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CHAPTER 45 



FIGURE 45-2. Marcus M. Rhoades {in 1959) examines striped corn plants in the 

 foreground. Unstriped corn plants are in the background. 



symbiotic microorganism can become so well- 

 adapted to its host that it becomes a part of 

 the host's genetic system and determines 

 some of the traits of the host. Like kappa, 

 the rickettsial organism that causes Rocky 

 Mountain spotted fever is visible and in- 

 herited through the cytoplasm. These organ- 

 isms, as well as the virus and spirochaete we 



have already discussed in this Chapter, also 

 determine certain traits of their hosts. Where- 

 as each of the cases so far mentioned involves 

 an organism which seems to be foreign to its 

 host at present, we cannot be sure that the 

 organism originated as a parasite or sym- 

 biont. Could some of the now-foreign 

 organisms located intracellularly originally 



