116 Early Work in North America 



fungi cause disease in plants to a belief that not only fungi, but 

 also bacteria, are "vegetable parasites" which cause diseases of 

 agricultural crops. Burrill's inoculum appears to have been the 

 "sticky, half-fluid substance" exuded from blighted branches of 

 pear and apple trees. In 1881 he reported that sixty-three per 

 centum of inoculated twigs became diseased in contrast to less 

 than two per centum when similarly punctured "with sterile 

 knife and solution." ^* The point of even greater importance than 

 his technique, whether with or without the use of pure cultures, 

 was that he had established that a bacterium, and not fungi in any 

 way, was the cause of pear blight. 



Burrill, in ascertaining the cause of pear blight, had performed 

 a great service to his state and his nation. After his work, intelli- 

 gent restrictive efforts toward its control became possible. The 

 states immediately south of the Great Lakes were not the only 

 valuable fruit-growing areas to become affected. Later in Cali- 

 fornia economic losses from the malady were figured over a period 

 of years as in the millions of dollars.^' Smith believed'''*^ that 

 Burrill had proved 



four things conclusively; 1) The absence of any fungus in the blighting 

 pear twigs; 2) The constant presence of a motile bacillus in enormous 

 numbers in the freshly blighted twigs, which bacillus, moreover, could 

 always be found pushing into the sound tissues some centimeters in 

 advance of the visible browning and death; 3) The infectious nature of 

 the freshly blighted material; 4) The identity of the blight on pear, 

 apple and quince. 



Arthur in 1886, after his studies of pear blight were practically 

 completed, mapped the disease's distribution for Scribner's report 

 of the mycological section. Smith believed that not only was 

 Arthur's technique better than Burrill's but also that Burrill's stu- 

 dent, M. B. Waite, finally isolated and worked out the cultural 

 characters of the "right" causal organism.''" Arthur in 1899^^ 

 found Smith's evaluation of his work an " excellent and discrimi- 

 nating statement. ... I have known for some time," he wrote, 



" Charles F. Hottes, op. cit., 7. 



*" E. F. Smith, An introduction to bacterial diseases of plants, 54-55, Phila. and 

 London, W. B. Saunders 1920. 



^^ Centralbl. j. Bakt. II, 5 (23): 812, 1899; idem, 5 (8): 276-277. 

 *' Letter, Smith to L. R. Jones, February 24, 1914. 

 "^ Letter, Arthur to Smith, December 30, 1899. 



