THE CAMBIUM AND ITS DERIVATIVE TISSUES 
III. A RECONNAISSANCE OF CYTOLOGICAL PHENOMENA 
IN THE CAMBIUM 
I. W. Bailey 
Introduction 
In the second paper of this series, the writer (19205) called attention to 
the fact that the dimensions and volume of the undifferentiated, actively 
dividing and growing cells of the lateral meristem or cambium vary greatly, 
not only in plants of different systematic affinities, but in different parts of 
a given individual and in stems grown under different environmental 
conditions. Therefore, the cambium provides an unusually favorable 
medium for the study of a number of fundamental cytological problems, 
particularly those of the "working sphere of the nucleus," the much dis- 
cussed ''nucleo-cytoplasmic relation," and phenomena of karyokinesis and 
cytokinesis in cells of unusual shapes and sizes. 
Sachs (1893) held that, although plants vary enormously in their linear 
dimensions, their constituent cells are minute and of relatively uniform 
size. His student Amelung (1893) endeavored to prove, by means of an 
extensive series of measurements, that variations in the size of an organ 
or plant are due to differences in cell number rather than to fluctuations in 
cell size; a view which subsequently was championed on the zoological 
side by Conklin (1896, 1898), Rabl (1899), Driesch (1898, 1900), Schultz 
(1904), and others. Sachs (1892, 1893, 1895) and Strasburger (1893) 
concluded that the size of uninucleated cells, particularly of the undiffer- 
entiated cells of embryos and meristems, is determined by the "energizing" 
or "working sphere" of the nucleus, which they considered to be very 
restricted. Both investigators noted that unusually large or much elon- 
gated protoplasts tend to be multinucleate, and Sachs emphasized the fact 
that large, uninucleated cells either contain much passive (non-cytoplasmic) 
material or are relatively inactive until energized by the formation of 
numerous nuclei. 
Are Cambial Initials Multinucleate? 
The cambium is composed of elements of two distinct shapes and sizes. 
The ray initials commonly are roughly isodiametric and of the same general 
order of magnitude as the cells of embryos and terminal meristems. The 
initials which divide to form the elongated elements of the xylem and 
phloem, on the contrary, have one long and two short dimensions and are 
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