172 FROM LAMARCK TO ST. HILAIRE. 



fages remarks that he does not clearly distinguish 

 between species, races, and varieties. 



The definition of species was in Lamarck's time 

 the test of the creed of the naturalist. Isidore St. 

 Hilaire, in the Histoire Naturelle Ghierale, gives us 

 an interesting outline of the history of these defini- 

 tions, beginning with that of Linnaeus, including 

 Buffon's earlier and later definitions, and Cuvier s 

 later definitions ; Lamarck's is admirable : — 



" A species is a collection of similar individuals which are per- 

 petuated by generation in the same condition, as long as their 

 environment has not changed sufficiently to bring about variation 

 in their habits, their character, and their form." 



Certainly no better definition of a species could 

 be given to-day. 



\\"e have seen that Lamarck's final conception of 

 filiation, or the idea of the branching of life, had not 

 been reached in 1802, in which he gives a vertical 

 scale of the succession of groups of animals quite 

 similar to that which had been developing on the 

 false conception of phylogeny from the time of Aris- 

 totle. It is interesting, therefore, to place, side by 

 side, his first scale of 1802 with that which he pub- 

 lished in the Philosophie Zoologiqtie, of 1809. 



