COMPOSITION OF CAUSES. 427 



hypothetical, from the laws which we know to govern 

 those causes when acting separately; because they 

 continue to observe the same laws when in combina- 

 tion, which they observed when separate : whatever 

 would have happened in consequence of each cause 

 taken by itself, happens when they are together, 

 and we have only to cast up the results. Not so 

 in the phenomena which are the peculiar subject of 

 the science of chemistry. There, most of the unifor- 

 mities to which the causes conformed when separate, 

 cease altogether when they are conjoined; and we are 

 not, at least in the present state of our knowledge, 

 able to foresee what result will follow from any new 

 combination, until we have tried it by specific expe- 

 riment. 



If this be true of chemical combinations, it is still 

 more true of those far more complex combinations of 

 elements which constitute organised bodies ; and in 

 which those extraordinary new uniformities arise, 

 which are called the laws of life. All organised 

 bodies are composed of parts, similar to those 

 composing inorganic nature, and which have even 

 themselves existed in an inorganic state; but the 

 phenomena of life, which result from the juxtaposition 

 of those parts in a certain manner, bear no analogy to 

 any of the effects which would be produced by the 

 action of the component substances considered as 

 mere physical agents. To whatever degree we might 

 imagine our knowledge of the properties of the several 

 ingredients of a living body to be extended and per- 

 fected, it is certain that no mere summing up of the 

 separate actions of those elements will ever amount to 

 the action of the living body itself. The tongue, for 

 instance, is, like all other parts of the animal frame, 

 composed of gelatine, fibrin, and other products of the 



