May- 1891.] BOTANICAL SOCIETY OF EDINBURGH, 105 



II. — Peogress OF Girth-Increase through the Growing 



Season. 



As the observations in 1888 and 1889 were less frequent 

 and precise than those in 1890, I shall fully consider the 

 latter first, showing afterwards, in a more general way, how 

 far the results are confirmed by those of the earlier years. 



Table II. gives the results for 1890, and is divided into 

 three parts. The first gives the results in five healthy and 

 fairly vigorous young pines ; the second, in five vigorous 

 young deciduous trees ; and the third, in three other de- 

 ciduous trees, which, although ascertained to be quick 

 growers for three years previously, for some reason or another, 

 and without any appearance of unhealthiness, fell off very 

 much in their girth-increase in 1890, and therefore might 

 not be following in that year their normal course. The 

 numbers in the Table, and which I shall use in the text, 

 represent thousandths of an inch. 



A. PlNACE^. 



1890. — Taking first the combined results for the five trees, 

 it is very evident that the progress of girth-increase was 

 not, as might be expected, a steady rise towards a maximum 

 in midsummer, followed by a steady decline towards the 

 end of autumn. On the contrary, after a steady rise from 

 40 in the first week of April to 440 in the third week of 

 May, there was a sudden fall to 185, and although a rally 

 from this very low figure took place immediately, yet the 

 weekly results continue to be low for no less than ten weeks, 

 never once approaching very near the 440 of the third week 

 in May, and falling in one week to a minimum of 125. It 

 was not till the first week in August that the amount ag-ain 

 reached 400 and upwards, after which the results were on 

 the whole large till the 20th of September. These strange 

 results will be more easily appreciated by arranging the 

 figures in fortnightly periods, and reproducing them from 

 the Table : — 



90, 300, 600, 750, 545, 665, 400, 350, 700, 700, 550, 775, 375, 175. 



