146 A MANUAL OF MENDELISM 



The possibilities of increasing the productivity of the 

 vegetable world are beyond comprehension. The timber- 

 grower 5 the planters of tea, coffee, and rubber ; the 

 producers of vegetable fibre ; the growers of grain, 

 roots, and forage ; the raiser of sugar-bearing plants ; 

 the florist ; the vegetable gardener and the pastoral 

 farmer are all interested. The initial step is to combine 

 in a single individual the different factors for yield 

 already existing in other individuals. These factors may 

 be for quicker and more energetic growth, for resistance 

 to drought, frost, wind, or disease, for greater activity 

 in one or more directions, as in seed, or leaf, or root 

 production, and so on. If the hybrid is a plant repro- 

 ducible by buds or shoots or suckers or in any way 

 other than by seed, the new variety is already produced. 

 Notable examples are the London plane which now 

 adorns the streets of many European and American 

 cities, the Huntingdon elm, the cricket-bat willow, the 

 poplar of Metz, the Californian Paradox walnut, the 

 loganberry, the Up-to-Date potato and many other 

 recent varieties of the same species. 



The present position with regard to grain crops might 

 be taken as perhaps the most instructive. The aver- 

 age yield of wheat in Britain is about 32 bushels to 

 the acre. It might be raised to 40 or even 50. For 

 every day by which the life of a variety of wheat is 

 shortened between seed-time and harvest, the wheat- 

 growing area in Canada reaches fifty or sixty miles 

 farther northwards. A vigorous, early ripening and 

 highly productive oat, together with a turnip having 

 the same characters, might increase the returns from 

 many a northern or high-lying farm in Britain and 

 might even be the means of causing many a pasture- 



