The Rhine and "Mosel wines, which usually are called Hock, are of a light amber tint varying in depth, of a moderate alcoholic content, from 8 to 11 percent, and carry a delightful aroma which is quite characteristic of this class of wines. Some of them are of rather high acidity, but others are less marked in this characteristic. The methods of harvest and manufacture of the wine are much the same as the general methods already described. Each vineyard, however, claims some peculiar manipulation which is considered to be particularly related to the character of the wine produced. There is one peculiarity of the great vineyards, however, which cannot be denied, namely, the particular character of the yeast which conditions the fermentation. There is no doubt of the fact that the yeasts which are native to these vineyards, and which have been perpetuated for hundreds of years, have acquired a distinct biological character which is of high value in determining the character of the wine. It is not so much the chemical constituents of the grapes as it is the environment or nature of the fermentation to which the peculiar character of the wine is due. In other words, if the grapes which grow in one of these grape vineyards were carried to an ordinary vineyard and subjected to the conditions of fermentation which there obtain, the character of the wine produced would be far inferior to that which is the result of the conditions which obtain in the vineyard itself. This fact is applicable to all the great vineyards that make wines which are famous in history and commerce.