The Scale of Structural Units 

 in Biopoesis 



J. D. BERNAL 



Birkbeck College, University of London 



In all discussions referring to the evolution of material systems, be they 

 galaxies, organisms or societies, two aspects have to be kept in mind simul- 

 taneously at every stage in the discussion — the dynamic and the static — the 

 processes and the structures. Living organisms are built from atoms and at the 

 same time they react and change according to the laws of atomic combination. 

 Systems of extraordinary complexity and variety are built up, maintained and 

 modified but all repose on the same elements, that is on certain simple pro- 

 perties common to all actual or possible Hfe. These provide the given data into 

 which all schemes of biopoesis must be fitted. At the first stage of emergence 

 from the inorganic world this corresponds to the considerations of the physical 

 and chemical properties of the simple molecules of water, carbon dioxide and 

 ammonia, discussed by Henderson in his Fitness of the Environment; later they 

 include the colloidal properties of globular and fibrous polymers of the proteins, 

 nucleic acids and of bimolecular hpid sheets, exempHfied in terrestrial life by 

 structures such as those of the proteins. We have learned of these properties 

 largely through their occiu:rence in organic structures but once the structures 

 are provided the properties have nothing specifically vital about them, as has 

 been shown by their occurrence in synthetic plastics and fibres. My object here 

 is to show that much of the apparent complexity and arbitrariness of Uving 

 systems is due to just such physical conditioning and that the true biopoetic 

 problems represent the residue after these have been allowed for. 



One argument which has been used from the highest antiquity against any 

 spontaneous evolution of life has been the apparent impossibility of such an 

 arrangement coming together by chance. It was akeady urged against the early 

 Greek atomists, of which we catch a seventeenth-century echo in John Hall's 

 Epicurean Ode: 



'Since that this thing we call the world 



By chance on Atomes is begot. 



Which though in dayly motions hurld. 



Yet weary not. 



How doth it prove 



Thou art so fair and I in Love ?' 



Some have taken up the same theme less poetically in modem times and 

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