Cell Layer

B longitudinal section through the axis, g primitive-gut cavity, a primitive mouth-aperture, i inner cell-layer (entoderm, endoblast, gut-layer), e external cell-layer (outer germinal layer, ectoderm, ectoblast, or skin-layer). ❋ Ernst Heinrich Philipp August Haeckel (1876)

The outer covering is the simple cell-layer of the epidermis (E). ❋ Ernst Heinrich Philipp August Haeckel (1876)

Its functions are represented by the simple cell-layer of the ectoderm, which the lower Metazoa have inherited from the Gastraea ❋ Ernst Heinrich Philipp August Haeckel (1876)

As regards the remaining organs of the Amphioxus, we need only mention that the gonads or sexual glands are developed very late, immediately out of the inner cell-layer of the body-cavity. ❋ Ernst Heinrich Philipp August Haeckel (1876)

In these cases the simple cell-layer of the ectoderm is at once skin, locomotive apparatus, and nervous system. ❋ Ernst Heinrich Philipp August Haeckel (1876)

The episomites or dorsal coelom-pouches of the Acrania, Cyclostomes, and Selachii (Figure 1.161 h) first develop from their inner or median wall (from the cell-layer that lies directly on the skeletal plate ❋ Ernst Heinrich Philipp August Haeckel (1876)