11 
The first generation plants of 32 later crosses were grown. The 
original hybridizing had been done by Miss Jeanne P. Walther 
in 1942. The parental varieties used in these crosses differed in 
their reaction to known physiologic races, and the data on the 
behavior of the second generation of the hybrids will be obtained 
during the coming year. 
CHESTNUT BREEDING WoRK IN 1943 
By ArTHUR HARMOUNT GRAVES 
This project has been fully explained in previous reports, but 
for those who are unacquainted with it I might say briefly that 
by breeding and selection we are endeavoring to develop a new 
chestnut stock which shall be of tall timber type and at the same 
time immune (or as nearly so as can be) to the dread blight which 
has killed off practically all chestnut in its natural range in the 
eastern .U. S. 
Breeding Work in 1943—Since the report of this year’s work 
must be brief, | shall say only that the crossing of our hybrids 
with each other and back crossing of them with resistant Japanese 
and Chinese individuals has gone on as usual. In early October 
we gathered 365 nuts, presumably all of hybrid nature, from these 
crosses. Most of these have been planted in pots in cold frames 
at the Hamden plantation, but a few are in the Garden cold 
frames. 
Inarching of Basal Shoots of Hybrids —We have continued the 
practice, explained in my report for 1941, of keeping our F1 
hybrids in a vigorous condition by inarching the basal shoots, 
thus bridging over lesions caused by the blight fungus. Nearly 
all of the grafts of this sort made this spring were successful, so 
that we have on hand a good supply of fine breeding stock. 
Hybrids of 1942.—This year the young trees resulting from the 
hybrid nuts of 1942 were set out according to pedigree in a special 
nursery: that is, the trees resulting from each particular cross 
(called, technically, ‘‘sibs’’) were planted in sequence in the rows 
in order that their behavior might be compared. Of these 
seedlings I selected at the end of the season, in mid-September, 
about 50 trees which had attained a growth of 2 feet or more, 
im 
