Con tc tits xiii 



CHAPTER III. CELLULAR BASIS OF HEREDITY AND DEVEL- 

 OPMENT 



A. INTRODUCTORY 



i. Definitions 



2. The Transmission Hypothesis 



3. Germinal Continuity and Somatic Discontinuity 

 •-.}. The Units of Living Matter . 



^^ £ Heredity and Development / 



B. THE GERM CELLS 



1. Fertilization 



2. Cleavage and Differentiation 



3. The Origin of the Sex Cells 



a. The Division Period 



b. The Growth Period 



c. The Maturation Period 



C. SEX DETERMINATION 



1. Chromosomal Determination 



2. Environmental Influence 



D. THE MECHANISM OF HEREDITY 



I. The Specificity of Germ Cells 

 II. Correlations between Germinal and Somatic Organization 



1. Nuclear Inheritance Theory 



2. Linkage of Characters and Chromosomal Localization 



a. Sex Linked Inheritance 



b. Other Cases of Linkage 



3. Cytoplasmic Inheritance 



a. Polarity 



b. Symmetry 



c. Inverse Symmetry 



d. Localization Pattern 



E. THE MECHANISM OF DEVELOPMENT 



1. The Formation of Different Substances 



2. Segregation and Isolation of Substances in Cells 



a. By Protoplasmic Movements 



b. By Differential Cell Divisions 



