THE EVOLUTION IDEA 143 



animals, like so many rings, are so closely united 

 that it is not possible either by observation or 

 imagination to determine where one ends or be- 

 gins." 



He was very familiar with both Bacon and 

 Descartes, and by the former had probably had 

 his attention called to the matter of Variation. 

 Huxley quotes from the Protogce (xxvi) a pas- 

 sage which proves that Leibnitz also had his own 

 thoughts and observations upon the mutability of 

 species. He is speaking of the fossil Ammonites 

 related to the living nautilus, and, after noting 

 the infinite variations in their shells and the gra- 

 dations which are presented among these forms, 

 says :^ 



Some are surprised that there are to be seen every- 

 where in rocks such objects as one might seek for in 

 vain elsewhere in the known world, or certainly, at 

 least, in his own neighborhood. Such are the horns of 

 Ammon [Ammonites], which are reckoned a kind of 

 Nautilus, although they are said to differ always 

 both in form and size, sometimes indeed being found 

 a foot in diam.eter, from all those animal natures 

 which the sea exhibits. Yet who has thoroughly 

 searched those hidden recesses or subterranean 

 depths ? And how many animals hitherto unknown to 

 us has a new world to offer ? Indeed it is credible that 

 by means of such great changes [of habitat] even 

 the species of animals are often changed. 



i/6id. Translation of Latin text. 



