Download Free Protoplasmatologia Kern Und Zellteilung A The Chromosome Complement By B John And K R Lewis B The Chromosome Cycle By B John And K R Lewis C Endomitose Und Endomitotische Polyploidisierung Von L Geitler D Riesenchromosomen Von W Beermann E Amitose 1 Die Amitose Der Tierischen Und Menschlichen Zelle Von O Bucher F1 Meiotic System F2 Les Alterations De La Meiose Chez Les Animaux Parthenogenetiques Par M Narbel Hofstetter F3 Fortpflanzungsmodus Und Meiose Apomiktischer Blutenpflanzen Von A Rutishauser G Der Kernteilungsmechanismus 1 The Behavior Of Centrioles Book in PDF and EPUB Free Download. You can read online Protoplasmatologia Kern Und Zellteilung A The Chromosome Complement By B John And K R Lewis B The Chromosome Cycle By B John And K R Lewis C Endomitose Und Endomitotische Polyploidisierung Von L Geitler D Riesenchromosomen Von W Beermann E Amitose 1 Die Amitose Der Tierischen Und Menschlichen Zelle Von O Bucher F1 Meiotic System F2 Les Alterations De La Meiose Chez Les Animaux Parthenogenetiques Par M Narbel Hofstetter F3 Fortpflanzungsmodus Und Meiose Apomiktischer Blutenpflanzen Von A Rutishauser G Der Kernteilungsmechanismus 1 The Behavior Of Centrioles and write the review.

Protoplasmatologia: Kern- und Zellteilung. A. The chromosome complement, by B. John and K. R. Lewis. B. The chromosome cycle, by B. John and K. R. Lewis. C. Endomitose und endomitotische Polyploidisierung, von L. Geitler. D. Riesenchromosomen, von W. Beermann. E. Amitose. 1. Die Amitose der tierischen und menschlichen Zelle, von O. Bucher. F1. Meiotic system. F2. Les altérations de la méiose chez les animaux parthenogénétiques, par M. Narbel-Hofstetter. F3. Fortpflanzungsmodus und Meiose apomiktischer Blütenpflanzen, von A. Rutishauser. G. Der Kernteilungsmechanismus. 1. The behavior of centrioles

Published: 1968

Total Pages: 794


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neoessity for making it. Yet, clearly, the problem of development is largely one of filling "the vacuum between determinant and character" (DARLINGTON 1951). Nowadays the chromosome theory can be presented in much greater detail and with utter confidence, but its two main features remain the same. However, while the role of the chromosomes in heredity and development has been appreciated for a long time, the manner in which they perform their genetic and epigenetic functions has become amenable to critical investigation only in recent years. There is, therefore, still an unmistakable tendency to think of chromosomes in terms of the discrete threads of cell division and, in keeping with this conception, the chromosome cycle is gen erally considered in relation to the microscopically visible changes in morphology which occur during the mechanically active phases of mitosis and meiosis. Chromosome phenotype, however, changes not only during division but throughout the cell cycle. The changes which occur during interphase are, of course, scarcely revealed in morphological modifications of the restless "resting" nucleus. Consequently they are less obvious and correspondingly less amenable to investigation. This accounts for the concentration on the countable karyotype, with its visible properties of pairing and pycnosity, and the measurable movements of separation and segregation.
material can serve both autocatalytic and heterocatalytic functions. Thus not only is it unique in itB capacity for self-replication but its base sequence determines the specificity of proteins. And enzyme proteins are immediately responsible for the peripheral metabolism which enables the organism to impose its own kind of order on the raw materials it absorbs. The course of development is determined not only by the nature of the genetic material but by its over-all amount and the relative frequency of the different functional units. Differential rates of epigenetic activity matter also. In theory, therefore, differential development within or even between individuals could be determined by the differential replication of the various genetic elements or by their differential activity. And further variation could arise by the differential transmission of these elements between cells. Indeed it would appear that all these possibilities are exploited by living systems. If like is to beget like, however, any genetic change which occurs during development must be undone, or else germinal units preserved from change must be set aside. As far as is known, genetic changes, even those involving only quantity or relative amounts, are reversible to only a very limited extent so that a change once done cannot be undone. Consequently genetic changes during the development of presumptive germ-lines are either non existant or minor and confined to a small class of un aggregated deter minants.