Note 128 — Chapter VI · WHAT IS TAUGHT BY EMBRYOLOGY?
Reading edition
They state that the cells of the epiblast are the results of direct segmentation, whereas the cells of the other layers are formed at a subsequent period, and are only indirectly results of segmentation. But if the observations of Kowalewsky are exact, this is not the case with the hypoblast of the Amphioxus, which is from the first identical with the epiblast.