at tlie Surface of the Terrestrial Globe. 389 



historical studies, and divides those who have reflected on the 

 facts established by observation ; this is the investigation of 

 the origin of living beings, and of the connection which has 

 existed between them at all the epochs of change through 

 which the earth has passed. Of what nature is this connec- 

 tion ? What opinion are we to form in regard to those con- 

 stantly recurring discussions on the succession of living beings, 

 on the links which unite them, on the gaps which it is pre- 

 tended exist among them, on their similarity, and on their ap- 

 pearance at different periods % 



There was a time when the earth was uninhabited ; and there 

 is therefore in its history an epoch when life manifested itself 

 for the first time on its surface, by producingadiversity of animal 

 and vegetable forms, quite different from those v/hich we see 

 existing and reproducing themselves under our eyes. Further, 

 the different types of animals and of vegetables have under- 

 gone notable transformations in the various phases of the his- 

 tory of the earth, transformations which separate us from that 

 first appearance of living beings to such an extent, that at each 

 of the great geological epochs the animals and plants have been 

 very different from what they were at other times. These 

 results have been obtained by science, through the exertions 

 of geologists ; and if the whole of antiquity is not to be 

 doubted, it is plain, that the ancient philosophers, in order to 

 construct the world, rather interrogated the secrets of human 

 nature, than the external nature which surrounded them. 

 And yet how many cosmogonies exist ! All nations have 

 their own, and all have converted them into religious dogmas. 

 Without pausing to examine doctrines as contradictory as 

 they are superficial, let us see what we are taught by facts la- 

 boriously collected during the last few centuries. 



Wherever the hand of man has opened up the bowels of 

 the earth, wherever changes at the surface have exposed the 

 deeply-seated layers of its crust, wherever time has fractured 

 its solid masses, the observing eye discovers traces of beings 

 which no longer exist ; here there are the debris of mammi- 

 fera, or reptiles, whose forms are as colossal as they are 

 strange ; there the whole rocky mass seems composed of the 

 debris of microscopic animalcules, which escape even the most 

 practised eye. Far from the coasts of the sea, beds of 



