Evolution of Plants 301 



of siliceous chert, of carbonaceous shales, or of colloid-iron 

 rocks are not infrequent, and all suggest the activity of simple 

 cellular organisms belonging to the groups of the bacteria 

 or of the Blue-green Algse. Elsewhere (13: 253) the writer 

 has advanced reasons for believing that the plant groups just 

 named were the most primitive of which we have any exact 

 knowledge at the present day There also he has tabulated 

 or indicated the existence of nearly a hundred species — in 

 part algoid, in part bacterial— which can flourish in hot waters 

 of 45-75° C. temperature. 



Now, while there are clear indications that dry land and 

 seas, denudation areas, and shore cliffs, much like those of the 

 present day, then existed, there is equally clear evidence that 

 extensive volcanic action, rock displacement, stratigraphic 

 distortion, and often intense baking or destruction of rock 

 masses prevailed over wdde areas, during archsean times. The 

 agents that effected such changes, and the varied changes in 

 themselves, would all contribute to variation, modification, 

 and evolution of organic types. So an increasing richness 

 and diversity of species would slowly arise, at the same time 

 that a gradual decrease in temperature occurred amongst 

 many inland expanses of fresh or mineral water. 



Such a view presupposes that organisms developed at first 

 in warm fresh-water or mineral-water expanses that corre- 

 sponded closely to the hot-spring regions of the present day, 

 and such has been accepted above for reasons given elsewhere 

 by the writer (13: 253). If further it is found on investigation 

 that a preponderating number of plant and animal sj^ecies 

 have evolved in land-locked water areas of greater or less 

 extent, or upon dry land, added testimony is secured for such 

 a position. In the present and succeeding cliapters the at- 

 tempt is made to collect botanical data that may guide us. In 

 later chapters a like attempt is made from the zoological side. 



But, before studying such, a well-kno^^Tl and important 

 fact should be taken account of that has far-reaching conse- 

 quences. When the pahrontological record is examined even 

 cursorily, one is vividly imi)ressed by the aj^parent sudden 



