Behaviour of Chromonemata in Mitosis IX

On the configurations assumed by the spiralized chromonemata

Abstract

1. Spiralized chromonemata present different configurations. The configurations can be classified into two general types, the spiral configuration and the twisted configuration.
2. These configurations are mutually transformable from one to the other. These changes are experimentally demonstrated in the resting nucleus.
3. In the twisted configuration, the nucleus shows a diffuse structure, while in the spiral configuration it presents an aggregate structure, the chromosome territories being perceptible.
4. When staminate hairs are observed in water medium, the prophasic nucleus is transformed directly into the resting nucleus without passing metaphase and anaphase, an “abbreviated mitosis” which is comparable with the endomitosis. It is pointed out that in one mitosis the chromosome splitting never takes place twice, but that it only appears to do so, when one of the two successive mitoses is an “abbreviated” one.
5. From the fact of the spiralized chromonemata presenting different configurations, the problems of 1) the anaphasic or telophasic split, 2) the minor spirals, 3) the fine structure of the nucleus in connection with the problem of the chromonema number in chromosomes, 4) the type of the chromonema spirals, and 5) the optical sign of chromosomes are discussed.