PRUNING. 235 



the latter are actually produced by the former, as in 

 the case of a single eye of a vine struck as a cutting ; 

 forgetting, that in the case of a pollard, or any other 

 tree, an intermediate vital member previously exists 

 to form the connection ; and which is constitutionally 

 calculated to allow intercommunication between the 

 moving extremities, without any portion of the shoot 

 descending to the root, or any part of the latter, 

 except juices, ascending to the former. The inter- 

 mediate channel is the vital indusium, containing a 

 compages of sap vessels, which, while they conduct, 

 are themselves enlarged by the impulse and qualities 

 of the rising current *. 



An argument in support of heading down young 

 and judiciously pruning old deciduous trees, may be 

 drawn from the natural history of many sorts of wil- 

 lows. They are not constituted to be permanent 

 trees. So far from their bulk, number of branches, 

 and quantity of foliage, being incentives to increased 

 vegetative power, an exactly contrary effect is the 

 consequence. As they increase in size the more 



* This circumstance deserves the notice of those physiologists, 

 who assert that u the matter" (?) which enlarges a stem descends. 

 Because as no upward or other current can he generated unless 

 there be an outlet or reservoir and as the bursting buds, lengthen- 

 ing shoots, and respiring leaves, are these outlets, why may not the 

 sap be deemed capable of enlarging and distending the stem in its 

 ascent, as well as attributing the enlargement solely to it, (or some 

 other matter,) in its descent ? 



