PALAEONTOLOGY AND GEOLOGY 



we certainly cannot deny the power of a Creator to 

 act; the second is merely a question of the number of 

 existing forms and their complexity of structure, as 

 no one supposes that evolutionary links connect two 

 species by existing intermediate forms; the third 

 source does show us that variation is the law of life, 

 but it also points to the persistence of species even 

 more strongly than to their variation, since with all 

 our contriving we have never been able to produce a 

 new species, and reversion to the common type occurs 

 when indiscriminate breeding takes place; and lastly, 

 embryology may show relations and connections be- 

 tween different types, but we cannot argue that, for 

 example, a mammal had a piscine ancestry because at 

 one stage its embryo has a gill organ instead of a 

 lung. 



It is this necessity for a palaeontological record 

 which first made me doubt the assertion of historians 

 of evolution that any of the early philosophers, or 

 men of science, had a conception of evolution. They, 

 to be sure, used the words, variation and change^ but 

 they did so in a quite different sense from that now 

 attached to them. Their discussions about the dura- 

 tion of the world and the changes which have oc- 

 curred were purely academic, and we cannot find any 

 records to show that they ever considered the form 

 and structure of prehistoric life. Because of the im- 

 portance of the evidence of palaeontology, it is neces- 

 sary to state the current beliefs as to the real causes 



