Vii.] OX THE PHYSICAL BASIS OF LIFE. 131 



which lias been called " heat-stiffening" though Klihne's 

 beautiful 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 proto- 

 plasm, or physical basis, of life, in whatever group of 

 living beings it may be studied. But it will be under- 

 stood 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 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 

 origin, 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 innumerable permu- 

 tations, 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— 



" Debcmur morti nos nostraque," 



with a profoundcr meaning than the Eoman poet attached 

 to that melancholy line. Under whatever disguise it 

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



