xn.J Sff* rigitt jof Spwies. 289 



of species, partly by Ms general cosmological and geolo- 

 gical views ; partly by the conception of a graduated, 

 though irregularly branching, scale of being, which had 

 arisen out of his profound study of plants and of the 

 lower forms of animal life, Lamarck, whose general line 

 of thought often closely resembles that of De Maillet, 

 made a great advance upon the crude and merely specu- 

 lative manner in which that writer deals with the ques- 

 tion of the origin of living beings, by endeavouring to 

 find physical causes competent to effect that change of 

 one species into another, which De Maillet had only 

 supposed to occur. And Lamarck conceived that he 

 had' found in Nature such causes, amply sufficient for the 

 purpose in view. It is a physiological fact, he says, that 

 organs are increased in size by action, atrophied by 

 inaction ; it is another physiological fact that modifica- 

 tions produced are transmissible to offspring. Change 

 the actions of an animal, therefore, and you will change 

 its structure, by increasing the development of the parts 

 newly brought into use and by the diminution of those 

 less used; but by altering the circumstances which 

 surround it you will alter its actions, and hence, in the 

 long run, change of circumstance must produce change 

 of organization. All the species of animals, therefore, 

 are, in Lamarck's view, the result of the indirect action 

 of changes of circumstance upon those primitive germs 

 which he considered to 'have originally arisen, by spon- 

 taneous generation, within the waters of the globe. It 

 is curious, however, that Lamarck should insist so 

 strongly 1 as he has done, that circumstances never in 

 any degree directly modify the form or the organization 

 of animals, but only operate by changing their wants 

 and consequently their actions ; for he thereby brings 

 upon himself the obvious question, how, then, do plants, 



1 See Phil. Zoologique, vol. i. p. 222, et seq. 



a 



