. The biology of death; being a series of lectures delivered at the Lowell Institute in Boston in December 1920. Death (Biology); Death. FIG. 2.—Showing the changes in nerve cells due to age. 1, spinal ganglion cells of a still- born male child; 2, spinal ganglion cells of a man dying at ninety-two years; N. nuclei. In the old man the cytoplasm is pigmented, the nucleus is small, and the nucleolus much shrunken or absent. Both sections taken from the first cervical ganglion, X 250 diameters; 3, nerve cells from the antennary ganglion of a honey-bee, just emerged in the perfect form; 4, cells f
. The biology of death; being a series of lectures delivered at the Lowell Institute in Boston in December 1920. Death (Biology); Death. FIG. 2.—Showing the changes in nerve cells due to age. 1, spinal ganglion cells of a still- born male child; 2, spinal ganglion cells of a man dying at ninety-two years; N. nuclei. In the old man the cytoplasm is pigmented, the nucleus is small, and the nucleolus much shrunken or absent. Both sections taken from the first cervical ganglion, X 250 diameters; 3, nerve cells from the antennary ganglion of a honey-bee, just emerged in the perfect form; 4, cells from the same locality of an aged honey-bee. In 3, the large nucleus (black) is surrounded by a thin layer of cytoplasm. In 4, the nucleus is stellate, and the cell substance contains large vacuoles with shreds of cytoplasm. (From Donaldson after Hodge). There are other and perhaps even more general and striking morphological changes in senescence than the changed relation between cytoplasm and nucleus. Conklin says: By all odds the most important structural peculiarity of senescence is the increase of metaplasm or differentiation products at the expense of the general protoplasm. This change of general protoplasm into products of differentiation and of metabolism is an essential feature of embryonic differentiation and it continues in many types of cells until the entire cell is almost filled with such products. Since nuclei depend upon the. 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 Pearl, Raymond, 1879-1940. Philadelphia, London, J. B. Lippincott Company
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