70 TREATISE ON 



the horizontal branches will dwindle, & the lower part of the tree will thin out. 



Proposition 5. The farther that the sap moves away from the center of the tree, 

 the more active it becomes. 



The sap exerts its main activity at the tender tips of the branches where it finds 

 much less resistance than it does at their origins where the woody layers have hardened. 

 It puts out many new branches at those places in proportion to its quantity. The result is 

 that if you prune a branch that has eight branch buds, & if there's only enough sap to 

 open three of them, the three that open will be at the tip, & the five others will remain 

 dormant. 



So one must 1°. avoid pruning a branch too long, leaving too many outlets & 

 making it too easy for the sap to leave the middle of the tree that soon will become bare. 



2°. Avoid pruning too short, which forces the sap to act too forcefully & 

 abundantly on the small number of buds remaining on the newly pruned branch and yield 

 only strong branches. Moreover, pruning too short in this way forces the sap to flow back 

 into previously pruned branches and to open up abnormal outlets & to produce false 

 wood branches. 



3°. If one side of a tree predominates, its strongest branches must be pruned short 

 so that the sap, encountering more resistance & fewer, more restricted outlets there, & 

 consequently less favorable circumstances for its function, will generate only moderate 

 growth in that location. But all medium & weak branches that can continue on there 

 without disarray must be kept & pruned long so that the sap is consumed & isn't forced 

 to open up any abnormal channels. The weaker side, in contrast, should be freed of all of 

 its weak branches. The medium ones are pruned short, retaining only those necessary for 

 filling out its shape. The strong branches are pruned long in order to attract the main 

 movement of the sap. 



