Development of Mechanical Tissue. 523 
that of the Apple in every way, except size. It is larger, and 
the swelling is greatest near the middle, decreasing from this 
point in both directions. The upper part withers after fruit- 
bearing. In arrangement and division of tissue the part 
below the insertion of the lateral vegetative bud is similar 
to the corresponding part of the Apple. Instead, however, of 
bast-fibres, the supplementary mechanical tissue is scleren- 
chyma. The sclerenchyma-cells are slightly elongated and 
taper-pointed, with thick and strongly lignified walls. Bundles 
of these cells are placed just outside of the fibro-vascular 
bundles, and are scattered throughout the cortex, medullary 
rays, and pith in the upper part of the shoot. Like the bast- 
fibres in the Apple, they decrease in number near the base of 
the shoot. 
An early variety of Pear, of unknown name, was selected 
for study. Measurements were made in the same manner as 
for the apple, the sections being taken near the base in each 
case. Although the largest possible vegetative shoots were 
used, they were, as a rule, no longer than the fruit-bearing 
ones. 
Table 4. — Average percentages of tissue 
in one-year-old shoots. 
Cortex. 
Wood. Pith. 
Five vegetative shoots . 
. 42*20 
23.12 34.68 
Five fruit-bearing shoots 
4 x *36 
22.10 36-54 
— 0*84 
- 1-02 +I-86 
There is very little difference in the proportionate amount 
of tissue in these shoots, but an examination of the tables 
of absolute measure will show that the advantage, as far as 
amount of mechanical tissue is concerned, is largely with the 
fruit-bearing shoot. 
Table 5. — Average absolute measure of tissues in the same shoots as in Table 4. 
Cortex. 
Wood. 
Pith. 
Total. 
Vegetative shoots 
106.6 
58.4 
87.6 
252-6 
Fruit-bearing shoots . 
146-0 
78-0 
129-0 
353*6 
+ 39-4 
+ 196 
+ 41-4 
N n 2 
