370 The Outline of Science 



granted their continuance, something more is needed their sift- 

 ing. As we have said in a previous article, the process of evolu- 

 tion is a long drawn-out process of testing all things and holding 

 fast that which is good. The variations or novelties are the quali- 

 ties to be tested; the struggle for existence, which includes the 

 organism's endeavours, is the sieve that tests; heredity secures 

 the holding fast of what has proved good. To employ a meta- 

 phor which has the defect of triviality, the variations are the 

 ever-fresh hands of heredity cards that are given to the organism 

 to play with ; the organism uses these in the struggle for existence 

 with its strange mixture of active endeavour and fortuity. 

 But when the organism with a good hand a persistently good 

 hand becomes eventually tired and vacates its chair for a suc- 

 cessor, it hands on its luck, and its cunning, too. Thus the 

 essence of Darwinism is that nothing succeeds like success. 



As regards Variations 



The fountain of change is even more copious than Darwin 

 supposed. What is so clear in regard to pigeons and poultry, 

 dogs and horses, that they are continually producing something 

 new in their humanly controlled breeding, finds abundant illustra- 

 tion in wild nature. There are conservative types, it is true, 

 which persist in a well-poised organic equilibrium, but in many 

 cases there is flux. Outlying variants link one species to another. 

 When the novelties or variations are registered statistically they 

 often form what is called the Curve of Frequency of Error, 

 which means that the number of variants of any particular magni- 

 tude will be in inverse proportion to the amount of the deviation 

 from the mean. If the mean stature of the population be 5 ft. 

 8 in., there will be (as Alfred Russel Wallace points out) in 

 2,600 men, taken at random, one of 4 ft. 8 in. and one of 6 ft. 8 in., 

 twelve of 5 ft, and about twelve of 6 ft. 4 in. In fact, there will 

 be equal numbers at equal distances on each side of the mean, 





