16 TABLE OF CONTENTS 



PAGE 



of the former. — Their properties ; an explanation 

 of biological phenomena. — The persistence of force 

 and the instability of the homogeneous. — Other 

 hypotheses. 



CHAPTER VIII 



Darwin, Naegeli, De Vries, and Their Theories 



of Heredity 119 



Theories based upon representative particles. ,, 

 Darwin's pangenesis; gemmules representing the * 

 cells of the body; their migration through the 

 organism. — Objections. — Particles representing 

 properties of the organism. — Naegeli's theory ; 

 the micella? and their groupings; the two types of 

 protoplasm ; elementary characters. — Discussion of 

 this system. — De Vries' theory; the pangenes, 

 their migration through the cells. 



CHAPTER IX 

 Weismann's Theory 134] 



The two kinds of protoplasm; germ plasm. — 

 Constitution of the nucleus; ids, idants, determi- 

 nants, biophors. — Ontogenetic differentiation. — 

 Disintegration of determinants; migration of bio- 

 phors. — The continuity of the germ plasm. — 

 Hereditary likeness. — Reserve determinants. 



CHAPTER X 



Germinal Selection. A Discussion of Weis- 

 mann's Theory 150 



A theory created in support of natural selection. 

 — Roux's struggle between the parts ; the struggle 



