CHAPTER I 



Life in the Primary Period 



HPHE remains of plants and animals of former times, preserved 

 -*- in strata, deposited, abandoned, covered again, and under- 

 mined in turn by the sea or given over first to the eroding 

 action and then to the deposition of new layers of mud by 

 fresh water, form a series too incomplete for it to be possible 

 to reconstruct, from these resources alone, the world's primeval 

 aspect. Some of these remains — and it will appear strange that 

 they should be so few — have remained to some extent enig- 

 matical, or rather have left the palaeontologists uncertain as 

 to their true nature ; but the very rarity of such doubts clearly 

 demonstrates that the bounds set as the result of the study of 

 nature to-day have never been broken, that at all times the 

 same laws have presided over the evolution of life, and that the 

 considerations enabling us to relate existing forms retain their 

 full value for the past. They imply an order in the appearance 

 of organic types that determines for each series which forms 

 must have appeared the first ; they fix the position of those 

 that have disappeared, and even enable us to classify as 

 necessary evolutionary links certain forms that would be 

 perplexing if we had no such considerations before our minds. 

 It is interesting, therefore, to compare the indications of theory 

 with the evidence palaeontologists have hitherto obtained. 



So far as plants are concerned, investigations from the 

 Silurian deposits onwards yield remarkable agreement between 

 theory and fact. The earlier strata also certainly contained 

 organisms. Theory indicates Algae as the first living earthly 

 organisms ; if we ever succeed in creating life artificially, 

 experiment will no doubt solve the problem ; but palaeonto- 

 logy provides no precise information as to the nature of the 

 earliest organisms. The oldest sedimentary deposits have 

 undergone in fact profound transformation. Certain layers 



