X CONTENTS 



I'aoe 



CHAPTER IX 

 Cytology of Reproduction in Animals 118 



The Germ Cells — Spermatogenesis — Oogenesis — Synganiy — Cleavage — 

 Parthenogenesis — Protozoa. 



CHAPTER X 



Cytology of Reproduction in Angiosperms 136 



The Flower — Microsporogenesis and the ]\Iale Gametopyhte — Megasporo- 

 genesis and the Female Gametophyte — Syngamy — Embryogeny and Seed 

 Development — Aberrations of the Reproductive Process — Conclusions. 



CHAPTER XI 



Cytology of Reproduction in Plants Other than Angiosperms 148 

 Gymnosperms — Ferns — Mosses and Liverworts — Algae — Fnngi — Conclu- 

 sions. 



CHAPTER XII 



Cytology and Mendelian Heredity 168 



Examples of Mendelian Heredity — Terminology — Explanation in Terms 

 of Chromosomes — Assignment of Genes to a Chromosome — Recombination 

 and Crossing Over — Position of Genes in the Chromosome — The Special 

 Case of Sex — Sex-linkage — Summary and Conclusions. 



CHAPTER XIII 



Chromosomal Aberrations 193 



Deletion — Inversion — Translocation — Duplication — Aberrations and the . 

 Nature of the Gene. 



CHAPTER XIV 



Chromosome Numbers and Their Alteration 204 



Terminology — Tetraploidy — Triploidy — Higher Degrees of Polyploidy — 

 Other Types of Heteroploidy — Significance of Autoheteroploidy in Nature. 



CHAPTER XV 



Cytological Aspects of Hybridity 216 



Chromosome Behavior in Diploid Hybrids — Hybridity Involving Polyploid}' 

 — Amphidiploidy — Cytological Types of Hybriditj' — Conclusions. 



CHAPTER XVI 



The Role of the Cytoplasm in Development and Heredity. . 227 

 Reciprocal Crosses — Chlorophyll Characters — Conclusions. 



CHAPTER XVII 



Cytology and Taxonomy 234 



Cytological Evidence of Relationship: Chromosome Number — Chromo- 

 some Morphology — Chromosome Behavior in Crosses — Aberrations in 

 Reproduction — The Role of Chromosomal Changes in Speciation — Experi- 

 mental Taxonomy — Conclusions. 



Suggested Rk.vding 251 



Index 261 



