blastocystis

This is converted into a gastrula, and this in turn into a blastocystis (or embryonic vesicle).

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

The visceral embryonic vesicle (blastocystis or gastrocystis) of a rabbit (the "blastula" or vesicula blastodermica of other writers), a outer envelope (ovolemma), b skin-layer or ectoderm, forming the entire wall of the yelk-vesicle, c groups of dark cells, representing the visceral layer or entoderm.

The Evolution of Man — Volume 1 Ernst Heinrich Philipp August Haeckel 1876

For these reasons it is very necessary to recognise the secondary embryonic vesicle in the mammal (gastrocystis or blastocystis) as a characteristic structure peculiar to this class, and distinguish it carefully from the primary blastula of the amphioxus and the invertebrates.

The Evolution of Man — Volume 1 Ernst Heinrich Philipp August Haeckel 1876

* (* The blastula of the lower animals must not be confused with the very different blastula of the mammal, which is properly called the gastrocystis or blastocystis.

The Evolution of Man — Volume 1 Ernst Heinrich Philipp August Haeckel 1876