37^ RETROSPECT 



its roots in the fundamental principles of the latter, so should bio- 

 morphology be considered simply as a highly developed system, evolved 

 from molecular and micellar morphology to the shaping of cells and 

 organisms. Only the first step in this development at present lends 

 itself to deductive reasoning, viz., the transition from molecular to 

 micellar morphology. This has been made possible by the modern 

 evidence on the structure of highly polymeric chain molecules and 

 globular macromolecules. 



There are two guiding principles, of the utmost importance to 

 biomorphology, which are already recognizable in the configuration 

 of chain molecules. They are: i. The principle of repetition, which 

 is the foundation of all lattice structures and of every form of banding, 

 and 2. The principle of specificity. The first principle is represented, 

 on the one hand, by the ever-recurring members of the chain (intra- 

 molecular spacing) and, on the other, by the assemblage into a lattice 

 pattern of kindred chains (intermolecular spacing), as for example 

 frame substances, reserve substances, and lipid layers. Only if all the 

 members of a certain kind of chain are of exactly the same structure 

 can true intermolecular repetition take place. This law does not 

 normally apply to polypeptide chains, since their side groups are often 

 of different structure. In consequence, we find the second principle 

 holding sway, i.e., the capacity of otherwise similar molecular ele- 

 mentary units to assume a specific arrangement which may be repeated 

 for its part in long-range periods. We do not yet know how the 

 visible specific forms of cellular organelles, cells, tissues and organ- 

 isms grow out of this specificity, but doubtless causal relations do 

 ■exist between molecular morphology and morphogenesis, as fore- 

 shadowed by enzyme chemistry and the asymmetrical synthesis of 

 organic compounds. 



A problem no less difficult than causal morphological development 

 is that of the molecular morphology of heredity; for, assuming that 

 €very kind of visible form owes its origin to particular configurations 

 of concrete hereditary entities which cannot arise spontaneously, then 

 their complicated structure must be constantly reproducing their like. 

 Although the multiplication of the virus molecules presents some 

 analogy to this, we have nothing to go upon to build up a clear picture 

 of the auto-reproduction of those complicated structures, the genes. 

 Fox the present, submicroscopic morphology has been successful 



