366 PHYSIOLOGICAL EEGULATIONS 



The most interesting correlation in behavior is, I think, the 

 modification of behavior with load of component. The animal 

 deprived of food does things to find it that the well-fed animal does 

 not. Such a correlation was found for water content and atmos- 

 pheric humidity in rat and in cockroach (§ 43 and "§> 47). It means 

 that preference for moisture is greater in water deficits, even as 

 drinking is faster in water deficits. 



Very often it is said that an animal in water deficit has "drive" 

 or "thirst drive." That term denotes a hypothetical state of the 

 animal, and connotes a virtual force that expends itself in seeking 

 water. It is comparable to inferring that a force of "osmotic" 

 pressure moves water into the body, and if I were to call it "drink- 

 ing pressure" no fault could be found. But what is directly 

 measured is not drive, but either water deficit or water drinking. 

 The intermediate term can be dispensed with, and water load be 

 used to describe the physiological state. 



In brief, behaviors that diminish losses or enhance gains in defi- 

 cits, and those that enhance losses or diminish gains in excesses, 

 protect against inconstancies. Rarely is any one behavior con- 

 tinuously operative, so long as many components are being pre- 

 served by a single individual. But, however modified by condition- 

 ing or intelligence, appropriate behaviors are found widely in 

 organisms that observably respond to environments. 



§ 133. Sequences in time 

 By comparisons and inductions from data such as figure 176, 

 sequences of load are found to fall into a generalized tolerance dia- 

 gram (A, fig. 180). The scale of times as well as of loads varies 

 enormously for diverse components, and somewhat for diverse 

 species. Five periods or phases may be distinguished, in each of 

 which a different physiological state (load) prevails. 



(I) Control or initial state, in which load is zero. 

 (II) Transitional or loading state, in which an increment or 

 load is gained under the influence of component, agent, 

 or conditions. 



(III) Stationary state, in which load is relatively uniform; 

 often conditions are constant. 



(IV) Recovery or unloading state, in which load is lost. 



(V) New control state, in which recovery is completed or 

 nearly so ; it may or may not differ from the initial con- 

 trol state I. 



