1Q2 BOTANICAL GAZETTE [OCTOBER 
of therays. In this view the rays are clearly seen to be multiseriate. 
Occasionally the rays are seen to join together, giving rise to still 
wider ones. In a great many cross-sections the rays do not take a 
direct course through the xylem, but are often broken and their 
course considerably interrupted. In many cases this ray paren- 
chyma is scattered among the wood fiber and wood parenchyma 
elements. 
The vessels have become greatly distorted throughout (fig. 2). 
This is due to the flattening of the tubes in a radial direction. In 
most cross-sections the pores are few in number, and in sections of 
some galls they are entirely absent (figs. 2, 9). Considerable 
increase in wood parenchyma cells is seen in the diseased wood. 
a great many cases the wood fibers are bent at right angles, the 
bend always being toward the periphery. Due to the bending, a 
transverse section often shows these fibers in a longitudinal view 
(fig. 2). This distortion is brought about largely as a result of © 
crowding, due to the great increase in the number and size of the 
cells of the medullary rays. 
In fig. 4 is shown a tangential section of diseased wood through 
a gall which illustrates to good advantage the characteristics of the 
medullary rays, which vary from one to several cells wide tangen- 
tially. This broadening is due to the increase in number, as well as 
to the increase in size of the individual cells making up the rays. 
That these ray cells are larger in the diseased wood than in the- 
normal wood is apparent by comparison of fig. 3 and fig. 4, the 
magnification in both cases being the same. It is also evident that 
there is considerable increase in the size and number of the wood 
fiber and wood parenchyma elements. The medullary rays some- 
times become so broad that their tangential diameter equals, or is 
even greater than their vertical diameter (fig. 4). 
The average of one hundred measurements of the diameter of 
the medullary ray cells, in the tangential sections of normal and dis- 
eased wood of the same age, gave for the former 13.2 » and for the 
latter 27.94. This shows an increase of slightly over 100 per cent 
in these cells as a result of the diseased condition. Measurements 
of the diameters of the wood fibers in the same sections gave 42 
average in the normal wood of 12 u and in the diseased wood an 
average of 16 yp. 
