THE EVOLUTION OF CONTINUITY 167 



Attraction inevitably induces Repulsion, and Aggrega- 

 tion invariably ends in Segregation. 



Segregation frequently reflects environmental hostility 

 in a near or immediate form, and it is through this that atoms, 

 molecules, the products of cell-division, and Individuals 

 separate from each other to come under the action of different 

 modifying forces. For example, the segregation occurring 

 on the splitting up of a molecule results in momentarily 

 segregated atoms encountering new affinities. And the 

 segregation of cell-division during development entails that 

 the future product of a division-result appears in the young 

 Individual in a definite region where special cell-characters 

 are necessarily acquired and maintained. This is the 

 segregation through whose help are evolved the different 

 cell-species of the body. 



At the same time, Environment may act as a segregator 

 in the form of suddenly acting physical force. It may set 

 up natural barriers which have the same effect as removal 

 to a distant environment, or it may actually carry potential 

 Individuals to places far distant from the habitat of the 

 original stock, where special influences mould the develop- 

 ment on new lines. The wind, water currents, birds and 

 animals frequently act as transporters of potential Individuals, 

 but the periodical alternation of elevation and subsidence 

 of the ocean-bed has without doubt been one of the most 

 important segregating factors in past evolution. By the 

 process of elevation a marine stock could be brought to 

 acquire terrestrial characters, while through subsidence 

 of a stretch of the ocean-bed a given organic type could be 

 caused to develop in depths where increased water-pressure 

 would proceed to multiply previous Continuity. Multipli- 

 cation of numbers would itself lead to segregation and the 

 invasion of new environments. 



In many different ways, therefore, Segregation would 

 lead to the invasion of new environments where greater 

 water-pressure obtained, and where Continuity could be 

 further multiplied, during development. 



It has already been pointed out that the discreteness of 

 the various strata of the earth's crust, and the sudden 

 appearance, and occasionally disappearance, of certain 

 fossil forms in given strata, are indications of alternating 



