XIL] THE ORIGIN OF SPECIES. 251 



though Linnaeus may have played with the hypothesis of trans 

 mutation, it obtained no serious support until Lamarck adopted 

 it, and advocated it with great ability in his &quot; Philosophic 

 Zoologique.&quot; 



Impelled towards the hypothesis of the transmutation of 

 species, partly by his general cosmological and geological 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 

 speculative manner in which that writer deals with the question 

 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 

 modifications 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 



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



