168 Sir Eobert Christison 07i the 



defective. But this appeared to arise rather from the 

 ravages of superabundant insects than from atmospheric 

 inclemency ; and certainly in most places, and in respect to 

 trees generally, foliage was healthy and abundant. 



In the adjoining table are re-stated from my last paper 

 on this subject the girth of the trees in the beginning of 

 May 1878, and the successive increments in that favourable 

 year, and in the unfavourable year of 1879 ; and there 

 is now added the increments for 1880. On comparing the 

 columns of increments with one another, it will be seen at 

 a glance that, with very few exceptions, the growth of 

 wood last year was even more below the average of equally 

 favourable years than in the bad year of 1879. Of fifteen 

 leaf-shedding trees of various species, exclusive of the oak 

 tribe, the average growth of trunk-girth in the three suc- 

 cessive years was 0'80 of an inch for each, 0*45, and 0*35. 

 For four specimens of the oak tribe it was 0-82, 0*77, and 

 0-54. For twenty trees belonging to the evergreen Pinacece 

 the increments were 0'81, 0"68, 0'65. For six of the com- 

 mon yew the growth for 1879 and 1880 was 0*37 and 0*29 

 on an average ; and of the only two of these measured also 

 in 1878, the average growth in the three years was 0*55, 

 0*37, 0*28. The observations made on two specimens of 

 evergreen oak {Q. ilex) are remarkable. One of them made 

 0-4 in 1879 and only 0-1 in 1880 ; but the other, a much 

 finer plant, made only 0"3 in the former year and 0"8 last 

 year. It will be seen presently how easily this apparent 

 discrepancy may be explained. 



It appears then that with few exceptions trees of all 

 kinds failed to make the growth of wood which in ordinary 

 circumstances so fine a season as that of 1880 might have 

 been expected to produce ; and that the defalcation was even 

 greater than in the very unfavourable season of 1879 ; that 

 leaf-shedding trees suffered most, exclusive of the oak 

 tribe ; that the evergreen Finacece suffered least ; and that 

 the oaks, though intermediate in tliat respect between the 

 two foregoing denominations, suffered decidedly more in 

 1880 than in 1879. 



Some more special facts deserve a little notice : — 



1. The beech (7) suffered less in 1879, but more in 1880, 



