. A compendium of general botany. Plants. 12 COMPENDIUM OF GENERAL BOTANY. nuclear division or " karyokinesis," but will limit myself to the explanation of the c-ccompanying ligures. One usually distinguishes a "chromatin" and an "achromatin" nuclear figure. The former is distinguished by the readiness with which the nuclein is colored by various stains, the latter is composed of the slightly staining portions of the nuclear substance. In the illustrations tlie chromatic figure is. Fig. S.—Successive stages of nuclear division.' (After Strasburger.) In A an irregu
. A compendium of general botany. Plants. 12 COMPENDIUM OF GENERAL BOTANY. nuclear division or " karyokinesis," but will limit myself to the explanation of the c-ccompanying ligures. One usually distinguishes a "chromatin" and an "achromatin" nuclear figure. The former is distinguished by the readiness with which the nuclein is colored by various stains, the latter is composed of the slightly staining portions of the nuclear substance. In the illustrations tlie chromatic figure is. Fig. S.—Successive stages of nuclear division.' (After Strasburger.) In A an irregularly wound thveail is formed from the nuclear network (spirem, Knauel). In B and C are seen the " chromatin-granules " resulting from the breaking up of the chromatin. At E and i^a certain arrangement and longitudinal division of cliroinafiii-threads takes place. Somewhat previous to this the nchromatin nuclear figure makes its appearance (delicate lines in J?and F). The two halves of the chromatiii-threads move along the fine achromatin lines in opposite directions to the poles (J)and form the " spirem " (Knauel) stage of the daughter-cells (M. O). Out of the spirem is f<irmed the network, nucleoli appear, also a nuclear membrane, and the daughter-nuclei are complete. When a septum is to be formed a cellulose plate forms between the two daughter-nuclei at the points where the thickenings occur on the nuclear spindle: otherwise the nuclear spindle (achromatin-flgure) disappears with the thickenings. indicated by heavy dark lines, the achromatin figure by light lines (^, F, J, M). Roux assumes hypothetically that the purpose of karyokinesis is to transmit hereditary peculiarities by means of the dividing decisive substances (chromatin threads or bands). How- ' In connection "with indirect nuclear division should also be mentioned the recently discovered and studied " centrospheres " or "directive spheres," small spherical bodies
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectplants, bookyear1896
