54 EVOLUTION 



was slowly developing in the direction of life. It must 

 have passed through myriads of phases, and it would be 

 just as difficult to pick out one of these as "the beginning 

 of life" as to fasten on a particular point in the dawn as 

 the time when the day begins and the night ceases. It 

 is utterly impossible for us to reproduce those successive 

 transformations which ended in the production of living 

 plasm. We must select our point arbitrarily, and the 

 best thing to do is to assume a time when minute 

 particles of this plasm are found to be living independent 

 and individual lives in the primitive ocean. The 

 geological record gives us no assistance. Not only 

 would these specks of jelly-like stuff not be preserved, 

 not only would the traces of them be burnt up or other- 

 wise destroyed in the intense heat and pressure of the 

 early rocks if they were preserved, but in point of 

 fact they did not (normally) die at all. The lowest 

 organisms may not improperly be described as immortal. 

 They may be poisoned, but usually each merely sub- 

 divides into two new creatures and nothing in the nature 

 of a corpse is left behind. 



We have therefore to look for the lowliest of existing 

 organisms and gather from these some idea what primi- 

 tive types of life were like. Some writers take the 

 Amoeba as one of the simplest known types of life, but 

 this is far from correct, as we shall see. We find still 

 lower types in the botanical world, and may take the 

 Nitrobacteria and the Chromacea as representing the 

 simplest form of life that is found in nature to-day. 

 Many groups of the Chromacea are familiar to every 

 reader in a rough way. The grayish or greenish deposit 

 that one so often sees on damp rocks or wood consists 

 of countless millions of them. If we put a little under 

 the microscope, at high power, we may single out 

 the tiny specks that represent each individual plant. 



