Excretory system properly dissolved, they have the ability to build up, and form these kidney stones. These stones are most commonly made up of substances such as calcium, cystine, oxalate, and uric acid, as these are the substances that normally would dissolve within the urine. When they do not dissolve correctly and further build up, they will commonly lodge themselves in the urinary tract and in this case, are usually small enough to pass through urine. In extreme situations, however, these stones may lodge themselves within the tube that connects the kidney and the bladder, called the ureter. In this case, they
Pig bladder Mob football, Medieval football, and La soule.) For centuries before the invention of the paint tube, artists used to store their paints in pig bladders. When the artist was ready to use the paint, they would puncture a hole in the bladder and squeeze out the desired amount of paint. They would have to mend the hole when finished and the whole process was quite messy. The oil paint tube was invented in 1841, as the primary packaging of paints for transport and storage. In the bian lian ("face changing") style of Chinese opera, painted pig bladders were used as