236 DISEASE OF THE VINE. 



lied to 1800 diameters. The first utricle is in the ordinary state, 

 attached to the apex of the ascending filament, with a portion of 

 the corresponding mycelium. Two other utricles are in the pro- 

 cess of germination, and vegetate, and reproduce the plant after 

 the manner of grafts or cuttings. The appendage which they 

 emit from one extremity of the axis (which is always excentrical) 

 resemhles the pollen tuhe issuing from its grain. It is very 

 easy to ohtain this result. It suffices to moisten a bit of glass 

 with the breath, to cause a number of fresh utricles to attach 

 themselves to it, disarticulating from the filaments. After about 

 three hours nearly the whole of them will vegetate, and the germs 

 will grow under the eye of the observer, till after one or two days, 

 the nutriment supplied to them by the internal substance of the 

 utricle being exhausted, they will die and dry up. A fourth 

 utricle in the above-mentioned preparation No. 4 shows the 

 manner in which these organs usually shrivel and dry up. On 

 losing by evaporation or any other cause the fluid by which the 

 membi-ane was distended, it compresses on three sides. The 

 extremities, being of a more compact substance, do not give way 

 so much, and hence three longitudinal ribs or angles are formed, 

 and the central one, by an optical illusion occasioned by the 

 manner in which the light is refracted, may easily be mistaken 

 for an aperture, whilst it is in fact nothing more than a plait or 

 fold. The fifth utricle in the preparation is a representation of 

 an artificial section in order to show the very variable globules, 

 and the mucilaginous liquor which the membrane contains. * 



From the above data it clearly results that the cryptogam pre- 

 vailing on our grapes, which is identical in all the specimens I 

 have been able to procure within a radius of twenty miles round 

 Florence, is a very different plant from the Erysiphe communis, 

 which no one has observed to appear upon the Grape berry, f 



* Fig. 4, magnified 1000 diameters, shows at x three utricles in germina- 

 tion. At y are two fresh utricles showing the little globules, and the mu- 

 cilaginous liquid contained in them. At z is an utricle shrivelled up by 

 lateral compression, which has given rise to the optical illusion of a longi- 

 tudinal slit. 



t The Chevalier Rendu, Inspector-General of Agriculture in France, has 

 had the kindness to transmit to me diseased Grapes from the neighbour- 

 hood of Bastia and of Marseilles, in which I have recognised the same 

 cryptogam as that which attacks our own Vines. So also Sig. Ferrari, 

 Secretary of the Agrarian Society of Bologna, has sent me Grapes from 

 eight different localities of that pontifical province, on which was the same 

 plant in fructification. From these more recent observations I am led to 

 conclude that the cryptogam which lias spread over the Vine in various 

 countries forms everywhere but one species. 



