286 



TRANSACTIONS AND PROCEEDINGS OF [Sess. LVi. 



off greatly, and the tree is straggling and weak-looking. The 

 same is true of the others, except Thuja Craigieana, which 

 gives the worst results of all and yet looks well. Pinus 

 austriaca looked and did well the first two years, but has 

 fallen off since. In 1891, when its increase was only 0*35, 

 that of a vigorous-looking specimen, somewhat older, in the 

 Arboretum was 1'25. 



d. Annual Variation in the Aggregate Girth-increase. 



The average for the five years being 19*70 inches, 

 the worst year was 1891, with a deficit in round numbers of 

 2| inches, and 1888 follows next with a deficit of only 

 I inch. 1890, the best year, exceeded the average by 1^ 

 inch. 



In the depression of 1891, 21 of the Pinacea; suffered a 

 diminution of girth-increase, 4 showed a slight increase, and 

 5 were unaffected, in comparison with the previous year. 



Comparison of the Annual Variation in GiRTn-lNCREASE 

 OF THE Deciduous and Evergreen Classes. 



The differences between the two classes are considerable. 



In the first place, the annual variation is much more 

 marked in the Deciduous than in the Evergreen group. The 

 average yearly amount in the two being not far apart, — viz., 

 in round numbers, 22 inches in the former and 20 in the 

 latter, — there is a difference of 7 inches between the highest 

 and lowest years in the Deciduous trees, and only of 3 J in 

 the Conifene. Or, while the worst year of the former is 4^ 

 inches below average, the worst of the latter is only 2| below 

 average. 



