The evolution of man: a popular exposition of the principal points of human ontogeny and phylogene . Figs. 180, 181.—Haliphysema primordiale, an extant 180. External view of the whole spindle-shaped animal (attached by-its foot to seaweed). Fig. 181. Longitudinal section of the same. Theprimitive intestine (d) opens at its npper end in the primitive month {m).Between the whip-cells (g) lie amoeboid eggs (e). The skin-layer (h) belowis encrusted with grains of sand, above with sponge-spicnles. opening at the top is the mouth-opening (Fig. 181, m).The two cell-strata forming t
The evolution of man: a popular exposition of the principal points of human ontogeny and phylogene . Figs. 180, 181.—Haliphysema primordiale, an extant 180. External view of the whole spindle-shaped animal (attached by-its foot to seaweed). Fig. 181. Longitudinal section of the same. Theprimitive intestine (d) opens at its npper end in the primitive month {m).Between the whip-cells (g) lie amoeboid eggs (e). The skin-layer (h) belowis encrusted with grains of sand, above with sponge-spicnles. opening at the top is the mouth-opening (Fig. 181, m).The two cell-strata forming the wall of the pouch are the 6S THE EVOLUTION OF MAN. two primary germ-layers. These most simple Plant-Animalsdiffer from the gastrula principally in the fact that theformer are attached by one end (that opposite to the mouth-opening) to the bottom of the sea, while the latter arefree. Moreover, the cells of the skin-layer are coalescent andhave included many foreign bodies, such as sponge-spicules,sand-grains, etc., which serve to support the body-wall(Fig. 180). The intestinal layer, on the
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Keywords: ., bookcentury1800, booksubjectembryologyhu, booksubjecthumanbeings
