of extension between points of contact
with scion and stock. The second point of value consists in allowing the
actinic ray in the sunlight to act upon the chlorophyl in bud and bark
of the scion and it does not attract the destructive heat ray. This is
perhaps the most important single point of value and due to the
transparency of the paraffin. Third, the paraffin coating, impervious to
air, maintains the sap tension equally in the course of fluctuation
between negative and positive pressures occurring between night and
day, and under varying conditions of light and temperature. This
maintenance of equalised sap tension, I believe to be important. The
paraffin is waterproof and prevents evaporation from the scion, which
otherwise is prone to dry out before granulation of the wound has taken
place in the hickories, as in other species which callus slowly. Fifth,
under the paraffin coating of stock and scion, the plant apparently does
not have that anxiety which would otherwise lead it to introduce the
protective feature of superization, the spreading of a corky layer over
the wound surface between stock and scion, thus introducing a mechanical
obstacle to union.

This method of grafting has extended the grafting season for nearly two
months, apparently. Formerly, I hurried to get all of the grafts in
while buds were bursting, in early May. During the season of 1919 I
grafted hickories up to August sixth experimentally. The last grafts
which caught well in a practical way were put in on July twenty-first.
After that the proportion of catches was small and the growth feeble.
Incidentally, it may be remarked that filberts grafted as late as August
sixth, did perfectly well. The scions employed were cut in late winter
and kept in the sawdust of my icehouse. I formerly supposed that ice
beneath the sawdust was important, but this year I could not get ice and
the scions kept just as well. In July, experiments were tried with
grafting directly from one tree to another, using wood of the season's
growth. This worked well with hazels, but not with hickories or walnuts,
only one out of many hickory grafts catching. That one, however, is
significant and I hope to work out principles which will allow of direct
grafting of hickories as readily as may be done with the hazels.

When a hickory graft is to be inserted into a small stock or branch, the
ordinary cleft graft does well. In stock recipients much larger than the
graft a sid