14 TRANSACTIONS OF ROYAL SCOTl'lSH ARBORICULTURAL SOCIETY. 



tiers of side branches, and to considerable delay in the time at 

 which pruning will become possible, 



The best planting distance for the production of fine timber 

 can only be learnt by experiment, and many years must elapse 

 before the experiments can be put to the decisive test of the 

 felling of mature crops. As soon as the experimental plots 

 are ready for a first thinning, different methods of thinning can 

 be tried, so that it would be desirable to have two or three 

 series of plots in each experiment. It is suggested that there 

 should be six plots in each series, each of one-tenth of an acre, 

 planted at distances of 3 feet, 3 ft. 6 ins., 4 feet, 4 ft. 6 ins. 

 5 feet, and 5 ft. 6 ins. If it is desired to make experiments at 

 wider distances for the production of pit-wood, another series of 

 five plots will be necessary,^ and it will be best to keep these 

 entirely separate from the plots intended for experiments in 

 timber production. 



It is to be hoped that both series of experiments may be 

 tried in many different districts. There is no doubt that the 

 repetition of identical experiments under different conditions 

 of soil, shelter, altitude and rainfall would be of great value to 

 the Forestry Commission, and it is hoped that the District 

 Officers would be willing to give general supervision to the 

 experiments. 



The alarming attacks of fungus disease described by Dr 

 Malcolm Wilson in the November number of the Transactions 

 may cause us to reconsider the question of to what extent 

 Douglas fir can be planted safely without some mixture of 

 other species. Mr M. G. Grainger gave in 1916 the following 

 estimate of the percentage of different species in the forests of 

 British Columbia : — 



1 At distances of 6 feel, 6 ft. 6 ins., 7 feet, 7 ft. 6 ins., and 8 feet. 



