PllOFESSOll VON WOHL 



less extent. lu this manner there arise upon the berries little 

 knots wliich are perfectly visible to the naked ej^e, and on the 

 branches the large brown spots described above. 



There can be no doubt, that we have in these processes the 

 points from whence the parasitic fungus exercises its baneful 

 influence on the vine, as it is in contact with them that the 

 cuticle becomes diseased, inducing tlie destruction of the outer 

 layers of bark, and in the berries preventing the further growth 

 of the skin, and in consequence of the continued undisturbed 

 growth of the pulp, the rupture of the fruit. At the same time 

 the most certain proof that the disease of the vines does really 

 proceed from the fungus is afforded by these relations, and more 

 especially in the above-described series of phenomena. 



I have already stated above that the leaves are not eligible for 

 this purpose. The processes and brown spots are not produced 

 on the firm cuticle of tlie upper surface of the leaves, nor have I 

 found them in the interstices of the veins of the under side, but 

 only upon the cuticle of the veins themselves, where, however, 

 their examination is very difl&cult, in consequence of the thickset 

 hairs with which the veins are clothed. Connected possibly with 

 this protection against the attacks of the fungus, which the 

 parenchym of the leaves enjoys, is the fact, that the grow'th of the 

 leaves, even when thickly coated with fungus, is not impaired ; the 

 parenchym of the leaf does not become brown like the outer strata 

 of bark, and the nourishment of the plant, at least according to 

 the investigations recorded above, seems to remain normal. 



The first discoverer of these processes was Dr. Zanardini, at 

 Venice, who on the 19th of July, 1851, made a communication 

 respecting them to the Venetian Institute, and gave them the 

 name oi fulcra. I cannot, however, agree in many respects with 

 the description which is given of them with reference to the obsei*- 

 vations of Prof. Visiani, in the above-mentioned report of the 

 Venetian commission. Visiani believes that he has discovered 

 that they penetrate into the epidermal tissue after the fashion of 

 roots. This I have never been able to establish, but I find, on the 

 contrary, the cuticle perfectly entire (as Amici asserts, who, how- 

 ever, appears not to have recognised these organs), and the pro- 

 cesses themselves attached only superficially and in many cases 

 even separable together with the threads of the Mycelium (Figs. 4. 

 b b) without injury. In a second point again I cannot contirm the 

 observations of Visiani. He asserts, that at the place where the 

 processes spring from the underside of the threads, from two to 



