The Individual Plant 
experiments to trace this process of self-surgery. Leaves 
were cut in various ways or pieces punched out of them, 
and sometimes they were only bruised at one point.’ 
In many cases, everything outside the injured tissue 
was deliberately sacrificed, the living protoplasm acting 
like an army whose outpost line has been suddenly 
surprised, and which deliberately abandons its advanced 
posts and entrenches itself behind a new layer of im- 
provised cork cells. Something of the same sort happens 
regularly before the fall of the leaves in autumn. Not 
only a cork scar is formed across the bases of the leaf 
stalks, but a special separation layer is formed outside 
the cork, and the dead leaf drops away from the clean, 
corked-in scar. Many curious cases, in which injured 
or worn out parts of the stem itself have been deliber- 
ately cut off by cork scars and thrown away, have also 
been described. There are other well-known cases in 
which one is much impressed by the readiness for any 
emergency of every live cell in the plant body. 
In the stem of Liquidambar (or Balsam of Tolu), for 
instance, the younger wood cells will be peacefully per- 
forming their usual duty of assisting to raise the sap or 
of filling themselves with temporary stores of starch or 
other reserve food material. A sudden emergency arises, 
for some one has made a deep cut or slash through the 
bark and into the young growing wood tissue. 
The cells at once begin to secrete resin, which at 
first fills the intercellular spaces, forming small canals 
or ducts ; then the cells begin to break down, and a net- 
work of such resin canals is formed, which pours an 
abundance of secretion over the wounded surface, com- 
pletely covering it over andsealing itup. Other cells, in 
the cortex, at once begin to make a cork cushion, which 
gradually and slowly grows inward over the wound.’ 
The future of and the claims upon every living cell 
between the dead outside cork and the dead heart wood 
154 
