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 controlhng of all the parts). The develop- 

 ing creature becomes more visibly complex ; it also becomes 

 knit together as a unity. Development always impKes 

 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 quahties 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 pecuharities, 

 and will persist for a while even when the environment is 

 altered. 



This variabihty of the Uving 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 variabihty in the crystaUization 

 of one and the same chemical substance, which may appear 

 in several different forms. Every one has looked at the 

 beautifur diversity^ among snow-flakes. Now it may be 



