296 APPLICATION OF PEINCIPLES. 



of plants by the ordinary means of propagation, such, 

 as cuttings, layers, grafts, and so on, has already been 

 explained ; there are, however, some other topics con- 

 nected with this important subject which require to 

 be touched upon. 



Propagation by division is inapplicable to annuals 

 or biennials, or at least can be practised upon only a 

 very limited scale, and for such plants the gardener 

 has to trust to seeds alone. But it is an axiom in 

 vegetable physiology that seeds reproduce the species 

 only, while buds (that is, propagation by division) 

 will multiply the variety ; and this is undoubtedly 

 true as a general rule. But the skill and care of the 

 gardener often enable him to perpetuate by seed the 

 many races of cultivated annuals, varieties of the same 

 species, improved and altered by centuries of domes- 

 tication, with as much certainty as if he were operat- 

 ing with cuttings. In a well managed farm we see the 

 various breeds of Turnips and Corn preserving each 

 its own peculiar character \inchanged year after year, 

 and yet they must all be propagated by seed alone ; 

 and in gardens the varieties are innumerable of Peas, 

 Lettuces, Cabbages, Eadishes, &c., whose purity is 

 maintained by the same means. The manner in 

 which this is effected is of the first importance to be 

 understood. 



Although it is the general nature of a seed to per- 

 petuate the species only to which it belongs, and it 

 cannot therefore be relied upon, in ordinary cases, to 

 renew a particular variety of species, yet there is al- 

 ways a visible tendency in it to produce a seedling 



