CONTENTS 



XI 



CHAPTER V 



X The Chromosomes ....... 



A. The Continuity of the Chromosomes 



B. The Composition of the Chromosomes of Smaller Units . 



C. Variation in the Number of Chromosomes . 



1. Variation in Chromosome Number due to Fragmentation 



or Linkage ...... 



2. Variatio7i in Chromosome Number due to Irregularities 



of Mitosis ...... 



3. Variation in Chromosome Number due to Multiplication 



or Fusion ...... 



I'AGE 



123 

 124 



134 



139 



144 



147 



CHAPTER VI 



Heredity and Morphogenesis ..... 



A. The Equality of Inheritance from Male and Female 

 Parents ....... 



. B. The Process of Mitosis and its Implications. The 

 Functional Differentiation of the Chromosomes 



C. The Process of Meiosis .... 



D. The Parallel which exists between Chromosome Be- 



haviour AND THE Results of Breedinc. Experiments 



1 . The Genetics of a Tetraploid Plant 



2. Segregation and /\irthenogefiesis 



3. Segregatio7i and Bud-Variation 



4. The Interchange of Hereditary Factors 



logons Chromosomes . 



5. The Cytological Basis of Mutation 



E. Sterile and Partially Sterile Hybrids 



F. The Nucleus in Morphogenesis 



G. Chromidia and Chondriosomes 



1. Chromidia 



2. Chondriosomes . 



3. The Relation between Chromidia and Chondriosomes 



between Homo 



154 



