56 



SIR ROBERT CHRISTISON AND DR CHRISTISON ON THE 



deciduous trees, and the corresponding results for the growing months of 1882 

 in the larger number of trees then under observation. 



The Table shows that in 1880 June and July were the best growing months 

 for the five selected trees. The amount in these two months was nearly equal. 

 The united growth of August and September, of which September's share was 

 very trifling, was not much less than that of June or July, while that of May 

 was only half that of August. 



The year 1881 is not fully available for this inquiry, no measurements 

 having been taken for May ; but as the united growth of May and June but 

 little exceeded that of July or August, it is fair to conclude that the increase in 

 June alone was less than in either of the subsequent months. 



In 1882 the growth of the five trees in question was apparently distributed 

 over a longer period. May takes a more prominent place with 21 per cent. 

 The growth for June and combined August and September is not much 

 greater, while July takes a decided lead with 31. The preponderance of the 

 early-growing Hungary oak in the small number of selected trees, however, 

 gives a false impression of the increased deciduous growth in May of this year. 

 If we consider the whole number of deciduous trees, twenty-eight in all, under 

 observation in 1882, the percentage for May is reduced to 16, which is still, 

 no doubt, a substantial and probably an unusual amount. 



2, b. The Months in which the Growth of Wood is most active in Evergreen 

 Trees. 



Table VII.— Monthly Percentage of Increase in Girth of Evergreen Trees. 





May. June. M T a ? and 

 J June. 



July. 



August. 



6 Selected evergreen trees, 1880, 



„ „ 1881, 



1882, 



18 Evergreen trees, 1882, . 



37 + 24 = 61 



51 



35 + 33 = 68 



34 + 29 = 63 



30 

 18 

 19 



21 



9 

 31 

 13 



16 



It is more difficult to determine from the available data the month of 

 greatest growth in evergreen than in deciduous trees. Not only are the varia- 

 tions in this respect in different years greater in the former than the latter, but 

 it is doubtful whether a part of the increment attributed to May ought not to 

 be credited to April in the case of evergreen trees. This doubt arises from 

 Sir Robert having concluded, probably too hastily, that no growth takes place 

 in April. I can find no evidence in his papers of his having ascertained this by 

 measurement, and I do not know how he came to form and act upon that con- 

 clusion. Further observations are evidently necessary to settle this doubt, and 



