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Report on Botany. 



determining the proper time for cutting off the excrescences. 

 Some report that they have tried this remedy without 

 success. Want of success may be ascribed to three causes. 

 1st. The remedy may not be employed at the proper time. 

 If the black knots be trimmed off in summer or even in 

 spring it is evident that the trouble will not be effectually 

 cured, for the whole or part of a crop of spores will already 

 have been disseminated to produce new excrescences the 

 following autumn and spring. It is true if the cutting 

 process be carefully repeated at sufficiently short intervals, 

 it would in the end accomplish the desired result if done at 

 any time, provided the tree could endure the frequent 

 repetition of the operation. But in our opinion November 

 is the best time for cutting off and destroying the knots. 

 At this time the coming crop of spores is not mature, the 

 leaves do not hinder the ready detection of the swellings, 

 and the young excrescences, the foundation of a second 

 succeeding crop, are also then visible to a close observer, so 

 that thorough work may be done at one operation. 



2d. The operation may not be properly performed. Phy- 

 sicians, in the excision of a cancer from the human body, 

 insist upon the necessity of an entire removal of every parti- 

 cle and fibre of the extraneous growth. So in this case we 

 must insist on the complete removal of all the affected 

 part of the branch. It has already been stated that in 

 November new swellings appear just below the old excres- 

 cences. Should the old excrescence be cut off just before 

 the appearance of this new swelling it is quite possible that 

 ~a part of the affected branch may be left behind, since the 

 new affection sometimes extends down the branch several 

 inches. Should any such part be left behind it would 

 develop into a new excrescence. It would be interesting 

 to know whether these apparent extensions of the excres- 

 cences are the product of a new sowing of the spores or 

 are produced by an advance of the mycelium of the old 



