THE WONDER OF LIFE 479 



sion. Out of the apparently simple there arises the obvi- 

 ously complex, as the chicken is ' coined and minted out 

 of the egg '. There are the two great processes : differen- 

 tiation (which is the structural side of division of labour), 

 and integration (which means the unification and har- 

 monization and controlling of all the parts). The develop- 

 ing creature becomes more visibly complex ; it also becomes 

 knit together as a unity. Development always implies 

 these two processes. 



Variability. It is well known that some of the simplest 

 organisms which remain single cells occur in different 

 forms and with different qualities in different circumstances. 

 Thus the same Bacterium may be virulent or relatively 

 attenuated in its poisoning capacity, and * polymorphic ' 

 Protozoa, e.g. some Trypanosomes, are described. It does 

 not seem that these diversities are simply individually 

 acquired peculiarities, due to some peculiarity in the parti- 

 cular environment. They may have arisen in some such 

 way, but they often appear to have taken grip of the con- 

 stitution ; they are not individual, but racial peculiarities, 

 and will persist for a while even when the environment is 

 altered. 



This variability of the living organism is characteristic 

 and fundamental. It has to be accepted, at present, as a 

 primary fact of life, but some suggestions may be considered 

 which tend to leave it less apart. In the inanimate world 

 there is a tendency in matter to complexify, for atoms to 

 build up molecules, and molecules larger molecules, and so 

 on. There is also a certain variability in the crystallization 

 of one and the same chemical substance, which may appear 

 in several different forms. Every one has looked at the 

 beautiful diversity among snow-flakes. Now it may be 



