ABSTRACT 



This is a monograph recording an investigation in quantitative 

 physiology. Regulations in organisms are maintenances of rela- 

 tive constancies. They are described from suitable data by selected 

 relations of the following sorts : 



(1) Variations, especially in the successive values found for 

 one sort of measurement in an individual. These represent the 

 results of all those events that antagonize the occurrence of wider 

 variations. 



(2) Changes and exchanges as correlated with excesses over, 

 or deficits under, the control values (contents). These are rates of 

 processes, and express what is done to recover the usual physio- 

 logical state. 



(3) Behaviors that exhibit preferences for environments which 

 either promote or prevent exchanges of diverse components. 



Water is chosen as the prototype of component that tends to be 

 in quantitatively regular amounts in living units. Data for the 

 dog show in how far water contents (body weights), intakes, and 

 outputs vary from hour to hour and from day to day ; and how the 

 rates of intakes and outputs are modified with each experimentally 

 provided content. The latter relation is investigated both in sta- 

 tionary states of unusual content, and in recoveries from them. 

 Preservation of content may be regarded as a pattern of particular 

 relations among the rates provided in diverse paths of exchange. 



Man, frog, and many other species of animals, including several 

 of invertebrates, manifest similar relations in water exchange. 

 Organs, tissues, and cells are also recognized as having the pattern. 

 From these materials the general features common to many living 

 units are formulated. Quantitative differences among species are 

 also ascertained. A variety of other measurements, particularly 

 upon blood and other parts, is correlated with water content, to 

 characterize the physiological states of water excess and deficit. 

 Thus an intensive and comprehensive account of water relations 

 of animals and their tissues results. 



Analogous data are set forth concerning other quantities than 

 water. Some of these are heat, glucose, oxygen, carbon dioxide, 

 lactate, frequency of heart beat, and blood pressure. For each a 

 similar pattern of equilibration is found. 



