viii CONTENTS 



Page 



I). Differences of dosage no! confined to individual genes I 17 



/'- The heterozygote as dosage difference 154 



7. The interaction of the genea 156 



8. The type of reaction controlled by the tnutanl gene .... 171 



A. Reactions within the cells 171 



B. React ions of an induct ive type 181 



1. Terminology lsi 



2. Genie products of the hormone type 182 



3. Diffusion of growth— or similar substances 190 



4. The determination stream 193 



9. The problem of pattern 200 



A. Pattern in development 200 



B. Genes controlling developmental processes 205 



C. Genes and pattern 209 



1. Patterns of growth and form 210 



2. Symmetry 221 



3. Special patterns superimposed upon the general pattern 228 



4. Composite patterns 241 



a. General embryological features 241 



b. Pattern localization 245 



c. Additional facts 255 



III. The Cytoplasm and the Activation of the Gene 263 



1. Interaction of nucleus and cytoplasm 263 



2. The activation of the genes 265 



3. Cytoplasmic heredity 267 



A. Merogony 267 



B. Plastids 269 



C. Cytoplasmic influence upon gene-controlled characters. . . 270 



D. The theory of the plasmon 275 



E. Cytoplasmic inheritance and Dauer-modification 276 



F. Cytoplasm and sex 278 



G. Genes controlling cytoplasmic properties 280 



4. Conclusions 280 



IV. The Nature of the Gene 282 



1. The gene as an active molecule or group of molecules 283 



A. Mutation as change in quantity 285 



B. Mutations as changes of side chains or residues 288 



C. Mutations as changes of a stereoisomer^ type 292 



D. Mutations as polymerizations 292 



2. The theory of the gene as based upon physical deliberations 293 



3. The gene as an aggregate of different parts 295 



A. The genomere theory of Anderson and Eyster 295 



B. The theory of the Serebrowsky school 295 



C. The hypothesis of Thompson 297 



4. The gene as loss of chromosome material 298 



5. The gene as part of a higher unit 299 



