9/18 ULTRA STABILITY IN THE ORGANISM 



less continuously. The influence of the gene-pattern can thus be 

 traced in R, giving it certain anatomical tracts, biochemical pro- 

 cesses, histological structures, and thus determining whether it 

 shall adapt as a dog does or as a starfish does. 



The nature of the parameters in S is wholly under genetic 

 control, for their physical .embodiment has probably been selected 

 for suitability by natural selection. (Here the nature of the 

 parameters — whether they are reverberating circuits, or molecular 

 configurations, etc. — must be clearly distinguished from the values 

 that any one parameter may take.) 



Finally there is the relation between the essential variables and 

 those in S — that the essential variables must force those in S to 

 change when the essential variables are outside their physiological 

 limits, and not to change otherwise (S. 7/7). As this relation is 

 entirely ad hoc, it must be determined by the gene-pattern, for 

 there is no other source for its selection. 



These are the ways, then, in which the gene-pattern must act 

 as determinant to the living organism's mechanism for adaptation. 



9/18. A question that must be answered is whether ultrasta- 

 bility, as described here, can reasonably be supposed to have been 

 developed by natural selection; for the ad hoc features of the 

 previous section have no other determinant adequate for their 

 selection and adjustment. 



For ultrastability to have been developed by natural selection, 

 it is necessary and sufficient that there should exist a sequence of 

 forms, from the simplest to the most complex, such that each form 

 has better survival-value than that before it. In other words, 

 ultrastability must not become of value to the organism only 

 when some complex form has all its parts and relations correct 

 simultaneously, for such an event occurs only rarely. 



Suppose the original organism had no step-mechanisms; such an 

 organism would have a permanent, invariable set of reactions. 

 If a mutation should lead to the formation of a single step-mech- 

 anism whose critical states were such that, when the organism 

 became distressed, it changed value before the essential variables 

 transgressed their limits, and if the step-mechanism affected in any 

 way the reaction between the organism and the environment, 

 then such a step-mechanism might increase the organism's chance 

 of survival. A single mutation causing a single step-mechanism 



135 



