INTR ODUCTION 



that organic structure and that Life exhibit are suf- 

 ficiently explained by the laws and actions of chemical 

 affinity, and therefore that the existence of any force 

 called Vitality is unfounded and superfluous. This 

 view has lost credence to a great extent within a few 

 years past, by the disproof of the main foundation on 

 which it rested the doctrine of Spontaneous Genera- 

 tion. The closer relations that have been established 

 between the phenomena of Physics and of Chemistry, 

 the conservation of Energy, and the acceptance of the 

 existence of the Ether, have widened the field of in- 

 vestigation, and even led to the possibility that what 

 were considered the " Ultima Thule " in chemical 

 science, the atoms, may be a compound, a pro- 

 duct of the Ether. The phenomena that Life offers 

 are more than those of Chemistry and Physics. 



The examination of the manifestations of Life 

 should begin with its development in its simplest 

 shapes, the " Monera " of Haeckel : those forms of 

 which it is impossible to say whether they are plants 

 or are animals. Among them, or closely related 

 thereto, are the Bacteria and similar low forms of 

 Life. The evil and the good that they give rise to 

 are pointed out. In what way Life manifests itself 

 and is transmitted without change in the lowest forms 

 of beings, by division or gemmation, and in the pro- 

 gressively higher forms by asexual and sexual genera- 



(xxiv) 



