Chapter VI

NON-ADVANCEMENT OF LOWER ORDERS. _Page_ 158.

Mr. Darwin's answer to the difficulty put by Agassiz is this;--"On our theory the continued existence of lowly organisms offers no difficulty; for natural selection, or the survival of the fittest, does not necessarily include progressive development,--it only takes advantage of such variations as arise and are beneficial to each creature under its complex relations of life."--_Origin of Species_, sixth edition, p. 98. This wears the aspect of a limitation of the theory, and to that extent an acknowledgment of the force of the reasoning of Agassiz.