586 THE BEGINNINGS OF LIFE. 



internal polarities. The constant co-operation of these 

 causes of changes must, however, tend to bring about 

 an increasing complexity of structure — although such 

 increase may be checked and limited in various ways, 

 and by causes which we, as yet, very imperfectly un- 

 derstand. Granting, however, that <^ living' matter like 

 all other forms of matter does tend to become more 

 heterogeneous — what is it which, in the main, is the 

 cause of this tendency ? It would not be deemed incor- 

 rect if we were to state that the form of any particular 

 crystal is determined by the polarities of its molecules, 

 although such polarity and consequently such form may 

 be modified by a change in the ' conditions ' under 

 which crystallization takes place j and similarly, it 

 would seem fair to say (as, in fact, Mr. Spencer does 

 elsewhere constantly affirm) that the form of an organ- 

 ism is determined by the polarities of its molecules. 

 New incident external forces can, in fact, only induce 

 changes so long as the elements of the living matter 

 upon which they act are capable of being diverted by 

 such forces into new modes of motion — that is, only so 

 long as the molecular composition of the matter is 

 capable of being altered by them, however slightly. But 

 new modes of motion imply new modes of growth and 

 development, which again could not be initiated unless 

 internal polarities continued to exist as ever-active 

 causes of change. It is, therefore, in every way, as it 

 seems to me, a contradiction of Mr. Spencer's other 

 arguments when he both denies that organisms possess 



