EIGHTEENTH CENTURY EVOLUTIONISTS 211 



new parts, attended with new propensities, directed 

 by irritations, sensations, volitions, and associations ; 

 and thus possessing the faculty of continuing to im- 

 prove by its own inherent activity, and of delivering 

 down those improvements by generation to its pos- 

 terity, world without end ! 



If we analyze this statement, which strikingly 

 reminds us of the closing paragraph in his grand- 

 son's Origin of Species, we see that it involves: 



First, a clear idea of the evolution of all forms 

 of life from a single filament or minute organic 

 mass — as we should express it today, a minute 

 mass of protoplasm. 



Second, that this evolution has occupied mil- 

 lions of years and has been controlled not by 

 supernatural causes but by natural causes. 



Third, the directing or adaptive power to 

 which he alludes has sprung from efforts to meet 

 new needs in the course of changing environment. 



Fourth, it is clear from the context that by the 

 term 'inherent activity,' Darwin does not allude 

 to an internal perfecting principle such as we 

 find originated with Aristotle, but that the power 

 of improvement rests with the animal's own ef- 

 forts, the effects of these efforts upon the body 

 being transmitted by heredity. 



Fifth, he does not build a branching or phy- 

 letic system of Evolution, as did Lamarck, but 

 simply leaves this part of the system out, and 



