82 MASSACHUSETTS HORTICULTURAL SOCIETY 



argument from one species to another is only an argument from 

 analogy. The main fact to consider in the present connection 

 is that we have no evidence that any weakness or loss of vitality 

 predisposes the chestnut tree to the bark disease ; nor any evidence 

 that seedling trees are more resistant than coppice. 



If weather or other environmental conditions have favored the 

 disease at all, it is more reasonable to suppose that the effect is 

 on the parasite rather than the host. On purely a priori grounds, 

 it is not an unreasonable hypothesis that meteorological conditions 

 might induce the development of parasitic characters in a sapro- 

 phyte; but this again is pure hypothesis. 



However, further research may be expected to reveal the facts 

 regarding both origin and relation to environment. In any case, 

 the origin of the disease is not a matter of practical moment, unless 

 the parasite can be shown to be now evolving from a native sapro- 

 phyte in many localities. The main things for the practical man 

 to consider are that the disease is here; that it has been rapidly 

 spreading for at least ten years, with no signs of stopping; that 

 judging by the record of these years we definitely face the possi- 

 bility of the commercial extinction of the chestnut; that judging 

 by this same record the disease will spread farther and faster during 

 the coming year than in any previous year; that we have the option 

 of doing nothing or of attempting to control the disease; and that 

 if any concerted action is to be taken it must be taken now or 

 never. 



The Control of the Disease. 



We are handicapped at the outset by lack of knowledge. The 

 damage already done by this disease is enough to warrant the most 

 radical views of earlier years and radical action now; but, as a 

 matter of fact, astonishing conservatism has prevailed regarding 

 the seriousness and the contagious character of the disease. In 

 consequence but few investigators have worked on the disease, 

 the impression prevailing that it was due to weather conditions 

 and would soon disappear naturally, and hence was not worth spe- 

 cial attention. What experiments on control have been made were 

 started too recently to give results that are dependable at this time. 



