48 II. FUNDAMENTAL STRUCTURE OF PROTOPLASM 



2. The Force Generated by Polymerization 



It is probably true to say that the thick water layer is attracted 

 onto the surface of virus particles by Rothen's long range force. But 

 it must be an important question : what is the nature of the force ? 



Prior to answering this question, Rothen's experiment referred to 

 above should be discussed in detail. He used bovine serum albumin as 

 the antigen and homologous rabbit antiserum as the antibody, and found 

 that the thickness of molecules of the antibody attracted by the layer 

 of the antigen molecules became greater as the number of the antigen 

 monolayers increased. When the antigen v/as a single monolayer the 

 thickness of the antibody was found to be about 30 A, while when anti- 

 gen was piled up in 8 layers it became 230 A. 



A possible explanation of this phenomenon is that the antibody- 

 attracting force of the antigen may result from its polymerization 

 and that the force may consist of electrostatic force arising from the polar 

 groups of the protein. If a molecule can be compared to an electric 

 cell, the force may be expected to become greater on the polymerization 

 or on piling up. The difference in the pattern of arrangement of polar 

 groups may account for the specificity of the force. 



Water molecules may be attracted by such a pattern of polar groups, 

 positive pole of the molecule being attracted by the negative pattern, 

 and negative pole by the positive pattern, so that the water layer thus 

 formed should have in itself the pattern of polar forces. If water 

 molecules are thus successively attracted in accordance with the pattern, 

 forming a thikness of, say, 1,000 A, the outside of the most outer layer 

 also may have the pattern. In such a case, it may be said that Rothen's 

 long range force can reach a distance of 1,000 A. However, as illus- 

 trated in Fig. 8, since the arrangement of water molecules may become 

 the more irregular as they exist in the more outer layer, the pattern 

 will become more incomplete with the increasing distance. It has been 

 reported that the long range force failed to be demonstrated if egg 

 albumin was used as an antigen instead of bovine albumin. This might 

 be due to the failure of the protein to polymerize regularly. 



Haurowitz (14) studied the reaction between the atoxyl-azo protein, 

 containing As in various proportions, and its antibody, and found that 

 the antibody-attracting force of the antigen seems to increase with the 

 increasing number of As molecules combined with the protein ; when 

 As quantity is very great a single molecule of the antigen can combine 

 with even 50 molecules of the antibody. This result may be expected 

 if the polymerization of the protein is enhanced with the increasing As 

 content, v/herein As-containing groups being piled up through the 



