VI. DEVELOPMENT FROM VIRUSES TO ORGANISMS 171 



the usual protoplosm, in order to multiply in blood the Rickettsiae 

 may require a quite strong assimilase activity not present in viruses. 

 As vv^ill be fully explained later, such a strong assimilase activity, in 

 the main, is apparently based upon its large particle size. 



In addition to Rickettsiae, there are many other small bacteria-like 

 bodies or organisms, found in higher animals on which they are 

 parasitic. They are, like viruses, usually unable to multiply without 

 cells of higher animals. The organism responsible for pleuropneu- 

 monia of cattle may be cited as one of the specimens. This was once 

 regarded as a kind of viruses, as it could pass coarse bacterial filters, 

 but this undoubtedly cannot be a virus, for it can sometimes grow in 

 nutrient media containing blood in the absence of living cells. It 

 stains with proper bacterial stains and is microscopically visible. 



The organism of contagious agalactia is also filtrable, and likewise 

 once thought to be a virus, but at present known to be an organism 

 akin to the above one, and can be also cultivated in the absence of 

 living cells. Furthermore, various bodies have been described by dif- 

 ferent workers in close association with the red blood cells of man 

 and animals suffering usually from certain types of anaemia. These 

 bodies are believed to be definite organisms and called Bartonella. 

 Non-pathogenic bodies similar to Bartonella are also found and named 

 Grahamella. 



It seems that these bodies or organisms occupy a position between 

 the Rickettsiae and the ordinary bacteria. Generally they can multiply 

 only in living cells as do viruses, but sometimes some of them can 

 manage to utilize blood proteins to produce their replicas. 



These organisms are distinct in the property to form specifically 

 shaped bodies, so that it may be possible to distinguish them by their 

 shapes in contrast to ordinary viruses. Primitive viruses may be able 

 to exhibit their action only when the protein molecules are polymerized 

 to a certain degree without being greatly concerned with their sizes 

 and shapes. However, in highly differentiated viruses, such as those 

 of lymphogranuloma inguinale and psittacosis, the property to form 

 peculiar bodies is manifestly forthcoming, presumably as a result of 

 the development of the structural pattern which may cause several 

 elementary bodies to associate regularly into a larger body. A regu- 

 larly associated product of the same molecules is a crystal, and its 

 shape is determined by the structure of the component molecule. 

 Since the assimilase is a liquid crystal of proteins, its shape should 

 be likewise determined by the structural pattern of the proteins, again 

 since such a structural pattern is to be transmitted successively to 

 daughter assimilases, the shape should be inherited. Thus, when some 

 protoplasm proteins, the structure of which has been changed to be 



