Animal Evolution. 195 



there should be little doubt that all are governed 

 by a similar electric energy, though it may be ex- 

 hibited in infinitely diverse ways. But of this more 

 anon. 



Animals as Machines. — One of the most important 

 points in connection with animal evolution is, that 

 each animal, much more than a vegetal, is a machine. 

 This mechanism, comparatively simple in a protozoon, 

 becomes more and more complex as we ascend the 

 scale of life, until it reaches its ultimatum, so far as 

 we know, in man himself. 



It may be profitable briefly to trace this increasing 

 complexity, so as to show that all animal forms have 

 not been created according to foreordained designs, 

 but have evolved in a haphazard and even a bungling 

 fashion, sufficient to discredit any omniscient Creator. 



In order to grasp the changes in motor complexity 

 between the protozoa and the metazoa, we begin with 

 the amoeba. In this typical example of the protozoon, 

 the mechanism is rudimentary, almost structureless. 

 It maintains no permanent form, indicates no definite 

 organisation, and creates inconstant arms and legs ad 

 libitum. When we remember, however, that it moves 

 from place to place, that it catches and eats its own 

 food, possesses a contractile vacuole, and contains 

 millions of atoms if not millions of molecules in its 

 body, it would be unwise to characterise it as either 

 structureless or devoid of a mechanism. Yet, com- 

 paring its normal mechanical manifestations with its 

 characteristic mode of reproducing itself by fission, 



