s from mature trees.

3) Prune leaves and probe to the growing cone without damage to tissue.

4) Pack a small wad of cotton into the terminal point.

5) Soak this cotton by dropping .2% aqueous solution of colchicine on
same.

6) Add glycerine to cotton to improve penetration of colchicine.

7) Place drop of colchicine on cotton morning and evening for four days.

8) Remove cotton wading from bud on 5th day.

9) If sufficient tests at hand, allow cotton to remain on some buds.

10) Try for at least one hundred buds treated.

11) Observe growth during first season and also next season.

12) If treated bud dies, watch for growth among lower laterals.

13) Evidence of changes appears in the new leaves, darker, thicker,
greener.

14) Conclusive evidence of doubling rests with microscopic and
anatomical analysis which is a task for trained technicians only.

The above procedures are suggestions for a start and everyone will wish
to make changes suited to his particular needs. The concentration of
colchicine need not be exact as in an analytical experiment in
chemistry. One gram dissolved in 500 ml. water is an adequate and a
sufficiently careful measurement. The local pharmacist or physician is
well acquainted with colchicine in the practise of medicine since this
drug is a standard for gout.

Effective use may be made from two specific areas of plant breeding.
First, doubling of chromosomes changes sterile hybrids into fertile
individuals. This is a promising field and whenever such hybrids are
discovered, efforts should be made to apply the colchicine technique.
Second, doubling of the chromosome number makes possible hybridization
of individuals heretofore unsuccessful in such effort. In both instances
germ plasm of wide genetic difference is incorporated into a new
propagating breeding stock. In the case of the sterile hybrid
transformed into fertile individuals, no counting of chromosomes is
necessary because restoration of fertility is evidence of changes in the
chromosomal makeup. However, the second type of experiment requires
microscopic analysis.

There are a number of fundamental research problems in the plant
sciences associated with the treatment of plants with colchicine. From
horticultural subjects such as the apple,(3) pear, cranberries,(4) and
grapes, it is obvious that periclinal chimeras will be of prime
importance in analysis of results in treatment of nut trees. Following
the treatment