302 Injormaiion Storage and Neural Control 



may band into face-to-face groups or larger social organizations 

 and societies. 



There is continuity and there are cross-level similarities in 

 structure and process at all levels of this hierarchy, even though 

 there are, of course, at the same time, many specific differences 

 among individual systems, species, and levels. We have sought 

 for and found cross-level "formal identities" which can be studied 

 experimentally. 



All living systems are open systems. That is, they maintain 

 steady states of several variables and counteract entropic dis- 

 integration by means of inputs and outputs. Living systems at 

 all levels process both energy and information. These always flow 

 together. For example, energic inputs such as food convey infor- 

 mation in the patterning of their molecular structures, and coded 

 verbal communications are carried on the energy of sound waves. 

 Energic and informational inputs are distinguished by whether 

 the receiver responds to their energic or their informational 

 aspects. Sometimes the response is to both. 



SUBSYSTEMS 



Living systems at any level require certain crucial subsystein 

 functions in order to survive, unless they exist in a relationship of 

 parasitism or symbiosis with another system which supplies them. 

 Free-living cells, for example, may be shown to have subsystems 

 that accomplish all the essential functions, while cells which are 

 part of organs may lack some of them. Groups which survive over 

 time isolated from other people have all these subsystems while 

 groups which are parts of organized societies almost never do. 

 Subsystems may be either local, like the eye, or dispersed, like 

 the reticuloendothelial system. 



There are essential subsystems which deal with the processing 

 of energy and others which process information. The essential 

 energy-processing subsystems in the general order of their operation 

 are: boundary, ingestor, distributor, decomposer, producer, energy 

 storage, excretor, and mover or output transducer. 



The essential subsystems in information processing, listed in the 

 general order of flow in information processing are: 



