. The cytology and life-history of bacteria. Bacteria. Fig. 33 FATE OF CHROMOSOMES IN CELL DIVISION A. Equational division. This does not occur in bacteria. Even if the occurrence of a classical mitosis (for which there is no reliable evidence) were accepted, it would entail migration of chromosomes across their own partners and across the newly-formed cell division. B. Reductional division. This appears to be the normal condition in bacteria. It was originally postulated bv cytologists ( in the first edition of this book), but is now supported by genetical evidence also (, Ryan, F. J.
. The cytology and life-history of bacteria. Bacteria. Fig. 33 FATE OF CHROMOSOMES IN CELL DIVISION A. Equational division. This does not occur in bacteria. Even if the occurrence of a classical mitosis (for which there is no reliable evidence) were accepted, it would entail migration of chromosomes across their own partners and across the newly-formed cell division. B. Reductional division. This appears to be the normal condition in bacteria. It was originally postulated bv cytologists ( in the first edition of this book), but is now supported by genetical evidence also (, Ryan, F. J. and Wainwright, J. K., J. Gen. Microbiol., ). Thus the vegetative cells are haploid but multinucleate, and mutant characters are rapidly segregated. of nucleur segregation described above. Filamentous cells, derived from the vegetative fusion process, behave as if they possessed a single chromosome ; an observation which confirms the occurrence of a fusion process. The nucleus of Azotohacter resembles that of yeasts in the possession of a number of chromatinic granules which appear to be attached to the nuclear membrane. In the case of yeasts these granules are believed to be the chromo- somes. In mitosis these chromosomes take part in the formation of two ribbon-like complexes. In Azotohacter, the nuclear material at cell division takes the form of two or four large rods, which divide with the cell and then fragment to reform the vesicular nucleus with its surrounding 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 Bisset, Kenneth Alexander. Baltimore : Williams and Wilkens
Size: 1203px × 2078px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectbacteria
