VARIATION AND HEREDITY 117 



legitimately argue back to what may have 

 occurred in remote antiquity. 



Facts bearing upon variations have been 

 gathered so industriously of late that assimila- 

 tion has hardly kept pace with accumulation; 

 and one evidence of this is to be found in the 

 confusing ambiguity of the terms used by 

 various biologists. The term " variation " is 

 used in reference to at least three readily 

 distinguishable kinds of organic change, and 

 the term mutation is also used in three senses. 

 The terminology will require to be standard- 

 ized by some International Congress of 

 Biologists; but pending this, let us do what 

 we can in trying to get the ideas clear. 



When we compare a number of members of 

 the same species men, ruffs, garter-snakes, 

 sticklebacks, snails, brambles, buttercups, 

 pansies, and so on we find that they differ 

 from one another. These differences can be 

 measured and registered under the title 

 " observed differences," which commits us to 

 no theory whatever. 



But these " observed differences " require 

 further analysis before a statement of them 

 can be very useful. Indeed a statement of 

 them without analysis is very apt to lead to 

 biological fallacy. Many of the differences 

 may be wrapped up with sex, and these can 



