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special modifications of the fundamental substance. The 

 mineral, carbonate of lime, assumes an immense diver- 

 sity of characters, though no one doubts that under all 

 these Protean changes it is one and the same thing. 



And now, what is the ultimate fate, and what the ori- 

 gin of the matter of life ? Is it, as some of the older 

 naturalists supposed, diffused throughout the universe in 

 molecules, which are indestructible and unchangeable in 

 themselves ; but, in endless transmigration, unite in in- 

 numerable permutations, into the diversified forms of life 

 we know ? Or, is the matter of life composed of ordinary 

 matter, differing from it only in the manner in which its 

 atoms are aggregated ? Is it built up of ordinary matter, 

 and again resolved into ordinary matter when its work is 

 done? Modern science does not hesitate a moment be- 

 tween these alternatives. Physiology writes over the 

 portals of life, 



" Debemur morti nos nostraque," 



with a profounder meaning than the Roman poet attached 

 to that melancholy line. Under whatever disguise it 

 takes refuge, whether fungus or oak, worm or man, the 

 living protoplasm not only ultimately dies and is resolved 

 into its mineral and lifeless constituents, but is always 

 dying, and, strange as the paradox may sound, could not 

 live unless it died. In the wonderful story of the " Peau 

 de Chagrin," the hero becomes possessed of a magical 

 wild ass's skin, which yields him the means of gratifying 

 all his wishes. But i'ts surface represents the duration 

 of the proprietor's life; and for every satisfied de- 

 sire the skin shrinks in proportion to the intensity of frui- 

 tion, until at length life and the last handbreadth of the 



