Variation and Natural Selection. 1 1 5 



which would be otherwise unable to hold their own, might 

 arise and have time to establish themselves. In an ex- 

 panding area migration would take place, local segregation 

 in the colonial areas would be rendered possible, differential 

 elimination in the different migration-areas would produce 

 divergence. There would be diminished elimination of 

 neutral variations, thus affording opportunities for experi- 

 mental combinations. In general, good times would favour 

 variation and divergence. 



Intermediate between good times and hard times would 

 come, in logical order, the times in which there is neither 

 an expansion nor a contraction of the life-area. One may 

 suppose that these are times of relatively little change. 

 There is neither the divergence rendered possible by the 

 expansion of life-area, nor the heightened elimination 

 enforced by the contraction of life-area.* Elimination is 

 steadily in progress, for the law of increase must still 

 hold good. Divergence is still taking place, for the law of 

 variation still obtains. But neither is at its maximum. 

 These are the good old-fashioned times of slow and steady 

 conservative progress. They are, perhaps, well exemplified 

 by the fauna of the Carboniferous period, and it is not at 

 all improbable that we are ourselves living in such a quiet, 

 conservative period. 



On the other hand, hard times would mean increased 

 elimination. During the exhibitions at South Kensington 

 there were good times for rats. But when the show was 

 over, there followed times that were cruelly hard. The 

 keenest competition for the scanty food arose, and the poor 

 animals were forced to prey upon each other. " Their 

 cravings for food," we read in Nature, " culminated in a 

 fierce onslaught on one another, which was evidenced by 

 the piteous cries of those being devoured. The method of 

 seizing their victims was to suddenly make a raid upon 



* I would ask historians whether there nave not been, in English history, 

 good times of free and beneficial divergence exemplified in diverse intellectual 

 activity, hard times of rigorous elimination, and intermediate times of placid, 

 somewhat humdrum conbeivatLsm. 



