TREVIRANUS. 191 



ciency of one part being made up by the greater 

 development of another. He also, as clearly as 

 Lamarck, perceives the causal relation between 

 function and structure. In his conception of 

 natural environment, he with Schelling perceives 

 that every class of animals exerts upon living 

 Nature influences similar to those exerted in the 

 animal or plant by their organs and systems of 

 organs upon each other. 



He has two chief thoughts in regard .to environ- 

 ment. First, the influences of life upon life, and of 

 life upon Nature ; and second, the constant revolu- 

 tions of life and climate. He says that the wider the 

 limits reached by the action or by the incidence or 

 impact of environment upon the living organism, 

 so much higher the grade of the organism must be. 

 The lowest rudiments of life vita minima are 

 those in which the action of environment falls with 

 least specialization, and these rudiments mark the 

 transition to lifeless matter. This conception of 

 environment, as the action and reaction of life upon 

 Nature and of life upon life, he amplifies in connec- 

 tion with the law of Buffon and Malthus, that the 

 struggle for existence consists, not only in repro- 

 duction, but in reproduction increasing in quantity 

 according to the destructive influences of surround- 

 ing life. An animal must have more progeny as the 

 number of its enemies increases. 



We thus see that Treviranus breathed the spirit 

 of the most philosophical of his predecessors, and 



