522 Pieters. — Influence of Fruit-bearing on 
the same age as the first, but upon which fruit had never 
been borne 1 * * . 
A study of these shoots showed a remarkable development 
in the fruit-bearing ones, both in size of the xylem-cylinder 
and in the thickness of the walls of the wood-cells. Most of 
this increase had been on the side nearest the fruit-scar, thus 
making the radii of the xylem-cylinder more nearly equal. 
The walls of the wood-cells were apparently as thick and as 
well lignified in the fruit-bearing shoots as in the vegetative 
shoots. Measurements of the tissues showed that the wood- 
cylinder in the fruit-bearing shoot had not only outgrown its 
former weakness, but that it now formed a greater proportion 
of the diameter of the cross-section than was the case in the 
vegetative shoot. 
Table 3 . — Amount of wood in the fruit-bearing and vegetative shoots at the 
end of the first, third , and fifth year of growth. 
Twelve vegetative shoots, first year . 
Twelve fruit-bearing shoots ,, 
47-77 
41.50 
! I 
o\ 
1 
Seven vegetative shoots, third year 
Seven fruit-bearing shoots „ ... 
! 23-5 
i 33 - 8 
+ 10.3 
Six vegetative shoots, fifth year .... 
Six fruit-bearing shoots ,, 
164-66 
1SS.33 
+ 23-67 
This increase in the development of the xylem, as well as 
in the walls of the wood-cells, indicates that the weakening 
effect of fruit-bearing upon the wood is temporary, and is 
quickly outgrown. That even the temporary effect is com- 
pensated for by the great development of supplementary 
mechanical tissue is shown above. 
Pear . — The fruit-bearing one-year-old Pear-shoot resembles 
1 To avoid using a cumbersome descriptive phrase, these three- and five-year-old 
portions of branches will hereafter be designated as three- and five-year-old fruit- 
bearing and vegetative shoots respectively. 
