LINN^AN DEFINITION OF SPECIES. 89 



who defend the stabihty of species rather imagine that, 

 with Cuvier, they are entitled to interpret facts in their 

 own favour; whereas they partly remain unconsciously 

 involved in hereditary prejudice, and partly contrive to 

 be deliberately blind to all that evidently contradicts the 

 immutability of species. 



Since Linnaeus referred- to the Creation, he attributed 

 the individuals to a species, of which the pedigree as- 

 cended in direct line to the pair which proceeded from 

 the hand of the Creator. Owing to the state of science 

 in general, an examination of this pedigree was totally 

 impossible in his time; and, indeed, with the strict reli- 

 ance on sacred tradition, it was scarcely necessary. 

 Cuvier, although a very unprejudiced and cool observer, 

 nevertheless radically accepted the Linnsean definition 

 of species. According to him, the species is the aggre- 

 gate of individuals descending from one another and 

 from common ancestors, and of those who resemble them 

 as strongly as they resemble one another.^^ 



" In this definition," says Haeckel, " to which the 

 majority have ever since more or less closely adhered, 

 two things are obviously required of an individual as be- 

 longing to a species: in the first place, a certain degree 

 of resemblance or approximate similarity of character; 

 and secondly, a kindred connection by the bond of a 

 common descent. In the numerous attempts of later au- 

 thors to complete the definition, the chief stress is laid 

 sometimes on the genealogical consanguinity of all the 

 individuals, sometimes on morphological uniformity in 

 all essential characters. But it may be generally as- 

 serted that in the practical application of the idea of 

 species, in the discrimination and nomenclature of the 



