Organization 451 



All of them, or their rudiments, seem to be present in all plants. They 

 provide the basic ingredients, so to speak, out of which the developmental 

 norm is produced. Just what a specific norm will be depends on the 

 interaction between these inherent protoplasmic traits and two other 

 factors: the genetic constitution of the individual and the environment 

 in which it develops. 



The genetic constitution is the complement of genes in the organism. 

 These act on the protoplasmic traits just mentioned to produce the form 

 characteristic of that organism. This form, however, is not a specific pat- 

 tern of polarities, gradients, spiralities, and symmetries but results from 

 a specific reaction to a specific environment. Neither genes nor environ- 

 ment alone determines what an organism is, for their action is comple- 

 mentary and one cannot be separated from the other. In practical experi- 

 mental work, however, much can be learned by studying the effects of 

 different genotypes under the same environment or of the same genotype 

 in different environments. The latter method has so far been much more 

 fruitful, as is shown by the vast literature in the fields of the morpho- 

 genetic effects of light, water, temperature, mechanical factors, and 

 various chemical substances. There is still opportunity for much fruitful 

 work in all these fields. A study of gene action, on the other hand, al- 

 though actively pursued, has thus far been concerned chiefly with the 

 effects of genes on metabolic processes or on the synthesis of specific 

 substances. How genes control developmental relationships, and thus 

 the production of organic form, is almost unexplored territory. 



In a given individual, therefore, through the interaction of its genotype 

 and the particular environment in which it lives, both acting on the basic 

 tendencies toward polarization, gradients, symmetry, and spirality, there 

 is at any given stage of its development a norm to which it conforms. 

 This involves more than a mere interaction between organism and en- 

 vironment. What emerges from the developmental process is an organized 

 system in which the various parts are related and mutually interdependent 

 and which controls its own development by a process of self -regulation. 

 This is to be seen most clearly in the familiar phenomena of growth. A 

 plant or animal exists in an environment of which the chemical constitu- 

 ents (atoms, molecules, or larger particles) are a heterogeneous mass and 

 dispersed at random. When these particles are drawn into the organism 

 they lose this randomness and each now comes to occupy a particular 

 place in the living system. By some means this orderly disposition of new 

 material into an organized whole is controlled. When death ensues, the 

 control disappears and the dispersive tendencies of lifeless matter break 

 down the system. This system is specific and is different in every indi- 

 vidual. The mass of data now accumulated from studies of regeneration 

 suggests that all the cells, at least at their beginnings, are totipotent and 



