THE BEGINNINGS OF IIFE. 27 



union occurs. Why does oxygen unite with hydrogen 

 to form water ? why docs hydrogen unite with nitrogen 

 to form ammonia ? Probably for a reason similar to 

 that which enables colloid molecules to give rise to 

 those much subtler combinations which form the basis 

 of what we call ' living matter '. 



It is, we think, of importance to call attention to 

 this consideration that living matter is the result of a 

 molecular combination, towards the occurrence of which 

 (with suitable materials) there may be just as natural 

 an aptitude as there is to the formation of any of the 

 simpler combinations which are daily occurring on all 

 sides of us. Let us look to the facts, and see how 

 capable they are of bearing such an interpretation if 

 we could but clear away all the misconceptions which 

 are only too apt to warp our judgment. 



Nitrate or carbonate of ammonia, free carbonic acid, 

 and water with a few saline substances, constitute the 

 materials which, under the influence of the modified 

 physical forces operating in the living plant, fall into 

 similar modes of combination, and go to increase the 

 bulk of its living tissues. Thus out of simplest ele- 

 ments is living protoplasm continually being produced 

 in the substance of every plant that grows — thus are 

 those higher combinations, resulting in the production 

 of living matter, continually brought about — thus is 

 the supposed gulf between the living and the not-living 

 continually bridged. No higher compounds are needed 

 as starting-points for carrying on the nutrition of 



