Chap. I. Rudiments. 25 



vaiiations supervening at a rather late embryonic period, and 

 being inherited at a corresponding period, how it is that the 

 embryos of wonderfully different forms should still retain, more 

 or less perfectly, the structure of their common progenitor. 

 No other explanation has ever been given of the marvellous fact 

 that the embryos of a man, dog, seal, bat, reptile, &c., can at first 

 hardly be distinguished from each other. In order to understand 

 the existence of rudimentary organs, we have only to suppose 

 that a former progenitor possessed the parts in question in a 

 perfect state, and that under changed habits of life they became 

 greatly reduced, either from simple disuse, or through the natural 

 selection of those individuals which were least encumbered with 

 a superfluous part, aided by the other means previously in- 

 dicated. 



Thus we can understand how it has come to pass that man and 

 all other vertebrate animals have been constructed on the same 

 general model, why they pass through the same early stages of 

 development, and why they retain certain rudiments in common. 

 Consequently we ought frankly to admit their community of 

 descent; to take any other view, is to admit that our own 

 structure, and that of all the animals around us, is a mere snare 

 laid to entrap our judgment. This conclusion is greatly 

 strengthened, if we look to the members of the whole animal 

 series, and consider the evidence derived from their afBnities 

 or classification, their geographical distribution and geolo- 

 gical succession. It is only our natural prejudice, and that 

 arrogance which made our forefathers declare that they were 

 descended from demi-gods, which leads us to demur to this 

 conclusion. But the time will before long come, when it wiU be 

 thought wonderful that naturalists, who were well acquainted 

 with the comparative structure and development of man, and 

 other mammals, should have believed that ench was the work 

 of a sspaxate act of creation. 



