38 THE SCIENTIFIC EVIDENCES OF 



towards maintaining it in others. But the theory 

 of descent with continued adaptive modification 

 fully explains all the known cases ; for in every 

 case the degree of divergence from the typical 

 structure which an organism presents corre- 

 sponds with the length of time during which the 

 divergence has been going on. Thus we scarcely 

 ever meet with any great departure from the 

 typical form — such as the absence of limbs — 

 without some of the other organs in the body 

 being so far modified as of themselves to in- 

 dicate, on the supposition of descent with 

 modification, that the animal or plant must have 

 been subject to the modifying influences for a 

 long series of generations. And this combined 

 testimony of a number of organs in the same 

 organism is what the theory of descent would 

 lead us to expect, while the rival theory of 

 design can offer no explanation of the fact, 

 that when one organ shows a conspicuous de- 



