viii Contents 



C. The Theory of Chromosomal Hierarchy 110 



a. Precursor Ideas 111 



b. Chromosome Breakage 114 



c. Position Effect 119 

 aa. The Bar Case 120 

 bb. Frequency and Types 126 

 cc. Some Special Features 134 

 dd. Position Effect and Point Mutation 141 



aaa. Deficiencies and Minutes 141 



bbb. Stickiness and Mutators 143 



ccc. Mutable Loci in Maize 145 



ddd. Mottling in Maize and Drosophila 151 

 ee. Theory of Position Effect and Genie Structure of the 



Chromosome 156 



aaa. Breakage and Mutant Effects 156 



bbb. The Chromosomal Sections of Action 159 



ccc. Pseudoallelism and Position Effect 167 



ff. On Allelism 176 



d. Further Members of the Hierarchy 180 

 aa. Larger Segments 180 

 bb. The Chromosome as a Whole 184 



D. Conclusions: The Modem Theory of the Gene 186 



PART II: 



THE CYTOPLASM AS SEAT OF GENETIC PROPERTIES 



1. Prolegomena 194 



2. The Cytoplasm as Specific Substrate 197 



A. Maternal Inheritance and Conditioning of the Cytoplasm 197 



B. Dauermodifikation 201 



C. Plasmon Action of the Specific Substrate Type 205 



a. Mendelian Segregation in Different Cytoplasm 205 



b. Genomes in Different Cytoplasm 209 



c. Evidence from Merogony 214 



D. Genuine Plasmon 215 



E. Cytoplasmic Heredity of the Particulate Type 

 (Plasmagenes) 219 



a. Genoids 219 



b. So-called Cytoplasmic Mutation in Yeast 222 



c. The KiUer Effect 226 



d. The Plastids 228 

 aa. Nature of Plastids 228 

 bb. Plastids and Surrounding Cytoplasm 231 

 cc. Primary Plastid Differences 234 



3. Conclusions and Theoretical 239 



