Development of Mechanical Tissue . 529 
2. In the Peach the fruit-bearing shoot has more wood than 
the vegetative shoot, and the walls of the wood-cells are as 
thick in the former as in the latter. 
3. In general it may be said that the effect of fruit-bearing 
upon the tissues is local. In the Apple and Pear it is percep- 
tible throughout the one-year-old shoot ; in the Plum and 
Peach it is confined to a small area in the immediate neighbour- 
hood of the fruit-stalk. 
4. The local effect of fruit-bearing tends to an increase of 
cells, with a decrease in the thickness and lignification of the 
walls of the wood-cells. The cortex is especially enlarged, 
giving rise in the Apple and Pear to the swollen condition 
of the fruit-bearing shoot. 
5. In all cases the increase in growth is greatest on the 
side near the fruit-stalk, although the wood in the Apple 
and Pear is best developed on the side of the lateral vegeta- 
tive bud. 
6. The local effect of fruit-bearing on the wood-cylinder 
disappears with time. The study of Apple-shoots that had 
borne fruit during their first year showed that in the two or 
four years following there had been a rapid increase of wood, 
especially on the side of the fruit-scar. This side was weakest 
at the end of the first year. These shoots at the end of three 
and five years had a better xylem-development than shoots 
of the same age that had never borne fruit. 
7. Fruit-bearing has a temporary local effect upon the 
lignification of the walls of wood-cells. It prevents their 
lignification wholly or in part, according to their distance 
from the fruit-stalk. The lignification of other cell-walls is 
promoted by fruit-bearing. In the fruit-stalk the greatest 
part of the tissue has become lignified, and in the upper part 
of the Apple- and Pear-shoot there is an abundance of well- 
lignified sclerenchyma and hard bast, which is either not 
found in the vegetative shoot or only sparingly so. 
