VIII. REPLICATION OF VIRUS PATTERN 105 



timate enough to make them in the end identical with one another 

 in their structure. Such an ideal association cannot be established but 

 for the interposition of lipids among the protein molecules. This must 

 he the main reason for the presence of lipids in the protoplasm. 



On the other hand, as for viruses lipids are not only unnecessary, 

 but unfavourable since viruses which may easily change their structure 

 as does the usual protoplasm may commonly be unable to act as a 

 strong virus. Rigid, unchangeable structure should be necessary for a 

 virus to act as the template, since the action consists in the ability of 

 changing the structure of the opponent. The great resistance of cry- 

 stalline plant viruses to chemicals or heat may be attributed to the 

 absence of lipids. 



Even with the same content of lipids, the mode of association or 

 constellation of protein molecules may effect the manner of the trans- 

 mission of change in the protoplasm. The general susceptibility of 

 young cells to viruses may be dependent upon the flexibility of the 

 young protoplasm protein. There are good reasons to suppose that 

 newly generated proteins possess a property to be easily altered in the 

 structure as will be discussed in Part IV. The phage susceptibility of 

 young bacteria can be retained for long periods at a low temperature, 

 although immediately lost at a higher temperature, indicating that the 

 flexibility of young proteins can be preserved at a low temperature 

 (101). 



If elementary bodies of protoplasm are irreversibly coagulated, 

 viruses cannot multiply in the firotoplasmi because the protoplasm in 

 such a state may surely be" inadequate- for the production of replicas as 

 well as for the transmission of the change. The irreversible coagula- 

 tion must mean the death of protoplasm. But if protoplasm is killed 

 ^vithout such a coagulationv the multiplication of viruses may not be 

 impossible in the dead protoplasm. It has been established by a num- 

 ber of workers that phage can" multiply in bacteria which have been 

 rendered^ non-viable by chemical or physical agents such as penicillin, 

 mustard-gas, formaldehyde, and ultraviolet rays. Similar |)henomena 

 have been proved also with other viruses. For example, chick embryos 

 killed by prolonged storage at room temperature or at 4^ are capable 

 of supporting the multiplication of influenza virus upon incubation at 

 35 C (143). The growth of Shope's papilloma virus is also possible in 

 the cells sterilized by ultraviolet irradiation (144). According to Weiss 

 (145), feline pneumonitis virus, a typical virus of the psittacosis- 

 lymphogranulom.a group, was cultivated for 20 passages in the yolk 

 sacs of dead chick embryos ; the rate of its growth was claimed to be 

 almost similar to that in living embryos. 



Multiplication of viruses in such dead cells is expected to be never 



