BOTANY: I. W, BAILEY 
283 
PHENOMENA OF CELL DIVISION IN THE CAMBIUM OF ARBO- 
RESCENT GYMNOSPERMS AND THEIR CYTOLOGICAL 
SIGNIFICANCE 
By Irving W. Bailey 
BussEY Institution for Research in Applied Biology 
Communicated by W. M. Wheeler, May 8, 1919 
In connection with a series of investigations upon the variations in size and 
structure of tracheary cells in vascular plants, the writer had occasion to search 
for information concerning the processes of growth and cell division in the 
cambium of arborescent plants. He was unable to find satisfactory descriptions 
of these phenomena in the botanical literature, and was assured by several 
cytologists that comparatively little was known about them; in all probabihty , 
owing to the difficulty of sectioning the lateral meristem (cambium) of woody 
plants. It seemed advisable, accordingly, to initiate a special histological 
and cytological investigaton of this important tissue. 
During 1917 and 1918, specimens of the cambium of Pinus Strohus L. were 
collected — from trees of different ages and varying environments — at frequent 
intervals during the growing season, April to September. Methods were per- 
fected for fixing, sectioning and staining this material, which was compared 
with that secured from 14 other genera of Coniferae. The results of this in- 
vestigation and of a similar study of arborescent dicotyledons will be published 
in extenso at a later date, but certain of the cytological phenomena encountered 
are so significant as to merit a brief preliminary description in these pages. 
The cambium, although essentially an undifferentiated or 'embryonic' type 
of tissue, is composed of cells which are considerably elongated. In Pinus 
Strohus L., as in other arborescent gymnosperms, the cambial initials are com- 
monly from one hundred to several hundred times as long as they are wide 
(radial diameter) . From the point of view of Sachs' and Strasburger's theories 
of the 'working sphere of the nucleus' and the observations of Treub, Kallen, 
Buscalioni, Pirotta and Buscalioni and others upon the occurrence of many 
nuclei in elongated protoplasts of the higher plants, it might have been 
expected a priori that these long meristematic cells would contain more than 
one nucleus each.^ 
This did not prove to be the case, however, in any of the material examined 
by the writer. Each cell contains a single nucleus, which is centrally located 
and placed so that its longest axis is approximately parallel to the long axis of 
the cell. 
During mitosis, on the other hand, the polar axis of the division figure — 
late prophase, metaphase, anaphase, early telophase — does not stand, in most 
cases at least, at right angles to the long axis of the cell} 
As is shown in figure 1 {A and D) the mitotic figure is placed diagonally 
across the cell, at an angle of from 20 to 40 degrees. That this phenomenon 
