74 DISEASE IN PLANTS. 



so-called Square-heads, which then came into the 

 market. His experiments, even with the above 

 varieties, are worth noting, however, for they show 

 how promising the results of carefully conducted 

 crossing and selection may be. 



The crossing was done in 1875, in both direc- 

 tions. In 1876 the few grains obtained were 

 found to yield plants almost all alike, with the 

 long loose ear of the German parent, but the 

 paler colour of the English wheat. 



In 1877 the plants, obtained by sowing the 

 finest grains, were found to consist of pure 

 white, pure red, and of forms which appeared to 

 vary and revert in all possible degrees as regards 

 colour, density, and other characters intermediate 

 between these. 



By carefully separating the closest and densest 

 white wheats from the closest and densest red 

 ones, he got in 1878 a large number of each 

 coming nearer to the type sown than did the 

 mongrel forms intermingled with them : these 

 reversions and intermediate forms were then rigidly 

 eliminated, and only the deepest coloured and 

 densest red and white forms again sown. 



In 1879 these two chosen varieties were con- 

 stant, so far as concerned those selected from the 

 crossing of female English white with male 

 German red wheat, and the following year proved 

 the constancy of the red variety in the reciprocal 

 cross. In 1886 all four varieties i.e. the two 

 reds and the two whites of both the crossings 

 had become constant. 



