PREFACE 



''His body temperature is always the same; if it were not he 

 would be sick." That empirical rule is rediscovered daily. To 

 physiologists the rule is a challenge to seek further relations among 

 bodily functions. How are the specific properties of an organism 

 maintained? What sorts of processes are provided so that the 

 temperature is not upset in a body subjected to twenty-fold in- 

 creases in heat production and to winter's icy blasts? 



Physiological regulations are patterns of processes; the out- 

 come of all those operating characteristics that assure the con- 

 stancy of a property such as body temperature. The creature's 

 endowments are not merely material ; activity is provided continu- 

 ously. Of all the possible combinations of chemical velocities, 

 physical responses, and organismal behaviors that are possible, 

 those very ones prevail that fit into a scheme of self -perpetuation. 

 This scheme is the object of investigation. The invisible pattern 

 according to which in a given physiological state, whether of action 

 or of rest, these particular velocities are operating and others not, 

 constitutes regulation. 



Physiology seems to me more than a science of individual work- 

 ing parts. I found it fun to compare the manners in which a kid- 

 ney excretes various substances. But then I wondered whether 

 there was some rhyme in the heights of the several thresholds and 

 the hypertonicities of various urines. It next became obvious that 

 measured ingestion saved excretion many a day's work. Evi- 

 dently excretion is subservient to organism, a kidney to a body. 

 The scale of renal clearances seems utterly arbitrary until one 

 thinks of the millions of body cells that have to tolerate and even 

 transform what the kidneys do not excrete. 



At one time I supposed that the pattern of physiological re- 

 search was fixed once for all. The newcomer merely went into 

 more detail with modified apparatus. Now, I believe that fingers 

 and levers are to be supplemented by concepts. There is no limit 

 to the patterns of physiological investigation, for every concept 

 adds a pattern of search. Physiology is more than a technology, 

 more than information. It develops new aspects at every turn; 

 as long as it lives it will include the unorthodox. The unorthodox 

 of today becomes the standard of tomorrow; let no one make a 



