226 THE REIGN OF LAW. 



difference in the amount of lime held in solution 

 in the water, but upon some power in the secret- 

 ing organs of the animal to appropriate more or 

 less of it, according to its own need. The effects 

 of this power are seen where there is no difference 

 of condition except difference of exposure. It 

 is said that they are observable, for example, in 

 the shells which lie on the different sides of 

 Plymouth Breakwater, — the sheltered side and 

 the exposed side. The same power of adaptation 

 is seen in many other forms. Trees which are 

 most exposed to the blast are the most strongly 

 anchored in the soil. Limbs which are the most 

 used are the most developed. Organs which 

 are in constant use, are strengthened, whilst organs 

 in habitual disuse have a tendency to become 

 weaker. 



All these results arise by way of natural 

 consequence. How shall we describe them ? 

 Shall we say that they are the result of Law ? 

 We may safely do so, remembering only that 

 by Law, in this sense, we mean nothing but the 

 co-operation of different natural Forces, which, 

 under certain conditions, work together for the 



