The cell in development and inheritance . ell-denned delicate wall which The character of the chromatm-network . ^ (^fl«cAro/«a^^>) is accurately shown. The upper glVCS the UUClCUS a sharp COUtOUr nucleus contains three piasmosomes or true and differentiates it clearly from nucleoli; the lower, one. A few fine linin-threads , •?. , TV, {oxychromatin) are seen in the upper nucleus ^hC SUrrOUndmg CytOplasm. 1 UlS running off from the chromatin-masses. The wall SOmCtimCS StainS but VCry clear spaces are occupied by the ground-sub- t -Ui-i j i t, j-c -gj,^j^j,g ^ p J b slightly, and can scarcel
The cell in development and inheritance . ell-denned delicate wall which The character of the chromatm-network . ^ (^fl«cAro/«a^^>) is accurately shown. The upper glVCS the UUClCUS a sharp COUtOUr nucleus contains three piasmosomes or true and differentiates it clearly from nucleoli; the lower, one. A few fine linin-threads , •?. , TV, {oxychromatin) are seen in the upper nucleus ^hC SUrrOUndmg CytOplasm. 1 UlS running off from the chromatin-masses. The wall SOmCtimCS StainS but VCry clear spaces are occupied by the ground-sub- t -Ui-i j i t, j-c -gj,^j^j,g ^ p J b slightly, and can scarcely be dif- ferentiated from the outlyingcytoplasm. In other and perhaps more frequent cases, it approachesin staining capacity the chromatin. b. The nuclear reticulum. This, the most essential part of thenucleus, forms an irregular branching network or reticulum which con-sists of two very different constituents. The first of these, forming thegeneral protoplasmic basis of the nucleus, is a substance known as linin 1 Calkins, 98, THE NUCLEUS 33 (Schwarz), invisible until after treatment by reagents, which in sectionsshows a finely granular structure and stains like the cytoplasmic sub-stance, to which it is nearly related chemically (Figs. 7, 49). Thesecond constituent, a deeply staining substance known as chromatin(Flemming), is the nuclear substance/«r excellence, for in many casesit appears to be the only element of the nucleus that is directly handedon by division from cell to cell, and it seems to have the power to pro-duce all the other elements. The chromatin often appears in the formof scattered granules and masses of differing size and form, which areembedded in and supported by the linin-substance (Figs. 7, 19). Insome cases the entire chromatin-content of the nucleus appears to becondensed into a single mass which simulates a nucleolus; for exam-ple, in Spiiogyra and in various flagellates and rhizopods ( Acti-nosphceriuni, Arcellci); or there may be seve
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1902
