CREATION BY LAW. 225 



by way of natural consequence from the outward 

 circumstances or physical conditions, which re- 

 quired them, and from the living effort of Organ- 

 ism sensible in some degree of that requirement. 

 Now, inadequate and even grotesque though this 

 idea may be as explaining the Origin of new- 

 Species, it cannot be denied, that it makes its 

 appeal to a process which, at least to a limited 

 extent, does operate in producing modifications of 

 organic structure. For example, the same species 

 of Mollusc has often a shell comparatively weak 

 and thin, or a shell comparatively robust and 

 strong, according as it lies in tranquil or in stormy 

 water. The shell which is much exposed needs to be 

 stronger than the shell which is less exposed. But 

 it is obvious that the mere fact of the need cannot 

 supply the thing needed, unless by the adjustment 

 of some machinery for the purpose. How the 

 vital forces of the Mollusc can thus be made to 

 work to order, under a change of external con- 

 ditions, we do not know. But we do know, as a 

 matter of fact, that the shell is thickened and 

 strengthened, according as it needs resisting power. 

 This result does not appear to arise from any 



