1888-89.] Anmud Increase in Girth of Trees. 397 



Thus it appears that the increase never rallied effectually 

 from the great depression of the years 1879-80-81. For 

 while in the deciduous group the amount in 1878 was 11 "3 6 

 inches, it never afterwards reached 9 inches, and in the 

 evergreens the amount of 8*27 in 1878 was not afterwards 

 approached nearer than 7"05. This result is probably due 

 chiefly to the prolonged effects of injury done in the tlu'ee 

 consecutive bad winters 1879-80-81, operating mainly, 

 however, on trees which had already reached or passed the 

 meridian of their growing power. 



Another result shown is that the deciduous or evergreen 

 groups did not always suffer equally, or at all, in the same years. 

 Thus the deciduous species, as a whole, were subjected to 

 serious depression in 1879, 1880, 1885, 1886, and 1887, 

 while the evergreens suffered in 1879-80-81, 1883, and 1887. 

 It does not follow, however, that these differences were due 

 to any inherent tendencies in the two classes as such, be- 

 cause, in the first place, the number of species tested may 

 be insufficient to establish general rules ; and, secondly, in 

 each of the depressions to which a class was subjected, 

 certain sjKcies of that class escaped. In the succeeding 

 divisions of my subject, I have endeavoured to analyse these 

 depressions, and to show the degree to which each species 

 was affected by them. 



5. The Depression in Girth- Increase of 1879, 1880, and 



1881. 



The three successive seasons of 1879, 1880, and 1881 pre- 

 sent a series which has probably been unprecedented in 

 Scotland for low winter temperature and other circumstances 

 which may be supposed to be unfavourable to tree-life. In 

 that respect, therefore, it is fortunate that these seasons fall 

 within our decennial period, as we are enabled to appreciate 

 in some measure their effects upon the growth of timber, 

 although in other respects it is unfortunate, as these effects 

 have greatly complicated the general investigation by pro- 

 ducing abnormal results upon the whole period. 



I shall consider the subject under several heads: — 



1. The Nature of the three consecutive Bad Seasons and the 

 general Effects they produced upon Girth- Iner case. — The failure 



