54 



Dr David Christison on the 



[SESS. LI. 



in girth earlier than deciduous trees. My subsequent 

 measurements of twenty trees confirm this, as on an average 

 of five years tlieir growth before June amounted to 28 per 

 cent, of their annual increment, or nearly double the propor- 

 tion of the deciduous group. It was remarkable, however, 

 that the greater energy in spring of the evergreens was con- 

 fined chiefly to the month of May, as the proportion for the 

 two groups in April was almost the same. So that it would 

 appear as if the evergreens did not start earlier than the 

 deciduous trees, although they quickly surpassed them in 

 activity of growth. 



Going into details, it appears that of the twenty trees 

 under observation, seven in 1883, six in 1884, two in 1885, 

 ten in 1886, and fourteen in 1887, did not increase at all in 

 April; that the aggregate growth in these years respectively 

 was 1-30, 1-50, 2-05, 0-43, and 045 inches, the falling off in the 

 last two years, owing to backward springs, being very marked ; 

 and that the most remarkable tree for early growth was a 

 Pinus austriaca at Craigiehall, which increased fully a third 

 of an inch in April three years in succession. So marked 

 a result in this tree is sufficient in itself to prove decisively 

 that an increase in the girth of trees may take place in April. 



Signs of activity in early spring might be expected to be 

 more marked in evergreen than in deciduous trees, but my 

 observations show even less indications of early movement 

 among the former than among the latter. As will be seen 

 from the Table below, of seven trees in the Botanic Garden, 



Measurements in early Spring of Evergreen Trees. 



