82 On a new Method of training Fruit Trees. 



luxuriant shoots of the Peach Tree, the origin and office of 

 which, as well as the right mode of pruning them, are not at 

 all understood, either by the writers on Gardening of this 

 country, or the Continent. 



I have shown in the Philosophical Transactions of 1805, that 

 the alburnum, or sap wood of Oak trees loses a considerable 

 part of its weight during the period in which its leaves are 

 formed in the spring : and that any portion of the alburnum 

 affords less extractive matter after the leaves have been formed 

 than previously. I have also shown that the aqueous fluid which 

 ascends in the spring in the Birch and Sycamore, becomes 

 specifically heavier as it ascends towards the bads ; which I 

 think, affords sufficient evidence that the alburnum of trees 

 becomes, during winter, a reservoir of the sap or blood of the 

 tree, as the bulb of the Hyacinth, Tulip, and the tuber of 

 the Potaloe, certainly do of the sap or blood of those plants. 

 Now a wall-tree from the advantageous position of its leaves 

 relative to the light, probably generates much more sap, 

 comparatively with the number of its buds, than a standard 

 tree of the same size ; and when it attempts to employ its 

 reserved sap in the spring, the gardener is compelled to de- 

 stroy (and frequently does so too soon and too abruptly) a 

 very large portion of the small succulent shoots emitted, 

 and the Aphis too often prevents the growth of those which 

 remain. The sap in consequence stagnates, and appears 

 often to choke the passages through the small branches ; 

 which in consequence become incurably unhealthy, and 

 stunted in their growth : and nature then finds means of 

 employing the accumulated sap, (which if retained would 

 generate the morbid exudation, gum,) in the production of 



