42 



Both species of Tilletia appear to have about the same temper- 

 ature ranges for infection, although the results apparently 

 indicate that infections with Tilletia laevis may be obtained at 

 somewhat higher temperatures than with T. tritici. These 

 experiments were carried out with both fall sown and spring sown 

 varieties and there was a fair correspondence between the results. 

 Other factors, as the influence of growth conditions, subsequent to 

 seed germination, the influence of the rate of germination of wheat 

 and the influence of soil moisture were also studied. Preliminary 

 data were secured bearing upon the question as to the existence of 

 specialized races of these two parasites. 



Report on Chestnut Bark Disease Investigations. By Arthur 



Harmount Graves 



As already noted {Brooklyn Bat. Card. Rec. 12: 40, 1923, and 

 13; 27, 1924) certain wild chestnuts in New York City and 

 immediate vicinity show a partial resistance to the bark disease. 

 During the past year, as far as time would permit, the inquiry 

 has been pushed further as to the cause of this resistance. Repre- 

 sentative trees at Inwood, Manhattan, at HoUis, Queens, and 

 at Valley Stream, I.. I., have been selected, and their bark is 

 now being analyzed under the Direction of Dr. ¥. P. Veitch, of 

 the Leather and Paper Laborator}^ Bureau of Chemistry, 

 U. S. D. A. I^ark of similar trees, apparently non-resistant, 

 from West \'irginia, collected by Dr. Dow V. Baxter, U. S. D. A., 

 and from liamden, Connecticut, and North Windham, Maine, 

 collected by the writer, is also being analyzed for comparison 

 in its chemical content with that of the resistant New York trees. 

 I'^rom these comparative chemical anal^'ses it is hoped to obtain 

 some light on the cause of the resistance of these remarkable 

 New York trees, some of which are still In good condition and 

 bearing fruit. 



For many years it has been obser\ed that apparently healthy 

 basal or coppice shoots develop from the bases of diseased trees 

 or from their cut stumps. These shoots continue their growth 

 sometimes for many years and ha\'e attracted such general 

 notice as to have given rise to the popular impression that the 

 chestnut is "coming back." Experiments were begun during 



