256 



Dr Christison on the 



[.SESS. Lir. 



expected to increase materially after attaining a girth of 6 1 

 feet, in soil similar to that of the Botanic Garden. 



The healthy-looking yonng lime, Xo. 18, has also a poor 

 record. In 1878, indeed, it increased 0"70, but never since 

 has its increase amounted to much more than half of that, 

 This tree is a good deal encumbered by neighbours, but 

 this seems an insufficient cause for so sudden and marked a 

 decrease. 



No. 21* conies out worst of all, with the miserable average 

 of O'lT, although it is- a line tree, and has always had dense 

 healthy foliage. Unlike the others, its increase was very 

 poor even in 1878. 



The individual range has been very gi^eat, particularly in 

 Xo. 2, the extremes being 0'65 and O'OO. Even in No. 18, 

 which suffered least, they were 0"70 and O'lo. The aggregaie 

 range was also vei'y great. 



The maximum growth of the three trees was 1*40 in 1878 

 and 1882, the minimum ()-25 in 1880 ; but 1883, 1885, 1886, 

 and 1887 were all years of great depression, and on the 

 whole progressively so. 



There was no appreciable destruction of branches or twigs 

 during the first depression, but the results upon girth-increase 

 were very marked indeed. From 140 in 1878 the amount 

 fell to 0-70 in 1879, and to 0-25 in 1880. Xext year, how- 

 ever, a rally began, which was complete in the following 

 year. It seems that some new calamity overtook the species 

 in 1883, causing a fresh and progressive depression in the 

 increase. The most remarkable fact is that along with this 

 there is no deterioration in tlie apparent healthiness of the 

 trees. 



Acer Pscudo-Platanus. 



Four of tliis species were under observation, but two 

 proved ineligible. One of these is the largest sycamore in 



