Text-book of comparative anatomy . MPARATIVE ANATOMY CHAP. body, which till now has been tolerably round, begins to flatten ; the surfacein which the mouth lies can as the ventral surface be distinguished from the dorsalsurface under which lie the eyes and brain. The mesoderm cells everywherespread out between the intestine and the body epithelium, and form a continuousmass, which is thicker at the ventral side. Those layers of mesoderm which lieclose under the epithelium yield the dermal musculature ; the deeper mesodermcells yield the body parenchyma, and most probably also the germ-preparin
Text-book of comparative anatomy . MPARATIVE ANATOMY CHAP. body, which till now has been tolerably round, begins to flatten ; the surfacein which the mouth lies can as the ventral surface be distinguished from the dorsalsurface under which lie the eyes and brain. The mesoderm cells everywherespread out between the intestine and the body epithelium, and form a continuousmass, which is thicker at the ventral side. Those layers of mesoderm which lieclose under the epithelium yield the dermal musculature ; the deeper mesodermcells yield the body parenchyma, and most probably also the germ-preparing organsof the genital apparatus. In a series of Polydada whose embryos leave the egg shell very early as free-swimming Miillers larvae (Fig. 118), a ring of strong and long cilia which encirclesthe body arises directly in front of the mouth; this is the so-called preoralciliated ring, running out round 4 or 8 processes of the body, one of which liesimmediately before the mouth and one in the middle line of the back, while the
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
