[Vol. It 



4 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



done at an early date, and at a time when foreign bacteriologists 

 of high standing opposed the idea that bacteria could be the 

 primary cause of disease in plants, the contribution is all the 

 more significant. 



Wehmer ('98) published extensively the results of his inves- 

 tigations of potato diseases. In Part 3 he describes a bacterial 

 rot of the tuber, but he definitely takes the attitude that the 

 bacteria found associated with the rot were not the primary etio- 

 logical agents. His attitude may be taken as representative of 



the belief of most German botanists and bacteriologists of that 

 time. 



There occurred in the vicinity of St. Petersburg, Russia, in 

 1898, a potato bacteriosis which was described by Iwanoff ('99). 

 The causal organism was described as a short, oval-cylindrical, 

 active rod found (in the tissues) to measure 1.5m X O.o\i. The 

 disease was one which affected the leaves and stems, early symp- 

 toms being manifest in the leaves. Later, the stems were af- 

 fected and showed symptoms of the disease. Brown lesions ap- 

 peared externally on the stems, the pith was attacked and de- 

 stroyed, and the stems wilted and died. Starch was not de- 

 stroyed. Iwanoff contended that the disease he described was 

 similar to that described by Smith ('96) as due to B. solanacea- 

 rum. It appears to the writer that he was mistaken in the view 

 presented, and from our limited knowledge of the situation it 

 seems more likely that the potato disease prevalent in Russia 

 near St. Petersburg in 1898 was the blackleg disease. 



Jensen ('00) investigated a bacterial disease of the potato 

 which he referred to as "blackleg". As a result of microscopic 

 investigations of potato plants affected with "blackleg" he con- 

 cluded that the disease was caused by bacteria ("Mikrokokken"). 



What Smith ('14) refers to as "The French Disease" was 

 first described by Delacroix ('01) in a succession of short papers 

 appearing in 1901. Delacroix first stated that the potato mal- 

 ady due to B. solanacearum E. F. Smith was prevalent in France. 

 Later, he concluded that the disease referred to above, the one 

 for which he suggested the name "brunissure," was caused by 

 a bacterium new to science which he named Bacillus solanicola. 

 Smith ('14), however, claimed that, "Here again, it is uncertain 

 whether we have to do with Bacillus phytophthorus, Bacterium 

 solanacearum, or some third organism. The writer obtained a 



