xviii Contents 



Lecture Page 



and embryonic variability. Sugar-canes. 

 Flowering cannas. Double lilacs. Other 

 instances. Burbank's method of selec- 

 tion. 



XXVII. Inconstancy of improved races . . . 770 

 Larger variability in the case of propaga- 

 tion by seed. Progression and regres- 

 sion after a single selection, and after 

 repeated selections. Selection experi- 

 ments with corn. Advantages and effect 

 of repeated selection. 



XXVIII. Artificial and natural selection . , . 798 

 Conclusions. Specific and intra-specific 

 selection. Natural selection in the field. 

 Acclimatization. Improvement-selection 

 of sugar-beets by various methods. Rye. 

 Hereditary percentage and centgener 

 power as marks by which intra-specific 

 selection may be guided. 



Index 827 



