VII. THE MODE OF VIRUS MULTIPLICATION 95 



the nucleic acid content. It has been well established that nucleic 

 acid concentration is much higher in rapidly growing embryonic tissue 

 than in the corresponding adult tissue. The virus infection, there- 

 fore, should lead to the increase in the nucleic acid content of the 

 protoplasm. If such protoplasm is coagulated into particles after be- 

 ing endowed with virus structure, virus particles containing nucleic 

 acid in rich amount must be formed. 



As already described, virus-like particles are never recovered 

 from normal, untreated rabbit skin tissue, whereas when the tissue is 

 injected with staphylococcus toxin or sapotoxin, the tissue becomes 

 inflamed and swelled just as in the case of vaccinia virus injection, 

 and particles containing nucleic acids like those of vaccinia virus are 

 isolated in large quantities. If the apparent relation of nucleic acids 

 to virus multiplication is merely due to the rapid growth of the cells 

 there should be no change in the nucleic acid content when virus 

 multiplication occurs in the cells which were preliminarily rendered 

 nonviable. Actually, Price (115) claimed that when phage proliferates 

 in the cells whose viability was lost on penicillin treatment, there 

 occurs neither increase in the nucleic acid content nor change in the 

 amount ratio of desoxyribonucleic to ribonucleic acid. 



3. The Mode of Production of Virus Structure 



As mentioned in Part I, the relation between a virus and its host 

 cell protoplasm is considered to be analogous to that between an 

 enzyme and its substrate. A virus can combine with host cell proto- 

 plasm through the complementarily arranged polar groups distributed 

 between them just as does an enzyme with it substrate. 



To begin with, virus particles adsorbed to host protoplasm through 

 such polar groups should unfold its coiled structure to show its full 

 pattern. It is an established fact that globular protein molecules can 

 readily spread in monomolecular films on the intermediate surface. 

 The spreading of virus particle on the protoplam surface into a state 

 corresponding to such a monomolecular film, may be caused by some 

 physicochemical influence coming from the protoplasm, in this spread- 

 ing certain amino acids or proteins with low molecular weights as well 

 as inorganic salts may play an important role. 



The unfolding of globular proteins including virus particles to a 

 state of filaments is brought about, as already pointed out, by the 

 presence of inorganic salts in proper concentrations. At the same time, 

 there are a number of evidences that proteins with low molecular 

 weights like albumin can exhibit the same effect upon the spreading 



