24 FUNDAMENTALS OF S UBMI C RO S C OPIC MORPHOLOGY I 



acid. Their partition is such that the first always contains the second 

 in the form of enclosed droplets. 



This can easily be demonstrated, as the negative nucleic acid coacer- 

 vate can be selectively stained by alkaline dyes such as methyl green. 

 This is regarded by Bungenberg de Jong as a model for a nucleus 

 imbedded in cytoplasm. Personally, however, I do not believe that 

 such comparisons are admissible, since both nucleus and cytoplasm 

 possess a structure, whereas the liquid coacervate droplets are com- 

 pletely amorphous. For that reason, the picture suggesting the resem- 

 blance to the cell may be incidental and should therefore not be used 

 in analogy to cytological phenomena. There would otherwise be too 

 great a temptation to over-simplify the relationships between cyto- 

 plasm and nucleus. The nuclear changes in karyokinesis, for instance, 

 cannot possibly be attributed to changes in hydration or electric 

 charges alone. These phenomena are attended with complicated struc- 

 tural alterations. 



Whereas the early upholders of the theory of coacervation were 

 principally concerned with the surfaces of the colloid particles with 

 their solvation layers and electric charges, attempting to gain more 

 knowledge of the structure of boundary layers (see p. 40 and 267), 

 their studies were later extended to include the inner structure of 

 coacervate systems. In biological objects we have to assume that the 

 coacervate has a submicroscopic gel structure (Bank, i 941). Therefore, 

 apart from a knowledge of boundary structure, we are also in need of 

 deeper insight into the inner structure of colloid particles and coacer- 

 vate flocculates. In order to advance in this direction we must appeal 

 to structural principles. 



§ 2. Principles of Structure 



By structural principles we mean the laws governing the mutual posi- 

 tions of atoms, ions, and molecules. The positions of the atoms in the 

 molecule are studied by structural chemistrj, which in this respect 

 appears as a morphological science. For example, when we represent 

 the carbon atom by its 4 valencies or a benzene ring by the well- 

 known hexagon (Fig. 24), these are morphological illustrations based 

 on certain properties of these substances. The exact location of the 

 valency bonds in space and the distances between the atoms remained 



