II. THE SIZE OF VIRUS PARTICLES 



15 



expected from the view point above mentioned. However, it should be 

 borne in mind that the particles shown in electron micrographs are in 

 the desiccated state, while those treated with the membrane are in a 

 hydrated state combining with a great quantity of water as will be 

 described in the next section, and as a consequence the membrane 

 method must give a much greater value if the experiment is carried 

 out with the same particle. But the results obtained were entirely 

 reverse, indicating the presence of the striking difference in the parti- 

 cle size between the average sized particle and the smallest that narrowly 

 retains the activity. 



3. Water Quantity Combining with Virus Particles 



Virus particles shown in electron micrographs are in the dry 

 state, not in the hydrated state in which they are naturally existing, 

 and hence, at least in this respect, they fail to reveal the true feature 

 of virus particles. According to the writer's findings, when suspended 

 in water, virus particles are combined with the quantity of water ten 

 times as much as its dry weight, and always being accompanied by this 

 combined water (34). The evidences found by the writer from which 

 the conclusion was derived are as follows : 



Firstly, when the virus particles agglutinated in a weakly acid 

 solution were centrifuged and sedimented by an ordinary centrifuge 

 for a long period of time and the water content of the precipitate thus 

 sedimented was measured at intervals during the course of centrifuga- 

 tion, then it was found that the water content of the sediment dimini- 

 shed rapidly at the beginning of the centrifugation but that at later 



96 



3 93 



"Si 



-S 52 

 o 



a 91 



to 



5 90 



«-• 



Z S9 



J ea 



a 



g S7 



B 66 



?Z7 20 30 '*0 SO 60 70 60 90 WO 770 730 

 Time of centrifugation in minutes. 



Fig. 1. Cenrifugal precipitation of coli-phage protein particles. I : 

 Phage-protein, sample No. 1. II : Phage-protein, sample No. II. 



