5 1 6 Pieters . — Influence of Fruit-bearing on 
show the influence upon any tissue-system of the strain to 
which a tree is subjected in the production of fruit and seeds. 
Material and Methods. 
The trees studied are Apple, Pear, Peach, and Plum. The 
shoots to be compared were selected with reference to simi- 
larity in size and vigour, and were taken in each species from 
the same tree, often, indeed, from the same branch, in order 
to avoid, as far as possible, the influence of dissimilar 
conditions. When collected, these shoots were numbered 
and put into 50 per cent, alcohol, in which, to avoid unequal 
shrinkage, all were left for the same length of time. 
To study the shoots, free-hand cross-sections were made, 
and the tissues measured with an eye-piece micrometer under 
a power of about 100 diameters. The measurements were 
made in two diameters at right angles to each other, and the 
average thickness of the zones of tissue determined h For 
comparing fruit-bearing and vegetative shoots these figures 
were reduced to percentages, which are given in terms of the 
diameter of the shoot. The figures were carried to two 
decimal places, and the remainder, if less than 0*005, was 
ignored, and if greater was counted as o*oi and added to the 
result. Further details concerning the material and methods 
used will be given when the different species are discussed. 
Discussion of Species. 
The Apple 2 . — A study of the influence of fruit-bearing upon 
the mechanical tissue of a tree involves two points : (1) the 
immediate and temporary effect, and (2) the permanent effect. 
1 For illustration a sample measurement is given as follows : — 
Cortex. Wood. Pith. Wood. Cortex. 
Section 2 near S First diameter 7 ° 4 ° 135 45 7 ° 
’ ^ ( Second diameter 73 45 137 60 90 
Average . . . 71-5 42-5 136 52.5 80 
3 The trees selected for study were of the Rhode Island Greening variety. 
