103 



Dll. MElUvEL: Then, apparently, the cleaii-ciittiiig in tliis 

 case, unfortunately, is not a proof that tlie fungus can be kept 

 out, because it has not been present long enough; is that the 

 idea? 



rROFESSOK DAVI.S : Yes. 



DR. A. K. FISIIEll, of the iinreau of Biological KSnrvey, 

 Washington: Mr. Cliairnian: I would like to ask Dr. Stewart 

 what evidence he has to show that birds are important factors 

 in spreading the disease? Dr. Metcalf made that statement 

 in the Farmers' Bulletin, that birds were one of the important 

 factors in sx)reading the blight, but, in private conversation 

 with the doctor, he stated that he had no positive evidence; but 

 that birds traveled here, hence, thence, and he thought it most 

 probable. Now the very birds which are accused of carrying 

 blight are the woodpeckers, which are more or less stationary in 

 their life historj^; especially the downy woodpecker. There is 

 no vay of telling just how far a bird will go from the nest in 

 which it was born, but there is pretty good reason to believe that 

 the downy woodpecker never goes over four or five miles from its 

 home. In fact, a woodland of a few hundred acres will hold a 

 pair or more of birds, which probably Ijve there throughout their 

 lives. I know of one or two pairs near Washington that we are 

 reasonably sure to see at any time of the year. It seems to me 

 that wind and weather, which carry other forms of diseases, are 

 very much more liable to carry the germs of this disease. When 

 wind will carry heavy articles a thousand miles and, it is said, 

 carry volcanic dust half way around the glol)e, it seems to me 

 that we do not have to look to birds or nmmmals, or even in- 

 sects, as the means of spreading the disease, when other known 

 factors are present. 



THE CHAIRMAN: Dr. Fisher asks Dr. Stewart what evi- 

 dence he has that birds are responsible for carrying the chestnut 

 tree blight. 



DR. STEWART: The evidence is largely inferential. This 

 should be considered: Many of the infections, — in fact. Dr. Met- 

 calf states a majority of the infections, — occur in the tunnels 

 made by borers. The borers are in tliose tunnels, Wood]>eck- 



