444 THE MULTIPLICATION OF EFFECTS. 



sociated with chemical combination. Thus, by the original 

 mechanical force expended in the collision, at least five, and 

 often more, different kinds of forces have been produced. 

 Take, again, the lighting of a candle. Primarily, this is a 

 chemical change consequent on a rise of temperature. The 

 process of combination having once been set going by ex- 

 traneous heat, there is a continued formation of carbonic 

 acid, water, &c. in itself a result more complex than the 

 extraneous heat that first caused it. But along with this 

 process of combination there is a production of heat ; there is 

 a production of light; there is an ascending column of hot 

 gases generated; there are currents established in the sur-. 

 rounding air. Nor does the decomposition of one force into 

 many forces end here. Each of the several changes worked 

 becomes the parent of further changes. The carbonic acid 

 formed, will by and by combine with some base; or under 

 the influence of sunshine give up its carbon to the leaf of a 

 plant. The water will modify the hygrometric state of the 

 air around ; or, if the current of hot gases containing it come 

 against a cold body, will be condensed: altering the tempera- 

 ture, and perhaps the chemical state, of the surface it covers. 

 The heat given out melts the subjacent tallow, and expands 

 whatever it warms. The light, falling on various sub- 

 stances, calls forth from them reactions by which it is modi- 

 fied; and so divers colours are produced. Similarly even 

 with these secondary actions, which may be traced out into 

 ever-multiplying ramifications, until they become too mi- 

 nute to be appreciated. Universally, then, the 

 effect is more complex than the cause. Whether the aggre- 

 gate on which it falls be homogeneous or otherwise, an inci- 

 dent force is transformed by the conflict into a number of 

 forces that differ in their amounts, or directions, or kinds; or 

 in all these respects. And of this group of variously-modi- 

 fied forces, each ultimately undergoes a like transfor- 

 mation. 



Let us now mark how the process of evolution is fur- 



