x CONTENTS. 



PAGE 



defence of, and attack on, Darwinism, 187. The Weis- 

 mannian theories, 188. Panmixia, 190. The theory of 

 germinal selection, 193. The physical and chemical 

 structure of protoplasm, 194. Objections to the theory 

 of germinal selection, 200. Roux's theory of intra-selec- 

 tion, or the battle of the parts, 201. Objections to Roux's 

 theory, 203. The theory of organic selection, or ortho- 

 plasy, 208. 



APPENDIX: List of Weismann's evolution papers, 212. 

 Theories of ultimate protoplasmic structure, 214. Encase- 

 ment theory, 215. Micromeric theories, 215. Buffon's 

 theory, 216. Spencer's theory, 217. Darwin's theory, 

 218. Nageli's theory, 219. De Vries's theory, 220. Hat- 

 schek's theory, 222. Delage's criticisms, 224. Le Dantec's 

 criticisms, 224. Verworn's biogen hypothesis, 225. De- 

 lage's machine theory, 225. Le Dantec's theory of 

 chemism, 225. Neo-vitalism, 226. Morgan's criticism of 

 Weismann's method of argument, 229. References to 

 discussions of orthoplasy, 229. 



CHAPTER IX. 



OTHER THEORIES OF SPECIES-FORMING (Continued}: 



THEORIES AUXILIARY TO SELECTION (Continued} 232 



Isolation theories, 232. Wagner's "Separations-theorie," 

 234. Jordan's upholding of the importance in species- 

 forming of geographic isolation, 237. Biologic and sexual 

 isolation, or physiological selection, 243. Gulick's work 

 and conclusions, 249. 



APPENDIX: References to discussions of isolation, 253. 

 Haacke's summary of Wagner's theory, 253. Grinnell's 

 studies of geographic differences in the chickadee, 255. 

 Further references to discussions of isolation, 261. 



CHAPTER X. 



OTHER THEORIES OF SPECIES-FORMING (Con- 

 tinned}: THEORIES ALTERNATIVE TO SELEC- 

 TION . . 262 



Three general groups of theories proposed to replace the 

 selection theories as explanations of species-forming and 

 evolution, 262. The Lamarckian theory, 262. Objections 

 to the Lamarckian factors, especially that of the inheritance 



