ANALOGIES. 39 



essential to the earlier machine might, al- 

 though useless, be found in the new, pro- 

 vided it did not interfere with efficiency. 



Then he may also point out that the 

 development was not invariably towards 

 higher specialisation, for, as in the case of 

 the steam-hammer, the new machine was 

 sometimes less highly specialised than its 

 antecessor. 



All these features in the development of 

 the steam-engine have parallels in the evolu- 

 tion of life. 



Like the first steam-engine, the earliest 

 forms of life were the simplest. Embry- 

 ology tells us that, so far as the organisa- 

 tions were alike, every new type of life was 

 based on its antecessor, and that some organs 

 of an antecessor became transformed in its 

 successor ; while occasionally the fragments 

 of an organ, essential in the old type, are 

 to be found, although apparently useless, in 

 the new. 



Again, the expert might dwell on the wide 

 gap in some cases between an old type of 

 engine and a new, in whose structure in- 

 termediate developments had been entirely 

 superseded by new inventions. 



Similarly, and possibly for similar reasons, 

 wide gaps in the evolution of life some- 



