44 ORGANS OF SECRETION. 



the product of two different species was mixed in order to pro- 

 duce the finest color, as Pliny gives the proportion of 200 pounds 

 of juice of " Buccinum," and 111 pounds of that of "Pelagia" as 

 suitable for obtaining a beautiful amethyst color, sufficient for 50 

 pounds of wool. The extent of the Tyrian ind\istry is visible in 

 numerous holes in the rocks, two to three feet deep, containing 

 the breccia of shells anciently crushed in them for the extraction 

 of the dye. The arms of the cit}^ as preserved on its medals was 

 the purpura shell, and in the time of Strabo the multiplicity of 

 dye-works unpleasantly aft'ected the air of the vicinity. The 

 Romans used various species in great quantity for dyeing pur- 

 poses, and the remains of Murices form vast heaps; indeed, in 

 one case, at Tarento, the mass is so large as to have received the 

 name of " Monte Testaceo." 



The color was prepared by ])Ouuding up small specimens, or 

 by breaking the shells of larger ones and extracting the purple 

 gland. This fluid was mtxed with five or six times its weight of 

 water, with twenty ounces of soda to every hundred pounds. 

 Placed in lead or tin vessels the mixture was exposed to the sun 

 for several days, until the hue desired was obtained, when the 

 wool was simply plunged into it and allowed to remain for a few 

 hours. Under Augustus the dyed wool brought as much as $200 

 per pound. 



The Indians of the new world also understood the art of purple 

 dyeing from shell-fish, and it is proliable that all ancient peoples 

 inhabiting seashores have become accidentally acquainted with 

 this property, common to so many mollusks, at a very earl}^ 

 date. The Roman law prohibiting the use of purple garments to 

 any but the imperial family, was a deathblow to this industry, 

 which thenceforth rapidly declined. During the middle ages the 

 very existence of such a dye was considered fabulous ; but 

 with the revival of the arts and civilization its properties were 

 rediscovered, and for awhile successfully utilized. Chemistry 

 has now supplied us with even more brilliant colors, whilst 

 saving much of the cost of procuring material. 



The anal gland accompanies the })urple gland in Murex and 

 Purpura and has not been discovered in other mollusks. It lies 

 on the left side of the rectum and consists of a central canal 

 witli lateral branches having a dendritic appearance. It opens 



