436 PHYSIOLOGICAL KEGULATIONS 



equally ''fruitful." (b) That some procedures are incapable of 

 the accomplishments made by others, (c) That recognition of the 

 validity and effectiveness of additional general methods in physiol- 

 ogy need not reduce but rather reinforce the solidity and assured- 

 ness achieved by use of those procedures already employed. 



§ 156. Summary 



It requires re-emphasis that correlations alone may be highly 

 enlightening, without reference to causes or mechanisms, or even 

 to possible purposes or origins. Biometry has evolved on the in- 

 terests inherent in correlations; its lessons have usually been 

 limited to a particular subject content instead of being used freely 

 in other fields of biology. ' ' Physiometry ' ' might supplement much 

 of present-day physiology. 



Both specific outlines of the present investigation and general 

 methods of choosing variables and relations are reviewed. It is 

 useful, in multiplying relations among phenomena, to keep selected 

 variables present through more than one study. Uniformities and 

 patterns of relation may then be reached by inductions. 



Will scientists continue to add knowledge at faster and faster 

 rates without having plans for coordinating and assimilating what 

 they add? For physiology, some of the plans here reviewed are 

 available. In particular the mapping of coordinated physiological 

 components, and the prolonged search of these maps for uniform- 

 ities of relations, may become a major activity of those interested 

 in living units. 



General methods and procedures are of use both in planning 

 investigations and in reporting them. They help clearly to segre- 

 gate hypotheses and opinions. Descriptive physiology is the study 

 of multiple relations among phenomena, expressed in language 

 that is freed to the utmost of hypotheses. So far, description 

 furnishes the only tested explanation of physiological regulations ; 

 it tells what the net processes of regulation accomplish. This fact 

 suggests that the definition, classification, and correlation of 

 selected variables may constitute a method to be used in various 

 fields. It can indicate how each activity of organisms is actually 

 performed. 



