B. P. I.-650. 



CROWN-GALL OF PLANTS: ITS CAUSE AND 



REMEDY. 



HISTORY IN BEIEF. 

 EUROPE. 



This disease has been known in Europe on various plants for many 

 years (50 or more in literature) and has been generally ascribed to 

 frosts or to mechanical injuries (Goethe, Viala, Sorauer, Briem, 

 Prillieux, and others) ; but to bacteria by (3orvo ? (Phylloxera of 

 grape) 1885; Cuboni (grape) 1889; Comes (grape) 1892; Cavara 

 (grape) 1897 and 1900, (peach? and juniper?) 1898; Scaha (rose) 

 1903; andBrizi (poplar) 1907. 



Cavara was the first to demonstrate the bacterial nature of the 

 disease (on vines) by means of inoculations from pure cultures. 

 His studies, as well as those of other writers of southern Europe, 

 having been generally overlooked in this country, it appears to be 

 worth while to summarize the leading French and Italian papers 

 somewhat carefully, in so far as they have ascribed this disease to 

 bacteria. 



The labors of Corvo and Cuboni being early, they are not bacterio- 

 logical in any modern meaning of that term. Their views as to the 

 cause of the disease appear to the writers to have been happy guesses 

 based on the resemblance of the tumors of the grape (rogna) to the 

 tubercle of the olive, then much talked about, rather than opinions 

 based on convincing proofs, for the reason that the bacteria seen by 

 them appear to have been common saprophytes lodged in cracks and 

 crevices of the dead parts of the older galls, quite after the manner of 

 the bacterial occupation of the olive tubercle, whereas the actual 

 gall-forming organism in this case, as Cavara first pointed out, occurs 

 in small numbers scattered through sound-looking tissues, and is 

 very difficult to see even when stained. This will be better under- 

 stood after reading the following summary : 



In 1885 Corvo published a note (C. R. des Se. de I'Acad. des Sci., 

 Paris, T. 101, p. 528) in which he maintained that there is no such 

 disease as Phylloxera of the vine, strictly speaking, but only a 

 tuberculosis due to bacteria which are transmitted by the insects, but 



213 



13 



