vi CONTENTS. 



CHAPTER XIX. 



Pages 



Heterogenesis in Higher Organisms .. .. .. .. 307-368 



CHAPTER XX. 

 Heterogenesis in Lower Organisms .. .. .. 369-427 



CHAPTER XXI. 

 Transformations of Euglenae and other Organisms: Modes 



of Origin of Ciliated Infusoria .. .. .. .. 428-490 



CHAPTER XXII. 



Transformations of Ciliated Infusoria : Modes of Origin of 



Rotifers, Tardigrades, and Nematoids .. .. .. 491-540 



CHAPTER XXIII. 



Individuals, Ephemeromorphs, and Species .. ... .. 541-604 



CHAPTER XXIV. 

 General Considerations : Conclusion . . . . . . . . 605-640 



APPENDICES. 



Appendix A. On some Organisms and other Products of 

 Uncertain Nature met with in boiled Solutions of 

 Ammonic Tartrate, and also in others containing 

 Ammonic Silicate . . . . . . . . . . . . i-xiv 



Appendix B. On the Living Matter and Organisms con- 

 tained within Crystals of Neutral Ammonic Tartrate xv-xxix 



Appendix ,. Comparative Experiments .. .. .. xxx-lii 



Appendix D. On the Variability of the Lower Forms of 



Living Matter liii-cviii 



Appendix E. On the ' Germ-theory ' in relation to Epidemic 



and ' Specific ' Contagious Diseases . . . . . . cix-clv 



