OAKS TRAINED TO PRODUCE CORK 
ately begins to put on a new outer skin to protect 
itself. 
Strangely, this new skin is not like the old. It is a 
thick, spongy layer. It is allowed to grow for eight or 
ten years; then it too is ripped off to just the right depth. 
This layer, however, is not yet cork. Ten more years pass 
and, at the age of forty-five, another layer of skin is taken 
off the cork tree. This layer is almost cork. It is good 
enough for fishermen to use on their nets to float them, 
but not good enough for bottle stoppers. 
Finally, when the oak tree is in its fifties, it is stripped 
for the fourth time. This time the bark is fit for its 
choicest uses. Each ten years for half a century after 
this, the cork layer is removed, and each time the tree 
puts on a new layer to protect itself. In the end, how¬ 
ever, it tires of its labor, becomes unprofitable, and the 
cork farmer cuts it down. 
Some decades ago, when California became a wine- 
producing State, she worried considerably about what 
would happen if the foreign supply of cork should be cut 
off. Cork oaks were brought to California and planted. 
They grew well on the foothills of the Sierra Nevada 
mountains. Thus the United States has laid the basis 
for growing its cork at home if it ever finds it necessary 
to do so. 
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