84 



plant was for the second time tided over by a single dose of active 

 antigen. 



No. 113 — Aug. 4^ '25. Tree one inch in diameter and healthy. 

 Native American. Received antigen on this date. 



Oct. 26, '25. Tree healthy but of course do not expect one dose to 

 protect. 



May 1, '26. Grnfted to Merribrook, — a native American. 



May 4, '27. Injected. No evidence of blight. 



May .30, '27. Injected. No evidence of blight. 



Sept. 2, '27. Tree apparently healthy, but has not made mucli 

 growth. This tree evidently withstood two injections of inactive anti- 

 gen witli no noticeable untoward results other than probably a stunted 

 growth. It will be interesting to watch its future performance, es- 

 pecially if it becomes infected. 



The action of No. 103, whose bud became infected, would rather in- 

 dicate that the action had not received much resisting quality from the 

 stock. Neither did it have any before being placed, as it was taken 

 from Fuller, a non-resistant tree. This may be interesting in con- 

 nection with the idea which some of us are entertaining of placing 

 grafts of the finer American chestnuts on the stock of the more re- 

 sistant mollissima. I might also mention that the performance of this 

 bud was similar to others placed on the Chinese stock — the bud having 

 become infected and killed the scion during the second year, as well as 

 part of the limb of its host. 



Any one who has seen the above experiments and is familiar with 

 tlie conditions in our blight infected district could scarcely draw any 

 other conclusion than that chestnut trees will immunize under induced 

 antigen. The main question then is simply to carry it to a point at 

 which it will inhibit the progress of the invading fungus, or destroy it. 

 This I am optimistic enough to believe will come about in due season. 

 I, for one, am willing to wait the outcome. 



The question has been asked time and again, "What is this material 

 you are using?" It is an antigen, prepared from the dead bodies of 

 Endothia parasitica, a fungus which invades and destroys the cambium 

 layer of the chestnut tree, and is recognized as the cause of this per- 

 plexing situation which lias j^laycd liavoc with our cliestnuts and de- 

 stroyed our finest timber, to an extent that is incomputable from a 

 monetary' standpoint. 



