48 
Oyster Bay region where three of the Japanese parents are grow- 
ing, some in clean gravel, and the rest ina mixture of sand, garden 
foam, and leaf mold. They have been kept in the cool propagating 
house, and up to the close of the year there has been no indication 
of germination, although most of the nuts seem sound. 
The most significant thing shown by this large harvest is the 
demonstration that with persistence and properly timed effort 
plenty of crosses can be made between the American and Japanese 
The methods used have already 
species and sound nuts secured. 
resume will be 
been described in my report for 1930, but a brie 
given here. A reference to Fig. 3 will make the situation clearer. 
The chestnut trees to be pollinated must be visited before the lower 
or staminate catkins have commenced to shed their pollen. At 
this time not only these catkins, but also the part of the andro- 
ynous catkins above the pistillate flower clusters (the latter in- 
dicated by the white arrows) must be cut off, and the remnant of 
the branch, now bearing only the pistillate clusters, enclosed in a 
lays later, when the pistillate clusters are presum- 
— 
~ 
bag. A few « 
ably receptive, the tree is again visited, the bags removed, and the 
pistillate flowers rubbed gently with staminate catkins taken from 
an American chestnut tree. The bags are then replaced. To 
increase the chances of fertilization, this operation is repeated once 
or twice more, at intervals of from three to six days, and then the 
bags are left on until no more pollen is being shed by the other 
flowering branches of the tree. In September the nearly mature 
burs are again enclosed in the bags in order to prevent loss from 
their dropping to the ground or shedding their nuts. Tinally, 
when the burs have opened inside the bags, the nuts are collected. 
The whole process necessitates six or seven visits to the tree 
Table Hil presents a time-table of the crossing work in 1931. 
Sources of the American Pollen.—Since the times of flowering 
of the Japanese trees are in most cases earlier than the flowering 
period of the native chestnut in this vicinity, it 1s necessary to use 
pollen shipped from a more southern latitude, where the American 
chestnut blooms earlier. Generous quantities of this American 
pollen were shipped to us at the proper time by the Division of 
For est Pathology, U.S. Department of Agriculture, Washington, 
D. C., and also by iis Ohio Agricultural Experiment Station, 
