1 68 WHAT DOES MAN LIVE UPON ? 



furnished by the bog soil, which would not also thrive 

 exceedingly well in other places, if the necessary moisture 

 were afforded them. Most of the plants belonging to 

 these soils so rich in humus, are members of the families 

 of the Rushes and Sedges, which are wholly useless, and 

 odious enough to the agriculturalist under the name of 

 sour pasture. On the other hand, the other class nourishes 

 the whole vegetation of our latitudes, in a multiplicity 

 which is varied enough to our eyes, unused to the tropical 

 world, and we generally find the richest abundance on the 

 soils which are poorest in humus but richest in inorganic 

 constituents, on basaltic, granitic, porphyritic and calcareous 

 soils. All those different plants return to us year after 

 year in the same form, the circle of their characteristics is 

 limited within narrow bounds ; and if we search through 

 the newest geognostic formations, we find the plants of 

 the present world with exactly the same characters as those 

 they now exhibit, enclosed in the ruins of the last revolu- 

 tion of the earth's surface. For instance, all Hamburg, its 

 harbour, and a broad tract toward the south-east and north- 

 west of the city, rest upon a sunken forest, which now lies 

 buried from 30 to 100 feet below the surface. This forest 

 was composed of Limes and Oaks, exactly like those we 

 now meet with in that place ; excavations for very different 

 purposes have there brought to light, thousands of hazel- 

 nuts, which differ in no respect from our hazel-nuts of the 

 present day. Thus the wild vegetation of our latitudes has 

 retained, during thousands of years, the same character 

 which it assumed when the climatal conditions were 

 adjusted, after the last great change upon the globe, in the 

 way in which we in the present day observe them to exist. 

 The case is quite different with the soils we have culti- 

 vated, of which I will here only consider garden-land, 



