Nilsson: Plant-Breeding in Sweden 



287 



preceding work, that the only true 

 starting-point for the fixation of differ- 

 ent types must be plants taken one by 

 one; the only unity with which we 

 should work must be the living plant 

 itself and not at all — as had thitherto 

 been supposed — its individual organs: 

 the ear, the grain, etc., to which different 

 hereditary dispositions had been at- 

 tributed. 



SVALOF method OF PLANT BREEDING 



This discovery completely changed 

 our outlook on the problem of plant 

 breeding, and also — as we realized very 

 clearly — on the methods of selection. 

 No sooner had we obtained sufficient 

 proof than our operations were changed 

 and immediately directed in accordance 

 with the new principles. 



In the first place we demonstrated 

 the existence, in our material, of a 

 large number of independent forms, 

 having widely divergent qualities and a 

 practical value that was quite variable. 

 Thanks to our separate cultures, each 

 one deriving from a single plant — 

 "pedigreed culture" — which was easy 

 to control, we have found that most of 

 the descendants are constant, and only 

 in rare cases are they in the heterozygous 

 condition resulting from crossing. Thus, 

 while we had formerly been absolutely 

 incapable of producing a single variety 

 which would really breed true, we found 

 ourselves from then on able to produce 

 as large a number as we pleased of new 

 and stable sorts, suitable for extended 

 culture. 



In employing the old method of 

 "selection in mass" and methodical 

 order of choice, we were working blindly 

 without knowing how or when or even 

 whether we would some day reach 

 stability of the type, which was more 

 important than any other quality. 



On the other hand, if we commence 

 by a pedigreed culture, as at present, all 

 fear of failure because of insurmountable 

 variations is eliminated. The varieties 

 are already there, and fixed from the 

 beginning of work; the only difficulty is 

 to learn to recognize them and to place 

 the proper valuations upon them. The 

 principal and only decisive work thus 

 comes after the fixation, and when the 



variety is already established and in our 

 possession. 



The long scries of selection-operations 

 which we had previously been obliged to 

 make each year on thousands of plants 

 and for their different organs — on the 

 plant as a whole, on its straw, on its 

 various ears, on the haulms and on the 

 grains — all that was now superfluous, 

 since we recognized that the plant itself 

 was the ultimate unity, to be treated by 

 a comparison with all the other in- 

 dividuals of its generation. The in- 

 genious instruments which had previous- 

 ly been indispensable in our researches 

 have now been set aside as museimi 

 exhibits, to be used at most for an 

 occasional control-examination : the field 

 of experience is from now on the place 

 for appraising our results. 



the most essential work. 



It will be understood, also, that 

 although this simple operation created 

 a complete revolution in our methods, 

 pedigree-culture has nevertheless re- 

 ceived only a secondary place among 

 the operations at Svalof. It has be- 

 come only a preparatory and practical 

 auxiliary for getting out properly the 

 material which we desire to utilize. The 

 greatest interest and the most essential 

 work, on the contrary, remain in further 

 investigation of the practical value 

 of the innumerable little elementary 

 species. 



The decisive qualities of each species 

 being surprisingly numerous, and com- 

 bining with each other in related forms 

 according to a fabulously rich scheme, 

 the determination of their comparative 

 values becomes an extremely arduous 

 task, the more so since it is necessary 

 to start with as large and varied a 

 collection as possible, if we want to 

 have a chance really to find the best. 

 Accordingly, since that time the principal 

 work of Svalof has been connected with 

 these problems. That is why it has 

 become so preponderant, why it has 

 stamped its character on the whole 

 system at Svalof. 



The first thing to do was to divide up 

 the work among the competent persons 

 available, in such a way as to give to 

 each one a limited field, comprising one 



