78 



(47, p. 11) says: " Even if the new sorts actually are superior and deserve to 

 be spread, it may nevertheless be insisted that by displacing the old so- 

 called native sorts there may be a danger of losing for all time many valuable 

 constituents which they may possess and which might become of value in 

 breeding work. From this standpoint it is necessary that the old sorts be 

 conserved and further worked upon." These experiences would seem to 

 indicate the advisability of a breeding station adopting some definite plan 

 whereby representative cultures of the best old races may be retained in 

 their natural composite condition in order that a perennial source of new 

 selections and material for continued crossing work may thus be provided. 



Artificial Investigation into the origin of hereditary variations in cultivated crops 



hybridization having led to the conclusion that these variations consist very largely of 

 different combinations of segregating units or factors resulting from natural 

 crossing, the breeder's whole manner of thinking must be guided by those 

 laws upon which the performance of such products is based. He must not 

 only seek to take advantage of such combinations as nature has already 

 provided, but he must at the same time bring his own skill and intelligence 

 to bear in endeavouring to effect artificially still better unions. Since the 

 reappearance in 1900 of Mendel's epoch-making papers on heredity, artificial 

 crossing has been elevated, not only to a process of immense scientific interest, 

 but to one of great practical importance. Although this process had occupied 

 a prominent place in the work of different breeders for many years previous, 

 having been practised by Knight during the early part of the Nineteenth 

 Century and later by such savants as Vilmorin, Bestehorn, Cymbal and 

 many others, yet its significance was not fully appreciated until after the 

 true nature of hereditary variations and the idea of segregation and combina- 

 tions was explained by Mendel. 



Experience gained in the application of this law during the past ten 

 years seems to afford clear and convincing evidence as to why earlier attempts 

 at hybridization at Svalof were unproductive of results. The following are 

 submitted as the main causes: 



1. The sorts chosen as parents were neither suitable for cultivation 

 nor were they crossed with any idea of effecting a combination of characters. 

 A good example is given in the crossing between Old Squarehead and Dividend 

 Autumn wheats. Many crosses were also made between Spring wheat sorts 

 whose values had not been sufficiently tested and which were later found to 

 be of little consequence. It is now recognized that if results are to be 

 expected, the crossed varieties must be fully known with respect to their 

 practical value when grown under given conditions and the crosses must 

 always be made with a definite purpose of combination. 



2. Sorts were crossed which were too unlike each other, e.g.: the 

 English Squarehead wheat was crossed on the Swedish velvet chaff, two sorts 

 which are widely different in character, both as regards type of plant and 

 winter-hardiness. In such cases the greater number of differentiating units 

 to be dealt with make possible the creation of a great number of different 

 combinations, thus rendering the work difficult and precarious. 



