. An introduction to the study of zoology. Zoology. THE CELL AND ITS STRUCTURE. SO large that the middle parts would get no oxygen and no food, on account of being so far from th& surface. Division begins ia the nucleus. This goes through a remarkable cycle of changes, to which has- been given the name of karyokinesis, which means, literally, tlie actiuity of the nucleus. As has jast been stated, the substance of the nucleus is seen, when highly magnified, to consist of a network of fibres that stain dark in a material that stains more lightly ; these are therefore called respectively chro
. An introduction to the study of zoology. Zoology. THE CELL AND ITS STRUCTURE. SO large that the middle parts would get no oxygen and no food, on account of being so far from th& surface. Division begins ia the nucleus. This goes through a remarkable cycle of changes, to which has- been given the name of karyokinesis, which means, literally, tlie actiuity of the nucleus. As has jast been stated, the substance of the nucleus is seen, when highly magnified, to consist of a network of fibres that stain dark in a material that stains more lightly ; these are therefore called respectively chromatin and achromatin. When the nucleus is about to Fig e —Saccessive stages of the division of the nucleus, showing ^spmdle- shaped mass of achromatin. and dark masses of chromatin. the chromatin forms a wreath at the outside of it, and then the loops of the wreath sharpen into points, so that it becomes a star, while the achromatin forms a long spindle-shaped mass which looks as if it were threaded through the wreath. The next change is that the chromatin star splits in half, and the halves travel towards the ends of the cell. Then the twO' new stars go back to the wreath form, and mean- while the protoplasm of the cell is dividing across. When the halves are severed the new nuclei assume the usual 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 Lindsay, B. London, S. Sonnenschein
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
