Ig12] THOM PSON—RAY TRACHEIDS 333 
Elongated ray tracheids of the type described by the writer 
(Joc. cit.) as common in the young root of Pinus were also frequently 
observed. One of them is shown in fig. 9. The tail-like projection 
extends to the extreme upper right of the figure. A unilateral 
bordered pit may be observed in contact with the ray and a bilateral 
one in contact with a wood tracheid. 
_The figures just described show that ray tracheids of all kinds 
are present in this wounded root of A. amabilis. Normal material 
of the same species, root, stem, and branch was carefully examined, 
and, in accordance with all former observations, not a single ray 
tracheid found. Therefore, it must be concluded that those ob- 
served were in definite association with the wounds. In fact, their 
occurrence recalls precisely that described by Jerrrey for C. 
sinensis. Occurring, as they do, in one of the two abietineous 
genera which normally are entirely without them, their presence 
is all the more significant. 
In JEFFREY’s material of Cunninghamia the ray tracheids were 
found only on the side remote from the wound. In my material 
this was not the case, as they were often in direct contact with the 
traumatic canals. Of course, the position of the various traumatic 
series (see fig. 1) would indicate that the root had probably been 
wounded at different points on its circumference, and therefore 
even if JEFFREY’s observation held good for this material, the ray 
tracheids ought to be found on any radius. However, in material 
of another species to be described immediately, such was distinctly 
not the case. 
Let us now turn to the other species examined. A radial section 
of a wounded branch of A. concolor is shown in fig. 7. The short 
septated elements at the central part of the extreme left are part 
of the traumatic series. Following these on the margins of both 
rays are bordered-pitted elements which are obviously ray tracheids. 
The conditions existing in the wounded root of A. amabilis are thus 
exactly duplicated in the wounded branch of A. concolor. In both 
species the ray tracheids are often in line with parenchyma cells, 
as in fig. 7. The usual condition is the appearance of one or two 
parenchymatous cells in the summer wood and a similar number 
of ray tracheids conterminous with them in the first-formed spring 
