GARDENING. 59 



tion of the air; where an increase of food is suppHed, 

 the medium through which that food is taken up by the 

 plant should be increased; and when the temperature 

 is increased, evaporation becomes greater. 



Hence the advantage of watering by surface or 

 subterraneous irrigation, manual supplies to the root^ 

 showering over the leaves, steaming the surrounding' 

 atmosphere, &c. 



TO inchease the number, and improve the quality 



OF PARTS OF VEGETABLES. 



It is necessary in this case, to remove such parts of 

 the vegetable as are not wanted, as the blooms of bul- 

 bous or tuberous rooted plants, when the bulbs are to be 

 increased, and the contrary. Hence the important op- 

 erations of pruning, ringing, cutting off large roots, &c. 

 It may be said that this is not nature, but art; man, 

 though an improving animal is still in a state of nature, 

 and all his practices in every stage of civilization are as 

 natural to him, as those of the other animals are to them; 



To form new varieties of vegetables, as well as of 

 flowers and useful plants of every description, it is ne- 

 cessary to take advantage of their sexual differences, 

 and to operate in a manner analagous to crossing the 

 breed of animals. Hence the origin of new sortfe of 

 fruits, grains, and roots. New varieties or rather sub- 

 varieties are formed by altering the habits of plants, by 

 dwarfing through want of nourishment, variegating by 

 arencious soils, &c. 



TO PROPAGATE AND PRESERVE PLANTS FROM DEGENERACY. 



In doing this, we should have recourse to the different 

 modes of propagating by extension. Thus choice ap- 

 ples and tree fruits could not be perpetuated by sowing 

 their seed, which experience has shown, would produce 

 progeny more or less different from the parent, but they 

 are preserved and multiplied by grafting; others such 

 as the pine apple, by cuttings or suckers; choice car- 

 nations by layers; potatoes by cuttings of the tubers, 

 &:c. But approved varieties of vegetables are in general. 



