FROM LAMARCK TO ST. HILAIRE 287 



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 envi- 

 ronment: first, the influences of life upon life, 

 and of life upon Nature; and second, the con- 

 stant revolutions 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 ac- 

 tion of environment falls with least specializa- 

 tion, 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 connection 

 with the law of Buffon and Malthus that the 

 struggle for existence consists, not only in re- 

 production, but in reproduction increasing in 

 quantity according to the destructive influences 

 of surrounding 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 predeces- 

 sors and was essentially modern in his method. 

 We therefore expect to find an equal breadth of 

 view in his treatment of the problems of animal 

 descent or phylogeny. Here we are disappointed. 



