426 The Inward Urge to Change 



person stimulates you or inhibits you in a distinct way. 

 You yourself affect each of the others in a distinct way; 

 and from the meeting of any two there must emerge a 

 unique quality. 



We can perhaps look upon organic variability itself as 

 due to emergence. The individual starts, as we have seen, 

 as a fertilized Qgg. The germ cells themselves resulted from 

 repeated cell-division, accompanied by increase in mass 

 through assimilation of foreign matter. Even if the cell- 

 divisions are quite uniform and precise, the fact of growth 

 introduces variables at every stage. There are qualitative 

 and quantitative differences in the nutrients available. The 

 situation of each succeeding cell differs from that of every 

 other, with relation to heat or moisture or chemical factors 

 in the environment, and so on. After the fertilization, it 

 is almost inconceivable that the development should proceed 

 with all the conditions for every individual absolutely identi- 

 cal at every stage and for every detail of structure. Vari- 

 ability is thus unavoidable, involved in the very fact of or- 

 ganization and complexity. 



The way of life entails assimilation under a variety of 

 circumstances, and so variation in the course of development. 

 The same principle may be conceived to apply to the pro- 

 gressive multiplication of germ cells, although, as compared 

 to body cells, these are relatively well protected. We have 

 not been able through experimental methods, as by change 

 of temperature, salinity, etc., to bring about consistently 

 fundamental changes in germ cells. There are nevertheless 

 indications that external conditions do influence the behavior 

 of the chromosomes; and MuUer has succeeded in obtaining 

 relatively large numbers of mutations in Drosophila through 

 graded doses of radium emanations (page 164). 



Lamarck assumed that the tendency to vary toward 

 greater complexity is inherent in the nature of living matter, 

 and accepted this as a final fact, without attempting to seek 

 its cause. It is given with life, and thus to be treated as a 

 datum. It may be that Lamarck was right in this, and that 



