STTJDIES IN ANIMAL LIFE. 99 



tlirougli tlie long and gradual accumulation of mi- 

 nute differences in divergent directions. 



It is clear, from what has just been said, that the 

 many angry discussions respecting the fixity of spe- 

 cies, which, since the days of Lamarck, have dis- 

 turbed the amity of zoologists' and speculative phi- 

 losophers, would have been considerably abbrevia- 

 ted had men distinctly appreciated the equivoque 

 which rendered their arguments hazy. I am far 

 from implying that the battle was purely a verbal 

 one. I believe there was a real and important dis- 

 tinction in the doctrines of the two camps ; but it 

 seems to me that, had a clear understanding of the 

 fact that species was an abstract term been uniform- 

 ly present to their minds, they would have sooner 

 come to an agreement. Instead of the confusing 

 disputes as to whether one species could ever be- 

 come another species, the question would have been. 

 Are animal forms changeable? Can the descend- 

 ants of animals become so unlike their ancestors, in 

 certain peculiarities of structure or instinct, as to be 

 classed by naturalists as a different species ? 



No sooner is the question thus disengaged from 

 equivoque than its discussion becomes narrowed 

 within well-marked limits. That animal forms are 

 variable is disputed by no zoologist. The only 

 question which remains is this : To what extent are 

 animal forms variable ? The answers given have 

 been two : one school declaring that the extent of 

 variability is limited to those trifling characteristics 



