THE LIFE OF MATTER. 429 



Possible extinction of a-ci'ystnJUne species.— Kt^ these crystals melt at 

 18"^, that toiiiperuture represents the point of fusion of solid glycerin 

 or the point of solidification of liquid glycerin. Yet the liquor does 

 not solidify at all if its temperature falls below 18'-', nor does it solid- 

 ify at zero, nor even at 18"^ below zero, it merely thickens and ))ecomes 

 pasty. We only know gh^cerin, then, in a state of surfusion, a fact 

 which chemists have not learned without amazement. 



With these conditions, so analogous to the appearance of a living 

 species, to its unlimited propagation and to its extinction, the mineral 

 world offers a quite faithful counterpart to the animal world. The 

 living being illustrates here the history of the brute body and facili- 

 tates its exposition, and, inversely, the brute body in its turn thiows 

 a remarkable light on the subject of the living body and upon one of 

 the most serious problems relative to its origin, that of spontaneous 

 generation. 



Conclusion. — These facts lead to a single conclusion. Up to the time 

 when the concourse of propitious circumstances favorable to their 

 spontaneous generation was brought al)Out, crystals were obtained only 

 by filiation. Up to the time of the discovery of electro-magnetism 

 magnets were made only by filiation, by means of the simple or double 

 application of a preexisting magnet. Before the discovery which fable 

 attributes to Prometheus, every new fire was produced onl}- by means 

 of a spark deriv(Hl from a preexisting fire. We are at the same his- 

 torical stage as regards the living world, and it is for this reason that 

 never up to this time has there been formed a single particle of living 

 matter except l>y filiation, except by the intervention of a preexisting 

 livino- organism. 



