RIVER OF LIFE 41 



branches of the North Atlantic over which the Ocean River 

 and its tributaries may once have coursed. These have laid the 

 foundations of our present understanding of evolution and the 

 history of life, for trapped among the sediments are the skele- 

 tons and sometimes even traces of the soft parts of the strange 

 sea beasts of the past. From these we piece together a history 

 of life within the River, much as we seek ancient ruins and 

 old manuscripts for evidence of human history along the banks 

 of the River. 



Nobody can say for sure what the first living creature was 

 like. It was certainly very small and without a skeleton, so that 

 it would scarcely leave a recognizable fossil to survive the mil- 

 lions of years of enormous pressure due to thousands of feet of 

 overlying rock or the twisting of earth movements. The first 

 abundant animal fossils known are comparatively far along in 

 evolution and nearly all possess skeletons of some kind. We 

 are therefore driven to indirect evidence and speculation in 

 trying to piece out the history of early life in the ocean. 



The beginnings of life were probably made possible by the 

 presence in the ancient sea of small amounts of organic chem- 

 ical compounds, known as hydrocarbons. These were formed 

 when the world was still hot, by the interaction of water and 

 such simpler carbon compounds of rock origin as the carbides. 

 The hydrocarbons and their derivatives may have formed in- 

 creasingly large and complex molecules with the peculiar prop 

 erties of what chemists call colloids. Though such colloidal 

 particles are certainly not alive, they possess fascinating prop- 

 erties that have a striking resemblance to the behavior of living 

 protoplasm. Under certain conditions they grow, and when 

 they reach a certain size they tend to divide or reproduce and 

 so become unstable. They have other important properties 

 similar to those of protoplasm, though they do not possess the 

 organization that is characteristic of living creatures. It is also 

 true that one organism, the tobacco virus, has been obtained 



