104 II. FUNDAMENTAL STRUCTURE OF PROTOPLASM 



purines (140). However, Hershy and Chase (141) showed that after 

 infection with S^^ labeled phage most of the sulphur containing phage 

 protein could be stripped from the bactrial surface without inter- 

 fering with phage production. The resulting phage contained little or 

 no S"^ indicating that the protein fragments fails to be utilized by the 

 bacteria in contrast to the nucleic acid constituent. 



These findings are interpreted by some workers as indicating that 

 phage is decomposed on the cell surface into protein and nucleic acid. 

 fragments which the latter only penetrate into cells to act as the tem- 

 plate. In the opinion of the writer, however, the decomposition of the 

 virus should be accompanied by the destruction of the virus activity, 

 so that decomposed nucleic acid cannot act as the template, only serv- 

 ing as the cell constituents required for the cell growth. The virus 

 particles which can achieve their purpose of reproduction should have 

 complete structures. 



Recently, Mackal and Kozloff (139 c) have actually confirmed that 

 the material found in the progeny is largely, if not entirely, due to 

 the use of fragments of the parent nucleic acid in the synthesis of 

 the progeny nucleic acid, and they concluded that most of the transfer 

 of parent material of phage to progeny is unessential for the reproduc- 

 tion process. 



The viral pattern may be replicated on the cell surface on which 

 the extended virus is attached and the replicated pattern may be trans- 

 mitted to the inner side of the cell. However, it is conceivable that 

 the virus itself can penetrate into the cell to impress its pattern di- 

 rectly to genes cr gene-like particles, because according to Coons et al. 

 (142) various proteins injected intraveneously into mice were clearly de- 

 monstrated in the unaltered form in the nucleus of certain cells, often 

 even in higher concentrations than in the cytoplasm. Similar penetra- 

 tion of viral nucleoproteins into cells may be possible. 



3. Essential Factors for the Spread of the Structural 

 Change Caused by a Virus 



The first replica will be produced only in the portion of protoplasm 

 with which a virus directly combines, no matter whether it be cyto- 

 plasm or a nuclear mass. The replica thus form.ed, however, is to be 

 transmitted throughout the whole protoplasm. For the occurrence of 

 such a transmission the association among the protein molecules in the 

 protoplasm should not be too strong, as otherwise each protein molecule 

 may be unable to change its structure independently of others even 

 for a short period, whilst there must be associations among them in- 



