THE MODERN STUDY OF ZOOLOGY 11 



tive names ; we should then define the position of 

 any one dot by simply saying in which division it 

 was. As our whole paper is divided up, every dot 

 must fall into some one or other of these divisions, 

 so that our classification is at any rate a simple 

 and a convenient one. 



Or, again, imagine a map of England in which 

 the county boundaries are laid down, but all the 

 towns and villages are left out ; such a map would 

 give us a classification of the inhabitants of Eng- 

 land, and a classification by definition. Stress is 

 laid simply on the boundary lines between the 

 several divisions, and the sole interest attaching to 

 any particular individual consists in the question on 

 which side of a given arbitrary line he happens to 

 reside. It follows also that in such a scheme those 

 individuals who reside in the centres of the several 

 counties are subordinate in interest to those near 

 the margins of the counties, since about these latter 

 there may be doubt as to which division they should 

 be referred to, while such doubt can hardly exist in 

 the case of the former. Such a map might be very 

 useful, and for purposes of minor importance, such 

 as a parliamentary election or a cricket match, 

 might contain all the information necessary, the 

 sole interest consisting in which side of an arti- 

 ficially drawn line a given individual happened to 

 live. 



As the knowledge of anatomy advanced ; as 

 zoologists became gradually acquainted with the 

 structure of a larger and continually increasing 

 number of animals ; as the microscope in the hands 



