312 CULTIVATED PLANTS AND THEIR ORIGIN 



to the selection of the best forms and the rejection of the worst, 

 another part of the garden was sown in 1890 with the wild seed 

 and the plants were allowed to remain and sow themselves down 

 year by year. The average sugar-content of the roots of the 

 latter rose year by year : in 1893 it was 4-5 per cent, in 1894 

 9-38, their average weight in 1893 was 147 grams and in 1894 

 232 grams. By a comparison with the previous figures it will be 

 seen that the process of selection had nearly doubled the sugar- 

 content and very considerably raised the average weight of each 

 root. 



A. L. de Vilmorin by the selective process continued through 

 four generations, obtained from the slender-rooted annual wild 

 carrot (Daucus Carota L.) biennial plants having thick fleshy 

 roots resembling some of the ordinary types of cultivated carrots 

 in colour, form and size. 



Professor J. Buckman is said to have raised the large hollow- 

 crowned ' Student ' parsnip from the small-rooted wild parsnip 

 by a similar process of selection. 



These may be taken as instances of the rapid modification of 

 wild species by choosing and propagating by seed what are 

 considered the' best specimens of several succeeding generations, 

 all other plants being rejected or destroyed. 



Cultivated varieties now existing can be ' improved ' 01 

 rendered more useful than they are at present in a similar 

 manner, and generally more easily than wild species. 



4. Variations : how induced. — From the foregoing account 

 it will be understood that the improvement of plants depends 

 primarily upon their variability ; for if plants were all alike, and 

 did not vary at all, there could be no selection. Moreover, in 

 plants raised from seeds, the variation must be hereditary, for 

 unless the peculiar quality or character possessed by a specially 

 selected individual plant is passed on to the next generation, the 

 selection becomes useless. For example, no progress can be 

 made in the development of a stiff-strawed race from a kind of 



