THE ROOT 69 
the stele is the pith, a large-celled tissue appearing 
something like the cortex. There is no difficulty in 
observing all these details provided the section is cut: 
thin enough. Don’t try to cut the section as you 
would a slice of bread, but just slide the wet razor 
along the flat surface of the severed end without trying 
to cut anything, and then, by accident as it were, you 
will get a slice sufficiently thin. 
The functions of the wood and bast may to a certain 
extent be observed. Hang a young bean plant with 
the lower parts of its roots dipping into a solution of 
eosin or red ink. After a few hours cut sections, 
beginning a little way above the root tip, and examine 
these with a good lens. It will be found that the red 
colouring matter has passed into the root hairs and 
made its way through to the vessels of the wood, and, 
above a certain point, it is only in these vessels that 
it will appear. By eutting further sections the path 
of the coloured liquid may be traced upward along 
the vessels from root to stem. Moreover, if some of 
the plants be left long enough in the solution, the red 
colouring matter will appear in the veins of the leaves, 
showing that these are continuous with the wood vessels 
of root and stem. It is therefore evident that the 
function of the vessels of the wood is to conduct water 
containing dissolved minerals from root to leaves. 
The funetions of the bast and cortex, though not 
a simple thing to demonstrate in the ease of either 
root or stem, are more easily investigated in the latter. 
Ring a braneh of a tree (2.e., cut away the cortex and 
bast). Leave the tree for a year and examine the 
branch again. It will be found that below the ring 
there has been no inerease in girth, while above, 
development has proceeded almost as before. The 
absence of growth below the ring indicates that the 
nutritive materials built up in the leaves were unable 
to pass the cut and hence must have formerly travelled 
