. The cell in development and inheritance. Cells. 414 INHERITANCE AND DEVELOPMENT the nucleus into the cytoplasm, and, there becoming active, set up specific changes and determine the character of the cell, this way or that, according to their nature. But what influence guides the migrations of the pangens, and so correlates the operations of devel- opment? Both Driesch and Oscar Hertwig have attempted to. Fig. i88. — Diagrams illustrating the value of the quartets in a polyclade {Leptoplatta), a lamel- libranch {(Jnio), and a gasteropod {Crepidiila). A. Leptoplana, showing mesoblast-formation
. The cell in development and inheritance. Cells. 414 INHERITANCE AND DEVELOPMENT the nucleus into the cytoplasm, and, there becoming active, set up specific changes and determine the character of the cell, this way or that, according to their nature. But what influence guides the migrations of the pangens, and so correlates the operations of devel- opment? Both Driesch and Oscar Hertwig have attempted to. Fig. i88. — Diagrams illustrating the value of the quartets in a polyclade {Leptoplatta), a lamel- libranch {(Jnio), and a gasteropod {Crepidiila). A. Leptoplana, showing mesoblast-formation in the second quartet. B. Crepidiila, showing source of ectomesoblast (from a", b'^, c'^) and en- tomesoblast (from quadrant D). C. U>iio, ectonipsoblast formed only from a^. In all the figures the successive quartets are with Arabic figures ; ectoblast unshaded, mesoblest dotted, entoblast vertically lined. answer this question, though the first-named author does not commit himself to the pangen-hypothesis. These writers have maintained that the particular mode of development in a given region or blasto- mere of the egg is a result of its relatioti to the remainder of the inasSy a product of what may be called the intra-embryonic environ-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Wilson, Edmund B. (Edmund Beecher), 1856-1939. New York, Macmillan
Size: 1527px × 1636px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectcells, bookyear1911
