6 MR. \. RUSHTON : STRUCTURE OF THE 
A detailed description is given below of each species and the main points 
of interest brought out. 
JUNIPERUS RECURVA, Ham. 
The wood of this species is moderately hard and light reddish brown in 
colour. The growth is slow, in my specimen 44 rings per inch of radius, 
but Gamble points out that 22 rings per inch is common for Sikkim wood, 
and twice as many for wood grown in the North-West area. 
Macroscopic (naked eye). 
The annual rings are well marked off from each other, the summer wood 
is narrow and dense, and the medullary rays just visible. 
Microscopie (tracheids). 
The tracheids occur in well-marked radial rows as seen in transverse 
sections, 22-42 occurring in each row, of which from 8-25 beiong to the 
summer-wood area and the rest to the spring, the latter gradually changing 
to the former. In some a slight indication of an attempt at double-ring 
formation occurs very near the outer limit of the year’s growth. The 
bordered pits on the radial wall of the spring tracheids are round and do not 
touch each other. The orifices are circular in the early spring tracheids 
(fig. 7), but more lenticular as the summer wood is reached (fig. 8). The 
pits on the tangential walls of the latter are more scattered, with narrow 
lens-shaped orifices (fig. 9). 
The length of the tracheids is 1-2 mm. аз a rule, but shorter ones, 0°5 mm. 
long, are not uncommon, witha thickness of wall and width of lumen as 
follows :— 
Width of lumen. Thickness of wall. 
Radial. Tangential Radial. Tangential. 
Spring wood ......... 20 u 19 p 2-5-3 и 25-3 u 
Summer wood........ 5-6 15р 3-4 u 3—4 u 
The tracheids do not all run straight, as some, when they come in contact 
with a medullary ray, bend radially and run along the ray for some distance 
with their ends more or less pointed (fig. 1), but where they do end abruptly 
оп а ray their ends are flattened. In other cases they follow an irregular 
course, and where the ends of two tracheids meet a bordered pit occurs 
between them (fig. 2), and often pits occur on the tangential walls in these 
areas. ‘Tangential sections in such a region often show large oval spaces 
surrounded by a lignified wall, which are the bent tracheids cut in an oblique 
direction (fig. 10), and where these bent tracheids end by the side of a 
medullary ray they have a tendency to push the ray-cells to one side, 
causing them to appear irregular in shape instead of round (fig. 11). 
