OF FRUIT TREES. 29 



full of fruit, while others, that are not ringed, often 

 have none or very little on them. This effect is 

 explained from the theory of the motion of the sap. 

 As this ascends in the wood and descends in the bark, 

 the above operation will not prevent the sap rising 

 into the upper part of the branch, but it will pre- 

 vent its descending below this cut, by which means 

 it will be retained in and distributed through the 

 upper part of the branch in a greater portion than 

 it could otherwise be, and the branch and fruit will 

 both increase in size much more than those that 

 are not thus treated. The twisting of a wire or 

 tying a strong thread round a branch has been often 

 recommended as a means of making it bear fruit. 

 In this case, as in ringing the bark, the descent of 

 the sap in the bark must be impeded above the 

 ligature, and more nutritive matter is consequently 

 retained, and applied to the expanding parts. The 

 wire or ligature may remain in the bark. Mr. 

 Knight's theory, on the motion of sap in trees, is 

 "that the sap is absorbed from the soil by the bark 

 of the roots, and carried upward by the alburnum 

 of the root, trunk and branches; that it passes 

 through the central vessels into the succulent mat- 

 ter of the annual shoots, the leaf-stalk and leaf; 

 and that it is returned to the bark through certain 

 vessels of the leaf-stalk, and descending through the 

 bark, contributes to the process of forming the 

 wood. A writer in the American Farmer says, he 

 tried the experiment of ringing some apple, peach, 

 pear, and quince trees on small limbs, say from an 

 inch to an inch and a quarter in diameter. The 

 result was, the apples, peaches, and pears were dou- 

 ble the size on those branches, than on any other 

 part of the trees : in the quinces there was no dif- 

 ference. One peach, the heath, measured, on a 

 ringed limb, in circumference 111 inches round, and 

 1H inches round the ends, and weighed 15 ounces. 



