 to 35±1℃ and kept up to the relative humidity of 80-84%.Under these conditions the tortoise is ready for hatching on the forty-five to forty-eight days.It is twenty to twenty-five days Less than the period needed for natural incubation.It is of great importance in raising survival rate of fertilized eggs and of equal significance for extending growth period of young tortoise to yearling.