In a late stage of incubation the Ca content of the egg proper increased; that of the shell decreased. Thus the shell furnished some building material for the embryo. In the early stages of incubation the alkali metals, sulphates and chlorides were present in greater quantity in the egg white than in the yolk. On the 7th day of incubation the alkalis of the yolk suddenly increased and at the same time the chlorides and sulphates also increased; they decreased, however, in the egg white. The alkalis passed through the yolk sac into the yolk in mobile form. From the yolk they were taken up by the embryo.