42 BOTANICAL GAZETTE [JULY 
cambial cells the erect cells of the two rays come into contact, and 
soon merge into the condition where a single cell spans the space 
between the rays. As before, such cells lose their contents and 
become greatly compressed in the radial direction. 
Fig. 8, from the same root as fig. 7, represents a case where two 
rays are practically in contact. A cambial cell is seen to give rise 
on the phloem side to pairs of cells which appear to have earlier 
been undivided, as seen in the extreme left of the figure; the nature 



Fis. 6 Fic. 7 
es 6, ed ig. 6, P. Sir obus, 6-year root: region between two rays, with radial 
ay erging into erect cells; 275; fig. 7, 5-year root: two rays nearer than in 
of these cells is shown by the sieve areas as before. On the xylem 
side the cambial cell has given rise to irregular shaped tracheids 
which are evidently of the kind described by THomPson (7), and 
by him regarded as transitional forms between ray tracheids and 
regular tracheids of the xylem. 
— 2 a probable that the prismatic cells lying between 
yes SR Tays, as shown in figs. 6-8, are of the same nature 
cells of the radial groups, inasmuch as the contents, pitting, 
