150 transactions of royal scottish arboricultural society. 



Selection of Groups. 

 At the outset a careful survey of the four compartments in 

 question was made. They cover some 200 acres, over which 

 area suitable groups of advance growth were located. In the 

 selection of these, attention was paid to such points as the 

 following : — None were chosen covering an area smaller than 

 •8 square pole, while the maximum tor any group was about 

 I square pole; only pure groups were selected, and no group 

 was taken in which some individuals were dominant to the 

 extent of suppressing others and thus preventing by their shade 

 a normal development of the group as a whole. Ten such 

 areas were selected for beech and eleven for oak. In order to 

 get as many stages of variation as possible for each species, the 

 groups were made representative of all possible conditions of 

 light-intensity. The assignment of groups to different degrees 

 of shade was done by ocular estimate, the intensity of light 

 being gauged approximately by the density of the canopy. 

 The terms " deep," "medium," and " light " shade, respectively, 

 were employed to classify the areas. Later, as will be seen, the 

 actual intensity of light on each area was accurately measured 

 by photometric methods. 



Method of Counting Seedlings. 

 After the selection of the groups, each was considered 

 separately, and the number of seedlings was carefully counted on 

 a definite area marked out in it. The method was as follows : — 

 By means of a Gunter's chain, five squares, each one-hundredth 

 of a square chain, were pegged out with arrows in every group ; 

 and the number of seedlings in each square and hence the total 

 for the group were then ascertained. To ensure the greatest 

 possible accuracy in this, a diagonal was always put into the 

 square, the seedlings in every group being thus counted on ten 

 comparatively small areas. The sum of the five squares is 

 exactly -8 square pole, and as the maximum size of a group 

 is about one square pole, the area marked out formed in each 

 case a fair sample of the group. In addition, it may be 

 mentioned that the five squares were distributed in such a 

 manner as to be truly representative of each group. 



Photometric Method. 

 An attempt was made to measure the intensity of light 

 obtaining in each group and to represent it in the form of a 



