IV. THE CRYSTALLINITY OF VIRUSES 61 



could isolate a similar crystal from apparently healthy leaves of tomato 

 plant. According to our experiments, such a crystal was obtained only 

 from the young leaves in spring, in summer no crystalline mass being 

 isolated even from infected leaves. 



There should be a physicochemical association between protoplasm 

 protein and lipids, so that the expulsion of lipids may have considerable 

 influences upon the protein. When treated with ether at laboratory 

 temperature, both vaccinia virus and phage were readily inactivated, 

 and Japanese encephalitis virus protein isolated by our method was 

 deprived even of the complement binding faculty. Ammonium sulphate 

 may cause the expulsion of lipids either by damaging the combination 

 between the protein and lipids or by enhancing the direct, mutual com- 

 bining force of proteins. Whether the cause may be, there seems little 

 doubt that the salt can expel the lipids out of some plant elementary 

 bodies. Vaccinia virus or phage particles were immediately inactivated 

 by the addition of the salt, showing the strong effect of the salt upon 

 the virus protein. The fact that some plant viruses can be isolated in 

 a crystalline form by the addition of this salt may therefore indicate 

 the remarkable stability of the virus protein. There are, however, 

 ample evidences, as will be described later, to show that the expulsion 

 of lipids may occur during the infection of plants with a virus prior to 

 the treatment with ammonium sulphate, which may only promote the 

 aggregation of proteins. 



At any rate, the fact that some plant virus proteins can retain 

 their action even in a crystalline form, in which no lipids are contained, 

 must be of the utmost importance in the consideration of the nature of 

 virus action, since this fact shows that no lipid is necessary for the 

 virus action. Accordingly, the virus action must be attributed to the 

 purely polymerized protein molecules. The virus inactivation on the 

 removal of lipids, as already pointed out, may be, therefore, caused by 

 some alteration in the protein structure occurring as a result of the 

 lipid elimination. Hence, the presence of lipids may be responsible only 

 for the maintenance of the characteristic liquid crystalline state of pro- 

 toplasm. If protoplasm consisted of proteins polymerized without in- 

 termixing lipids and existed in a sort of solid crystalline state, various 

 complicated life phenomena would never be revealed. However, since 

 the action of a virus consists in the function as a template, lipids are 

 never needed for the action, but necessary for the protoplasm to de- 

 velop a change responding to the template. Lipids are indispensable 

 for producing a replica but not for acting as the template. 



That lipids have no concern with the virus action may be evident 

 also from the inconstancy of the lipid contents. Of animal viruses, 

 that of papilloma has been claimed to have so little quantity of lipids 



