ON PROGRESS IN THE STUDY OF 

 VARIATION. 



THAT variation is a subject worthy of study for its 

 own sake is becoming recognised, and the numbers 

 of naturalists who are devoting themselves to this study 

 steadily increases. Probably, however, if the nature of the 

 observations required were more generally understood pro- 

 gress would be much more rapid. 



The first object of the study is to throw light on the 

 origin of species. An exact knowledge of the facts of varia- 

 tion concerns many departments of biology, but it is in their 

 bearing on the origin and nature of specific distinctness that 

 these facts have their most direct and most manifest im- 

 portance. It is, then, essential that the subjects chosen for 

 investigation should be such as may be supposed to have 

 this bearing. 



Elsewhere (2) I have argued that it is reasonable to 

 suppose that variations of a discontinuous nature may play a 

 preponderating part in the constitution of new species, inas- 

 much as individuals presenting discontinuous variation in 

 any character differ already from the normal of their own 

 species — in respect of that character — much as one species 

 differs from another. 



For various reasons many have taken exception to this 

 suggestion, and though I do not now propose to enter with 

 any detail into matters of theory, nevertheless it may be 

 well to note the fallacy of one line of reasoning upon which 

 objectors have especially relied. It is said for example that 

 discontinuous variation is an exceptional phenomenon, that 

 " sports " are so rare that they may be neglected, and that 

 the appearance of discontinuous variation often seen in 

 collected series of specimens is due to an arbitrary system 

 of collection. These objections are founded partly on an 

 imperfect understanding of the suggestion that discon- 

 tinuous variation may be a chief factor in evolution, but far 

 more often they proceed from a want of familiarity with 

 the class of facts upon which the suggestion is based. 



