On Plant Pahioiogv and I^acthriology 109 



tubers were inoculated witli bacteria.'" " As a rule," he said/' 

 "saprophytic bacteria may, under speciiil conditions, attack, make 

 sick, and destroy livint; plant tissues as facultative parasites." 



Burrill began to publish on pear blight in December 1877, when 

 as chairman of the Illinois State Horticultural Society's com- 

 mittee on Botany and Vegetable Physiology he presented a paper, 

 styled simply, " Pear Blight." '- Even his second paper on this 

 subject preceded Prillieux's first paper, and Burrill's study of 

 the disease, "extending over several years," had anticipated, in 

 fact searched for, an " entirely different kind of parasite " than the 

 fungi, or a " fungous origin of the malady." He did not call the 

 " very minute moving particles " he saw in the blighting tissue and 

 exudate bacteria. He was mindful of fungi which later appeared 

 in some of the blighted stems. In the cambium of blighted 

 branches and in the exudate he observed "very minute moving 

 particles, very similar to those known as Spermatia in fungi and 

 other low plants." But he left to future experiments the clearing 

 up of their origin, relationship, and development. "Are the two 

 in any way connected in origin or growth?," he asked. "Are the 

 later forms products, through germination or otherwise, of their 

 forerunners ? " He had observed the blight in winter and summer; 

 and he recommended the " careful removal and burning of every 

 dead limb or twig as soon as observed, winter or summer." '^ 



By the next year he was more confident of his conclusions. His 

 inoculation experiments yielding definite results, he ascribed the 

 cause of pear blight to bacteria — a conclusion confirmed by all 

 subsequent experimentation. Again in December 1878, he went 

 before the Illinois State Horticultural Society, meeting at Spring- 

 field, and presented a paper on " Fire blight of the pear." ^* 



If wc remove the bark of a newly affected limb and place a little of 

 the mucilaginous fluid from the browned tissues under our microscope, 

 the field is seen to be alive with moving atoms known in a general way 

 as bacteria. Sometimes a thick, brownish fluid oozes from the bark of 

 dying limbs and spreads over the outside or falls in drops. This is appar- 

 ently made up of the living things, myriads of them are to be seen at once. 



^^ The bact. dis. of plants: a critical review, op. cii., 627; also note 69- 

 " Bad. in Rel. to Plant Dis., op. cit., 2:11. 



'-Trans. Illinois St. Hort. Sac. for 1877, 114-116, Chicago, 1878. 

 '^ Based on a memorandum prepared by Smith, perhaps for Bacteria in Relation 

 to Plant Diseases IV which was never completed. 



''^ Trans. III. St. Hort. Soc. for 1878: 79-80, Chicago, 1879. 



