PLANT BACTERIA. VOL. III. 



PLATE 45. 



Loss of Virulence in Bacterium solanacearum. 



Livingston's Dwarf Aristocrat tomato after infection with Bad. solanacearum. Each plant was inocu- 

 lated on one petiole by means of delicate needle pricks from a 3-day agar culture. Plants in hot- 

 house subject to 35 C. (July temperatures), and alike. A B, end of 5 days; CD, end of 7 days. 



(1) Florida potato (1914). Organism on culture media about 2 months, and still actively virulent. There were two more 



in this set, both badly wilted. 



(2) Medan III (1913). Organism on culture media about 12 months. It was isolated by Honing in the summer of 



1913 and was extremely virulent when received, and for several months thereafter, but is now weak (see page 179). 

 Only 2 of the 6 plants showed any trace of wilt those in center of figure. 



(3) Creedmore tobacco (1914). Organism on culture media about 5 weeks. In this set were 6 plants, all badly wilted. 



(4) Same as 2. In each of the 6 plants the inoculated petiole was now wilting. 



