"The culture," says a correspondent at Varna, "which is used for the preparation of yogourt, is known as 'Maya' or as 'Bulgarian Maya.' The milk which is to be converted into yogourt must first be freed from all bacteria by boiling and allowed to cool to the temperature of 45° C.; it is then inoculated with maya and maintained at an even temperature of 45° C. during several hours. There are two kinds of maya, or ferment, one known as sour, and the other as sweet maya. "In Europe small stoves, made expressly for the purpose, are used to maintain the milk at the proper temperature. In this country, however, after the milk has been boiled, it is merely poured into a bowl and allowed to cool to approximately 45° C., then a tablespoonful of this tepid milk is well mixed (in a small bowl apart) with a similar quantity of maya, and the mixture, when it has become quite homogeneous, is added to the bowl of tepid milk and stirred slightly. (One tablespoonful of maya is sufficient to ferment one litre of milk.) A cover is then placed on the bowl and the whole is enveloped in flannel and left in a warm place for three hours in summer, and somewhat longer in winter. "The process of preparation is complete when the mixture assumes the appearance of a soft mass somewhat resembling cream cheese, but less solid. The flannel is then removed, the bowl uncovered and placed in a cool spot until needed for consumption. Of the yogourt thus prepared, a tablespoonful is kept to serve as maya for the following day. "The best yogourt is prepared from sheep's milk, the second quality from buffaloes' milk, and the third quality from cows' milk. Yogourt forms an almost daily article of diet with the natives in this country."[12] With regard to the time stated for the fermenting process, it must be noted that since the subject has been investigated so thoroughly, the time required for fermentation has been found to be nearer ten than three hours, but this will be dealt with in a subsequent chapter.