THE ORIGIN OF THE ERECT CELLS IN THE PHLOEM 
OF THE ABIETINEAE 
M. A. CHRYSLER ~ 
(WITH TWELVE FIGURES) 
In the course of a comparative study of the phloem of conifers, 
certain facts have come to light which seem to demonstrate the 
origin of the cells found on the margins of medullary rays in their 
course through the phloem, the so-called “erect cells” of the rays. 
These cells are distinguished from the other cells of a ray by their 
elongation in the vertical direction, their almost total lack of starch, 
and their possession of sieve areas. Of these three criteria, the third 
is the final one, while the other two afford presumptive evidence of 
the nature of cells which may be found at the margin of a ray. 
Such cells are characteristic of the following genera: Pinus, Picea, 
Larix, Pseudotsuga, Cedrus, Tsuga, Abies, and also occur sporadi- 
cally in Juniperus and Thuja (7). 
In pitting and contents these cells strongly suggest a homology 
with sieve tubes, as STRASBURGER (5) has pointed out. The same 
author observed that like sieve tubes these cells lose their contents 
and collapse as the season advances, while the central cells of a ray 
enlarge and become laden with starch. In his paper on ray tra- 
— THompson (7) goes so far as to say that the erect cells are 
virtually ray sieve tubes,” and, from the fact that marginal cells 
of both xylem and phloem portions of a ray arise from the same 
cambial cell, argues that the marginal cells in the xylem are tra- 
cheary in origin. The assumption that erect cells are sieve tubes in 
nature or origin is to be put to a test in the present paper. 
= There are several possible origins for these cells. They may, 
‘he oe (prone) cells of a ray, merge into the pericycle, or 
i y simply be prone cells which have taken on a new function 
‘ ba et ® Special shape, or they may be cells distinctly added or 
pied to a ray already existing in a simple condition, that is, 
constituted only of prone cells. 
An obvious method zt : 
of attaining a solution of the question is 
Botanical Gazette, vol. 56] q a 

