A Phase-Contrast Microscopic Study of Pollengrain Germination, Nuclear Movement and Pollentube Mitosis in Tradescantia virginiana

Abstract

A phase-contrast microscopic study of pollengrain germination, nuclear movements and pollentube mitosis in Tradescantia virginiana is presented in this paper.
Some of the kinetics of germination and nuclear movement have been analyzed.
It has been shown that a vacuole in the pollengrain is important in pollengrain germination. Nuclear movements have been ascribed to the resultant of friction forces, together with a cytoplasmic pushing force towards the distal nuclear part.
It is described how the generative nucleus passes the vegetative one and the attention is drawn to this phenomenon in order to explain the different opinions found in literature about the question, what nucleus first enters the pollentube.
No evidence was found, which favours the “cell within a cell” state of the pollengrain.
It is unlikely, that in the mature pollengrain the vegetative nucleus is degenerative.
Some attention is drawn to possible causes of failure of pollengermination.
The stages of generative nuclear mitosis have been described.