406 Dr Christison on the [sess. liii. 



It will be observed that of the twelve trees in this table 

 nine touched their absolute minimum in 1887, the period 

 during which they were under observation ranging between 

 eight and ten years. 



Taking a general view of the depressions in girth-increase, 

 they show a singular variety in their incidence, not only upon 

 the deciduous and evergreen classes, but also on the species 

 within each class. Thus, to take some pronounced examples 

 of the latter kind : — Cedrus Deodara sufiered a great decline 

 in 1880, 1881, and 1"883, but none in 1886, and but little 

 in 1887 ; Sequoia gigantea, on the other hand, was seriously 

 affected in 1883, 1886, and 1887. So that, in five years of 

 depression, these two species were affected in the same year 

 only once. Again, in 1883, the year of greatest depression 

 in the evergreens, Araucaria imhricata escaped entirely, and 

 Taxus haccata almost entirely. Lastly, Taxus laccata, after 

 nearly altogether escaping the previous depressions, suffered a 

 fall of nearly 50 per cent, in 1887, when the only other ever- 

 green species affected was Sequoia gigantea. It is also worthy 

 of note that in no instance, as far as I could see, did the 

 depressed species show any external marks of sickliness. 



Inquiry into the causes of these differences is beset with 

 difficulty from the variety of effects upon species growing in 

 the same locality, some, which differ greatly in results, like the 

 Deodars and Sequoias, side by side. It is to meteorological 

 returns that we must look for the solution <jf these difficul- 

 ties, but these have not yet been fully published for the 

 period under review. For this reason, and as it is desirable 

 to study the question in connection with monthly as well 

 as annual growth, I postpone its consideration till all the 

 necessary data ha\'e been obtained. 



Miscellaneous Results and Queries. 



1. Loss of th(? to[)-s]iooL in ]iiiic3 does not seem necessarily 

 to check the growtJi of wood. I'hus in Pinus austriaca at 

 Craigiehall, two years' growtli of the top-shoot perished from 

 the low temperature of 1880, yet no diminution occurred in 

 the girth-increase of the following years, and tlie results 

 continued to be the highest of all our measured trees. In 

 tlie Abies Lovrlana, indeed, a lasting, though not extreme, 



