1913] CHRYSLER—PHLOEM OF ABIETINEAE 43 
and fate of the cells are the same in both cases. Where two rays 
are in vertical proximity, it is to be expected that the intervening 
space will be occupied by one or two cells, but here, as in the case 
of the radial plates of cells, there is seen a tendency for the cambial 
activity to be localized in the region of a ray. 
Several of the figures illustrate a point which must be 
emphasized, namely, a ray uniformly begins its course in the outer 
phloem as a simple structure consisting exclusively of “prone’’ 
cells which at certain times of year contain abundant starch, and 




Fic. 8, 9.—Fig. 8, P. Strobus, 5-year root: two rays almost in contact; fig. 9, 
P. aristata, 7-year root: origin of erect cells by cutting off a cell from the end of a 
sieve tube; 275. 
only after cells of a radial group become applied to its margin does 
the ray come to have a border of “erect” cells. Such a border is 
usually added to only one edge of the ray at a time, though cases 
occur in which borders are added to both edges simultaneously. 
A slightly different mode of origin of the erect célls has been 
observed in a number of cases. One of these is shown in fig. 9, 
from a 7-year root of P. aristata. Beginning at the left it will be seen 
that the ray is not provided with a border of erect cells, but that 
sieve tubes come in contact with the ray. A little farther to the 
right an elongated cell provided with sieve pores is cut off from a 
