106 II. FUNDAMENTAL STRUCTURE OF PROTOPLASM 



accompanied by any nucleic acid change, since the multiplication should 

 only be the rearrangement of polar groups in the protoplasm. In fact. 

 Price (146) has confirmed that, during phage multiplication in bacteria,, 

 killed by penicillin, no change in nulcleic acids can be found. This 

 shows that the nucleic acid change is not indispensable for virus pro- 

 liferation. 



The cell multiplication has to be accompanied by the protein syn- 

 thesis for which great quantities of energy should be needed. In the 

 above examples host cells are regarded as being dead because of their 

 inability to multiply, which may be attributed to the destruction of 

 energy-supplying system. If so, the fact that virus multiplication is 

 achieved in dead cells, suggests that little or no energy, accordingly no- 

 protein synthesis, is required for the rearrangement of polar groups 

 leading to the virus multiplication. 



On the other hand, it has been reported that, in contrast to penicil- 

 lin, streptomycin reduces bacteria on killing them incapable of produc- 

 ing phage. (147) (148). In this case, streptomycin may give rise in the- 

 protoplasm to a change thereby the rearrangement of polar groups due 

 to the virus becomes impossible. While penicillin reveals no phage-in- 

 activating ability, streptomycin can inactivate the virus, showing its- 

 strong action in disturbing the structure of the assimilase. In a similar 

 manner the structure of bacterial cell protoplasm may be so disturbed 

 as to be rendered incapable of performing the rearrangement. The 

 inability of penicillin to inactivate phage indicates that penicillin has no- 

 such a strong disturbing faculty, although it can "kill" the bacteria 

 presumably by destroying the energy-supplying system necessary for 

 protein synthesis. If some host cells are "killed" in the same way by 

 a certain agent other than penicillin, virus can multiply even in them. 



Bacteria killed by ultraviolet-irradiation can produce phage, but 

 the virus grows slower, and yields a smaller number of new particles- 

 (149). This suggests that the protoplasm structure is so changed by the 

 killing action as to become somewhat unfavourable for the replication 

 of the virus pattern. However, in order to suppress completely the 

 ability of the cell to support the virus growth, enormous hits of the 

 irradiation are required to reduce to half the number of bacteria capable 

 of inhibiting phage after infection (150). 



It has been reported that chick embryo tissue cultivated for 13- 

 days in Hank's balanced salt solution prior to infection lost its ability 

 to suport the growth of psittacosis virus, but this capacity could be 

 restored by the addition of beef embryo extract at the time of in- 

 fection (150 a). A significant amount of virus was adsorbed to the 

 tissue cultivated under this condition without addition of beef embryo 

 extract, indicating that the failure of virus to grow was not due ta 



