. The biology of the Protozoa. Protozoa; Protozoa. Fig. 29.— Vahlkampfia Umax; chromatin forming the nuclear membrane and giving rise to chromidia. (After Calkins.) formation, antecedent to gamete formation described above, the nuclear membranes are probably formed from the cytoplasmic reticulum in which the chromidiosomes are lying. Chromomeres also take part in the formation of nuclear membranes in some cases, e. g., in Vahlkampfia Umax, where the linin membrane is too delicate to be seen, although the definite limitation of the chromo- meres indicates its presence (Fig. 29). One peculiarity
. The biology of the Protozoa. Protozoa; Protozoa. Fig. 29.— Vahlkampfia Umax; chromatin forming the nuclear membrane and giving rise to chromidia. (After Calkins.) formation, antecedent to gamete formation described above, the nuclear membranes are probably formed from the cytoplasmic reticulum in which the chromidiosomes are lying. Chromomeres also take part in the formation of nuclear membranes in some cases, e. g., in Vahlkampfia Umax, where the linin membrane is too delicate to be seen, although the definite limitation of the chromo- meres indicates its presence (Fig. 29). One peculiarity of the nuclear membranes of Protozoa which dis- tinguishes them from nuclear membranes of tissue miclei, is that in the majority of cases they remain intact during all phases of cellular activity and only rarely disappear, or disappear in part only, flaring division processes of the cell. (For description of chromatin, mem- branes etc., during division, see p. 114.) (d) Plastin,— Plastin, perhaps not dift'erent from linin, has been definitely identified only in a few cases of Protozoa, and much remains to be done before an accurate account of its functions in the nucleus can be written. Probal)ly a deri\'ative of chromatin as early suggested by van Beneden, it is an important substance in. 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 Calkins, Gary N. (Gary Nathan), b. 1869. Philadelphia, New York, Lea & Febiger
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