228 LOUIS AGASSIZ. 



I see by your letter that you cling to the idea 

 of internal vital processes of the earth, that 

 you regard the successive formations as differ- 

 ent phases of life, the rocks as products of 

 metamorphosis. I think this symbolical lan- 

 guage should be employed with great reserve. 

 I know that point of view of the old " Natur- 

 philosophie ; " I have examined it without pre- 

 judice, but nothing seems to me more dissimi- 

 lar than the vital action of the metamorphosis 

 of a plant in order to form the calyx or the 

 flower, and the successive formation of beds 

 of conglomerate. There is order, it is true, 

 in the superposed beds, sometimes an alterna- 

 tion of the same substance, an interior cause, 

 sometimes even a successive development, 

 starting from a central heat; but can the 

 term life be applied to this kind of move- 

 ment? Limestone does not generate sand- 

 stone. I do not know that there exists what 

 physiologists call a vital force, different from, 

 or opposed to, the physical forces which we 

 recognize in all matter; I think the vital 

 process is on'y a particular mode of action, of 

 limitation of those physical forces ; action, the 

 nature of which we have not yet fully sounded. 

 I believe there are nervous storms (electric) 

 like those which set fire to the atmosphere, 



