12 



I. INTRODUCTION TO VIRUSES 



show that the activity for a unit mass of phage or vaccinia virus pro- 

 tein varies with the particle size and that larger sized particles are 

 more active than smaller ones. Using collodion membranes having 

 various pore diameters, we demonstrated that particles capable of 

 passing through a membrane of a smaller pore diameter have a much 



Table 1 

 Filtrability of Virus Proteins 



Virus protein 

 isolated from 

 vaccine pulp 



Virus protein 

 isolated from 

 rabbit testicle 



Coli- Coli- 

 phage, phage, 

 No. I. No. II. 



Filtrability 

 tlirough 

 Berkefeld V. 



Protein 

 Virus action 



1/100 

 1/100-1/1,000 



1/5 

 1/10 



Filtrability 

 through 

 collodion 

 membrane of! 

 0.9 M average! 

 pore diame- 

 ter 



Protein 

 Virus action 



12% 

 1/10 



almost total 



Filtrability 

 through 

 collodion 

 membrane of | 

 0.58 M ave- 

 rage pore 

 diameter 



Protein 

 Virus action 



less than 1% 

 1/1,000-1/10,000 



16% 

 1/10 



almost almost 

 total total 



61% 

 49% 



84% 

 45% 



Filtrability 

 through 

 collodion 

 membrane of! 

 0. 34 A« average' 

 pore diame- 

 ter 



Protein 

 Virus action 



less than 1% 



1/1,000-1/10,000 



7.1% 

 2% 



9.5% 

 3% 



About 0.1% virus protein water solution (pH 7.5) was used for the filtra- 

 tion. The protein quantity was measured nephelometrically. 



less activity as shown in Table 1. This can be clearly shown with 

 phage as its activity can be precisely expressed in numerical values. 

 Some workers were liable to consider that viruses were regularly pro- 

 vided with extremelly small sizes, and occasionally they even insisted 

 that larger particles were only a concomitance, but this fact indicates 

 that rather the reverse is the case (16). 



The difference in the activity attributable to the difference in the 

 particle size was found with phage to be very striking. The ratio 

 of the activity of phage protein for a single particle, which could not 

 pass through 0.58^ membrane, to the activity of the protein which could 



