i88i.] RECIPROCAL ACTION. 229 



and appliances which art can invent, is certainly the most likely to 

 advance that art which strives to give to colder climes that which 

 more sunny climes produce. Wm. Forbes. 



AiiCKLAND, N.Z., Fclriiary 2, 1881. 



RECIPROCAL ACTION. 



This phrase has a rather learned and respectable sound when used by 

 a writer on the subject of roots or branches, and is supposed to ex- 

 press much or little meaning just according to circumstances; but it is 

 a much-prostituted term, and ought to be properly cleared up. The words 

 were, we believe, invented by the physiologist to denote some kind of 

 sympathetic action existing between the roots and the top of a tree — 

 akin to that which is said to exist between the dog's head and its tail; 

 but what that sympathy is, and where it begins or ends, nobody knows, 

 although its presumed existence is made to do duty in a hypothetical 

 capacity on many occasions. Teetotallers say the tippler's general apology 

 is, that he requires spirits in winter to keep him warm, and in summer 

 to keep him cool ; and gardeners and botanists, it is to be feared, em- 

 ploy " reciprocal action " on the same principle — it is a good peg. We 

 are taught that if we want to create superabundant vigour in a vine or 

 other tree, we must encourage growth in order to encourage roots, and 

 a corresponding development of both ; and next, that the way to in- 

 crease the vigour of the same tree is to cut all this growth away at 

 the winter pruning, or nearly all, — two quite opposite methods of at- 

 taining the same end. One much-respected and noted author is at 

 great pains to explain, physiologically, how the top limbs of certain 

 horizontally-trained fruit-trees are very apt to grow over-luxuriantly 

 at the expense of the lower ones unless persistently checked by the 

 stopping of the summer's growth ; and in the same breath it is also 

 stated that in order to make the w^eak lower branches stronger, they 

 must be pruned back severely : and it is all connected in some mys- 

 terious way with " reciprocal action " — so we are told. It has struck 

 the writer frequently that it must be a marvellously consistent theory 

 which teaches that in order to produce vigorous Vines, for example, 

 we must encourage them to produce as many limbs and leaves as 

 possible the first year or two, and then cut all the said limbs off at 

 pruning-time for exactly the same reason that they were encouraged 

 to grow. A greater writer than practitioner has written and ex- 

 plained how the leaves pump up moisture with astonishing force, and 

 that the more pumps the more roots— ^.e., reciprocal action— forgetting 

 that some plants, like the Vine, send up their sap with the greatest 

 mechanical force when there are no leaves, otherwise pumps, upon the 

 tree at all. But though the cultivator blames the branches for encour- 

 aging the roots— or, as was said lately, " it is the leaves that apply the 



