The wine cellars of Jerez are known as bodegas, but they are not always cellars. In Jerez the bodegas are usually a building of one story covered with tiles and supported on brick walls. The bodegas are kept scrupulously clean, and everything is whitewashed periodically except the casks. The floor is kept covered with clean sand. There is always a very large storage space between the casks and the roof, affording an abundant supply of air. One thing, however, in a sherry cellar is never cleaned and that is the casks themselves, for these retain the organisms which are continued from cask to cask so that the character of the wine remains constantly the same. The casks are usually never completely emptied, but refilled with new vintages and thus a continuity of character is maintained throughout many years. Especially is the dust which forms on the outside of the cask respected as a matter to be venerated, just as old wine bottles are valued largely by the amount of grime and dirt that they carry.

Although great care is taken, as already described, to preserve the dust on the outside and the germs in the interior of the cask, yet it is perfectly certain that great changes have taken place in the character of sherry wines since the Shakespearean times. In fact, changes modifying considerably the character of the wine have been made within the last 100 years.