THE TRANSMUTATION OF SPECIES. 247 



more than a variety? Every working naturalist will 

 heartily concur in the truth of these remarks. 



Lamarck, therefore, though willing to accept the 

 ordinary definition of a * species' as 'a collection of 

 similar individuals which were produced by individuals 

 like themselves,' rejected the idea of the constancy of 

 species. He maintained that those characters of a species 

 which we call * specific' were liable to variation, and he 

 supposed that this variation was indefinite. Hence, he 

 maintained that the constancy of species is not absolute, 

 but only relative to the circumstances in which all the 

 individuals of the species are placed. 



Species, then, according to Lamarck, represent groups 

 of individuals which are only stable so long as their 

 environment remains essentially unchanged. That species 

 should appear to us to be permanent, he explained 

 upon the ground that our observations had only extended 

 over a few thousand years, and that this period had not 

 been long enough to allow of the transformation of 

 any one species into any other, especially as terrestrial 

 changes have been quite slight and unimportant during 

 the whole period embraced by human observation. 



'A multitude of facts,' says Lamarck, * teach us that 

 in proportion as the individuals of our " species " change 

 their locality, their climate, their manner of living, or 

 their habits, in the same proportion they become subject 

 to influences which bit by bit change the consistence 

 and proportions of their parts, their form, their faculties, 

 even their organisation, in such manner that, given suffi- 

 cient time, everything in them participates in the muta- 

 tions to which they are exposed. 



