. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DETERMINATION IN SABELLAKIA 225 To avoid possible effects of the lobe cytolysis on the differentiation of the larva, the lobe was, in fifteen cases, allowed to remain fused to the dividing cells only until the embryo began to show signs of move- ment, when it was removed. The contact is long enough so that the blue color of the dye diffuses from the lobe into adjacent cells. The larvae which develop from such cells are in no essential way altered by contact with the lobe (Fig. 6, G}. The presence of the polar lobe, fused to
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DETERMINATION IN SABELLAKIA 225 To avoid possible effects of the lobe cytolysis on the differentiation of the larva, the lobe was, in fifteen cases, allowed to remain fused to the dividing cells only until the embryo began to show signs of move- ment, when it was removed. The contact is long enough so that the blue color of the dye diffuses from the lobe into adjacent cells. The larvae which develop from such cells are in no essential way altered by contact with the lobe (Fig. 6, G}. The presence of the polar lobe, fused to the larva for five hours (when it is removed), or within the larva for eleven hours (at which time it is ejected), does not induce the formation of larval structures. Transplantation of Blastomeres to Whole Eggs Table II, B summarizes the types of transplants made to whole eggs, at the trefoil, two-cell, and four-cell stages. The transplants. FIG. 7. Differentiation of larvae after transplantation of blastomeres to whole eggs. A. E plus CD larva, 27 hours. B. E plus C larva, 24 hours. C. E plus I) larva, 79 hours. D. E plus AB larva, 40 hours. are in some cases stained with Nile Blue sulphate before being fused to the host. It is possible to follow the stained region through the first day of development, but beyond this time the dye is not visible. The orientation is varied, but no correlation between any particular orientation and type of development is found. The differentiation of the transplanted AB, CD, C, or D blasto- meres does not bring about the development of additional structures in the host; those structures which are duplicated in the larva arise from the self-differentiation of the transplanted cells. Seven of the nine E plus CD larvae show two apical tufts; six (out of the seven surviving) show two sets of post-trochal bristles ( 7, A). In six of the ten E plus C larvae, two apical tufts are visible (Fig. 7, B). Ten of the fourteen E plus D larvae possess tw
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
