The evolution of man: a popular exposition of the principal points of human ontogeny and phylogenyFrom the German of Ernst Haeckel . Ftgs. 180, 181.—Baliphysema primordiale, an extant 180. External view of the whole spindle-shaped animal (attached byil^s foot to seaweed). Fig. 181. Longitudinal section of the same. Theprimitive intestine (d) opens at its upper end in the primitive mouth (»).Between the whip-cells (g) lie amoeboid eggs (e). The skin-layer (h) belowis encrusted with grains of sand, above with sponge-spicules. opening at the top is the mouth-opening (Fig. 181,
The evolution of man: a popular exposition of the principal points of human ontogeny and phylogenyFrom the German of Ernst Haeckel . Ftgs. 180, 181.—Baliphysema primordiale, an extant 180. External view of the whole spindle-shaped animal (attached byil^s foot to seaweed). Fig. 181. Longitudinal section of the same. Theprimitive intestine (d) opens at its upper end in the primitive mouth (»).Between the whip-cells (g) lie amoeboid eggs (e). The skin-layer (h) belowis encrusted with grains of sand, above with sponge-spicules. opening at the top is the mouth-opening (Fig. 181, m).The two cell-strata forming the wall of the pouch are the 68 THE EV^OLUTION 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 oj)posite 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-graius, etc., which serve to support tlie body-wall(Fig. 180). The intestinal layer, on
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Keywords: ., bookcentury1800, booksubjectembryology, booksubjectembryologyhum
