14 CLASSIFICATION AND ADAPTATION 



fluides vers cette partie de leur tete, et il s'y fait une 

 secretion de matiere cornee dans les uns (Bovidae) 

 et de matiere osseuse melangee de matiere cornee 

 dans les autres (Cervidae), qui donne lieu a des pro- 

 tuberances solides : de la I'origine des cornes, et des 

 bois, dont la plupart de ces animaux ont la tete 

 armee.' 



Darwin, on the other hand, definitely set before 

 himself the problem of the origin of species, which 

 the majority of naturalists, in spite of Lamarck and 

 his predecessor Buffon, regarded as permanent and 

 essentially immutable types established by the 

 Creator at the beginning of the world. This prin- 

 ciple of the persistence and fundamentally un- 

 changeable nature of species was regarded as an 

 article of religion, following necessarily from the 

 divine inspiration of the Bible. This theological 

 aspect of the subject is sufficiently curious when we 

 consider it in relation to the history of biological 

 knowledge, for Linnaeus at the beginning of the 

 eighteenth century was the first naturalist who 

 made a systematic attempt to define and classify the 

 species of the whole organic world, and there are few 

 species of which the limits and definition have not 

 been altered since his time. In fact, at the present 

 time there are very numerous groups, both in 

 animals and plants, on the species of which scarcely 

 any two experts are agreed. 



In many cases a Linnaean species has been split 

 up till it became, first, a genus, then a family, and, in 

 some cases, an order. What one naturalist considers 

 a species is considered by another a genus containing 

 several species, and, vice versa, the species of one 

 authority is described as merely a variety by another. 



