1 88 THE VARIATION OF ANIMALS IN NATURE 



examples of mimicry, protective coloration, etc. The extent 

 to which evolutionary inquiry has become a prey to histori- 

 cal influences is seen remarkably clearly in the frequency 

 with which long-discredited evidence is quoted in support of 

 Natural Selection (e.g.) without any reference to information 

 or reasoning subsequently brought to bear upon it. 



Procedure. — It seems to us that the unwieldy mass of facts 

 and arguments that has been brought forward both for and 

 against this theory may, for the purposes of this analysis, be 

 dealt with in the following order : 



I. Artificial selection. (a) Under domestication. (b) 

 Under experimental conditions. 

 II. Direct evidence for Natural Selection — studies of the 

 incidence of death-rates in nature. 



III. The nature of variation. Do living organisms vary 



in such a way that a selective death-rate would be 

 expected to be operative ? 



IV. Indirect evidence for and against the Natural Selection 



theory. Do the structure and constitution of living 

 organisms suggest that Natural Selection has been 

 an important agent in their evolution ? 



It should be noted that the following discussion is concerned 

 with two main controversial points : 



(i) Evidence for and against the existence of a selective 



process in nature. 

 (2) Evidence for and against the theory that such a process 



has been responsible for the evolution of the lower 



taxonomic categories. 



(1) is mainly dealt with in the second section ; until the 

 point at issue here is settled, any discussion of IV is irrelevant. 

 But as the chance of any such settlement appears to be very 

 remote, we have in the meanwhile to consider (2) independently. 



I. Artificial Selection. — (a) The origin of domesticated 

 races. — It is a curious fact that the value of the major proof 

 brought forward by Darwin in favour of Natural Selection — 

 viz. that selection (either conscious or unconscious) by man 

 has produced forms as divergent as natural races and species — 

 has not been finally settled. By some it is considered worthless 

 as evidence and is simply neglected. Others (e.g. Goodrich, 



