PLUMS : THEIR CULTIVATION AND VARIETIES. 107 



planting as ornamental trees, exceedingly subject to the black 

 knot, and he advised caution in planting them. He recommended 

 the Drap d'Or as a very fine early plum for family use ; it is too 

 small for the market. He did not agree with the essayist that 

 Smith's Orleans is only of fair quality ; he thought it one of the best. 



President Walcott said that the black knot has close analogy 

 with some diseases in man, and, as with those, there are two points 

 to be considered — first the cure of the individual, and second, 

 the proper healing of cut surfaces so as to exclude infection. A 

 surgeon is very careful not to leave an open cut, lest disease should 

 be communicated to it ; and so when a black knot is cut out, if the 

 wound is not covered you have provided a resting place for spores. 

 He asked why those who wished to exterminate the black knot 

 should be subjected to danger from their neighbors. He would 

 have worthless trees infested with black warts destroyed, as we 

 take a person who has smallpox to the hospital to prevent the 

 spread of the disease. 



Mr. Hyde suggested that the wounds made in cutting out the 

 black knots should be covered with a solution of shellac. 



Mr. Wood said that any ordinary paint would be equally good 

 for the purpose. 



[The following letter from Charles V. Riley, was read at a later 

 meeting of the Society, but as it contains valuable information 

 relating only to the subject of discussion at this meeting, it is 

 inserted here as a part of the proceedings.] 



United States Department of Agriculture. 

 Division of Entomology. 



Washington, D. C, March 8, 1889. 

 Mr. L. M. Chase, 



Master of the Dudley School, Roxbury, Mass., 

 Dear Sir : Your letter of the 7th inst. asking certain informa- 

 tion regarding the plum curculio has been received. In reply I 

 may briefly state that the black knot of the plum is not caused by 

 the plum curculio, although this insect occasioaall}' breeds in the 

 black knot. This excrescence is a fungous growth and the scien- 

 tific name of the fungus is Plowriglitia morhosa. 



There can be no question as to the advantage of spraying plum 

 trees with some one of the arsenical mixtures. The adult beetles 

 feed somewhat in the early spring and in mid-summer, and spray- 



