THE ORIGIN OF LIFE. 45 



ditions had so changed that protoplasm could no 

 longer be developed by the original spontaneous 

 method. Perhaps for ages protoplasm existed un- 

 able to use^organic food, but finding sufficient food 

 in the surrounding complex carbon compounds. 

 And when this power did at last become developed, 

 it was not acquired by all protoplasm. For just at 

 this point the organic world became divided into two 

 parts. One part did develop chlorophyll, and has 

 since been able to live upon inorganic matter, using 

 the energy of sunlight to build this matter into an 

 organic compound. Finding its food, carbonic acid, 

 water and nitrates and sunlight everywhere, this 

 class of organisms did not acquire the power of 

 motion. The other half of the living world never 

 developing chlorophyll became of necessity at last 

 parasitic upon the plants, and developed an almost 

 universal power of motion in order to enable it to 

 seek food. The animal and vegetable kingdoms were 

 thus finally separated from each other, with the 

 relations which they hold to-day. 



Such, in brief outline, is the substance of some of 

 the modern speculations concerning the method by 

 which life arose. It represents one phase of such 

 speculations, and is subject to great modification in 

 the minds of different thinkers. It is plainly open 

 to sufficient criticism, and it is equally clear that it 

 is not capable of direct proof, at least in the present 

 state of science. It is as moderate in its terms as 

 any of the suggestions upon the subject, and makes 

 as slight claims upon our credulity. It will, at all 

 events, serve our present purpose of giving an idea 



