150 GEOLOGICAL BIOLOGY. 



were different forms created in the beginning by the infinite 

 Being, and his binary nomenclature, in which each species is 

 given a specific and a generic name, is the foundation of mod- 

 ern Natural History. 



Definitions of Species. — TOURNEFORT (1656-1708) defined 

 gcmts of plants to be " the assemblage of plants which resem- 

 ble each other in structure," and species as " the collection of 

 plants which are distingJiisJicd by some particular characters." 



LiNNE (i 707-1 778) said that we count as species what has 

 been created of diverse form at its origin, and later Linne 

 considered that all the species of a genus were originally a 

 single species. 



BUFFON (1707-1788) described species as a " continuous 

 succession of similar individuals which reproduce themselves, 

 and the characteristic of the species is coiiti)iuous fecundity. '^ 



De Candolle (i 778-1 841), the celebrated botanist (as 

 translated by Wallace in his book on " Darwinism ")* defined 

 the term thus: " A species is a collection of all the individu- 

 als which resemble each other more than they resemble any- 

 thing else, which can by mutual fecundation produce fertile 

 individuals, and which reproduce themselves by generation in 

 such a manner that we may from analogy suppose them all to- 

 have sprung from one single individual." 



CUVIER (i 769-1 832) gave what is probably the standard 

 definition of this school: '■'■ Lespecc est la collection de tons les^ 

 corps organises nis les nnes des autres, on de parents coniniuns 

 et de ceux qui leur ressonblent autajit giiils se resseniblent entre 

 eux.'" In 182 I the first clause of the definition was changed to 

 '^ comprend les individns qui descendent les unes des autres." 

 This definition may be regarded as the foundation principle of 

 the school of naturalists of which Cuvier was, probably, the 

 most distinguished teacher. 



ZiTTEL. — In his treatise on Paleontologie, Zittelf says of 

 species : The single species was considered, by the great 

 classification naturalists, Linne and Cuvier, as having a real 

 existence and fixed invariable value ; this opinion was almost 



* A. R. Wallace, "Darwinism; an exposition of the theory of natural se- 

 lection, with some of its applications." London, i88g. 



f K. A. Ziltel, " Handbuch der Palieontologie," vol. I. pp. 45, 46. 



