PREFACE. ix 



about the origination of crystalline matter, and of 

 another set for inducing and regulating the growth of 

 crystals ? And may it not also be deemed just as absurd 

 and unnecessary that any such demands should be made 

 in reference to the origin of living matter and the 

 growth of organisms? 



Both crystalline and living aggregates appear to be 

 constantly separating de novo from different fluids, and 

 both kinds of matter now seem to be naturally formable 

 from their elements. It so happens, however, that one of 

 the fundamental properties of living matter that is to 

 say, its power of undergoing spontaneous division 

 is constantly entailing results which, owing to their 

 being of a more obvious nature, have long and unduly 

 monopolized the attention of biologists and of the 

 world in general. And yet the existence in living 

 matter of this power of spontaneous division, by which 

 processes of Reproduction' are brought about, is rendered 

 somewhat less exceptional and mysterious when we 

 consider that a fragment of crystalline matter artificially 

 severed from the parent mass will, under suitable con- 

 ditions, grow into a crystal similar to the original form. 

 The reproduction of similar matter takes place in each 

 case ; and surely the mere fact that the initial repro- 

 ductive separation may occur c spontaneously ' in the 

 case of living matter, is no argument against the pro- 

 bability that such matter may, like crystalline matter, 

 also come into being by an independent elemental 

 mode of origin. 



Our experimental evidence, therefore, merely goes to 

 prove that such an elemental origin of living matter 

 is continually taking place at the present day, that 



