THE BEGINNING OF LIFE ON THE EARTH. 23 



and the animal to enable them to bridge over the double gap 

 between the animal and the plant, and the animal and the 

 mineral, or that such creatures may in their early stages 

 carry on vegetable functions, and in their later those of the 

 animal. It is theoretically possible that life may have begun 

 with such creatures, which some of the results of micro- 

 scopical research would lead us to believe still exist. It is, 

 however, on the whole more probable that simple plants first 

 existed, and furnished pabulum to animals of low grade intro- 

 duced almost contemporaneously. 



Fourthly, all ou. knowledge of the succession of life leads us 

 to believe that it was not the higher plants and animals that 

 first sprang into existence from the teeming earth, but creatures 

 of low and humble organisation, suited to the then immature 

 and unfinished condition of the planet. It is also in accordance 

 with the amazing fecundity of the seas in all geological periods 

 in these lower forms of life, to suppose that the earliest living 

 things originated in the waters, and that the plants and animals 

 of the land are of later date. 



Do we know anything from actual observation of this earliest 

 population of the world ? Such knowledge we can hope to 

 acquire only by studying the oldest formations known to us ; 

 and these, it must be confessed, exist in a state so highly crys- 

 talline, and so much affected by internal heat, by mechanical 

 pressure, and by movement, as to render it little likely that 

 organic remains should be preserved in them in a state fit for 

 recognition. 



In many parts of the world, and notably in Canada and 

 Scandinavia, as well as in Wales, Scotland, and Bavaria, the 

 older Palaeozoic rocks, the lowest containing plants in great 

 abundance, rest on still older crystalline beds, which have 

 j become hard and crystalline in pre- Palaeozoic times, and have 

 contributed sand and pebbles to the succeeding very ancient 

 deposits. These old rocks — the Eozoic series of our table — may 

 be grouped ih two great systems, the Laurentian and Huronian 



