30 WHAT IS DARWINISM? 



existence. He says, " we cannot comprehend 

 what the figures 60,000,000 really imply, 

 and during this, or perhaps a longer roll of 

 years, the land and waters have everywhere 

 teemed with living creatures, all exposed to the 

 struggle for life, and undergoing change." 

 (p. 354). " Mr. Croll," he tells us, " estimates 

 that about sixty millions of years have elapsed 

 since the Cambrian period, but this, judging 

 from the small amount of organic change since 

 the commencement of the glacial period, seems 

 a very short time for the many and the great 

 mutations of life, which have certainly oc- 

 curred since the Cambrian formation ; and the 

 previous one hundred and forty million years 

 can hardly be considered as sufficient for the 

 development of the varied forms of life which 

 certainly existed toward the close of the Cam- 

 brian period." (p. 379). Years in this con- 

 nection have no meanins;. We misrht as well 

 try to give the distance of the fixed stars in 

 inches. As astronomers are obliged to take 

 the diameter of the earth's orbit as the unit of 

 space, so Darwinians are obliged to take a 

 geological cycle as their unit of duration. 



