638 POTA'JHJ ROT. 



hut such propagation is only the extension of an individual^ and 

 not a production of the species, as by seed. Accordingly, all 

 plants increased by buds, cuttings, layers or roots, retain pre- 

 cisely the peculiar qualities of the individual to which they 

 owe their origin." He further says : I cannot but assent to 

 Mr. Knight's opinion, that ^'- each individual thus propagated 

 has only a determinate existence, in some cases longer, in others 

 shorter; from which cause many valuable varieties of ap- 

 ples AND PEARS, KNOWN IN FORMER TIMES, ARE NOW WORN OUT, 

 AND OTHERS ARE DWINDLING AWAY BEFORE OUR EYES. 



" Gardeners know how many of the most hardy perennial 

 herbs require to be frequently renewed from seed, to exist in 

 full vigor ; and though others appear, to our confined experi- 

 ence, unlimited in that respect, we have many reasons to be- 

 lieve they are not so. Propagation by seeds is therefore the 

 only true reproduction of plants, by which each species 

 remains distinct." 



Again this author says — " Having examined the general 

 structure and external forms of plants, we now come to more 

 important and even essential, though more transitory organs — 

 the flower and fruit. By these, each species is perpetually re- 

 newed without limits — while, as already mentioned, all other 

 modes of propagation are hut the extension of an individual, 



AND SOONER OR LATER TERMINATE IN ITS TOTAL EXTINCTION. 



Those apple trees which have been continually propagated for 

 above a century by ingrafting, are now become so diseased 

 that though the fruit retains the same flavor, the trees are 

 worthless ; and grafts, inserted in other trees, are only an elon- 

 gation of the original tree, and must feel the effect of age, like 

 the tree they were taken froni.^^ 



The natural place, or native place, of the potato seems to 

 have been about latitude 35°, but being a hardy plant, it has 

 become naturalized throughout Europe and this country — from 

 the equator to 70° north. The tuber, in its native state, is 

 said to be very small, about the size of a nutmeg; its present 

 enlarged size being caused by cultivation. 



The Disease. That which has life must experience decay 

 and death. Unless endowed with immortality, there must be 



