On the Effects of Age upon Fruit Trees. 385 



of Herefordshire, without a single healthy, or efficient tree 

 having been obtained ; and, I believe, all attempts to propagate 

 those varieties have, during some years, wholly ceased to be 

 made. I have detailed in the Philosophical Transactions* an 

 account of some experiments, which I repeated, with the hope 

 of being able to ascertain which, amongst the various organs of 

 trees of aged varieties, first fail to execute their proper func- 

 tions ; and I came to the conclusion, upon the following, and 

 other evidence, that it is the leaf. Having obtained by layers 

 or cuttings, small plants of several of the most diseased of 

 the old varieties of the Apple, these were grafted within a 

 couple of inches of the surface of the soil with scions of new 

 seedling and luxuriant varieties ; and under these circum- 

 stances the roots of the most debilitated and diseased va- 

 rieties executed their office perfectly well, and were found, 

 upon examination, at the end of several years, wholly free 

 from every symptom of disease. This process was reversed, 

 and scions of old varieties were employed as grafts ; but into 

 the young growing shoots, which sprang from these, many 

 buds of new and luxuriant varieties were inserted, and in the 

 autumn every natural bud of the old varieties was destroyed. 

 The inserted buds vegetated in the following spring, and by 

 these efficient foliage was given ; when every symptom of 

 debility and disease disappeared, and the wood and bark of 

 the most exhausted and diseased varieties now constitute a 

 part of the stems of large Apple trees, and present, at the end 

 of thirty years, as much apparent health as other parts of the 

 stems of those trees. From these results I have inferred, 

 that the debility and diseases of such old varieties arise from 



* For the year 1810. page 178. 



yol. v. 3 E 



