The work in the mosaic decoration of St. Mark’s doubtless helped to develop the making of glass in Venice, and the lagunes were rich in marsh-loving plants that would yield alkali and furnish the fine sand requisite for its manufacture. Mention is made in one of the documents in the archives of Venice, dated 1090, of one Petrus Flavianus, who was a “phiolarius,” or glass maker, and the trade regulations of the glass makers’ societies or corporations are preserved at Venice and Murano, which show that in the thirteenth century they had become important bodies. Glass furnaces were becoming so numerous in Venice that the Great Council decreed, in 1291, they should be demolished, but permitted them to be set up outside the city, in the suburban districts. In the following year, however, the decrees were altered to the effect that the small glass workers might remain in the Rialto (the city proper), provided fifteen paces were left between each atelier. These decrees were made to guard against a possible spread of fire. It is supposed that this had the effect of moving many of the principal glass works to Murano, a district of Venice which had become renowned for the production of Venetian glass, and where to-day the eminent firm of Salviati & Co. have their extensive works. The glass house at Murano, which was known as the “Sign of the Angel” in the early half of the fifteenth century, was the most renowned of the ateliers of that century. Angelo Beroviero was one of its earliest directors, who was succeeded by his son Marino in that position. The latter was a head or master of the Company of “Phioleri” (Glass Makers’ Corporation) in 1468, which was a very strong society at that time and enjoyed exceptional privileges from the city council. The intercourse of Venice with the East furnished the Venetian glass makers with patterns of Damascus and Egyptian glass, and the enamelled and gilded Oriental varieties were imitated and improved on by the Murano artists. Some of the products of this period are preserved in the museums. The illustration (Fig. 300) is from a Venetian enamelled cup of green glass in the Kensington Museum. In the sixteenth century the glass-making furnaces of Murano had increased to a great extent, and were placed under the special protection of the Council of Ten. Owing to the jealousy at this time of other European States, Venetian glass-blowers were bribed by offers of money and large salaries to set up furnaces abroad, and laws were then made forbidding workmen to leave the country to carry on glass making in other places under the penalty of death. This, however, did not prevent Venetian glass-blowers from taking service under the protection of foreign rulers in such countries as Flanders, Spain, and England.