608 BULLETIN 347 
ment of Agriculture, as being very active in eating spores of the blight 
fungus. Therefore this beetle while destroying spores of the blight is 
at the same time covering its body with thousands of other chestnut 
blight spores which it carries from tree to tree, making it probably an 
injurious insect instead of a beneficial one in this respect.” 
Protection measures 
The only experiments reported on spraying were those of Merkel and 
the Pennsylvania Commission. The single application of bordeaux 
mixture made at the New York Zoological Park by Merkel in 1905 failed 
to check the disease. The Pennsylvania Commission conducted spraying 
experiments at Kenneth Square, Pennsylvania. Bordeaux mixture 4-4-50 
was applied with a power sprayer every two weeks from April until the 
middle of November, 1912. No definite results are reported from this 
experiment (Penn. Chestnut Tree Blight Com., 1913:51, Figs. 53-55). 
Immunization measures 
Many writers have suggested the possibility of selecting and breeding 
immune varieties. Morris (1914) sums up observations on different 
varieties planted among affected American chestnuts. Van Fleet (1914) 
has found Asiatic chinquapin hybrids promising. With the relatively 
high degree of resistance shown by the Japanese and Chinese chestnuts, 
there may be a possibility of breeding within these varieties. Crosses 
with the American chestnut seem hopeless. Metcalf and Collins (1911: 20) 
write: ‘‘ If the seed [of Japanese chestnuts] is raised in America, the 
trees are more than likely to be hybrids with the American chestnut 
and to vary greatly in resistance to the bark discase.”’ 
The investigators of the Pennsylvania Commission applied many kinds 
of fertilizers around trees and carefully recorded the effect on the rate 
of growth of cankers. At Mount Gretna, Pennsylvania, the following 
substances were used in different combinations and quantities: burned 
lime, nitrate of soda, acid phosphate, muriate of potash, and kainit. 
At Emilie, Ambler, and Valley Forge, Pennsylvania, iron filings and coal 
and wood ashes, in addition to the substances mentioned above, were 
applied. At Mount Gretna the trees were old and thick-barked. The 
cankers were outlined in spring at the time of application, and again 
in late fall. When the measurements were compared with the checks 
no differences were found except within the limits of the usual variations. 
In the experiments at Emilie, Ambler, and Valley Forge no variation 
on rate of growth of cankers was obtained. 
Also, at Emilie many secret preparations, applied as fertilizers or as 
injections, were tried. These were methods advocated by various laymen 
