The cell in development and inheritance . tarymorphological bodies, though there isstill no general agreement regardingtheir nature and relationships. Themost definite evidence in this directionrelates to the chromatic network. Inthe stages preparatory to division thisnetwork resolves itself into a definitenumber of rod-shaped bodies knownas chromosomes (Fig. 21), which splitlengthwise as the cell divides. Thesebodies arise as aggregations of minuterounded bodies or microsomes to whichvarious names have been given(r//;v;w^-meres, Fol; ids, Weismann). Theyare as a rule most clearly visible andm
The cell in development and inheritance . tarymorphological bodies, though there isstill no general agreement regardingtheir nature and relationships. Themost definite evidence in this directionrelates to the chromatic network. Inthe stages preparatory to division thisnetwork resolves itself into a definitenumber of rod-shaped bodies knownas chromosomes (Fig. 21), which splitlengthwise as the cell divides. Thesebodies arise as aggregations of minuterounded bodies or microsomes to whichvarious names have been given(r//;v;w^-meres, Fol; ids, Weismann). Theyare as a rule most clearly visible andmost regularly arranged during cell-division, when the chromatin is ar-ranged in a thread {spireme), or inseparate chromosovies (Figs. 8, D, 53,B); but in many cases they are dis-tinctly visible in the reticulum of theresting nucleus (Fig. 54). It is,however, an open question whether the chromatin-granules of thereticulum are individually identical with those forming the chromo-somes or the spireme-thread. The larger masses of the reticu-. Fig. 15. — An infusorian, Trachelo-cerca, with diffused nucleus consisting ofscattered chromatin-granules. [Gruber.] ^ Both chromatin-granules and nucleoli have been seen in a considerable number of livingcells (Fig. 9). Favourable objects for this purpose are according to Korschelt (96) the sillc-glands of caterpillars, where the whole nucleus may be seen to be tilled with fine granules(microsomes), among which are scattered many larger granules ( macrosomes). Thelater studies of Meves (97, l) make it probable that the latter are true nucleoli and the for-mer chromatin-granules. Korschelt, however, regards the macrosomes as composed ofchromatin and the microsomes as representing the so-called achromatic substance. 38 GENERAL SKETCH OF THE CELL lum undoubtedly represent aggregations of such granules, but whetherthe latter completely fuse or remain always distinct is the chromosomes at certain stages appear perfectly homoge-neous
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1902
