ON VARIETIES, RACES, Sl'B-SPECIES, AND SPECIES. 97 



Our views on the influence of circumstances in modifying 

 plants raised from seed may be thus summed up : — 



We sow seeds gathered from a plant not a native of the place 

 where the seed is sown, or if it be, it must have encountered 

 circumstances sufficient to have modified its seeds either in their 

 organization or their development. 



We choose from the plants yielded by the sowing those most 

 modified in the way desired ; we sow their seeds, of coui'se taking 

 care to prepare tlie soil and use those methods which we have 

 learned to be most proper for tlie end we have in view. 



The changes are not indefinite in the same place and under 

 circumstances actually^ existing : after a time a certain form is 

 obtained which is stable for a given state of things. 



A variety produced in any country can be improved for our 

 purposes in another place, by virtue of circumstances analogous 

 to, but more intense than those of the first place. There is then 

 a possibility of success if a variety indigenous to one country be 

 removed to another where it is exotic. 



But this variety may be modified in a way diflPerent from that 

 in which it was modified in the former place. 



1. It may revert to the type of tiie species and remain such. 



2. It may assume a modification of a type diflferent from that 

 it represented. 



3. It may revert to its type, and then after successive genera- 

 tions it may^ undergo changes different from those it originally 

 underwent. An example of this \\ould be afforded if it were 

 proved that the European fruits, sown in Virginia, first of all, 

 reproduced their wild type, and then, by successive sowings, 

 presented modifications different from those obtained in Europe. 



Thus suppose the centre c to represent tlie type ^ 

 of a species, a the modification obtained in Eu- 

 rope ; now, in Virginia, tlie modified plant would ^'\ 

 correspond with c, and then by successive gene- 

 rations with h, U, b". ^"^ 



§ V. OF THE MULTIPLICATION OP PLANTS BY DIVISION, AND 



OF THE DEGENERATION AND EXTINCTION OF THE PLANTS 

 so OBTAINED. 



It is first of all requisite to explain what we mean by the per- 

 fectioning and degeneration of plants and animals. In common 

 parlance, the first means that a livnig body has been rendered 

 more fit to satisfy^ the wants of man than it was before ; and the 

 last means just the reverse. Neither expression indicates that 

 a plant or animal has gained or suffered in point of vigour, 

 longevity, generative power, &c. ; for a plant that is said to be 



