V. FINER STRUCTURE OF VIRUS PARTICLES AND ITS SIGNIFICANCE 75 



have the diameter of approximately 0.1 ix; normal bacterial particles 

 are also of this size. 



Particles obtained from various normal and infected plant material 

 appears in the main to be of the same order of size, although their 

 sizes seem far more inhomogeneous than those of phage, whilst animal 

 particles are generally larger and their diameters appear mostly of the 

 order of 0.2 ix. Vaccinia virus recoverable from skin tissues is found 

 to be the largest, its diameter being estimated to be about 0.3 ix (7). 



From these facts the writer has formed the opinion that the size 

 of the coagulated elementary body, corresponding to the plant-virus 

 rods having the length of 0.3 /«, may be about 0.1 ix, in diameter. The 

 diameter of various phage particles in electron micrographs haye been 

 reported by a number of workers to be little less than 0.1 ii. This 

 may be the size of a single elementary body fully coagulated in the 

 dry state. Thus, an elementary body may be considered to undergo a 

 considerable shrinkage, thereby being reduced in length to about one 

 third to become a body with a diameter of the order of 0.1^, although 

 in the expanded state it is about 0.3 ;« in length. 



If the property of elementary bodies varied according to the kind 

 of cells, some tending to combine end-to-end with every two bodies 

 while the others with every three bodies, and if side-by-side combina- 

 tion corresponding to the end-to-end combination occurred on their 

 coagulation into cuboidal bodies, then the diameters of the coagulated 

 bodies would be about 0.2/.! and 0.3 /!, respectively; but when side-by- 

 side combination failed to occur in response to the end-to-end associa 

 tion, various intermediately sized particles would result. 



Molluscum contagiosum virus particles have been found by Rake 

 and Black (64) to be present plentifully in the inclusion bodies ; under 

 the electron microscope they proved to be brick shaped and 389 x272 m// 

 in size, consisting of unit particles of 100x83 m/<. According to the 

 writer's view these unit particles must be the coagulated element- 

 ary bodies. Many other examples can be cited to show that viruses 

 of large particles appear to be composed of smaller units like this 

 virus. 



If such a view is legitimate, particles smaller than 0.1 // must be 

 the decomposition products of the unit particle. When coagulation 

 occurred after the elementary body had been disintegrated into ele- 

 mentary bundles which could in turn undergo further decomposition, 

 various extremely small particles would be yielded. 



As already pointed out, phage particles isolated by our method 

 are not of a uniform size and when the particles are the smaller, 

 they are the more unstable and at the same time the activity is the 

 lesser ; this would only be a natural result if the virus activity arose 



