CHARACTER EVOLUTION 147 



inconceivably large number of "characters" or "character 

 complexes," structural and functional, some indissolubly and 

 invariably grouped and cooperating, others singularly inde- 

 pendent. For example, the zoologist infers that every one of 

 the most minute scales of a reptile or hairs of a mammal is a 

 "character complex" having its particular chemical formulae 

 and chemical energies which condition the shape, the color, 

 the function, and all other features of the complex. Through 

 researches on heredity each of these characters and character 

 complexes is now believed to have a corresponding physico- 

 chemical determiner or group of determiners in the germ- 

 chromatin, the chromatin existing not as a miniature, but as 

 an individual potential and causal. 



In the course of normal physicochemical environment, of 

 normal life environment, of normal individual development, 

 and of normal selection and competition, an organism will tend 

 to more or less closely reproduce its normal ancestral charac- 

 ters. But a new or abnormal physicochemical intruder either 

 into the environment, the developing individual, the heredity- 

 chromatin or the life environment may produce a new or abnor- 

 mal visible character type. This cjuadruple nature of the 

 physicochemical energies directed upon each and every char- 

 acter is tetrakinetic in the sense that it represents four complexes 

 of energy; it is tetraplastic in the sense that it moulds bodily 

 development from four different complexes of causes. This law 

 largely underlies what we call variation of type. 



In other words, the normal actions, reactions, and inter- 

 actions must prevail throughout the whole course of growth 

 from the germ to the adult; otherwise the visible body (pheno- 

 type, Johannsen) may not correspond with the normal expres- 

 sion of the potentialities of the invisible germ (genotype, Jo- 

 hannsen). 



