44 NATURE AND LIFE. 



to believe that they can transform the species. On exam- 

 ining the impressions of fishes and plants in the schists of 

 Halle, Leibnitz, for the first time, perceived in those re- 

 mains, not a sport of Nature, but testimonies to revolutions 

 on the globe, and to the existence of faunas and floras that 

 have perished. The " Protogaea," in which this important 

 question is particularly and deeply studied, fixes the start- 

 ing-point for modern geology and paleontology, and for all 

 explanations, on the Plutonic theory, of the earth's crust. 

 Hutton, Buffon, and Cuvier, drew inspiration for their la- 

 bors from this sketch of Leibnitz. 



He argues that, if it often happens in science that we 

 fail in the power of distinctly marking differences, that 

 results from our ignorance of both the minute parts and 

 the inward structure of things, that is, the principles by 

 which their fundamental nature might be accounted for. 

 That want of knowledge obliges us to pronounce by guess 

 on many phenomena, the full understanding of which is 

 reserved for the future. Therefore he builds great hopes 

 upon the use of the microscope, and upon comparative 

 anatomy (the term is his own), in which he believes that 

 the confirmation of many of his ideas will be found. 

 Among other conjectures he distinctly foresees the func- 

 tion and importance of the spermatozoa, in making the 

 assertion that it will be discovered how each sex supplies 

 some organized thing in the phenomena of generation. 

 And this assertion has a very just effect in correcting his 

 theory of the syngenetic preformation of beings, or the 

 incasement of germs, according to which all ova exist be- 

 forehand from the origin of the world, inclosed in that of 

 the first representative of each species. That theory, 

 proved to be erroneous by the whole result of observation 

 in embryogeny, is thus erroneous, precisely because the or- 

 ganized element contributed by the male sex is indispen- 

 sable to the growth of the embryo. 



