106 ON THE PHYSICAL BASIS. OF LIFE 



Nor can it be affirmed with perfect confidence, that 

 all forms of protoplasm are liable to undergo that pe- 

 culiar coagulation at a temperature of 40 50 centi- 

 grade, which has been called "heat-stiffening," though 

 Kiihne's beautiful researches have proved this occur- 

 rence 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 exist- 

 ence 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 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, dif- 

 fused 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, differ- 

 ing 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 rnorti nos nostraque," 



