THE MONTHLY BULLETIN. 



295 



and sudden wilting of the branch beyond, both effects being character- 

 istic of the disease as it occurs naturally. Similar cuts made in another 

 part of the same tree in healtliy limbs, without the insertion of the 

 fungus, healed up perfectly without producing any cankers or causing 

 any black sap to run out. One of these inoculations may be described: 



Fig 63. — ^Walnut trunk showing the location of a 

 large Melaxuma canker which had been cut out and 

 treated with Bordeaux paste the year previous. 

 (Original.) 



It was made on July 31st, into a limb 2^ inches in diameter and had 

 produced in less than two months a canker 2^ inches long and 2 inches 

 across, and the black sap was rimning down and staining the bark below. 

 Pure cultures of the same fungus as was put in were isolated from the 

 outer edge of this canker. A considerable number of similar inocula- 

 tions giving similar results proved conclusively that this fungus was 

 the causal agent in producing the disease. 



