Mr. Knight on the Effects of Age upon Fruit Trees. 195 



shoots, which sprang from these, many buds of new. and lux- 

 uriant varieties were inserted, and in the autumn every na- 

 tural 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 dis- 

 ease disappeared, and the wood and bark of the most ex- 

 hausted 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 de- 

 bility and diseases of such old varieties arise from the want of 

 a properly prepared circulating fluid; and that when such is 

 given by efficient foliage, the bark of the most debilitated va- 

 riety possesses the power to occasion the necessary secretions 

 to take place, and the alburnum is enabled to execute all its 

 offices. 



It has been urged against the conclusion, that old age is 

 the cause of debility and decay of those varieties of fruit which 

 have been very long cultivated, that many of the seedling 

 offspring of such varieties are as much diseased as their pa- 

 rents; and it is contended, that the failure of our best old 

 varieties of fruit has arisen from a succession of unfavourable 

 seasons. The fact, that many of the seedling offspring of old 

 diseased varieties of fruit are as much diseased as the parents 

 from which they spring, is unquestionable ; but this, I conceive, 

 proves nothing more than that diseases are hereditary in the 

 vegetable as they are in the animal world ; and it is scarcely 

 reasonable to expect that healthy and robust offspring can be 

 obtained from parents, whose lives have been extended be- 

 yond their natural periods by preternatural means, and whose 

 bodies are yearly faffing to pieces under the operation of dis- 

 ease ; and in which the whole of the circulating fluids are in 

 a morbid state. 



If a deterioration have taken place in our climate, and this 

 have occasioned the decay of our fruit trees, at what period 

 did this deterioration take place ? It is more than forty years 

 since I commenced experiments with the hope of being able 

 to raise healthy trees of the old varieties of the Cider Fruits of 

 Herefordshire; and I know that the progressive debility of 

 those had been pointed out some years before my birth by my 

 lather, who died an old man when I was an infant; and who 

 was an extremely competent judge of the subject. 



Parkinson also, who lived in the reign of Elizabeth, com- 

 plains of the unfavourable seasons in the latter part of his life. 

 The grapes did not then ripen as they had formerly done ; or 

 more probably, I believe, he did not find them so sweet as he 

 B b 2 thought 



