THE LARCH CANKER 57 



mined by observing the last annual ring of the trunk which 

 is continuous with the wood of the branch. 

 • In 30 cankers taken at random, in which this point could 

 be precisely determined, it was found that in 5 cases the 

 canker was initiated the same winter as the branch died, 

 in 12 cases it began the year after the branch died, in 7 cases 

 two years after, in 1 case three yeai's after, in 3 cases four 

 years after, and in 2 cases six years after. 



In the following table the observations are set out at 

 length : 



Age of section 



of tree in Number of years of 



which canker Age when Age when initiation of canker 

 branch died, canker began, after death of branch. 



6 7 1 



7 8 1 

 6 7 1 



2 8 6 



3 5 2 

 6 7 1 



3 7 4 



2 6 4 



4 7 3 



4 5 1 



3 4 1 



8 9 1 

 2 3 1 



5 7 2 

 2 3 1 

 2 3 1 



6 8 2 • 



2 8 6 



3 5 2 

 3 7 4 



3 3 

 6 6 



4 4 



5 6 1 



6 8 2 

 2 2 

 2 2 



2 3 1 



3 5 2 

 2 4 2 



This shows that in the large majority of cases the canker 

 begins at least a year after the death of the branch. In 



^ These specimens were kindly sent me by Mr. Alex. Luttrell from 

 Dunster Castle, Somerset. 



