APPENDIX. 305 



a 



APPENDIX TO CHAPTER III. (p. 131). 



PLANT-DISEASES CAUSED BY BACTERIA. 



The presence of parasitic bacteria has been recently 

 pointed out as the cause of diseases in plants. In 1880, 

 Burril, of Illinois, U.S., has declared the shrivelling of 

 pears to be due to a bacterium which attacks fruit-trees, 

 and of which he succeeded in making an artificial culture. 

 In 1882, the jaundice of hyacinth bulbs was ascribed by 

 Wakker, of Amsterdam, to the development of a bacterium 

 between the layers, which may finally destroy the plant. 

 In August, 1885, Luiz de Andrade Corvo presented a 

 paper to the Academy of Sciences, in which he asserted 

 that the vine- disease ascribed to Phylloxera vastatrix is 

 really due to a bacillus, or rather, according to his de- 

 scription, to a bacterium, which is always found in the 

 tubercles of the radicles and in the tissues of the vine 

 which are affected by this disease, termed by him tuber- 

 culosis. They are also found in the body of the insect, 

 Which thus becomes simply the agent of contagion. 



Neither Wakker in 1882, nor Burril in 1880, was the 

 first to point out the presence of microbes in the diseased 

 tissues of plants. As early as the year 1869, Bechamp 

 noticed the presence of microzyma, that is, bacteria, in the 

 affected parts of plants (Comptes rendus de VAcademie des 

 Sciences, vol. Ixviii. p. 4GG). 



