. A manual of zoology. Zoology. GENERAL ANATOMY 57 If the fluid be abundant, the nucleus appears vesicular. This is espe- cially the case when the lines of the framework are separated by consider- able amounts of nuclear fluid (fig. 19, 4). The chromatin enters into close relations with a less stainable element, also distinct from achromatin, the plaslin, {paranuclein, p). In the protozoan nuclei plastin and chromatin are usually intimately united, the first forming a substratum in which the latter is imbedded (clip). The united substances are most frecjuently closely and regularly dis- tribut
. A manual of zoology. Zoology. GENERAL ANATOMY 57 If the fluid be abundant, the nucleus appears vesicular. This is espe- cially the case when the lines of the framework are separated by consider- able amounts of nuclear fluid (fig. 19, 4). The chromatin enters into close relations with a less stainable element, also distinct from achromatin, the plaslin, {paranuclein, p). In the protozoan nuclei plastin and chromatin are usually intimately united, the first forming a substratum in which the latter is imbedded (clip). The united substances are most frecjuently closely and regularly dis- tributed as tine granules on the reticulum, so that the entire nucleus. ch p 4 56 Fig. 19.—^Vesicular nuclei with achromatic reticulum and different arrangements of the chromatin and nucleolar substance, p, plastin (nucleolar substance); ch, chromatin; clip, chromatin plus plastin. i and 2, nuclei of Actinosphccrium; 3, of Ceratium hirundella (after Lauterborn); 4, germinal vesicle of XJnio (after Flemming); 5, nucleus with many chromatin nucleoU. appears uniformly chromatic (fig. 18). More rarely the mixture collects into one or more special bodies, the chromatic nucleoli {amphinucleoli, caryosomes, fig. 19, i, 2). The nucleolus is ordinarily a rounded body, more rarely branched (fig. 19, i). In the nuclei of the Metazoa there may occur the same intimate mix- ture of plastin and chromatin (6). As a rule, however, the plastin (apparently not the whole, but a surplus) is separate from the chromatin. Thus there occur in the nuclei of many eggs nucleoli which consist of two distinguishable parts, the one containing chromatin, the other chromatin free (4). Usually in tissue cells only the plastin has the form of. 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterl
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