mall glass vials loosely stoppered with cotton.

Two lots of Corylus pollen of 80-1/2 and 96-1/2 initial viability
respectively, and one lot of Juglans Sieboldiana pollen of well over 50%
viability were used in the experiment. Storage temperatures of 0 deg. 40 deg.
and 10 deg. were used.

The Corylus pollen was placed in storage March 20, 1942, and the Juglans
April 12, 1942. The pollen was taken out of storage November 28, 1942
and germinated on the standard agar-sugar medium at 25 deg. C. for 24 hours.
Results are given in table II.

Table II. The effect of storage temperature and humidity on
percentage germination of Corylus and Juglans pollen

------------------------------------------------------------------
Kind of Temperature Degrees Per cent relative humidity
Pollen Centigrade 10 20 30 40 50 60 70 80
------------------------------------------------------------------
Corylus 10 deg. 0 0 0 0 0 0 0 --
Juglans -- 0 -- 0 3 0 0 --
Corylus 4 deg. 0 0 0 0 9.0 0 -- 0
Juglans -- 0 -- 0 -- 0 0 0
Corylus 0 deg. 3.0 1.0 4.5 8.5 0 0 0 0
Juglans -- 0 -- 12.0 -- 12.0 0 0
------------------------------------------------------------------

This preliminary work indicates that Corylus pollen can best be stored
at 0 deg. C. at 30 to 40% relative humidity and Juglans pollen at 0 deg. C. at
40 to 60% relative humidity.

_Summary_

1. The optimum sugar concentration for germination of Corylus pollen is
around 25% by weight in 1.5 per cent agar at 25 deg. C.

2. Forcing the catkins at a low temperature (4 deg. C.) and at high relative
humidity (80%) favors the development of a high percentage of viable
pollen.

3. The catkins contain some substance which when added to the
germination media inhibits pollen germination and causes abnormal types
of germination.

4. Preliminary results on pollen storage indicate that Corylus americana
pollen can be stored for eight months or more in a viable condition at
0 deg. C. with a range of 30 to 40% relative humidity. Juglans Sieboldiana
pollen can be stored at 0 deg. C. at 40 to 60% relative humidity. Whether or
not pollen stored for this length of time would be effective in plant
breeding should be tested by actual trial. The suppositio