'seminal sports' 30s 



buds upon the plant. Thus, single buds upon peach trees have 

 been observed to develop into shoots which, instead of bearing 

 peaches, bear nectarines, and plum trees ordinarily producing 

 purple fruit have been known to give rise to a single shoot 

 bearing yellow plums of a totally different character from any 

 previously known. 



Such sudden and extensive variation is termed bud-variation 

 or ' sporting,' and is most frequently met with in those species of 

 perennial plants which have been under cultivation for very long 

 periods of time. It is extremely rare among annual plants and 

 uncommon upon perennials which have only recently been 

 introduced into the garden. 



Very few 'sports' can be propagated by seeds; they must 

 consequently be removed from the parent and multiplied vege- 

 tatively, that is, by cuttings and layers or by budding and grafting. 



Many examples of new varieties of plants which have originated 

 from bud-variation are met with among garden flowers such as 

 roses, carnations, chrysanthemums, tulips and pelargoniums. 



Also in this manner have arisen practically all the variegated- 

 leaved and ' weeping ' forms of ash, willow, box, holly, and 

 other trees and shrubs. 



Among farm crops potatoes are subject to bud-variation, but 

 its occurrence is extremely rare : varieties bearing tubers with 

 purple skins have, however, been known to produce single white 

 tubers among those of ordinary colour, and purple-skinned tubers 

 have been observed with one or more white ' eyes ' which, on 

 being cut out and propagated, have grown into plants bearing 

 white-skinned tubers only. 



3. Variation among seedling plants. 



(a) ' Seminal sports ' : selection and fixation of varieties. — 

 One of the most important peculiarities of living things of all 

 kinds is the variability of their sexually-produced oifspring. 

 Although bean seeds always produce bean plants and wheat 

 grains invariably give rise to wheat plants, nevertheless no two 



