The relation between normal and abnormal development of the embryo of the frog: V. As determined by the removal of the upper blastomeres of the frog's egg

The appearance of the embryo~) of the frog on the black hemisphere of the egg in certain forms of abnormal development led me to suspect that the material out of which the normal embryo is formed may be contained at first, in part, in the upper hemisphere, and becometransferred during the early development to the equatorial regions. In still later stages a… (More)