n I placed the grafts that I had to quit and
get out of the sun. In spite of that 100% grew.

A study of the above record leads to the conclusion that there is very
little difference in plant and animal cells and it seems clear that
certain old, underlying principles must be dealt with. I need not refer
to heredity because, while it is undoubtedly quite possible, perhaps,
to influence heredity tendencies so as to get stocks to accept scions
more readily, it is not the major issue for most of us just now. Next
spring we will take what heredity has given us and be satisfied.
However, it appears certain that our results in grafting the various
stocks we now have will depend largely on our ability to:

1. Regulate plant circulation.
2. Stimulate cellular activity to a point compatible with wound
repair, defensive and growing processes.
3. Control plant cell nutrition.

One of the very first things we physicians do upon seeing a patient is
to investigate his circulation. If the pressure is too low or too high,
for any reason, we immediately take measures to correct it, because we
know that disastrous results will quickly follow if that is not looked
after. Plant circulation, or sap flow, is no less important. Mr. Riehl,
Mr. Jones and Dr. Morris made great strides when they advanced the ideas
of covering the wound and the scion completely to prevent evaporation,
thereby also controlling the sap pressure. With the exception of
shading, pruning and defoliating, this is about the only method we have
of preventing evaporation. Defoliation, of course, interferes with the
tree's power of growth. Controlling the humidity is probably not
practical on a large scale.

A proper and careful cutting of the tree beforehand is important. It
appears that to cut the top completely out while the tree is dormant, so
disrupts the routine circulation that the few lower branches which are
left intact, are well taken care of and, it seems to me, that this,
together with the stimulation of WOUND REPAIR by cutting and allowing
time enough for the cells to get into action, was the prime reason for
the 100% success in the three Hales and the cause of the 100% failure in
the other Hales tree.

Other methods of controlling the circulation are of course drainage,
irrigation, mulching, location of the orchard, placing of condensers of
moisture, such as stones and other hard substances beneath the trees,
and many other contrivances which a