266 PROFESSOR MOHL ON 



liad advanced far towards maturity, cracked iu multitudes. The 

 diminished growth of the flesh had no influence on that of the 

 seeds, for they were found in berries which had acquired only half 

 their normal size, as completely formed as in well-grown fruit. 



The effect of the diseased cuticle on the berry is not, however, 

 confined merely to this mechanical disturbance, by means of 

 which the parenchym is retarded in its growth, but the 

 maturation of the fruit is in a high degree impeded by the 

 diminished development of the parenchym, although not entirely 

 prevented. Such berries as are greatly hindered in their growth, 

 and attain only the size of coarse shot, simply dry up ; while 

 those on the contrary, as is more generally the case, which attain 

 about the half of their normal diameter, become at length, 

 though late, rather soft but very imperfectly ripe, with a faint 

 reddish tint, and sweetish taste, yet in so low a degree, that a 

 useful wine cannot be prepared from them. 



The splitting of the berries, likewise, does not absolutely 

 prevent maturation, only the fissured grapes are equally unfit for 

 wine-making. If the weather is dry for any length of time the 

 portion of the parenchym exposed to the air becomes perfectly 

 dry, whether it be altogether unripe, or whether the process of matu- 

 ration has already commenced ; in damp weather the parenchym 

 where it is exposed begins to decay from the attack of several kinds 

 of mould. The Oidium Tuckeri is, however, perfectly guiltless as 

 regards this decay, for it never attacks the exposed parenchym, 

 and inasmuch as this corruption does notdepend upon the particular 

 disease, but on the accidental irrigation of the parenchym with 

 rain-water, the name of Grape-rot (Traubenfaule) so often given 

 to the Vine-mildew is not correct. 



The phases of the Vine-mildew may be stated as follows : — 



1. The Vine shoots vigorous!}' in spring, and in no one^espect 

 betrays any appearance from which disease can be anticipated. 



2. The parasitic fungus is produced upon the perfectly sound 

 cuticle. 



3. A discoloration of the cuticle and its ultimate destruction 

 take place in those spots to which the parasite is fixed by its 

 suckers. 



4. The degeneration of the tissue on the bark of the bouglis 

 and' on the berries affects only the cuticle and the cells 

 immediately beneath it, while the more deeply seated tissue 

 undergoes no visible alteration, and in the leaves even the 

 destruction of the cuticle does not take place. 



