i8 
ALBAN STEWART 
the normal wood, three sorts of rays occur in the wood of the jack 
pine. According to Penhallow (13, p. 321) there are: "(i) low rays 
composed of oblong narrowly oval thin-walled parenchyma cells with 
narrowly oblong, terminal tracheids; (2) low rays of similar composi- 
tion, but the parenchyma cells much thinner walled; (3) the highest 
rays composed chiefly of narrow tracheids with a few broader, obiong 
parenchyma cells interspersed." I have found it difficult to dis- 
tinguish between groups i and 2, but the rays of group 3 are readily 
distinguished, and from the single specimen examined, I find that they 
are in general 6-10 cells high. Both low and high rays can be seen 
in tangential sections of the gall, the higher ones being the more 
common. These usually do not exceed the normal rays of group 3 in 
number of cells in height, but where exceptions occur the increase is 
largely due to the addition of moie rows of parenchyma cells. The 
individual cells composing the rays are usually larger than normal. 
With the exception of fusiform rays, Penhallow (13, p. 94) states 
that the rays are always uniseriate in Abies, Picea, and Pinus. It is 
a common thing to find rays in tangential sections of this gall which 
are two cells wide in part (plate I, figure 5) and occasionally a ray 
which is three cells wide. It is evident that these are not fusiform 
rays, which occur more abundantly in the gall than in normal wood, 
as they do not partake of the character of such rays. A similar condi- 
tion of ray structure also occurs in traumatic wood of this species of 
pine (plate I, figure 6). 
A sporadic tendency to a slight broadening of the rays occurs in a 
few of the living conifers according to Penhallow (13, p. 94). It 
may be met with in species of Pseudotsuga, Cupressus, Juniperus, 
Sequoia, Araucaria, and Larix. In Libocedrus the tendency is more 
pronounced. A significant broadening of the rays may take place 
according to Maule (ii, pi. 2, figure 8), in traumatic wood of Abies 
cephalonica, sl genus in which such does not occur normally. Wornle 
(18, p. 131, figure 8) has also recorded a marked broadening of the 
rays in stems of Juniperus infected with Gymno sporangium juni- 
perinum, ray-like structures figured by this author being nearly as 
broad tangentially as they are high in some instances. 
Certain authors have recently given a phylogenetic significance 
to the broadening of the rays in traumatic wood of some of the angio- 
sperms. I believe that it is pretty generally accepted that the uni- 
seriate ray is primitive in the Coniferae. If this conception is correct 
