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 years 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 



Specimen. occurred, branch died, canker began, after death of branch. 



I 1 20 6 7 1 



2 1 19 7 8 1 



3 1 17 6 7 1 



4 13 2 8 6 



5 13 3 5 2 



6 12 6 7 1 

 71337 4 



8 12 2 6 4 



9 12 4 7 3 



10 11 4 5 



11 11 3 4 



12 11 8 9 



13 11 2 3 



14 11 5 7 



15 11 2 3 



16 10 2 3 



17 10 6 8 2 



18 10 2 8 6 



19 9 3 5 2 



20 9 3 7 4 



21 9 3 3 



22 9 6 6 



23 8 4 4 



24 8 5 6 1 



25 8 6 8 2 



26 7 2 2 



27 6 2 2 



28 6 2 3 1 



29 63 5 2 



30 5 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 



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

 Dunster Castle, Somerset. 



