Abstract
By using a new method modifying Owen's one, number (one or two) of the Z-chromosome was mainly investigated in the primitive blood corpuscles sucked up from the vitelline vessels of the 6-8 days' chick embryos. The Z-chromosome showed its constant number and structure in one and the same embryo. From the embryological standpoint it is doubtless that the Z-chromosome constitution of the blood corpuscles under investigation will accord with that of the chick embryo itself.
