It has been asserted that this substance was not known in Europe until the time of the discovery of the passage to India round the Cape of Good Hope. But Dr. Bancroft has shown that indigo was brought by merchants from India to Alexandria, and thence to Venice, when that city was the _entrepôt_ of Europe and the East. It doubtless contributed to the excellence which the Italian states first attained in the wool manufacture. The drug was called _endigo_ in Venice, and it is from that city that we have derived its name and use. It was imperfectly known in England under its Spanish name in the sixteenth century, for we find in Hackluyt “Voyages” his instructions to a traveller who was going to Turkey to ascertain “if _anile_, that coloureth blue, be a natural commodity of those parts, and if it be composed of an herbe.” The general introduction of indigo into Europe was impeded by legislative enactments, prompted mainly by those employed in industries which it threatened to displace. These were chiefly the producers of and dealers in _woad_, formerly used exclusively for dyeing blue, and the corporation of woad dyers. When dyers from Italy and Flanders attempted to introduce the superior dyes of indigo, the woad interests were sufficiently powerful to induce the Elector of Saxony to denounce the use of the new dyestuff. It was pronounced in the Diet of the Empire as “a corrosive color,” and “fit food only for the devil,” _fressende teufels_. Similar propositions were made in England and France, in which latter the free use of indigo was not permitted until 1737. Although indigo as known in the arts is a product of vegetable origin, we must not omit to notice that one source of its production is the human body. It was discovered some years since that the blue color sometimes found in diseased urines, and in certain suppurations, is due to indigo. Dr. Schunck, in some papers read before the Royal Society, has shown that it is a frequent constituent of urine secreted by persons in a healthy state, and that, in fact, it is produced generally when persons do not take sufficient exercise; and he has several times succeeded in producing it by taking in his food a rather large excess of sugar. He has found this substance also in the urine of beef cattle. It must also be observed that the chemical actions of indigotine with oxidizing agents, showing indigo to have a very close relation to aniline and carbolic acid, both products derived from coal-tar, have produced in the minds of chemists the conviction that indigotine, like alizarine, the coloring principle of madder, will one day be artificially produced from coal-tar.