Mar. 1892.] THE BOTANICAL SOCIETF OF EDINBURGH. 



267 



81, 100, 121, 138, and 1-13 inches in 1887, under observation 

 for from seven to ten years previously, the average rate of 

 the whole having been 0"62, and that of the best, nearly 

 7 feet in girth, I'O.S. 



QUERCUS ROBUR. 



All four in the south belt of the Arboretum, well sheltered 

 from the south, but slightly exposed to the north. 



Nos. 70 and 72 were selected originally, but as the latter 

 showed signs of failure, N"os. 1 and 2 were added next year 

 to secure a better average. Nevertheless none of the others 

 show anything like so good an annual rate as ISTo. 70, which 

 yields O'Sl, compared with their 0-55, --lO, and -49. This 

 was probably due to the almost entire destruction of the 

 leaves in June 1888 from an insect plague which affected 

 Oaks in many parts of Scotland and England. I noted that 

 N'o. 70 recovered its full foliage next year, while the others 

 continued to look shabby both then and in 1890. A 

 corresponding variation in girth-increase appears from the 

 aggregate increments of the four trees, that of 1888 (1'30) 

 being not half those of 1890 (3-05) and 1891 (3-15). 



The immediate effect of the disaster was shown by the 

 fact that there was absolutely no increase in June in Nos. 

 70, 74, and only an increase of 0'05 in each of the others. 

 The annual loss would probably have been still greater but 

 for an abundant second crop of leaves in late summer. From 

 what has been said it is evident that the annual range must 

 have been great; in Xo. 70 it was from 0*50 to TOo ; in 72 

 and 2 from 0*20 to O'SO ; and in 1, from 0-40 to 0-75. A 

 much older tree, No. 12*, about 6 feet in girth, at 

 Craigiehall, grew for ten years at the slow rate of 0*37, but 

 like almost all the numerous Oaks at Craigiehall, it had a 



