38 THE ORIGIN AND EVOLUTION OF LIFE 



When we consider that those chemical "hfe elements" 

 which are most essential to living matter were for a great period 

 of time either absent or present in a highly dilute condition in 

 the ocean, it appears that we must abandon the ancient Greek 

 conception of the origin of life in the sea, and reaffirm our 

 conclusion that the lowliest organisms originated either in 

 moist earths or in those terrestrial waters which contained 

 nitrogen. Nitrate and nitrite occasionally arise from the union 

 of nitrogen and oxygen in electrical discharges during thunder- 

 storms, and were presumably thus produced before Hfe began. 

 These and related nitrogen compounds, so essential for the 

 development of protoplasm, may have been specially concen- 

 trated in pools of water to degrees particularly favorable for the 

 origin of protoplasm} 



It appears, too, that every great subsequent higher life 

 phase — the bacterial phase, the chlorophyllic algal phase, the 

 protozoan phase — was also primarily of fresh-water and sec- 

 ondarily of marine habitat. From terrestrial waters or soils 

 life may have gradually extended into the sea. It is probable 

 that the succession of marine forms was itself determined to 

 some extent by adaptation to the increasing concentration of 

 saline constituents in sea-water. That the invasion of the sea 

 upon the continental areas occurred at a very early period is 

 demonstrated by the extreme richness and profusion of marine 

 life at the base of the Cambrian. 



That life originated in water (H2O) there can be little doubt, 

 hydrogen and oxygen ranking as primary elements with nitro- 

 gen. The fitness of water to life is maximal - both as a solvent 

 in all the bodily fluids, and as a vehicle for most of the other 

 chemical compounds. Further, since water itself is a solvent 



' Suggested by Professor W. J. Gies. 



- These notes upon water are chiefly from the v'ery suggestive treatise, "The Fitness 

 of the Environment," by Henderson, Lawrence J., 1913. 



