Some Cytological Aspects of the Differentiation of Metaxylem in the Root ofAllium Cepa

Abstract
A cytological study was accomplished on the immature metaxylem of Allium cepa roots in the histological region between 500 and 3000 μ from the tip. Labelling experiments with 3H-thymidine, 3H-uridine and 3H-lysine were also carried out. The results show that in metaxylem maturation four morphologically detectable stages can be distinguished: The results of 3H-uridine and 3H-lysine incorporation are also reported.