226 Charles F. Ehret 



level and within the spheres of intracellular and extracellular molecular inter- 

 action, each set of the higher two classes is continuously capable of communica- 

 tion with every other set by means of diffusion and convection transport 

 phenomena. 



V. CONCLUSION 



In the introduction to this conference Bigelow suggested that in biological 

 systems with long time-constants, for a message to be useful at the receiving 

 point, 'all messages must be enormously complex groups of messages rather 

 than simple ones' (51). This expression is clearly related to the limited span 

 proposition (52), that is, that span of diversity is limited by difficulties of internal 

 control. Therefore it is not too surprising to find that epigenetic control 

 systems of the cell (whose internal difficulties are in the form of long time 

 functions and thermodynamic vulnerability) solve these difficulties by the 

 method of 'chunkmg' complex groups of messages into structurally and func- 

 tionally unitized subsystems. That the subsystems of primary organelles appear 

 to be phylogenetically ubiquitous might also have been predicted from the 

 principles of biochemical evolution. But that they are structurally so alike is 

 indeed a striking fact; although this is not to say that we should now expect 

 the cilium of whale bronchus, the axial fiber of fern sperm, the connecting 

 fibril of toad retina, the sweeping cilium of paramecium peniculus or the mantle 

 cilium of a mollusc to be exactly alike. We know that such organelles are 

 capable of antigenic distinctions even amongst the various stocks within a 

 species (53); indeed, the mechanism of such distinctions constitutes a most 

 crucial problem of molecular biology. That the functional and structural 

 diagrams of an organism in temis of its organelles are topologically homeo- 

 morphic is consistent with parallel relations at other levels; in its functions 

 between molecular and cellular levels of organization, the cell organelle fills the 

 last gap in a complex hierarchy of unitized subsystems that characterize the 

 organism from the atomic to the social level. The method of integrating these 

 hierarchies and of extracting quantity of infoiTnation from any organism that 

 employs such mechanisms remains to be accomplished. 



Acknowledgment — I wish to thank my many colleagues, particularly Howard 

 DucofF, E. Lawrence Powers, and Robert Schweisthal of Argonne National 

 Laboratory for their interest and cooperation, and Henry Quastler of Brookhaven 

 National Laboratory for his very helpful suggestions. 



REFERENCES* 



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2. L. Augenstine: Protein structure and information content. This volume. 



3. L. Monne: Functioning of the cytoplasm. Advances in Enzynwlogy 8, 1-69 (1948). 



4. D. E. Green: Organized enzyme systems. J. Cell. Camp. Physiol. 39, Suppl. 2, 75-111 

 (1952). 



5. W. T. Astbury: Introductory review: fibrous proteins and their biological significance. 

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