The Biological Bulletin Volume 30-31

The Biological Bulletin Volume 30-31

List price: US$9.98

Currently unavailable

Add to wishlist

AbeBooks may have this title (opens in new window).

Try AbeBooks


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. 1916 edition. Excerpt: the chromatin which presage the onset of mitosis (i. e., the clumping of the chromatin and its segregation into short rodlike masses and finally into a spireme) can take place in a nucleus which is undergoing constriction. Thus it appears that mitosis can proceed as usual in nuclei partially divided or wholly divided by the amitotic process. 1 Prophases alone were counted, in estimating cells in mitosis, since in this stage alone is it possible to distinguish the bipartite from the monopartite nucleus. on account of nuclear fusion in Stages later than this in the case of mitosis in the binucleate cell. _ _.4-1 DISCUSSION. The direct division of the nucleus is associated with certain changes of the cell as a whole. Elongation of the nucleus seems to be a prerequisite, and this apparently is secondary to a lengthening and narrowing of the cell body occasioned by the pull of its processes. It has been pointed out that the ce11trosphere is situated characteristically i11 a concavity at one side of the nucleus, and, when the nucleus lengthens, this body sinks deeper into its side; at the same time, judging from fixed preparations, and also from the appearance of the living and dividing nucleus, mitochondria come to lie across this narrow nuclear isthmus. These bodies, the centrosphere and associated mitochondria, seem to play a part in the fission of the nucleus. The exact manner of their' action is not clear, but it may be that streaming of the nucleoplasm away fron1 the equator of the nucleus follows upon the mechanical irritation of the nuclear membrane by their movements, or possibly upon local alteration of surface tension fro111 their chemical change. Certainly the position which these bodies take with reference to the...
show more

Product details

  • Paperback | 278 pages
  • 189 x 246 x 15mm | 499g
  • United States
  • English
  • black & white illustrations
  • 1236853547
  • 9781236853547