A Study of the Chromosomes of the Germ Cells of Metazoa. (Univ. of Pennsylvania. Contrib. from the Zool. Lab.)

A Study of the Chromosomes of the Germ Cells of Metazoa. (Univ. of Pennsylvania. Contrib. from the Zool. Lab.)

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 edition. Excerpt: ...I could not determine the relations of the chromatin nucleoli in the rest stage of these cells. In the rest stage of the spermatocyte (PI. V, Fig. 232) is found a large true nucleolus (iV), and separated from it, usually close to the nuclear membrane, a rounded chromatin nucleolus (N. 2). Pole views of the first maturation monaster (Fig. 233) show eleven chromatin elements; sometimes one appears much smaller than the others, and it may represent the chromatin nucleolus. Naucoridje. 41. Pelocoris femorata Pal. Beauv. Fourteen testes of this species were studied from adult and half-grown individuals of difFerent seasons of the year. There were an abundance of rest stages of spermatogonia and of spermatocytes in the growth period, but no maturation mitoses present. The chromosomes were counted in a number of pole views of the monaster stage of the spermatogonia, but in most cases they were so densely grouped as to make the numbers obtained very uncertain. In the most favorable case (PL V, Fig. 234) apparently twenty chromatin elements are present, but I could not be certain of this number. The relations of the chromatin nucleoli in the growth period are very puzzling. On preparations stained with Hermann's saffranine-gentian violet, there appear to be a variable number of rounded bodies of different volume which stain bright red; sometimes they are arranged in pairs, sometimes in long chains, sometimes they show no regular arrangement whatsoever. One nuclear body, much larger than the others and generally irregular in outline, may be a true nucleolus. If all the red-staining bodies are chromatin nucleoli, they would seem to be present in an unusually large number in this species. A study of further material will be necessary to explain the nature...show more

Product details

  • Paperback | 42 pages
  • 189 x 246 x 2mm | 95g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236625013
  • 9781236625014