XII 



general problem of the deduction of all homogeneous symmetrical arrangements. 

 The theory of Sohncke. The theories of Von Fedorow and Schoenflies. 

 Endless periodical patterns and crystal-structure. The space-lattice and Hauy's 

 law. The chemical structure of crystals. Various views. The Barlow-Pope- 

 theory of the unit-stere. The diffraction of Rontgen-rays in crystals. The 

 investigations of Laue, Bragg, and others. Space-lattices in crystals of sodium- 

 and potassium -chloride. The chemical molecule in crystals. Molecular and atomic 

 forces. Valency and co-ordination. Periodical arrangements in living nature. 

 Remarks on phyllotaxis. Contrast between living and inanimate objects. Con- 

 clusion p. 109. 



SEVENTH CHAPTER. 



Mimetic forms and apparent symmetry. Crystal-aggregates. Twinning. Forms 

 of approximate symmetry. Pseudo-symmetry. Mimicry. Compound twinning of 

 microscopical lamellae. Optical anomalies. Mallard's theory. The rotatory 

 power of crystals. Pseudo-symmetry and polymorphism. Mallard's hypothesis 

 concerning the pseudo -symmetrical character of all crystalline matter. Final 

 remarks P- 166. 



EIGHTH CHAPTER. 



Pasteur's law. The fission of racemoids. Molecular dissymmetry and 

 optical activity. The methods of fission. Spontaneous crystallisation; problems. 

 Transition-temperature. Partial racemism. Physiological action of antipodes. 

 Enzyme-action. Pseudo-racemism. Racemisation and its mechanism. Pasteur's 

 general views. Thetheoryof the asymmetric atom. Pasteur's law and Van 't Hoff- 

 Le Bel's theory; problems. The symmetry of chemical molecules. Crystal- 

 lonomical relations. Chemical composition and optical rotatory power. Asym- 

 metric metal-atoms. Enantiomorphism of cyclic compounds. Enantiomorphous 

 configuration and hemihedrism. Final remarks p. 198. 



NINTH CHAPTER. 



Pasteur's law (continued). The production of racemic or inactive substances 

 from inactive molecules. Chemical reactions between optically active and 

 inactive substances. The rotatory power of the reaction-products in comparison 

 with that of the original substances. The Wai den-in version. Reaction-velocity 

 of antipodes under different circumstances. Artificial and natural synthesis. 

 Views explaining asymmetrical or natural synthesis. The influence of optically 

 active molecules in the production of optically active substances from inactive 

 materials. Partially and totally asymmetrical synthesis. Directional influence of 

 pre-existing dissymmetry. Asymmetric conditions during synthesis. Problems 

 of the future p 270. 



ERRATA p. 307 . 



ALPHABETIC INDEX p. 30 g. 



