cions
in warm water, replaced them and refilled the tubes with pure glycerine.
I submerged a thin, zinc tag, stencilled with the varietal name and bent
to conform with the contour of the tube, inside of each one as a name
plate which could not easily be lost or removed. I also labeled each
cork with the name of the variety enclosed so that any one of them
could be located when looking down at a nest of tubes in a vertical
position.

In order to display these preserved specimens at illustrated lectures, I
had a rack made of redwood, of a size to hold twenty tubes. The tubes
could easily be taken from the rack for closer observation by members of
an audience. I find this to be an interesting adjunct to various nut
culture exhibits I make in trying to promote nut culture education.

Since I was able to identify my unlabeled, hickory grafts by means of
this catalogue of submerged scions, I consider it of great practical
worth. At the present time, I have about 50 hickory specimens, a good
catalogue, although not a complete one. I see no reason why the same
thing could not be done with black walnut or any other kind of nut
scions.

Chapter 20

HYBRIDIZING

Working with nature to develop new varieties of trees is fascinating
although it requires infinite patience and study combined with skill and
concentration. A person without experience may taste of this pleasure,
however, by trying his hand at cross-pollination, and there is no end to
the number of hybrids possible.

In attempting to make crosses, one must necessarily understand the
botanical relationship between the trees to be crossed. Trees of the
same species cross readily in almost all cases; trees of the same genus
are not as easily crossed; trees belonging only to the same family are
usually difficult to cross. It is generally assumed that trees not in
the same family are impossible to hybridize. The plum serves as a
practical example of this. The American wild plum crosses readily with
almost any other plum and particularly well with the Japanese plum.
These crosses have resulted in such phenomenal fruit as the Underwood
plum, a cross made between species. If a cross were made between a
chestnut and a walnut, it would be between members of different
families. I recommend to anyone who is attempting to cross-pollinate for
the first time, that he limit his work to crosses made within species.
His chances of success will be greater and such success add