II. THE SIZE OF VIRUS' PARTICLES 



17 



with vaccinia virus isolated form calf skin, and about 0.1 }x with coli- 

 phage, whereas by measuring the filtrability through collodion mem- 

 branes the average sized particle of the vaccinia virus and of phage 

 was estimated to be respectively in diameter about 0.5 ix, and about 

 0.2 IX. If the particles are always associated with the quantity of water 

 10 times as great as its dry weight, the diameter will be estimated to 

 be a little more than two times greater. 



0.125 °o 0.25; 



Concentration of sugars, %. 



Fig. 3. Sugar-impenetrable space of vaccinia virus particles. 

 I : Glucose, II : Fructose. 



For these reasons it was concluded that the virus particles in a 

 water solution would combine with the water about 10 times as much 

 as the dry weight. This appears to hold true generally for protoplasm 

 protein particles without reference to virus action. 



On investigating the space of vaccinia particles non-penetrable by 

 sugar or protein, McFarlane et al. (35) concluded that the particles 

 are surrounded by a considerably thick layer of water molecules which 

 fail to act as the solvent and which combine with the particles firmly 

 enough to sediment with them. At present, the writer believes that 

 their conclusion is proper, though at first the writer assumed that the 

 particles were in an extremely swelled state on absorbing all the esti- 

 mated quantity of water, an assumption which must be unreasonable. 

 As will be mentioned later there are many evidences to suggest that 

 the majority of the estimated water quantity is present outside the 

 particles forming a thick layer, and only a small portion of it being 

 absorbed by them as claimed by the above authors. If the water 

 quantity combines firmly with the particle also in the case of filtration 

 through collodion membrane, the diameter will naturally appear to be 

 approximately two times as great as that of the dry particle. 



