DE LAMARCK. 



^73 



climate, and of physical geography had happened, 

 and that whilst some species had become extinct 

 many had been changed, little by little, into others. 

 Lamarck, and M. Geoffrey St. Hilaire declared it 

 to be their opinion that there had been an uninter- 

 rupted succession in the animal kingdom, effected 

 by means of birth and offspring from parents, from 

 the earliest ages of the world to the present day, 

 and that the ancient animals, whose remains have 

 been preserved in strata, however different, may 

 nevertheless have been the ancestors of those now 

 in being. 



If the reader will turn to the short notice of 

 Aristoteles, he will find the ordinary idea of what a 

 species means given. But Lamarck added some- 

 thing : " A species consists of a collection of in- 

 dividuals resembling each other, and reproducing 

 their like by generation, so long as the surrounding 

 conditions do not alter to such an extent as to 

 cause their habits, characters, and forms to vary." 

 He stated what is only known to those naturalists 

 who have had experience ; the more we advance in 

 the knowledge of the different organized bodies 

 which cover the surface of the globe, the more our 

 embarrassment increases to determine what ought 

 to be regarded as a species, and still more how to 

 limit and distinguish genera. In proportion as our 

 collections are enriched, we see almost every void 

 filled up, and all our lines of separation effaced ; we 

 are reduced to arbitrary determinations, and are 

 sometimes fain to seize upon the slight differences 



