 | Princeton University. Department of Biology - Anatomy, Comparative - 1918 - 860 pages
...organs on one side, others on the other side, and correspondingly the snail shell coils in a clock-wise direction in one case, an anticlock-wise direction...found in the egg in the same relative positions and proportions as the ectoderm, endoderm, mesoderm, notochord and nervous system of the embryo. That the... | |
 | James McKeen Cattell - Electronic journals - 1919 - 670 pages
...unsegmented egg itself which is inversely symmetrical in sinistral as compared with dextral forms. by the activity of the cytoplasm indicates a definite...cytoplasm differs greatly in certain phyla, there being a ccelenterate type, an echinoderm type, a turbellarian-annelid-mollusk type, and a chordate type. The... | |
 | James McKeen Cattell - Electronic journals - 1920 - 642 pages
...unsegmented egg itself which is inversely symmetrical in sinistral as compared with dextral forms. by the activity of the cytoplasm indicates a definite...cytoplasm differs greatly in certain phyla, there being a coalenterate type, an echinoderm type, a turbellarian-annelid-mollusk type, and a chordate type. The... | |
 | National Academy of Sciences (U.S.) - Electronic journals - 1917 - 868 pages
...organs on one side, others on the other side, and correspondingly the snail shell coils in a clock-wise direction in one case, an anticlock-wise direction...found in the egg in the same relative positions and proportions as the ectoderm, endoderm, mesoderm, notochord and nervous system of the embryo. That the... | |
 | National Academy of Sciences (U.S.) - Electronic journals - 1917 - 810 pages
...organs on one side, others on the other side, and correspondingly the snail shell coils in a clock-wise direction in one case, an anticlock-wise direction...found in the egg in the same relative positions and proportions as the ectoderm, endoderm, mesoderm, notochord and nervous system of the embryo. That the... | |
 | James McKeen Cattell - Electronic journals - 1920 - 662 pages
...these reversals of cleavage could be followed cell by cell to the reversal of symmetry in the larva. Consequently the inverse symmetry of these snails...there being a coelenterate type, an echinoderm type, a turbellarian-annelid-mollusk type, and a chordate type. The type of egg organization foreshadows... | |
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inverse symmetry' of these snails may be traced back through the later and earlier cleavage stages to the unsegmented egg itself which is inversely symmetrical in sinistral as compared with dextral forms. (4) Types of Egg Organization. The polar differentiation... 