34 AN AMERICAN BARKER IN ENGLAND. 



CHAPTER V. 



DECAY OF VARIETIES. TWO THEORIES : KNIGHT S, DOWNING s. ENGLISH 



THEORY AND PRACTICE. PRACTICAL DEDUCTIONS.- CAUSES OF DECAY. 



REMEDIES. HINTS TO ORCHARDISTS. SPECIAL MANURES. PRUNING. 



THOROUGH DRAINAGE. A SATIRICAL SKETCH. SHOOTING THE APPLE- 

 TREE. 



IT is known that many varieties of apples, which fifty years 

 ago were held in high esteem as healthy, hardy sorts, 

 bearing abundantly very superior fruit, have now but a very 

 poor reputation, and varieties which a hundred years ago were 

 highly valued and extensively cultivated, are now extinct. It 

 is believed, too, that the most celebrated old varieties that are 

 yet cultivated, are much more subject to canker than others ; 

 or, in other words, that trees of these varieties are more easily 

 affected by unfavourable circumstances, or have a more deli 

 cate constitution. 



To account for this, there are two theories held by different 

 scientific horticulturists. The first which originated with the 

 late Mr. Knight, a distinguished vegetable physiologist of 

 England, who devoted much attention to the subject, and made 

 a long series of experiments upon it may be stated as 

 follows : 



Each seedling tree has a natural limit to its life, and within 

 that will have a period of vigour, succeeded by a natural and 

 inevitable decline, corresponding to the gradually increasing 

 feebleness which attends the latter part of the natural life of 



