414 CONNECTICUT EXPERIMENT STATION REPORT, 1912. 



is still advanced only tentatively. * * * Chester's Cytospora 

 on a Japanese chestnut noted at Newark, Del., in 1902, may 

 have been the bark disease." 



Recently Metcalf (35, p. 222) remarks: "Its origin is 

 unknown, but there is some evidence that it was imported from 

 the Orient." Later, in answer to a direct question as to its 

 origin, he adds (p. 227) : "That is exactly what we would like 

 to know more about. The fat that the disease has obviously 

 spread from a center leads me to believe that it is an importation 

 rather than a disease which has developed here. The fact 

 that the locality from which it has spread is the same locality 

 into which the Japanese chestnut was first extensively intro- 

 duced, that the Japanese and Corean chestnuts are highly 

 resistant, and are the only varieties that are at all resistant, all 

 suggest the hypothesis that the fungus parasite may have come 

 from the Orient. However, the origin of the parasite is not 

 a matter of practical importance, unless it could be shown that 

 the fungus parasite is developing spontaneously in many locali- 

 ties from some native saprophytic form, in which case the 

 difficulties of control would be greatly increased." 



In the preceding, Metcalf brings out four points in favor of 

 the Japanese origin of the fungus, as follows: (i) Immunity 

 of Japanese and Corean chestnuts; (2) Outbreak of disease 

 originally in Long Island, where Japanese chestnuts were first 

 imported; (3) Spread of the disease from a single center: 

 (4) Possibility of Chester's Cytospora on Japanese chestnut 

 being the blight fungus. Let us take up these four points for 

 further consideration. 



(i) The immunity of Japanese chestnut does not necessarily 

 mean that this fungus occurred on it in Japan, and when brought 

 to America spread to the American chestnut, and, finding it a more 

 favorable host, caused the serious outbreak here, as Metcalf 

 suggests. It may merely mean that the Japanese is a more 

 hardy species. From the statements of Morris (13, p. 43) we 

 take it that this is the case, since it is only the Japanese or Corean 

 varieties from the more northern regions that show this resist- 

 ance. Recently it has been found that the Japanese chestnut 

 is highly resistant to the black canker, a serious chestnut disease 

 now causing trouble in France. Arguing along Metcalf 's theory, 

 one could say that this French fungus was of probable Japanese 



