CHAPTER VI 



DEVELOPMENT FROM VIRUSES 

 TO ORGANISMS 



1 . Rickettsiae 



Lymphogranuloma-psittacosis group of viruses is believed to be 

 largest-sized, whilst there are much more differentiated, advanced 

 viruses or virus-like agents, which are commonly called Rickettsiae. 

 The Rickettsiae seem to occupy a place intermediate between the smal- 

 lest cultivable bacteria and the largest viruses. The diseases caused 

 by these agents are transmitted by arthropods, usually louse and ticks. 

 They resemble usual viruses since they will multiply only in living 

 cells, but differ from the former in that they fail, as a rule, to pass 

 through bacterial filters and that their particles are distinctly seen 

 under the ordinary microscope when stained properly. 



This property of easily staining with proper dyes is note-worthy, 

 because it may indicate the development of structure much different 

 from that of the protoplasm of the host cell. With the usual viruses 

 no staining technic have ever been found to make the virus particle 

 distinct from the protoplasm, showing that the virus is alike in struc- 

 ture to the protoplasm. Moreover, specific therapy by chemical 

 substances has usually been failed with virus diseases, whilst it proves 

 effective in Rickettsiae, indicating also the development of peculiar 

 structure in them. It is, however, known that specific chemotherapy 

 is likewise effective to some extent in viruses of psittacosis-lympho- 

 granuloma group, and that some viruses of this group sometimes stain 

 like Rickettsiae. These facts show the presence also in these viruses 

 of highly developed structures resembling to those of Rickettsiae. 



The fact that these highly developed viruses as well as Rickettsiae 

 are usually associated with rather uniform and large sized particles, 

 suggests that the protoplasm, when changed in its structure by these 

 agents, will decompose into large particles. Since the property to 

 form large particles should be determined by the structural pattern 

 peculiar to these viruses and Rickettsiae, and since this pattern is to 

 be transmitted to the protoplasm they affect, newly formed particles 

 will be always endowed with large sizes. The inheritance of the 

 shape may be thus established. 



