82 CHRISTISON—-OBSERVATIONS ON 
different conditions of soil, exposure, etc. ; unsuitability of the 
species to the climate or soil ; the complicated effects of weather 
affecting species or individual trees in different ways. But 
notwithstanding all this, the results in some species agree quite 
as remarkably as in others they disagree, and while greater 
confidence must be placed in the former, some idea may be 
formed, on a careful consideration, of the general tendencies in 
the latter also. 
A. Aggregate Results. 
A. FoR THE MONTHS SEPARATELY. 
The chief points to which attention will be directed under this 
head are—the aggregate increase in girth of the twenty trees 
due to each month in succession in each year and over the whole 
period ; the proportion or percentage of seasonal increase due to 
each month in each year and on the average ; the species that 
yield the largest and smallest proportions of seasonal increase 
in each month ; and the largest individual scores or records in 
a single year that may have happened in any species in each 
month. 
APRIL. 
Aggregate Results, 20 Trees. | . 1892, | 1893. | 1894. 1895. (Average. 
' 
Total increase, ... eat ss pot ee 1:15 | 1:30 0°50 0°77 
Percentage of seasonal increase, eS A 4:7 6-0 2°4 374 
Number with no increase, ...  ...| 17 (ee 11 | 96 
The average annual increase for April amounts to only three- 
quarters of an inch, somewhat less than for September, at the 
other end of the season, and, as might be expected from our 
variable springs, the range, ‘15 to 1°30 in amount and 06 to 60 
in percentage, is very great. 
The number of trees that yielded no increase in April in one 
or more seasons was large, the annual average default being 
about orie half of the whole, but the proportion of the default 
varied as much in the different years as from 3 to 17. 
