PREFACE. 



HARMONY is the universal law of Nature. Of all the number- 

 less forms of animals and plants that deck the surface of the 

 globe, there is not one that is not perfectly fitted for its peculiar 

 sphere. The configuration of our earth, and the physical laws that 

 govern the waters and the atmosphere, are in complete unison 

 with the wants of organic life ; and suns and planets wander 

 harmoniously through illimitable space. And as it now is, thus 

 it ever has been ; for the annals of our globe bear witness, 

 throughout all the changes of the primeval world, to the concord 

 which has constantly reigned between the physical condition of 

 the earth and its inhabitants at each successive epoch. 



In the following pages I have endeavoured to point out some 

 of the most striking examples of this fundamental truth, which 

 so forcibly proclaims the unity of creation. May I have ac- 

 quitted myself of my task so as to strengthen my readers in 

 the conviction that an All-wise and All-powerful Legislator has 

 constantly presided over the destinies of the universe ! 



GK HARTWia. 



HEIDELBERG : 

 9th April, 1866. 



