Fluctuating variability. Quetelet's law. Individual and partial fluctuations. Linear variability. Influence of nutrition. Periodicity curves.

XXVI. Asexual multiplication of extremes. 742

Selection between species and intra-specific selection. Excluding individual [xvii] embryonic variability. Sugar-canes. Flowering cannas. Double lilacs. Other instances. Burbank's method of selection.

XXVII. Inconstancy of improved races 770

Larger variability in the case of propagation by seed, progression and regression after a single selection, and after repeated selections. Selection experiments 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 intraspecific selection may be guided.

Index_________________________________________827

[1]

A. INTRODUCTION