2i6 FOOT-NOTES TO EVOLUTION. 



study, there we put our line of definition. " We can 

 only predicate and define species at all," says Dr. Coues, 

 "from the mere circumstance of missing links. Species 

 are the twigs of a tree separated from the parent stem. 

 We name and arrange them arbitrarily, in default of 

 means of reconstructing the whole tree in accordance 

 with Nature's ramifications."* 



What is true of birds is equally the case with other 

 groups of animals. Continued explorations bring to 

 light each year new species of American fishes, but the 

 number of new forms discovered each year is usually 

 less than the number of old supposed species which are 

 found to intergrade with each other, and have so become 

 intenable. 



There is the closest possible analogy between the 

 variations of species of animals or plants in different 

 districts and that of words in different 

 Analogy be- languages. The language of any people 

 tween variations . g ^ & ^ ^ . & m ^ e Qf wQrds 



of species and 

 words which have at various times and under 



various conditions come into it from the 

 speech of other people. The grammar of a language is 

 an expression of the mutual relations of these words. 

 The word as it exists in any one language represents the 

 species. Its cognate or its ancestor in any other lan- 

 guage is a related species. The words used in a given 

 district at any one time constitute its philological fauna. 



* Dr. Allen says : " We arbitrarily define a species as a group 

 of individuals standing out distinct and disconnected from any 

 similar group within which, though occupying different parts of 

 the common habitat, we recognise other forms characteristic of 

 and restricted to particular areas. These reach a maximum de- 

 gree of differentiation at some point in the habitat, and thence 

 gradually shade into other non-specific forms geographically con- 

 tiguous." The Auk, January, 1890, p. 7. 



