Abstract
In the present study, the conclusions drawn in the previous paper (No. II of this series) have been fully confirmed; namely,
(i) the two arms of a chromosome behave independently in the spiralization of their chromonemata, indicating that the kinetochore, though it connects the chromonemata on both sides, represents a fixed point in the mechanism of spiral formation, and
(ii) the frequency of reversal in direction of coiling is a function of the length of the arms, with a certain reservation that it can occur usually only in chromonemata of more than a certain length.
It was also pointed out that the chiasma bears no primary relation to the occurrence of changes in the direction of coiling, most of the latter being independent from one another and apparently fortuitous in their origin.
