EXPLANATION OF THE PLATES. 
237 
l to c. Fibres less numerous, less thick, less compact, 
and less hard. 
c to d . Weak fibres at a greater distance from one ano- 
ther: in the centre of each of which there is a tube which 
has been filled up in the fibres a to b and b to c. The cel- 
lular tissue is evidently more considerable in this part than 
in the space b to c, and still more than in the space a to b 9 
where the wood predominates. 
e. The oldest fibres. 
f. The fibres of a middle age. 
g . The youngest fibres. This arrangement shows that 
the growth of the wood is entirely different from that in 
the stem of dicotyledon plants. 
h. Union of the woody fibres as they run along the stem* 
Fig. 5. Vitis vinifera. Viniferce. A vertical and dia- 
metrical section of a young branch magnified. 
a to b. Bark. 
b to c. Wood. 
c to d. Pith. 
e. Woody fibre of the bark. 
f. Medullary rays. 
g. Cellular tissue, constituting the solid part of the wood* 
h. Large porous or slit tubes. 
i. A double trachea, or air vessel. 
k. Cells of the pith, 
L Porous cells. 
