INCREASE IN GIRTH OF THE CAMBIUM IN THUJA OCCIDENTALS L.

Abstract

Studies of serial tangential sections of the secondary xylem indicated that increase in girth of the cambium was accomplished not by regulated divisions spaced merely to bring about the required increase in circumference, but by such rapid multiplication of initials as to produce a great superfluity if all survived. Owing to the rapid production of new initials and the associated high ratio of disappearance, the pattern of cells in the cambium changed quickly. This necessitated extensive intercellular adjustments which apparently were of rapid completion. No support was found for Priestley''s theory that cell adjustments in the cambium are gradual and of a "symplastic" nature.