462 



SCIENCE. 



[N. S. Vol. XXII. No. 563. 



pearances of the wheat of the district. A 

 specially strong wheat from the Canadian 

 Northwest, after some considerable fall of 

 strength in the first English crop, has fallen 

 no further after three successive crops, and 

 still retains all the characters of an excep- 

 tionally strong wheat, although the yield 

 remains poor from an English standpoint. 

 Other varieties have rapidly and entirely 

 lost their strength when changed to English 

 conditions from America, or Hungary, or 

 Russia; many, however, while showing the 

 effect of climate, yet stand apart from the 

 typical English wheats and show no tend- 

 ency to 'acclimatize' in the sense of ac- 

 quiring the character of the local varieties. 

 In the whole work the thing which stands 

 up most prominently is the fundamental 

 importance of the 'variety' ; each race, each 

 botanical unit as it were, possesses an indi- 

 viduality and yields grain of a character- 

 istic composition; and though climate, soil, 

 season, manuring, are factors producing 

 variation in the composition, they are all 

 small compared with the intrinsic nature 

 of the variety itself. Similar conclusions 

 follow from the work of Wood and his col- 

 leagues upon the composition of mangels, 

 and of Collins on the composition of swedes. 

 The proportion of dry matter and sugar in 

 the root, while varying markedly in the 

 individual roots, possesses a typical value 

 for each race; and though season, locality 

 and to some extent manuring affect the 

 composition, the changes thus induced are 

 not great. 



Starting, then, from this point, that 

 variety or race is the chief factor in the 

 composition of a given plant, and that, 

 once the variety is fixed, the other factors, 

 which are more or less under control, such 

 as manuring, soil and climate, have but 

 minor effects upon the quality, the road to 

 the improvement of the quality of our farm 

 crops lies in the creation of new varieties 

 by breeding. An improved variety is all 



clear gain to the farmer ; climate, season 

 and to a large extent soil are outside his 

 control; while better manuring and culti- 

 vation, however much their cost may be 

 lessened by increased skill, yet involve 

 expenditure and become unremunerative 

 above a certain point. But an improved 

 variety, without costing any more to grow, 

 may increase the returns by 10 or 20 per 

 cent., in some cases may nearly double 

 them. 



As regards the value of selection. Wood 

 shows that the composition of the mangel, 

 which has been selected solely for such ex- 

 ternal qualities as shape and habit, has re- 

 mained stationary during the fifty years 

 or so for which we possess any information ; 

 while between 1860 and 1890 the sugar 

 beet has had its sugar content raised from 

 an average of 10.9 to 15 per cent, by the 

 steady selection of seed-mothers for their 

 richness. The prospects of breeding new 

 varieties of wheat, and particuarly of se- 

 curing improvements in such qualities 

 as 'strength,' have been enormously im- 

 proved within the last year or two through 

 the investigations which have followed on 

 the rediscovery of Mendel's law of inherit- 

 ance. Wheat as a normally self -fertilized 

 plant is particularly suited to the investi- 

 gation of Mendel's law, and the work of 

 Biffen shows that, with a few possible ex- 

 ceptions, the characters of the parent 

 varieties are inherited strictly in accord- 

 ance with the expectations derived from a 

 consideration of that law. The great 

 practical importance of this. generalization 

 lies in the fact that it thus becomes possible 

 to pick out with certainty fixed types in 

 the third generation of the hybrids, 

 Avhereas Avithout the guidance of Mendel's 

 law and working by the old plan of selec- 

 tion, followed by continuous 'rogueing,' it 

 was impossible ever to secure a pure strain 

 unless by chance an individual possessing 



