126 J. HOPKINSON ANNITEESAEY ADBEESS : 



of Erasmus Darwin, Lamarck, and Robert Chambers, to show what 

 a great advance the theory of natural selection was upon the views 

 which had previously been brought forward. 



Erasmus Darwin, in 1794, very nearly anticipated the theory of 

 his illustrious grandson, adducing changes taking place during life- 

 time ; changes introduced by cultivation ; similarity of structure ; 

 acquired and inherited transformations ; " the desire of the ex- 

 clusive possession of the female" in order that (here giving a 

 consequence as a cause) "the strongest and most active animal 

 should propagate the species, which should thence become im- 

 proved;" want of food resulting in improvement from the per- 

 petual endeavour to obtain it ; want of security resulting in 

 modifications of form and structure ; etc. ; as grounds for imagining 

 that " in the great length of time since the earth began to exist, 

 .... all warm-blooded animals have arisen from one living 

 filament, which the Great First Cause endowed with animality, 

 .... possessing the faculty of continuing to improve by its own 

 inherent activity, and of delivering down those improvements by 

 generation to its posterity, world without end ! " 



*' Organic life beneath the shoreless waves 

 "Was born, and nurs'd in ocean's pearly caves; 

 First forms minute, unseen by spheric glass, 

 Move on the mud, or pierce the watery mass ; 

 These, as successive generations bloom, 

 New powers acquire, and larger limbs assume ; 

 Whence countless groups of vegetation spring, 

 And breathing realms of fin and feet and wing." 



Lamarck then, in 1809, framed the theory that modifications of 

 structure arise chiefly from the use and disuse of organs, the 

 tendency to such use and disuse being engendered by changes in 

 outer circumstances. He proposed to alter the definition of species 

 from that of "every collection of individuals produced by other 

 individuals like themselves," to that of "a collection of individuals 

 resembling each other, and reproducing their like by generation so 

 long as the surrounding conditions do not alter to such an extent 

 as to cause their habits, characters, and forms to vary." In 

 support of this definition he showed that many species, and even 

 genera, run so imperceptibly into one another that it is often a very 

 difiicult matter to frame a definition of them ; that there has been 

 a gradual progress in past times from the lower forms of life to the 

 higher, each geological formation in succession containing fossils of 

 higher or more complex organisation ; and that the earth is of vast 

 antiquity, its strata having been very slowly deposited, and changes 

 in its condition having been very gradually brought about ; and he 



