Mar, 1892.] THE BOTANICAL SOCIETY OF EDINBURGH. 263 



occasional superiority and general inferiority of the soil 

 within the narrow limits of the Arboretum, that a number 

 of other Scots firs scattered about the ground are all wrecks, 

 although the biggest of them is not much more than half 

 the size of No. 11. The number of the selected Conifers 

 was 32, but not more than half of them proved satisfactory, 

 and of these several were temporarily disabled by being 

 transplanted. 



To guard against loss of results through abnormality, 

 accident, or disease in single specimens, at least two of 

 each species were generally put under observation, a 

 precaution which proved of great service. But what 

 witli slow growth in some, sickliness in others, and the 

 transplantation of not a few, the task of appreciating the 

 facts and attempting to deduce general laws has been no 

 easy one. 



The Point of Measurement in the old set of trees was 

 almost invariably five feet from the ground, but many 

 of the new set were too young to be measured so high up, 

 neither was it necessary at their early period of life ; 

 therefore a point between two and a half and five feet up 

 was selected according to the varying conditions of girth, 

 branching, &c. 



The Measuring Instruments used were the well-known 

 steel tapes of Chesterman, graduated to tenths or twentieths 

 of an inch, certain methods being used which are explained 

 in former papers. Accuracy with this instrument can be 

 depended on to the tenth of an inch in all trees which are 

 not very rough or apt to scale in the bark, and to the 

 twentieth of an inch in young trees with smooth symmetrical 

 stems ; nay, I am persuaded that, with practice, measure- 

 ments even to the fiftieth of an inch are reliable on carefully 

 selected stems. 



The figures in the tables and in the text, when referring 

 to measurements, represent inches and decimal parts of an 

 inch, unless otherwise stated. Percentages are calculated 

 only to a single decimal. 



The subject naturally falls under the two heads of Annual 

 and Monthly Ptesults, and each of these I have subdivided 

 into the history of the species separately, and the collective 

 results. 



