4 PROFESSOR VON MOHL ' 



improbable that the vines ai"e suffering from a general disease, 

 in consequence of which the local morbid phenomena and the 

 fungus make their appearance. 



Far less are the vines affected by a local malady ; for, as is 

 pi'oved by the phenomena which I am about to relate, the fungus 

 does not appear on parts of the plant already impaired by disease, 

 but on the contrary on perfectly sound organs, and the disease of 

 the tissues begins precisely at those spots to which the fungus 

 adheres by especial organs of attachment. Here then the con- 

 nection is so clear between cause and effect, between the agency 

 of the fungus and the disease of the plant, that the opposite 

 view, which is not confirmed by a single positive fact, appears to 

 me to be flatly contradicted." 



The only circumstance which can be adduced in favour of the 

 predisposition of particular vines for disease, a^d one which has 

 been much noticed in Italy, is that certain varieties of vine are 

 more subject to be attacked than others, those for instance the 

 skin of whose grapes is soft and the pulp juicy, while those with 

 a firmer skin and harder flesh are spared. This, however, may 

 be put aside as regards a peculiar susceptibility in the varieties 

 just mentioned, inasmuch as the harder grapes, in consequence 

 of the toughness of their tissues, present a greater resistance to 

 the attacks of the fungus. 



Independently, however, of the question whether the grape- 

 disease is the consequence of a general indisposition of the vines, 

 one of great importance arises, viz. : whether in consequence of 

 the mildew the general health of the vines is impaired. This, 

 as said above, was not in the remotest degree the case in Italy, 

 but it appears from the Journals of last year, that in many more 

 Southern districts, as in Madeira, the vines perished. It is con- 

 ceivable indeed that the attack of the fungus may produce such 



* This notion, that the vines are diseased only in consequence of the 

 attack of the fnngus, is most expressly defended in the report of the com- 

 mission appointed by the Venetian Institute, whose i-eporters were Prof. 

 Visiani and Dr. Zanardini (Rapporto della commissione norainata d.all' 

 I. R. Istituto Veneto di scienze, lettere ed arti per lo studio della malattia 

 deir uva ; in den Atti dell' I. R. Istituto Veneto, &c. Tom. IV. Serie II.) 

 It was of immense practical importance to give currency to this view, since 

 the proprietors fancied that they had a remedy against the disease, in 

 cutting the vines down to the ground, and the consequent renovation of 

 the shoots, a process, however, which entailed a certain loss for some years. 

 The Venetian Institute therefore received with thanks my letter printed 

 in the Official Gazette of Venice of the 1st of June of the cvirrent year in 

 which I stated the accoi-dance of my views in this respect with those of 

 Dr. Zanardini. 



