284 ON THE INFLUENCE OF CULTURE 



A species, you recollect, comprehends all those plants 

 which bear so great a resemblance to each other that we 

 may reasonably suppose them to be descended from the 

 same parent stock. But, independently of this general 

 similitude, each species admits of various shades of differ- 

 ence, some of which are strongly marked, and of a per- 

 manent nature ; others more slight and evanescent : hence 

 spring the three modifications of Races, Varieties and Va- 

 riations. Several races derive their origin from the same 

 species ; and the points in which they differ are of so de- 

 cided a character, that they are continued from the parent- 

 plant to its offspring, or, in other words, when it is pro- 

 pagated by seed. 



Varieties are a subdivision of races ; in which the points 

 of difference are of so slight a character, that they are 

 continued from one individual to another only when the 

 plant is propagated by subdivision ; that is to say, by graft- 

 ing, budding, or layers, but are obliterated when it is rais- 

 ed by seed. 



Variations are the feeblest of all deviations : they orig- 

 inate in the peculiar circumstances or situation of the 

 plant, such as peculiarity of soil, temperature, &c., and are 

 susceptible of being continued to successive individuals 

 only if placed under similar circumstances. 



Now, the art of man has great influence in varying and 

 multiplying these several modifications of species. If, for 

 instance, the pollen of the flower of one species be made 

 to fall on the pistils of another species, one of two things 

 may happen : either the flower will produce no seed ; or, 

 if it produce seed, the plant which results from it (which 

 is called a Hybrid) will partake of the form and nature of 

 the two plants from which it springs ; and hybrids very 

 rarely produce any seed. 



Caroline. It is then, I suppose, only performed as a 

 curious experiment, since the seed is lost, and nothing is 

 gained in exchange. 



Mrs. B. True ; but the result is very different, if, in 

 two plants of the same race but of different varieties, the 

 pollen of one be made to fall on the pistils of the other, 

 the blossom will in general bear fruit, and thus a new va- 



1530. What does a species comprehend! 1531. What less gener- 

 al shades of difference is there in plants'? 1532. What is said of 

 Races? 1533. Of Varieties'? 1534. Of Variations? 1535. 

 What is Hybrid, or how is it produced 1 1536. What is said of 

 the mixtures of two plants of the same race, but of different varieties! 



