CHESTNUT BARK DISEASE. 413 



of the field has not disclosed any fungous disease that seems 

 to be importantly connected with the condition of the trees." 



NATIVE HOME OF THE FUNGUS. 



General Considerations. Previous to the work of Merkel and 

 Murrill, no one had ever, so far as known, collected or 

 described the true chestnut blight fungus. Its sudden and 

 destructive appearance naturally leads to the question, Where 

 did it come from? Murrill has not tried to solve this problem, 

 although we understand he at first believed it to be a native 

 species. The writer is the only one who, claiming it a native 

 species, has attempted to give definite reasons for the belief, 

 and an explanation of its sudden and aggressive development. 

 Others have come forward with the suggestion that it is an 

 introduced parasite, brought in accidentally, either from Japan 

 or Europe. They have been led to their belief apparently 

 largely because the blight was reported at first from a restricted 

 region around New York City, and has apparently since then 

 spread from this center into the regions in which it is now 

 known. We shall consider in the following paragraphs each 

 of these possible habitats for this fungus. 



Japan. Metcalf has suggested most definitely that the fungus 

 originally came from Japan, and Marlatt (31), following this 

 suggestion, gives the blight as one of the most striking examples 

 of "why we need a national law to prevent the importation 

 of insect-infested and diseased plants." Metcalf 's (33*, p. 4) 

 first statement concerning the native home of this fungus is as 

 follows: "The immunity of the Japanese chestnut, together 

 with the fact that it was first introduced and cultivated on 

 Long Island and in the very locality from which the disease 

 appears to have spread, suggests the interesting hypothesis that 

 the disease was introduced from Japan. So far, however, no 

 facts have been adduced to substantiate this view." Later, 

 Metcalf and Collins (36, p. 46) say: "Investigations are in 

 progress to determine the origin of the bark disease in America, 

 and the details regarding its spread. The theory advanced in 

 the previous publication of this Bureau that the Japanese chest- 

 nuts were the original source of infection has been strengthened 

 by many facts. It lacks much of demonstration, however, and 



