320 Action of the Genetic Material 



pothesis assumes that a physical process is involved, comparable to the 

 sorting out of amino acids and also proteins in paper chromatography, 

 primed by what I called the conditions of the system, that is, all 

 physical and chemical features of the cell in its proper surroundings. 

 In principle, this is a mechanistic explanation involving specific move- 

 ments of materials. Waddington's explanation is a statistical one. It 

 needs a competition for substrate material with a following process of 

 selection, based upon the changes in the amount of the different sub- 

 strate materials. In my hypothesis the separation (stratification) is an 

 automatic consequence of the type of stuffs (different proteins, etc.) 

 and the physicochemical conditions prevailing at the proper time and 

 place in the system as a whole, and therefore an obligatory one. 

 According to Waddington's hypothesis, we do not know why the 

 competition for the substrate determines one synthesis in one cell and 

 a different one in another cell. In a model he assumes that this 

 happens when another substance is added to the cell. But where does 

 this come from? Why does it enter only one cell? It seems that here a 

 deus ex machina is introduced to make the competition-selection idea 

 work. In view of the amazing clocklike precision of development, I 

 have, in addition, misgivings about explanations of a statistical type 

 for large-size material processes of life which can hardly be compared 

 to the elementary processes of physics and their statistical background 

 (which is not acknowledged by all physicists). (See Schrodinger's 

 philosophical discussion, 1944. ) 



c. Activation of the genes 



The problem of what had been called "activation of the genes" 

 in their proper substrate now enters the discussion. Actually there are 

 two phases : ( 1 ) the genie control of the primary chemodifferentiation 

 and subsequent sorting-out process; (2) the selective action of the 

 proper part of the genie material with the competent substrate which 

 was produced by the sorting-out process. The first problem is discussed 

 by Waddington in a way similar to our previous analysis of Brachet's 

 work and, still earlier, our discussion of the primary gene products. 

 The genie material synthesizes a product (more or less similar to 

 itself) which, after passing into the cytoplasm, directs enzymatically 

 the syntheses of the materials for differentiation. It is a logical step, 

 then, to renounce the existence of plasmagenes which would inde- 

 pendently control such syntheses and which anyhow would at some 

 time be dependent upon the genie material. The second problem, the 

 "activation" of only definite genie actions in the presence of all genie 



