527 
Development of Mechanical Tissue. 
years is 36J, only a trifle more than the average of all of 
them for 1891. If fruit-bearing was the principal factor 
in reducing the amount of wood, we should expect its effects 
to appear more strongly in 1892 than in 1893; but more 
wood was formed in both 1891 and 1892 than in 1893. 
Peach . — The material for the study of the Peach was 
collected while the ripe fruit was still on the tree. Some 
of the shoots used bore two peaches, so near together as to 
be almost opposite. The vegetative shoots were selected as 
nearly like the fruit-bearing ones as possible, and of course 
of the same age. Sections near the base of the fruit-stub, 
as well as from points above and below the fruit, were studied. 
Measurements, with one exception, were made from sections 
cut about 2 centimetres below the attachment of the fruit. 
This avoided the local effect of fruit-bearing. 
The peach is borne on the shoot making its second season’s 
growth. It is supported by a rigid stub 2 or 3 millimetres 
in length. This stub is remarkable for the great amount of 
mechanical tissue it possesses. The wood-cylinder is dense, 
the walls of the wood-fibres are thick and well lignified. 
The modifications described above for the Plum also occur 
in the Peach-shoot. Just below the stub the stem is swollen 
and the tissues have the greatest development on the side 
toward the fruit. This irregularity is local ; at a distance of 
1 to 2 centimetres it has entirely disappeared. 
Great care was taken to cut the sections for measuring the 
tissues from points as closely comparable as possible and to 
have the shoots alike in size and vigour. All the shoots 
used were two years old. The tables which follow show 
that, in the Peach, fruit-bearing certainly does not produce 
a weak development of xylem. The effect is local and is 
confined to a very limited area. The proportion of xylem 
in the fruit-bearing shoot is greater than that in the vegeta- 
tive, while the proportion of cortex is greater in the latter. 
The cortex in the fruit-bearing shoot of both the Plum and 
Peach is not as well developed as in the corresponding shoots 
of the Apple and Pear ; the proportion of pith is smaller in the 
