12 LIFE OF 



had conspired to make him less and less inclined to enter into 

 general society, and he saw little of any one besides the 

 members of his own family, excepting during his visits, to 

 London. But these visits became each year more curtailed ; and 

 though to the last his mind retained all its freshness and 

 activity, it was evident to those about him that he wanted more 

 frequent collision with minds similarly constituted to his own ; 

 which is always more requisite to powerful and original intel- 

 lects than to those of humbler capacities. 



Mr. Knight's first communication to the Royal Society was 

 a paper " Upon the inheritance of decay among fruit- 

 trees, and the propagation of debility by grafting," read 

 April 30, 1795 ; and, in 1/97, he published a " Treatise on the 

 culture of the apple and pear, and on the manufacture of 

 cyder and perry." In this work he repeated the same opinions 

 which he had advanced in his paper, viz., that vegetable, like 

 animal life, has its fixed periods of duration ; and that however 

 the existence of a variety of a fruit-tree may be protracted 

 beyond the natural life of the original seedling plant, by graft- 

 ing, or by unusually favourable circumstances of soil or 

 situation, still there is a period beyond which the debility inci- 

 dent to old age cannot be stimulated ; and to this he attributed 

 the cankered and diseased state of most of the trees of the old 

 varieties of cyder apples in the orchards of Herefordshire. 



This hypothesis was so contrary to generally received 

 opinions, that at first it met with considerable opposition ; but 

 the increasing decay of the old fruits, even where grafted on the 

 most vigorous stocks, and the superior healthiness of the new 

 varieties produced from seed, has caused Mr. Knight's theory 

 to be now almost universally adopted. To remedy the ill-conse- 

 quences that would have followed the decay of the old fruits, 

 he set about raising new varieties of apples and pears from 

 seed ; but instead of following the old method of merely selecting 

 seeds from good kinds*, it occurred to him, that by artificially 



* So long ago as 1626, a Treatise on Orchards was published by "William 

 Lawson, in which he recommends for forming an orchard, that " the ground be 



