CHAPTER V 



FINER STRUCTURE OF VIRUS PARTICLES 

 AND ITS SIGNIFICANCE 



1. Decomposition and Fusion of Elementary Bodies 

 of Protoplasm 



As mentioned in the previous Chapter, some plant viruses tend to 

 reveal themselves in rod-shaped particles or sometimes in extremely 

 small globular particles which can be regarded as the fragments of 

 the rod. An important characteristic of these particles is that they 

 contain no lipids, unlike many other viruses which exist in spherical 

 bodies having never yet been obtained in crystalline forms. 



According to our experiments, phage particles or phage-like parti- 

 cles isolated from normal bacteria contain a considerable amount of 

 lipids, and their average diameter appears to be approximately 0.1 (x 

 (24) (9). In this connection, it should be noted that from many plant 

 materials particles similar in size and composition to these bacterial 

 particles were obtained. The writer was convinced that such parti- 

 cles are the coagulated elementary body of protoplasm itself. It can 

 easily be calculated that a single rod of tobacco-mosaic virus having 

 the size of 15x280 m/< cannot make such a particle even if it contains 

 som.e lipids, unless about a dozen of the rods are put together. On 

 the other hand, since, according to our estimation, the dry weight of 

 a single phage particle is of the order of lXlO""g, the number of 

 protein molecules in a single particle is estimated to be of the order 

 of 3x10^, and "molecular weight" of a particle of this size is calcu- 

 lated to be about 480,000,000, a value w^hich also indicates that about 

 a dozen of tobacco-mosaic virus particles whose molecular w^eight is 

 40,000,000 can only form a single particle of the phage. 



For such a reason the writer has formed the opinion that the 

 elementary body of protoplasm of certain cells tend to decompose into 

 about a dozen of elementary bundles ; rod-shaped viruses as above 

 mentioned are considered to be such bundles from which lipids have 

 been eliminated. 



Thus, several hundreds of extended protoplasm protein molecules 

 may associate in parallel alignment to make a bundle, /. e., an elemen- 

 tary bundle, and a dozen of the bundles, in turn, in parallel associa- 

 tion form a unit particle, /. e., an elementary body. The establishment 



