Growtubes

[David Sears]

Does anyone know anything about a device called a "grow tube" used to
accelerate
the growth of timber?  I saw a little segment on an educational tv show
about
how they are using them in South America.  I only saw the show in passng
and 
couldn't tape it and I would like some more info.  If you can tell me where
to look I would appreciate it.  Thanks.

-- 
David Sears
Vanderbilt University
Searsdw at ctrvax.vanderbilt.edu