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CHAPTER XL 



EXTEBNAL INFLUENCES. 



THE three principal factors in producing an 

 organism life-force, matter, and environ- 

 ment vary in their respective potencies in 

 different races, and among individuals of the 

 same race under different conditions. 



The prepotency of Specific life-force the 

 force that moulds the type is greater the 

 more complex the organisation, while, as we 

 descend in specialisation, the influence of one 

 or of both the other factors becomes more 

 evident ; that is, lower organisms are more 

 affected by external conditions, food, climate, 

 &c., and display greater differences in ex- 

 pression of type, than those more highly 

 specialised. 



The differences in the respective potencies 

 are readily observable in plants ; their size, 

 flowers, and fruit may be greatly varied by 

 more or less favourable conditions of growth. 

 If heat is inadequate, the plant (if it live) 



