85 



Mr. Bixby: I had reference also to applying the antigen after it 

 had been made. 



Dr. Zimmerman: I have tried a number of metliods. This year 

 I went so far as to make a can and to put on it the valve stem of a 

 bicycle tube, expecting to force some material right into the cells of the 

 tree under air pressure. My experience has been that they immunize 

 better if it is put on the cambium. My method is the same one I 

 spoke of last year. I make an incision across the tree. It is best not 

 to make it too far around the tree, because if it becomes infected the 

 blight goes around the tree and it has not to go far. Then I make 

 another incision at right angles about 6 in. long. Then I take the 

 knife and just raise the edge of the bark from the cambium on either 

 side. Then I fasten over it a piece of paper, with hot paraffine. That 

 makes a little cavity on the inside. With a medicine dropper I fill 

 that cavity with the antigen, then seal it with paper and paraffine. 

 Now I want to mention something else I have found. It is practically 

 necessary in treating a diseased tree to have an autogenous vaccine. 

 I found that in animal and human experimentation, and it is also 

 necessary in plant experimentation in order to get results, in lots of 

 cases. If there is any life left in a tree worth considering, it is possi- 

 ble to control the blight with an autogenous vaccine made from the 

 germs in that tree. 



There are other things besides blight that kill trees. I dug 

 down to the roots of a tree and I found a chain lying there. The tree 

 had grown up through the chain and it restricted nutrition. 



Mr. Reed mentioned the weevil. I have a great deal more con- 

 fidence in my ability to immunize a tree against the blight than I 

 have to take care of the weevil. 



Mr. Bixby : Do I understand. Dr. Zimmerman, that by autogenous 

 vaccine you mean for each tree you make up a specific vaccine from an 

 infection on that tree itself? 



Dr. ZiMMERAfAN: Yes. that is what I have planned to do. I 

 have selected the verv best chestnut varieties I can wet. I consider 

 the Fuller as first, then the Boone, the Dan Patch and the McFarland. 

 I am very partial to the McFarland, not only on account of the quality 



