CONTENTS XV 



SUPPLEMENTARY FACTORS OF EVOLUTION 



Page 



Courtship Selection 489 



Lamarckism — Acquired Characters; Use and Disuse; Influence of the Environ- 

 ment 489 



Neo-Lamarckism 491 



VARIATION 



Kinds of Variation — Discontinuous Variation. Adaptation to the Environment. 

 Somatic and Germinal Variation. Weismann's Views on the Non-Inheritance 

 of Acquired Characters. Organic Selection 491 



HEREDITY 



Weismann's Views on Germ-Plasma. Influence of Environment on Germ-Cells, 

 Experiments of Yung on Tadpoles, and Schmankewitsch on Crustaceans. 

 Gallon, Karl Pearson, and Mendel 492 



