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JOUR^'AL OF THE ROYAL HORTICULTURAL SOCIETY. 



restricted, tlie first effect is to diminisli the number and size of 

 the branches, while the annual increase in volume of the stem 

 is much less affected. The consequence is that by judiciously 

 crowding woods one produces a larger yield of timber, though 

 possibly not in all cases a larger aggregate yield, if one includes 

 both branches and timber. If the crowding be carried too far, 

 then the yield of timber will begin to decline, because the vital 

 functions of the trees are interfered with, but where the exact 

 turning-point is will depend on situation, species, and age. 

 To continue this subject further would lead us beyond the 

 limits of this paper, but those desirous of further informa- 

 tion may be referred to Professor Schlich's English adapta- 

 tion of Weise's " Tables for the Scotch Pine," pubhshed by 

 Allen & Co. 



Not only does the right degree of crowding ensure the pro- 

 duction of stems of the best form and timber comparatively free 

 from knots, and therefore timber which is strong and easily 

 worked, but it is now recognised to have a very powerful in- 

 fluence on the durability of timber. The capacity of timber to 

 resist decay depends largely upon the proportion of each wood- 

 ring occupied by the dense autumn-wood ; that is to say, the 

 more this portion of the ring is developed, and the less the zone 

 of spring-wood is represented, so much the higher will be the 

 quality of the timber. The spring-wood, so called, is chiefly 

 formed early in the growing season, while the autumn-wood is 

 formed later, and if by any means the commencement of the 

 formation of wood can be delayed, the production of spring-wood 

 is kept in check, and the zone of inferior wood in each annual 

 ring is represented in relatively small proportion. By delaying 

 the period of the commencement of activity in the cambium cells, 

 the total breadth of the annual ring will be less than it would 

 otherwise have been, but the average quality of the wood will be 

 very considerably higher. There seems little cause to doubt that 

 this is the reason why coniferous timber with narrow rings is 

 generally of such superior quality to wood of rapid growth. The 

 period at which the cambium will become active is chiefly regu- 

 lated by temperature, so that if there is a deficiency of heat in 

 late spring or early summer the commencement of growth will 

 be delayed. This will be most likely to occur : 



(1) In northern latitudes ; hence the reason of the excellent 



