ON THE PHYSICAL BASIS OF LIFE 101 



ful researches have proved this occurrence to take place in 

 so many and such diverse living beings, that it is hardly 

 rash to expect that the law holds good for all. 



Enough has, perhaps, been said to prove the existence of 

 a general uniformity in the character of the protoplasm, or 

 physical basis, of life, in whatever group of living beings it 

 may be studied. But it will be understood that this general 

 uniformity by no means excludes any amount of special 

 modifications of the fundamental substance. The mineral, 

 carbonate of lime, assumes an immense diversity o^ charac- 

 ters, 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 origin, 

 of the matter of life? 



Is it, as some of the older naturalists supposed, diffused 

 throughout the universe in molecules, which are inde- 

 structible and unchangeable in themselves; but, in endless 

 transmigration unite in innumerable 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 between 

 these alternatives. Physiology writes over the portals of 

 life— 



"Debemur morti nos nostraque," 



vvith 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. 



