QUANTITY 125 



Nor perhaps is this yet the end, for, when Extra 

 Squarehead II became available, a child of the cross 

 between it and a high yielding Danish variety called 

 Tystofte Smaawheat gave a higher yield than either 

 of the parents in the one year, 1912, in which it had 

 been tested. In the same year another variety selected 

 from the stock which produced 0801 gave a yield still 

 higher than any. The following table shows the yields 

 of all these varieties for the one year. For ease in 

 comparison, the yields are also reduced to the old 

 basis, but it must be remembered that they represent 

 one year's results only. 



Kilogrammes _ , , 

 per hectare Reduced 



(Extra Squarehead II 3950 130-5 



Parents: | Tystofte Smaawheat 4350 143-7 



Progeny: 0860 4750 154-5 



0801, new selection 4950 163-5 



Thus, by procuring higher yielding varieties, then by 

 eliminating the weaker plants, and, finally, by crossing 

 the best yielders and selecting their best descendants, the 

 Swedish farmer is now in possession of wheats which are 

 50 per cent, better than the old native varieties. 



But the question is : what interpretation may be 

 given to these phenomena ? Clearly there are pairs of 

 factors with whose distribution the yield varies in one 

 way or another. Professor Nilsson-Ehle mentions three 

 pairs, namely, resistance and non-resistance to rust, 

 resistance and non-resistance to winter, and resistance 

 and non-resistance to lodging. In no case does he say 

 which is the dominant and which the recessive, nor 

 does he indicate what is the numerical value of any 



