150 ON THE THVSIf'AL BASIS OF LIFE m 



the other needful constituents be supplied except 

 nitrogenous salts, and an ordinary plant will still 

 be unable to manufacture protoplasm. 



Thus the matter of life, so far as we know it 

 (and we have no right to speculate on any other), 

 breaks up, in consequence of that continual death 

 which is the condition of its manifesting vitality, 

 into carbonic acid, water, and nitrogenous com- 

 pounds, which certainly possess no properties but 

 those of ordinary matter. And out of these same 

 forms of ordinary matter, and from none which are 

 simpler, the vegetable world builds up all the 

 protoplasm which keeps the animal world a-going. 

 Plants are the accumulators of the power which 

 animals distribute and disperse. 



But it will be observed, that the existence of 

 the matter of life depends on the pre-existeuce of 

 certain compounds ; namely, carbonic acid, water, 

 and certain nitrogenous bodies. Withdraw any 

 one of these three from the world, and all vital 

 phenomena come to an end. They are as 

 necessary to the protoplasm of the plant, as the 

 protoplasm of the plant is to that of the animal. 

 Carbon, hydrogen, oxygen, and nitrogen are all 

 lifeless bodies. Of these, carbon and oxygen unite 

 in certain proportions and under certain conditions, 

 to give rise to carbonic acid ; hydrogen and oxygen 

 produce water ; nitrogen and other elements give 

 rise to nitrogenous salts. These new compounds, 

 like the elementary bodies of which they are 



