Contributions Volume 8-9

Contributions Volume 8-9

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 edition. Excerpt: ... cells with two or three nuclei, and Carnoy (10) finds as many as ten to thirty nuclei in the intestinal cells of Cirolana. So large a number is due, I have abundant reason to believe, to fragmentation of the nuclei, not to amitosis, as Carnoy states (I. 0.). Schonichen discredits McMurrich's evidence (to the same effect as my own), holding that the fragmented nuclei resolve on focusing carefully into the nuclei of the muscle fibres. He evidently has not seen the phenomenon reported by McMurrich. Space does not permit an account of the unquestionable cases of fragmentation which I have seen. A whole plate of figures might be given of cells containing from a dozen to twenty-five fragments of the nucleus. No explanation of the phenomenon can be given at present further than to say that there are many reasons to regard it as pathological, or " degenerative " in L6wit's sense (see page 296).. I have found the intestine of a young Porcellio, 1.8 mm. in length, which had recently moulted the posterior half (Sec. iii, (4) ), to be literally filled with amitotic division, both longitudinal and transverse, throughout its length (fig. 2, 0). Many nuclei were in process of division; those already separated were approximately half the volume of others not yet beginning to constrict. There can be no doubt that the large number of divisions was correlated with the increase in size of the intestine immediately following the moult. It seems equally plain that two nucleated cells which are larger than adjacent ones, as in fig. 2, A, may represent precocious nuclear divisions, the constriction which will divide the cell being deferred to the next moult, when the luminal end of the cell will be free to cover the. new furrow, as...
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Product details

  • Paperback | 138 pages
  • 189 x 246 x 8mm | 259g
  • United States
  • English
  • black & white illustrations
  • 123693458X
  • 9781236934581