186 MICRO-ORGANISMS AND FERMENTATION. 



in which the formation of apothecia takes place. The spores 

 germinate when they are set free, and the germ tubes grow 

 into condiophores. 



In rainy seasons, when Botrytis attacks the grapes at a, 

 time when they are unripe, the mycelium, penetrating through 

 the pulp, destroys the small amount of sugar in the grapes, 

 and, as it kills the cells, a fresh immigration of sugar from the 

 leaves is checked or rendered impossible. Such grapes act 

 injuriously upon the quality of the wine. As the mycelium 

 penetrates into the stalks also, causing them to die off, the 

 very young grapes on such a cluster do not generally develop, 

 but wither away. In years of good vintage the fungus does 

 not usually appear until just before the grapes are gathered, 

 and then gives rise to a different set of conditions. According 

 to Miiller-Thurgau's investigations the mycelium spreads 

 principally through the skin of the grape, which becomes 

 brown, leathery, and permeable to moisture. Thus in dry 

 weather part of the water evaporates, the juice becomes more 

 concentrated, and the grapes wither. The fungus does not 

 penetrate far into the interior of the grape, but its growth 

 affects both the acid and the saccharine constituents of the 

 juice, and the must obtained from such grapes appears rela- 

 tively richer in sugar and poorer in acids than is usual. Under 

 favourable climatic conditions, especially in a dry atmosphere, 

 white grapes which have been attacked by this " Edelfaule " 

 can thus produce a must weak in acid, and hence yields a 

 wine of finer quality and of special bouquet, due to some 

 extent to the action of the fungus. This is particularly the 

 case with varieties of vine which yield hard grapes with a 

 high sugar and acid content e.g., the Riesling vine. A 

 certain element of danger may, however, lurk in these attacks 

 on the grapes, partly because Botrytis absorbs part of their 

 albuminoids, rendering the must less nutritious for the yeast, 

 so that the latter develops more slowly, and partly, as de 

 Bary and, later, Behrens and Miiller-Thurgau have shown, 

 because the fungus secretes a poison which prevents the 

 development of the yeast. Wines of this description, there- 

 fore, mature slowly, and are exposed to the attacks of foreign 

 organisms. The fungus is invariably harmful to red and 



