16 CEOWN-GALL OF PLANTS. 



planted various species of vines, some of which were American, others Asiatic, along 

 with two varieties of Vitis vinifera. There were six shoots which, by means of 

 T-shaped incisions made after the necessary sterilization, were inoculated either 

 in the lower intemodes of shoots of the year or in upper intemodes, while as many 

 were simply incised without inoculation of the virus, for reasons of control. All were 

 then wound with taffeta and with paper and tied with thread at the point of incision. 

 " This inoculation experiment was made in July, therefore in a stage too advanced 

 perhaps to have hope of any success whatsoever. Weeks and months passed away 

 without there being shown in any of the vines any traces whatsoever of localized 

 and diffused hypertrophy. So I lost all hope and ceased to visit them any more. 



Toward the end of the winter the head gardener of the Botanic Garden, Signor 

 Giacomo Traverso, in pruning the vines of the above-mentioned garden plat, was 

 surprised by certain nodules which one of the European vines showed, and as he had 

 assisted me in the experiment, came to inform me in the laboratory with a specimen 

 which he had cut off, and which bore just two of the characteristic tubercles in corre- 

 spondence to the node and with the periderm raised up in bridles in a manner exactly 

 identical with that which had been observed on the vine shoots collected at Udine. 



Of the two varieties of European grape, one was inoculated in four of its branches, 

 the other left with simple incisions for control. All of the four inoculated branches 

 gave tubercles, not of large dimensions, it is true (1 to 1.5 cm. in diameter); but, I 

 repeat, of the same form and structure of those of the vine from Udine. The foreign 

 vines were not attacked. 



The microscopic examination of the shoots bearing the tubercles likewise revealed 

 bacteria scattered in the vessels and in the tissues of the bark of the small tubercles, 

 and I was able to establish that they do not form distinct foci as in the case of the olive 

 and the Aleppo pine, but are found scattered here and there in the various tissues. 



In order better to ascertain that bacteria of the rogna were really in question I made 

 some cultures with material of the same origin, infected in the Botanic Garden, and 

 obtained both on plates and in test-tube cultures the same mother-of-pearl color 

 colonies, and the same bacteria which had served for the inoculation experiment.^ 



In 1890, Cavara published a second paper on the subject, but this 

 is rather of a popular nature and adds nothing to the preceding paper, 

 except notes on the occurrence of the disease in Sardinia, and a very 

 good lithographic plate in colors, showing vine shoots bearing the 

 tubercles, which are like those occurring in the United States. 



Although Cavara's account is meager, there is little doubt in the 

 light of our own experiments that he had the right organism and 

 reproduced the disease with it as he says he did. 



In the same paper (Staz. Sper. Ital., 1897, vol. 80, p. 504) Cavara 

 describes a tuberculosis of the peach occurring frequently on young 

 shoots in a garden at Pavia, and attributes this also to bacteria, 

 which he states he cultivated out. He made no inoculations in this 

 case and his account of the disease renders it uncertain whether he 

 had to do with pathological formations identical with those occurring 

 on the peach in this country and studied by us. Our peach disease 

 occurs more commonly on crown and roots than on branches, but 

 this may be only a matter of environment. Doctor Farneti, who 



a Had Dr. Cavara obtained additional infections with these isolated bacteria he would have completed 

 his proof. 



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